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id="toc-Individual_systems" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Individual_systems"> <div class="vector-toc-text"> <span class="vector-toc-numb">1.1</span> <span>Individual systems</span> </div> </a> <ul id="toc-Individual_systems-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-District_networks" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#District_networks"> <div class="vector-toc-text"> <span class="vector-toc-numb">1.2</span> <span>District networks</span> </div> </a> <ul id="toc-District_networks-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-History" class="vector-toc-list-item vector-toc-level-1"> <a class="vector-toc-link" href="#History"> <div class="vector-toc-text"> <span class="vector-toc-numb">2</span> <span>History</span> </div> </a> <ul id="toc-History-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Heating" class="vector-toc-list-item vector-toc-level-1"> <a class="vector-toc-link" href="#Heating"> <div class="vector-toc-text"> <span class="vector-toc-numb">3</span> <span>Heating</span> </div> </a> <button aria-controls="toc-Heating-sublist" class="cdx-button cdx-button--weight-quiet cdx-button--icon-only vector-toc-toggle"> <span class="vector-icon mw-ui-icon-wikimedia-expand"></span> <span>Toggle Heating subsection</span> </button> <ul id="toc-Heating-sublist" class="vector-toc-list"> <li id="toc-Generation" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Generation"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.1</span> <span>Generation</span> </div> </a> <ul id="toc-Generation-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Distribution" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Distribution"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.2</span> <span>Distribution</span> </div> </a> <ul id="toc-Distribution-sublist" class="vector-toc-list"> <li id="toc-Water/steam" class="vector-toc-list-item vector-toc-level-3"> <a class="vector-toc-link" href="#Water/steam"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.2.1</span> <span>Water/steam</span> </div> </a> <ul id="toc-Water/steam-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Air" class="vector-toc-list-item vector-toc-level-3"> <a class="vector-toc-link" href="#Air"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.2.2</span> <span>Air</span> </div> </a> <ul id="toc-Air-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-Dangers" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Dangers"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.3</span> <span>Dangers</span> </div> </a> <ul id="toc-Dangers-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-Ventilation" class="vector-toc-list-item vector-toc-level-1"> <a class="vector-toc-link" href="#Ventilation"> <div class="vector-toc-text"> <span class="vector-toc-numb">4</span> <span>Ventilation</span> </div> </a> <button aria-controls="toc-Ventilation-sublist" class="cdx-button cdx-button--weight-quiet cdx-button--icon-only vector-toc-toggle"> <span class="vector-icon mw-ui-icon-wikimedia-expand"></span> <span>Toggle Ventilation subsection</span> </button> <ul id="toc-Ventilation-sublist" class="vector-toc-list"> <li id="toc-Mechanical_or_forced" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Mechanical_or_forced"> <div class="vector-toc-text"> <span class="vector-toc-numb">4.1</span> <span>Mechanical or forced</span> </div> </a> <ul id="toc-Mechanical_or_forced-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Passive" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Passive"> <div class="vector-toc-text"> <span class="vector-toc-numb">4.2</span> <span>Passive</span> </div> </a> <ul id="toc-Passive-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Airborne_diseases" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Airborne_diseases"> <div class="vector-toc-text"> <span class="vector-toc-numb">4.3</span> <span>Airborne diseases</span> </div> </a> <ul id="toc-Airborne_diseases-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-Air_conditioning" class="vector-toc-list-item vector-toc-level-1"> <a class="vector-toc-link" href="#Air_conditioning"> <div class="vector-toc-text"> <span class="vector-toc-numb">5</span> <span>Air conditioning</span> </div> </a> <button aria-controls="toc-Air_conditioning-sublist" class="cdx-button cdx-button--weight-quiet cdx-button--icon-only vector-toc-toggle"> <span class="vector-icon mw-ui-icon-wikimedia-expand"></span> <span>Toggle Air conditioning subsection</span> </button> <ul id="toc-Air_conditioning-sublist" class="vector-toc-list"> <li id="toc-Refrigeration_cycle" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Refrigeration_cycle"> <div class="vector-toc-text"> <span class="vector-toc-numb">5.1</span> <span>Refrigeration cycle</span> </div> </a> <ul id="toc-Refrigeration_cycle-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Free_cooling" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Free_cooling"> <div class="vector-toc-text"> <span class="vector-toc-numb">5.2</span> <span>Free cooling</span> </div> </a> <ul id="toc-Free_cooling-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Packaged_split_system" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Packaged_split_system"> <div class="vector-toc-text"> <span class="vector-toc-numb">5.3</span> <span>Packaged split system</span> </div> </a> <ul id="toc-Packaged_split_system-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Dehumidification" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Dehumidification"> <div class="vector-toc-text"> <span class="vector-toc-numb">5.4</span> <span>Dehumidification</span> </div> </a> <ul id="toc-Dehumidification-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Humidification" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Humidification"> <div class="vector-toc-text"> <span class="vector-toc-numb">5.5</span> <span>Humidification</span> </div> </a> <ul id="toc-Humidification-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Maintenance" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Maintenance"> <div class="vector-toc-text"> <span class="vector-toc-numb">5.6</span> <span>Maintenance</span> </div> </a> <ul id="toc-Maintenance-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-Energy_efficiency" class="vector-toc-list-item vector-toc-level-1"> <a class="vector-toc-link" href="#Energy_efficiency"> <div class="vector-toc-text"> <span class="vector-toc-numb">6</span> <span>Energy efficiency</span> </div> </a> <button aria-controls="toc-Energy_efficiency-sublist" class="cdx-button cdx-button--weight-quiet cdx-button--icon-only vector-toc-toggle"> <span class="vector-icon mw-ui-icon-wikimedia-expand"></span> <span>Toggle Energy efficiency subsection</span> </button> <ul id="toc-Energy_efficiency-sublist" class="vector-toc-list"> <li id="toc-Heating_energy" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Heating_energy"> <div class="vector-toc-text"> <span class="vector-toc-numb">6.1</span> <span>Heating energy</span> </div> </a> <ul id="toc-Heating_energy-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Ground_source_heat_pump" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Ground_source_heat_pump"> <div class="vector-toc-text"> <span class="vector-toc-numb">6.2</span> <span>Ground source heat pump</span> </div> </a> <ul id="toc-Ground_source_heat_pump-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Solar_air_conditioning" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Solar_air_conditioning"> <div class="vector-toc-text"> <span class="vector-toc-numb">6.3</span> <span>Solar air conditioning</span> </div> </a> <ul id="toc-Solar_air_conditioning-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Ventilation_energy_recovery" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Ventilation_energy_recovery"> <div class="vector-toc-text"> <span class="vector-toc-numb">6.4</span> <span>Ventilation energy recovery</span> </div> </a> <ul id="toc-Ventilation_energy_recovery-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Air_conditioning_energy" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Air_conditioning_energy"> <div class="vector-toc-text"> <span class="vector-toc-numb">6.5</span> <span>Air conditioning energy</span> </div> </a> <ul id="toc-Air_conditioning_energy-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Demand-controlled_kitchen_ventilation" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Demand-controlled_kitchen_ventilation"> <div class="vector-toc-text"> <span class="vector-toc-numb">6.6</span> <span>Demand-controlled kitchen ventilation</span> </div> </a> <ul id="toc-Demand-controlled_kitchen_ventilation-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-Air_filtration_and_cleaning" class="vector-toc-list-item vector-toc-level-1"> <a class="vector-toc-link" href="#Air_filtration_and_cleaning"> <div class="vector-toc-text"> <span class="vector-toc-numb">7</span> <span>Air filtration and cleaning</span> </div> </a> <ul id="toc-Air_filtration_and_cleaning-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Circulation_of_harmful_substances" class="vector-toc-list-item vector-toc-level-1"> <a class="vector-toc-link" href="#Circulation_of_harmful_substances"> <div class="vector-toc-text"> <span class="vector-toc-numb">8</span> <span>Circulation of harmful substances</span> </div> </a> <ul id="toc-Circulation_of_harmful_substances-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Industry_and_standards" class="vector-toc-list-item vector-toc-level-1"> <a class="vector-toc-link" href="#Industry_and_standards"> <div class="vector-toc-text"> <span class="vector-toc-numb">9</span> <span>Industry and standards</span> </div> </a> <button aria-controls="toc-Industry_and_standards-sublist" class="cdx-button cdx-button--weight-quiet cdx-button--icon-only vector-toc-toggle"> <span class="vector-icon mw-ui-icon-wikimedia-expand"></span> <span>Toggle Industry and standards subsection</span> </button> <ul id="toc-Industry_and_standards-sublist" class="vector-toc-list"> <li id="toc-International" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#International"> <div class="vector-toc-text"> <span class="vector-toc-numb">9.1</span> <span>International</span> </div> </a> <ul id="toc-International-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-United_States" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#United_States"> <div class="vector-toc-text"> <span class="vector-toc-numb">9.2</span> <span>United States</span> </div> </a> <ul id="toc-United_States-sublist" class="vector-toc-list"> <li id="toc-Licensing" class="vector-toc-list-item vector-toc-level-3"> <a class="vector-toc-link" href="#Licensing"> <div class="vector-toc-text"> <span class="vector-toc-numb">9.2.1</span> <span>Licensing</span> </div> </a> <ul id="toc-Licensing-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Societies" class="vector-toc-list-item vector-toc-level-3"> <a class="vector-toc-link" href="#Societies"> <div class="vector-toc-text"> <span class="vector-toc-numb">9.2.2</span> <span>Societies</span> </div> </a> <ul id="toc-Societies-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Codes" class="vector-toc-list-item vector-toc-level-3"> <a class="vector-toc-link" href="#Codes"> <div class="vector-toc-text"> <span class="vector-toc-numb">9.2.3</span> <span>Codes</span> </div> </a> <ul id="toc-Codes-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Technicians" class="vector-toc-list-item vector-toc-level-3"> <a class="vector-toc-link" href="#Technicians"> <div class="vector-toc-text"> <span class="vector-toc-numb">9.2.4</span> <span>Technicians</span> </div> </a> <ul id="toc-Technicians-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-United_Kingdom" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#United_Kingdom"> <div class="vector-toc-text"> <span class="vector-toc-numb">9.3</span> <span>United Kingdom</span> </div> </a> <ul id="toc-United_Kingdom-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Australia" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Australia"> <div class="vector-toc-text"> <span class="vector-toc-numb">9.4</span> <span>Australia</span> </div> </a> <ul id="toc-Australia-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Asia" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Asia"> <div class="vector-toc-text"> <span class="vector-toc-numb">9.5</span> <span>Asia</span> </div> </a> <ul id="toc-Asia-sublist" class="vector-toc-list"> <li id="toc-Philippines" class="vector-toc-list-item vector-toc-level-3"> <a class="vector-toc-link" href="#Philippines"> <div class="vector-toc-text"> <span class="vector-toc-numb">9.5.1</span> <span>Philippines</span> </div> </a> <ul id="toc-Philippines-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-India" class="vector-toc-list-item vector-toc-level-3"> <a class="vector-toc-link" href="#India"> <div class="vector-toc-text"> <span class="vector-toc-numb">9.5.2</span> <span>India</span> </div> </a> <ul id="toc-India-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> </ul> </li> <li id="toc-See_also" class="vector-toc-list-item vector-toc-level-1"> <a class="vector-toc-link" href="#See_also"> <div class="vector-toc-text"> <span class="vector-toc-numb">10</span> <span>See also</span> </div> </a> <ul id="toc-See_also-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-References" class="vector-toc-list-item vector-toc-level-1"> <a class="vector-toc-link" href="#References"> <div class="vector-toc-text"> <span class="vector-toc-numb">11</span> <span>References</span> </div> </a> <ul id="toc-References-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Further_reading" class="vector-toc-list-item vector-toc-level-1"> <a class="vector-toc-link" href="#Further_reading"> <div class="vector-toc-text"> <span class="vector-toc-numb">12</span> <span>Further reading</span> </div> </a> <ul id="toc-Further_reading-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-External_links" class="vector-toc-list-item vector-toc-level-1"> <a class="vector-toc-link" href="#External_links"> <div class="vector-toc-text"> <span class="vector-toc-numb">13</span> <span>External links</span> </div> </a> <ul id="toc-External_links-sublist" class="vector-toc-list"> </ul> </li> </ul> </div> </div> </nav> </div> </div> <div class="mw-content-container"> <main id="content" class="mw-body"> <header class="mw-body-header vector-page-titlebar"> <nav aria-label="Contents" class="vector-toc-landmark"> <div id="vector-page-titlebar-toc" class="vector-dropdown vector-page-titlebar-toc vector-button-flush-left" > <input type="checkbox" id="vector-page-titlebar-toc-checkbox" role="button" aria-haspopup="true" data-event-name="ui.dropdown-vector-page-titlebar-toc" class="vector-dropdown-checkbox " aria-label="Toggle the table of contents" > <label id="vector-page-titlebar-toc-label" for="vector-page-titlebar-toc-checkbox" class="vector-dropdown-label cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet cdx-button--icon-only " aria-hidden="true" ><span class="vector-icon mw-ui-icon-listBullet mw-ui-icon-wikimedia-listBullet"></span> <span class="vector-dropdown-label-text">Toggle the table of contents</span> </label> <div class="vector-dropdown-content"> <div id="vector-page-titlebar-toc-unpinned-container" class="vector-unpinned-container"> </div> </div> </div> </nav> <h1 id="firstHeading" class="firstHeading mw-first-heading"><span class="mw-page-title-main">Heating, ventilation, and air conditioning</span></h1> <div id="p-lang-btn" class="vector-dropdown mw-portlet mw-portlet-lang" > <input type="checkbox" id="p-lang-btn-checkbox" role="button" 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Available in 36 languages" > <label id="p-lang-btn-label" for="p-lang-btn-checkbox" class="vector-dropdown-label cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet cdx-button--action-progressive mw-portlet-lang-heading-36" aria-hidden="true" ><span class="vector-icon mw-ui-icon-language-progressive mw-ui-icon-wikimedia-language-progressive"></span> <span class="vector-dropdown-label-text">36 languages</span> </label> <div class="vector-dropdown-content"> <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li class="interlanguage-link interwiki-ar mw-list-item"><a href="https://ar.wikipedia.org/wiki/%D8%A7%D9%84%D8%AA%D8%AF%D9%81%D8%A6%D8%A9_%D9%88%D8%A7%D9%84%D8%AA%D9%87%D9%88%D9%8A%D8%A9_%D9%88%D8%AA%D9%83%D9%8A%D9%8A%D9%81_%D8%A7%D9%84%D9%87%D9%88%D8%A7%D8%A1" title="التدفئة والتهوية وتكييف الهواء – Arabic" lang="ar" hreflang="ar" data-title="التدفئة والتهوية وتكييف الهواء" data-language-autonym="العربية" data-language-local-name="Arabic" class="interlanguage-link-target"><span>العربية</span></a></li><li class="interlanguage-link interwiki-az mw-list-item"><a href="https://az.wikipedia.org/wiki/%C4%B0sitm%C9%99,_ventilyasiya_v%C9%99_havan%C4%B1n_kondisiyala%C5%9Fd%C4%B1r%C4%B1lmas%C4%B1" title="İsitmə, ventilyasiya və havanın kondisiyalaşdırılması – Azerbaijani" lang="az" hreflang="az" data-title="İsitmə, ventilyasiya və havanın kondisiyalaşdırılması" data-language-autonym="Azərbaycanca" data-language-local-name="Azerbaijani" class="interlanguage-link-target"><span>Azərbaycanca</span></a></li><li class="interlanguage-link interwiki-bn mw-list-item"><a href="https://bn.wikipedia.org/wiki/%E0%A6%A4%E0%A6%BE%E0%A6%AA%E0%A6%A8,_%E0%A6%AC%E0%A6%BE%E0%A6%AF%E0%A6%BC%E0%A7%81%E0%A6%B8%E0%A6%9E%E0%A7%8D%E0%A6%9A%E0%A6%BE%E0%A6%B2%E0%A6%A8_%E0%A6%93_%E0%A6%B6%E0%A7%80%E0%A6%A4%E0%A6%BE%E0%A6%A4%E0%A6%AA_%E0%A6%A8%E0%A6%BF%E0%A6%AF%E0%A6%BC%E0%A6%A8%E0%A7%8D%E0%A6%A4%E0%A7%8D%E0%A6%B0%E0%A6%A3" title="তাপন, বায়ুসঞ্চালন ও শীতাতপ নিয়ন্ত্রণ – Bangla" lang="bn" hreflang="bn" data-title="তাপন, বায়ুসঞ্চালন ও শীতাতপ নিয়ন্ত্রণ" data-language-autonym="বাংলা" data-language-local-name="Bangla" class="interlanguage-link-target"><span>বাংলা</span></a></li><li class="interlanguage-link interwiki-bg mw-list-item"><a href="https://bg.wikipedia.org/wiki/%D0%9E%D1%82%D0%BE%D0%BF%D0%BB%D0%B5%D0%BD%D0%B8%D0%B5,_%D0%B2%D0%B5%D0%BD%D1%82%D0%B8%D0%BB%D0%B0%D1%86%D0%B8%D1%8F_%D0%B8_%D0%BA%D0%BB%D0%B8%D0%BC%D0%B0%D1%82%D0%B8%D0%B7%D0%B0%D1%86%D0%B8%D1%8F" title="Отопление, вентилация и климатизация – Bulgarian" lang="bg" hreflang="bg" data-title="Отопление, вентилация и климатизация" data-language-autonym="Български" data-language-local-name="Bulgarian" class="interlanguage-link-target"><span>Български</span></a></li><li class="interlanguage-link interwiki-ca mw-list-item"><a href="https://ca.wikipedia.org/wiki/HVAC" title="HVAC – Catalan" lang="ca" hreflang="ca" data-title="HVAC" data-language-autonym="Català" data-language-local-name="Catalan" class="interlanguage-link-target"><span>Català</span></a></li><li class="interlanguage-link interwiki-da mw-list-item"><a href="https://da.wikipedia.org/wiki/VVS" title="VVS – Danish" lang="da" hreflang="da" data-title="VVS" data-language-autonym="Dansk" data-language-local-name="Danish" class="interlanguage-link-target"><span>Dansk</span></a></li><li class="interlanguage-link interwiki-de mw-list-item"><a href="https://de.wikipedia.org/wiki/Klimatechnik" title="Klimatechnik – German" lang="de" hreflang="de" data-title="Klimatechnik" data-language-autonym="Deutsch" data-language-local-name="German" class="interlanguage-link-target"><span>Deutsch</span></a></li><li class="interlanguage-link interwiki-et mw-list-item"><a href="https://et.wikipedia.org/wiki/Kliima-_ja_k%C3%BCtteseadmed" title="Kliima- ja kütteseadmed – Estonian" lang="et" hreflang="et" data-title="Kliima- ja kütteseadmed" data-language-autonym="Eesti" data-language-local-name="Estonian" class="interlanguage-link-target"><span>Eesti</span></a></li><li class="interlanguage-link interwiki-es mw-list-item"><a href="https://es.wikipedia.org/wiki/Climatizaci%C3%B3n" title="Climatización – Spanish" lang="es" hreflang="es" data-title="Climatización" data-language-autonym="Español" data-language-local-name="Spanish" class="interlanguage-link-target"><span>Español</span></a></li><li class="interlanguage-link interwiki-fa mw-list-item"><a href="https://fa.wikipedia.org/wiki/%DA%AF%D8%B1%D9%85%D8%A7%DB%8C%D8%B4_%D9%88_%D8%AA%D9%87%D9%88%DB%8C%D9%87%E2%80%8C%D9%87%D9%88%D8%A7" title="گرمایش و تهویه‌هوا – Persian" lang="fa" hreflang="fa" data-title="گرمایش و تهویه‌هوا" data-language-autonym="فارسی" data-language-local-name="Persian" class="interlanguage-link-target"><span>فارسی</span></a></li><li class="interlanguage-link interwiki-fr mw-list-item"><a href="https://fr.wikipedia.org/wiki/Chauffage,_ventilation_et_climatisation" title="Chauffage, ventilation et climatisation – French" lang="fr" hreflang="fr" data-title="Chauffage, ventilation et climatisation" data-language-autonym="Français" data-language-local-name="French" class="interlanguage-link-target"><span>Français</span></a></li><li class="interlanguage-link interwiki-ko mw-list-item"><a href="https://ko.wikipedia.org/wiki/%EA%B3%B5%EA%B8%B0%EC%A1%B0%ED%99%94%EA%B8%B0%EC%88%A0" title="공기조화기술 – Korean" lang="ko" hreflang="ko" data-title="공기조화기술" data-language-autonym="한국어" data-language-local-name="Korean" class="interlanguage-link-target"><span>한국어</span></a></li><li class="interlanguage-link interwiki-hi mw-list-item"><a href="https://hi.wikipedia.org/wiki/%E0%A4%A4%E0%A4%BE%E0%A4%AA%E0%A4%A8,_%E0%A4%B8%E0%A4%82%E0%A4%B5%E0%A4%BE%E0%A4%A4%E0%A4%A8_%E0%A4%A4%E0%A4%A5%E0%A4%BE_%E0%A4%B5%E0%A4%BE%E0%A4%A4%E0%A4%BE%E0%A4%A8%E0%A5%81%E0%A4%95%E0%A5%82%E0%A4%B2%E0%A4%A8" title="तापन, संवातन तथा वातानुकूलन – Hindi" lang="hi" hreflang="hi" data-title="तापन, संवातन तथा वातानुकूलन" data-language-autonym="हिन्दी" data-language-local-name="Hindi" class="interlanguage-link-target"><span>हिन्दी</span></a></li><li class="interlanguage-link interwiki-id mw-list-item"><a href="https://id.wikipedia.org/wiki/Pemanasan,_sirkulasi,_dan_pengondisi_udara" title="Pemanasan, sirkulasi, dan pengondisi udara – Indonesian" lang="id" hreflang="id" data-title="Pemanasan, sirkulasi, dan pengondisi udara" data-language-autonym="Bahasa Indonesia" data-language-local-name="Indonesian" class="interlanguage-link-target"><span>Bahasa Indonesia</span></a></li><li class="interlanguage-link interwiki-it mw-list-item"><a href="https://it.wikipedia.org/wiki/HVAC" title="HVAC – Italian" lang="it" hreflang="it" data-title="HVAC" data-language-autonym="Italiano" data-language-local-name="Italian" class="interlanguage-link-target"><span>Italiano</span></a></li><li class="interlanguage-link interwiki-sw mw-list-item"><a href="https://sw.wikipedia.org/wiki/Kiyoyozi" title="Kiyoyozi – Swahili" lang="sw" hreflang="sw" data-title="Kiyoyozi" data-language-autonym="Kiswahili" data-language-local-name="Swahili" class="interlanguage-link-target"><span>Kiswahili</span></a></li><li class="interlanguage-link interwiki-ku mw-list-item"><a href="https://ku.wikipedia.org/wiki/Germkirin,_Hewakirin_%C3%BB_Basarkirin" title="Germkirin, Hewakirin û Basarkirin – Kurdish" lang="ku" hreflang="ku" data-title="Germkirin, Hewakirin û Basarkirin" data-language-autonym="Kurdî" data-language-local-name="Kurdish" class="interlanguage-link-target"><span>Kurdî</span></a></li><li class="interlanguage-link interwiki-hu badge-Q70893996 mw-list-item" title=""><a href="https://hu.wikipedia.org/wiki/HVAC" title="HVAC – Hungarian" lang="hu" hreflang="hu" data-title="HVAC" data-language-autonym="Magyar" data-language-local-name="Hungarian" class="interlanguage-link-target"><span>Magyar</span></a></li><li class="interlanguage-link interwiki-nl mw-list-item"><a href="https://nl.wikipedia.org/wiki/HVAC" title="HVAC – Dutch" lang="nl" hreflang="nl" data-title="HVAC" data-language-autonym="Nederlands" data-language-local-name="Dutch" class="interlanguage-link-target"><span>Nederlands</span></a></li><li class="interlanguage-link interwiki-ne mw-list-item"><a href="https://ne.wikipedia.org/wiki/%E0%A4%A4%E0%A4%BE%E0%A4%AA%E0%A4%A8,_%E0%A4%B5%E0%A4%BE%E0%A4%AF%E0%A5%81%E0%A4%B8%E0%A4%9E%E0%A5%8D%E0%A4%9A%E0%A4%BE%E0%A4%B0_%E0%A4%A4%E0%A4%A5%E0%A4%BE_%E0%A4%B5%E0%A4%BE%E0%A4%A4%E0%A4%BE%E0%A4%A8%E0%A5%81%E0%A4%95%E0%A5%82%E0%A4%B2%E0%A4%A8" title="तापन, वायुसञ्चार तथा वातानुकूलन – Nepali" lang="ne" hreflang="ne" data-title="तापन, वायुसञ्चार तथा वातानुकूलन" data-language-autonym="नेपाली" data-language-local-name="Nepali" class="interlanguage-link-target"><span>नेपाली</span></a></li><li class="interlanguage-link interwiki-ja mw-list-item"><a href="https://ja.wikipedia.org/wiki/%E7%A9%BA%E6%B0%97%E8%AA%BF%E5%92%8C%E5%B7%A5%E5%AD%A6" title="空気調和工学 – Japanese" lang="ja" hreflang="ja" data-title="空気調和工学" data-language-autonym="日本語" data-language-local-name="Japanese" class="interlanguage-link-target"><span>日本語</span></a></li><li class="interlanguage-link interwiki-no mw-list-item"><a href="https://no.wikipedia.org/wiki/Varme-,_ventilasjons-_og_sanit%C3%A6rteknikk" title="Varme-, ventilasjons- og sanitærteknikk – Norwegian Bokmål" lang="nb" hreflang="nb" data-title="Varme-, ventilasjons- og sanitærteknikk" data-language-autonym="Norsk bokmål" data-language-local-name="Norwegian Bokmål" class="interlanguage-link-target"><span>Norsk bokmål</span></a></li><li class="interlanguage-link interwiki-nn mw-list-item"><a href="https://nn.wikipedia.org/wiki/HVAC" title="HVAC – Norwegian Nynorsk" lang="nn" hreflang="nn" data-title="HVAC" data-language-autonym="Norsk nynorsk" data-language-local-name="Norwegian Nynorsk" class="interlanguage-link-target"><span>Norsk nynorsk</span></a></li><li class="interlanguage-link interwiki-pl mw-list-item"><a href="https://pl.wikipedia.org/wiki/HVAC" title="HVAC – Polish" lang="pl" hreflang="pl" data-title="HVAC" data-language-autonym="Polski" data-language-local-name="Polish" class="interlanguage-link-target"><span>Polski</span></a></li><li class="interlanguage-link interwiki-pt mw-list-item"><a href="https://pt.wikipedia.org/wiki/Climatiza%C3%A7%C3%A3o" title="Climatização – Portuguese" lang="pt" hreflang="pt" data-title="Climatização" data-language-autonym="Português" data-language-local-name="Portuguese" class="interlanguage-link-target"><span>Português</span></a></li><li class="interlanguage-link interwiki-ro mw-list-item"><a href="https://ro.wikipedia.org/wiki/%C3%8Enc%C4%83lzire,_ventila%C8%9Bie_%C8%99i_aer_condi%C8%9Bionat" title="Încălzire, ventilație și aer condiționat – Romanian" lang="ro" hreflang="ro" data-title="Încălzire, ventilație și aer condiționat" data-language-autonym="Română" data-language-local-name="Romanian" class="interlanguage-link-target"><span>Română</span></a></li><li class="interlanguage-link interwiki-ru mw-list-item"><a href="https://ru.wikipedia.org/wiki/%D0%9E%D1%82%D0%BE%D0%BF%D0%BB%D0%B5%D0%BD%D0%B8%D0%B5,_%D0%B2%D0%B5%D0%BD%D1%82%D0%B8%D0%BB%D1%8F%D1%86%D0%B8%D1%8F_%D0%B8_%D0%BA%D0%BE%D0%BD%D0%B4%D0%B8%D1%86%D0%B8%D0%BE%D0%BD%D0%B8%D1%80%D0%BE%D0%B2%D0%B0%D0%BD%D0%B8%D0%B5" title="Отопление, вентиляция и кондиционирование – Russian" lang="ru" hreflang="ru" data-title="Отопление, вентиляция и кондиционирование" data-language-autonym="Русский" data-language-local-name="Russian" class="interlanguage-link-target"><span>Русский</span></a></li><li class="interlanguage-link interwiki-sq mw-list-item"><a href="https://sq.wikipedia.org/wiki/Ngrohja,_ventilimi_dhe_klimatizimi" title="Ngrohja, ventilimi dhe klimatizimi – Albanian" lang="sq" hreflang="sq" data-title="Ngrohja, ventilimi dhe klimatizimi" data-language-autonym="Shqip" data-language-local-name="Albanian" class="interlanguage-link-target"><span>Shqip</span></a></li><li class="interlanguage-link interwiki-so mw-list-item"><a href="https://so.wikipedia.org/wiki/Diiriye" title="Diiriye – Somali" lang="so" hreflang="so" data-title="Diiriye" data-language-autonym="Soomaaliga" data-language-local-name="Somali" class="interlanguage-link-target"><span>Soomaaliga</span></a></li><li class="interlanguage-link interwiki-sv mw-list-item"><a href="https://sv.wikipedia.org/wiki/VVS" title="VVS – Swedish" lang="sv" hreflang="sv" data-title="VVS" data-language-autonym="Svenska" data-language-local-name="Swedish" class="interlanguage-link-target"><span>Svenska</span></a></li><li class="interlanguage-link interwiki-ta mw-list-item"><a href="https://ta.wikipedia.org/wiki/%E0%AE%B5%E0%AF%86%E0%AE%AA%E0%AF%8D%E0%AE%AA%E0%AE%B5%E0%AF%87%E0%AE%B1%E0%AF%8D%E0%AE%B1%E0%AE%AE%E0%AF%8D,_%E0%AE%95%E0%AE%BE%E0%AE%B1%E0%AF%8D%E0%AE%B1%E0%AF%8B%E0%AE%9F%E0%AF%8D%E0%AE%9F%E0%AE%AE%E0%AF%8D,_%E0%AE%95%E0%AF%81%E0%AE%B3%E0%AE%BF%E0%AE%B0%E0%AF%8D%E0%AE%AA%E0%AE%A4%E0%AE%A9%E0%AE%AE%E0%AF%8D" title="வெப்பவேற்றம், காற்றோட்டம், குளிர்பதனம் – Tamil" lang="ta" hreflang="ta" data-title="வெப்பவேற்றம், காற்றோட்டம், குளிர்பதனம்" data-language-autonym="தமிழ்" data-language-local-name="Tamil" class="interlanguage-link-target"><span>தமிழ்</span></a></li><li class="interlanguage-link interwiki-th mw-list-item"><a href="https://th.wikipedia.org/wiki/%E0%B8%A3%E0%B8%B0%E0%B8%9A%E0%B8%9A%E0%B8%9B%E0%B8%A3%E0%B8%B1%E0%B8%9A%E0%B8%AD%E0%B8%B2%E0%B8%81%E0%B8%B2%E0%B8%A8" title="ระบบปรับอากาศ – Thai" lang="th" hreflang="th" data-title="ระบบปรับอากาศ" data-language-autonym="ไทย" data-language-local-name="Thai" class="interlanguage-link-target"><span>ไทย</span></a></li><li class="interlanguage-link interwiki-tr mw-list-item"><a href="https://tr.wikipedia.org/wiki/HVAC" title="HVAC – Turkish" lang="tr" hreflang="tr" data-title="HVAC" data-language-autonym="Türkçe" data-language-local-name="Turkish" class="interlanguage-link-target"><span>Türkçe</span></a></li><li class="interlanguage-link interwiki-uk mw-list-item"><a href="https://uk.wikipedia.org/wiki/%D0%9E%D0%BF%D0%B0%D0%BB%D0%B5%D0%BD%D0%BD%D1%8F,_%D0%B2%D0%B5%D0%BD%D1%82%D0%B8%D0%BB%D1%8F%D1%86%D1%96%D1%8F_%D1%82%D0%B0_%D0%BA%D0%BE%D0%BD%D0%B4%D0%B8%D1%86%D1%96%D1%8E%D0%B2%D0%B0%D0%BD%D0%BD%D1%8F_%D0%BF%D0%BE%D0%B2%D1%96%D1%82%D1%80%D1%8F" title="Опалення, вентиляція та кондиціювання повітря – Ukrainian" lang="uk" hreflang="uk" data-title="Опалення, вентиляція та кондиціювання повітря" data-language-autonym="Українська" data-language-local-name="Ukrainian" class="interlanguage-link-target"><span>Українська</span></a></li><li class="interlanguage-link interwiki-yi mw-list-item"><a href="https://yi.wikipedia.org/wiki/%D7%94%D7%99%D7%99%D7%A1%D7%A2_%D7%9C%D7%95%D7%A4%D7%98_%D7%A1%D7%99%D7%A1%D7%98%D7%A2%D7%9D" title="הייסע לופט סיסטעם – Yiddish" lang="yi" hreflang="yi" data-title="הייסע לופט סיסטעם" data-language-autonym="ייִדיש" data-language-local-name="Yiddish" class="interlanguage-link-target"><span>ייִדיש</span></a></li><li class="interlanguage-link interwiki-zh mw-list-item"><a href="https://zh.wikipedia.org/wiki/%E6%9A%96%E9%80%9A%E7%A9%BA%E8%AA%BF" title="暖通空調 – Chinese" lang="zh" hreflang="zh" data-title="暖通空調" data-language-autonym="中文" data-language-local-name="Chinese" class="interlanguage-link-target"><span>中文</span></a></li> </ul> <div class="after-portlet after-portlet-lang"><span class="wb-langlinks-edit wb-langlinks-link"><a href="https://www.wikidata.org/wiki/Special:EntityPage/Q1798773#sitelinks-wikipedia" title="Edit interlanguage links" class="wbc-editpage">Edit links</a></span></div> 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class="vector-body" aria-labelledby="firstHeading" data-mw-ve-target-container> <div class="vector-body-before-content"> <div class="mw-indicators"> </div> <div id="siteSub" class="noprint">From Wikipedia, the free encyclopedia</div> </div> <div id="contentSub"><div id="mw-content-subtitle"></div></div> <div id="mw-content-text" class="mw-body-content"><div class="mw-content-ltr mw-parser-output" lang="en" dir="ltr"><div class="shortdescription nomobile noexcerpt noprint searchaux" style="display:none">Technology of indoor and vehicular environmental comfort</div> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Rooftop_Packaged_Units.JPG" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/9/90/Rooftop_Packaged_Units.JPG/220px-Rooftop_Packaged_Units.JPG" decoding="async" width="220" height="146" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/9/90/Rooftop_Packaged_Units.JPG/330px-Rooftop_Packaged_Units.JPG 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/9/90/Rooftop_Packaged_Units.JPG/440px-Rooftop_Packaged_Units.JPG 2x" data-file-width="1471" data-file-height="974" /></a><figcaption>Rooftop HVAC unit with view of fresh-air intake vent</figcaption></figure> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Central_ventilation_tube2.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/0/01/Central_ventilation_tube2.jpg/220px-Central_ventilation_tube2.jpg" decoding="async" width="220" height="147" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/0/01/Central_ventilation_tube2.jpg 1.5x" data-file-width="250" data-file-height="167" /></a><figcaption><a href="/wiki/Duct_(flow)" title="Duct (flow)">Ventilation duct</a> with outlet <a href="/wiki/Diffuser_(thermodynamics)" title="Diffuser (thermodynamics)">diffuser</a> vent. These are installed throughout a building to move air in or out of rooms. In the middle is a <a href="/wiki/Damper_(flow)" title="Damper (flow)">damper</a> to open and close the vent to allow more or less air to enter the space.</figcaption></figure> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Control_circuit_in_household_HVAC_unit.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/5/57/Control_circuit_in_household_HVAC_unit.jpg/220px-Control_circuit_in_household_HVAC_unit.jpg" decoding="async" width="220" height="165" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/5/57/Control_circuit_in_household_HVAC_unit.jpg/330px-Control_circuit_in_household_HVAC_unit.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/5/57/Control_circuit_in_household_HVAC_unit.jpg/440px-Control_circuit_in_household_HVAC_unit.jpg 2x" data-file-width="4160" data-file-height="3120" /></a><figcaption>The control circuit in a household HVAC installation. The wires connecting to the blue terminal block on the upper-right of the board lead to the <a href="/wiki/Thermostat" title="Thermostat">thermostat</a>. The fan enclosure is directly behind the board, and the <a href="/wiki/Air_filter" title="Air filter">filters</a> can be seen at the top. The safety <a href="/wiki/Interlock" class="mw-redirect" title="Interlock">interlock</a> switch is at the bottom left. In the lower middle is the <a href="/wiki/Capacitor" title="Capacitor">capacitor</a>.</figcaption></figure> <p><b>Heating, ventilation, and air conditioning</b> (<b>HVAC</b>) is the use of various technologies to control the <a href="/wiki/Temperature" title="Temperature">temperature</a>, <a href="/wiki/Humidity" title="Humidity">humidity</a>, and purity of the air in an enclosed space. Its goal is to provide <a href="/wiki/Thermal_comfort" title="Thermal comfort">thermal comfort</a> and acceptable <a href="/wiki/Indoor_air_quality" title="Indoor air quality">indoor air quality</a>. HVAC system design is a subdiscipline of <a href="/wiki/Mechanical_engineering" title="Mechanical engineering">mechanical engineering</a>, based on the principles of <a href="/wiki/Thermodynamics" title="Thermodynamics">thermodynamics</a>, <a href="/wiki/Fluid_mechanics" title="Fluid mechanics">fluid mechanics</a>, and <a href="/wiki/Heat_transfer" title="Heat transfer">heat transfer</a>. "<a href="/wiki/Refrigeration" title="Refrigeration">Refrigeration</a>" is sometimes added to the field's abbreviation as <b>HVAC&R</b> or <b>HVACR</b>, or "ventilation" is dropped, as in <b>HACR</b> (as in the designation of HACR-rated <a href="/wiki/Circuit_breaker" title="Circuit breaker">circuit breakers</a>). </p><p>HVAC is an important part of residential structures such as single family homes, apartment buildings, hotels, and senior living facilities; medium to large industrial and office buildings such as <a href="/wiki/Skyscraper" title="Skyscraper">skyscrapers</a> and hospitals; vehicles such as cars, trains, airplanes, ships and submarines; and in marine environments, where safe and <a href="/wiki/Sick_building_syndrome" title="Sick building syndrome">healthy building</a> conditions are regulated with respect to temperature and humidity, using fresh air from outdoors. </p><p>Ventilating or <a href="/wiki/Ventilation_(architecture)" title="Ventilation (architecture)">ventilation</a> (the "V" in HVAC) is the process of exchanging or replacing air in any space to provide high indoor air quality which involves temperature control, oxygen replenishment, and removal of moisture, odors, smoke, heat, dust, airborne bacteria, carbon dioxide, and other gases. Ventilation removes unpleasant smells and excessive moisture, introduces outside air, keeps interior building air circulating, and prevents stagnation of the interior air. Methods for ventilating a building are divided into <i>mechanical/forced</i> and <i><a href="/wiki/Natural_ventilation" class="mw-redirect" title="Natural ventilation">natural</a></i> types.<sup id="cite_ref-ASHRAE_1-0" class="reference"><a href="#cite_note-ASHRAE-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup> </p> <meta property="mw:PageProp/toc" /> <div class="mw-heading mw-heading2"><h2 id="Overview">Overview</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Heating,_ventilation,_and_air_conditioning&action=edit&section=1" title="Edit section: Overview"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>The three major functions of heating, ventilation, and air conditioning are interrelated, especially with the need to provide thermal comfort and acceptable indoor air quality within reasonable installation, operation, and maintenance costs. HVAC systems can be used in both domestic and commercial environments. HVAC systems can provide ventilation, and maintain pressure relationships between spaces. The means of air delivery and removal from spaces is known as <a href="/wiki/Room_air_distribution" title="Room air distribution">room air distribution</a>.<sup id="cite_ref-Rock_and_Zhu_2-0" class="reference"><a href="#cite_note-Rock_and_Zhu-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading3"><h3 id="Individual_systems">Individual systems</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Heating,_ventilation,_and_air_conditioning&action=edit&section=2" title="Edit section: Individual systems"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <style data-mw-deduplicate="TemplateStyles:r1236090951">.mw-parser-output .hatnote{font-style:italic}.mw-parser-output div.hatnote{padding-left:1.6em;margin-bottom:0.5em}.mw-parser-output .hatnote i{font-style:normal}.mw-parser-output .hatnote+link+.hatnote{margin-top:-0.5em}@media print{body.ns-0 .mw-parser-output .hatnote{display:none!important}}</style><div role="note" class="hatnote navigation-not-searchable">See also: <a href="/wiki/HVAC_control_system" title="HVAC control system">HVAC control system</a></div> <p>In modern buildings, the design, installation, and <a href="/wiki/HVAC_control_system" title="HVAC control system">control systems</a> of these functions are integrated into one or more HVAC systems. For very small buildings, contractors normally estimate the capacity and type of system needed and then design the system, selecting the appropriate refrigerant and various components needed. For larger buildings, building service designers, mechanical engineers, or <a href="/wiki/Building_engineering" class="mw-redirect" title="Building engineering">building services</a> engineers analyze, design, and specify the HVAC systems. Specialty mechanical contractors and suppliers then fabricate, install and commission the systems. Building permits and code-compliance inspections of the installations are normally required for all sizes of buildings </p> <div class="mw-heading mw-heading3"><h3 id="District_networks">District networks</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Heating,_ventilation,_and_air_conditioning&action=edit&section=3" title="Edit section: District networks"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Although HVAC is executed in individual buildings or other enclosed spaces (like <a href="/wiki/North_American_Aerospace_Defense_Command" class="mw-redirect" title="North American Aerospace Defense Command">NORAD's</a> underground headquarters), the equipment involved is in some cases an extension of a larger <a href="/wiki/District_heating" title="District heating">district heating</a> (DH) or <a href="/wiki/District_cooling" title="District cooling">district cooling</a> (DC) network, or a combined DHC network. In such cases, the operating and maintenance aspects are simplified and metering becomes necessary to bill for the energy that is consumed, and in some cases energy that is returned to the larger system. For example, at a given time one building may be utilizing chilled water for air conditioning and the warm water it returns may be used in another building for heating, or for the overall heating-portion of the DHC network (likely with energy added to boost the temperature).<sup id="cite_ref-3" class="reference"><a href="#cite_note-3"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-4" class="reference"><a href="#cite_note-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-5" class="reference"><a href="#cite_note-5"><span class="cite-bracket">[</span>5<span class="cite-bracket">]</span></a></sup> </p><p>Basing HVAC on a larger network helps provide an economy of scale that is often not possible for individual buildings, for utilizing <a href="/wiki/Renewable_energy" title="Renewable energy">renewable energy</a> sources such as solar heat,<sup id="cite_ref-6" class="reference"><a href="#cite_note-6"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-7" class="reference"><a href="#cite_note-7"><span class="cite-bracket">[</span>7<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-8" class="reference"><a href="#cite_note-8"><span class="cite-bracket">[</span>8<span class="cite-bracket">]</span></a></sup> winter's cold,<sup id="cite_ref-9" class="reference"><a href="#cite_note-9"><span class="cite-bracket">[</span>9<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-10" class="reference"><a href="#cite_note-10"><span class="cite-bracket">[</span>10<span class="cite-bracket">]</span></a></sup> the cooling potential in some places of <a href="/wiki/Lake_cooling" class="mw-redirect" title="Lake cooling">lakes or seawater</a> for <a href="/wiki/Free_cooling" title="Free cooling">free cooling</a>, and the enabling function of <a href="/wiki/Seasonal_thermal_energy_storage" title="Seasonal thermal energy storage">seasonal thermal energy storage</a>. By utilizing natural sources that can be used for HVAC systems it can make a huge difference for the environment and help expand the knowledge of using different methods. </p> <div class="mw-heading mw-heading2"><h2 id="History">History</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Heating,_ventilation,_and_air_conditioning&action=edit&section=4" title="Edit section: History"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable">See also: <a href="/wiki/Air_conditioning#History" title="Air conditioning">Air conditioning § History</a></div> <p>HVAC is based on inventions and discoveries made by <a href="/wiki/Nikolay_Lvov" title="Nikolay Lvov">Nikolay Lvov</a>, <a href="/wiki/Michael_Faraday" title="Michael Faraday">Michael Faraday</a>, <a href="/wiki/Rolla_C._Carpenter" title="Rolla C. Carpenter">Rolla C. Carpenter</a>, <a href="/wiki/Willis_Carrier" title="Willis Carrier">Willis Carrier</a>, <a href="/wiki/Edwin_Ruud" title="Edwin Ruud">Edwin Ruud</a>, <a href="/wiki/Reuben_Trane" title="Reuben Trane">Reuben Trane</a>, <a href="/wiki/James_Joule" class="mw-redirect" title="James Joule">James Joule</a>, <a href="/wiki/William_Rankine" title="William Rankine">William Rankine</a>, <a href="/wiki/Nicolas_L%C3%A9onard_Sadi_Carnot" title="Nicolas Léonard Sadi Carnot">Sadi Carnot</a>, <a href="/wiki/Alice_H._Parker" title="Alice H. Parker">Alice Parker</a> and many others.<sup id="cite_ref-11" class="reference"><a href="#cite_note-11"><span class="cite-bracket">[</span>11<span class="cite-bracket">]</span></a></sup> </p><p>Multiple inventions within this time frame preceded the beginnings of the first comfort air conditioning system, which was designed in 1902 by Alfred Wolff (Cooper, 2003) for the New York Stock Exchange, while Willis Carrier equipped the Sacketts-Wilhems Printing Company with the process AC unit the same year. Coyne College was the first school to offer HVAC training in 1899.<sup id="cite_ref-12" class="reference"><a href="#cite_note-12"><span class="cite-bracket">[</span>12<span class="cite-bracket">]</span></a></sup> The first residential AC was installed by 1914, and by the 1950s there was "widespread adoption of residential AC".<sup id="cite_ref-13" class="reference"><a href="#cite_note-13"><span class="cite-bracket">[</span>13<span class="cite-bracket">]</span></a></sup> </p><p>The invention of the components of HVAC systems went hand-in-hand with the <a href="/wiki/Industrial_Revolution" title="Industrial Revolution">Industrial Revolution</a>, and new methods of modernization, higher efficiency, and system control are constantly being introduced by companies and inventors worldwide. </p> <div class="mw-heading mw-heading2"><h2 id="Heating">Heating</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Heating,_ventilation,_and_air_conditioning&action=edit&section=5" title="Edit section: Heating"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable">Main article: <a href="/wiki/Central_heating" title="Central heating">Central heating</a></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable">"Heater" redirects here. For other uses, see <a href="/wiki/Heater_(disambiguation)" class="mw-disambig" title="Heater (disambiguation)">Heater (disambiguation)</a>.</div> <p>Heaters are appliances whose purpose is to generate heat (i.e. warmth) for the building. This can be done via <a href="/wiki/Central_heating" title="Central heating">central heating</a>. Such a system contains a <a href="/wiki/Boiler" title="Boiler">boiler</a>, <a href="/wiki/Furnace_(house_heating)" class="mw-redirect" title="Furnace (house heating)">furnace</a>, or <a href="/wiki/Heat_pump" title="Heat pump">heat pump</a> to heat water, steam, or air in a central location such as a <a href="/wiki/Furnace_(house_heating)" class="mw-redirect" title="Furnace (house heating)">furnace room</a> in a home, or a <a href="/wiki/Mechanical_room" title="Mechanical room">mechanical room</a> in a large building. The heat can be transferred by <a href="/wiki/Convection" title="Convection">convection</a>, conduction, or <a href="/wiki/Radiation" title="Radiation">radiation</a>. <a href="/wiki/Space_heater" title="Space heater">Space heaters</a> are used to heat single rooms and only consist of a single unit. </p> <div class="mw-heading mw-heading3"><h3 id="Generation">Generation</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Heating,_ventilation,_and_air_conditioning&action=edit&section=6" title="Edit section: Generation"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Panna.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/f/f6/Panna.jpg/170px-Panna.jpg" decoding="async" width="170" height="336" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/f/f6/Panna.jpg/255px-Panna.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/f/f6/Panna.jpg/340px-Panna.jpg 2x" data-file-width="405" data-file-height="800" /></a><figcaption>Central heating unit</figcaption></figure> <p>Heaters exist for various types of fuel, including <a href="/wiki/Fuel#Solid_fuel" title="Fuel">solid fuels</a>, <a href="/wiki/Fuel#Liquid_fuel" title="Fuel">liquids</a>, and <a href="/wiki/Fuel#Gaseous_fuels" title="Fuel">gases</a>. Another type of heat source is <a href="/wiki/Electric_heating" title="Electric heating">electricity</a>, normally heating ribbons composed of high resistance wire (see <a href="/wiki/Nichrome" title="Nichrome">Nichrome</a>). This principle is also used for baseboard heaters and <a href="/wiki/Space_heater" title="Space heater">portable heaters</a>. Electrical heaters are often used as backup or supplemental heat for heat pump systems. </p><p>The heat pump gained popularity in the 1950s in Japan and the United States.<sup id="cite_ref-14" class="reference"><a href="#cite_note-14"><span class="cite-bracket">[</span>14<span class="cite-bracket">]</span></a></sup> Heat pumps can extract heat from <a href="/wiki/Heat_pump#Sources" title="Heat pump">various sources</a>, such as environmental air, exhaust air from a building, or from the ground. Heat pumps transfer heat from outside the structure into the air inside. Initially, heat pump HVAC systems were only used in moderate climates, but with improvements in low temperature operation and reduced loads due to more efficient homes, they are increasing in popularity in cooler climates. They can also operate in reverse to cool an interior. </p> <div class="mw-heading mw-heading3"><h3 id="Distribution">Distribution</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Heating,_ventilation,_and_air_conditioning&action=edit&section=7" title="Edit section: Distribution"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <div class="mw-heading mw-heading4"><h4 id="Water/steam"><span id="Water.2Fsteam"></span>Water/steam</h4><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Heating,_ventilation,_and_air_conditioning&action=edit&section=8" title="Edit section: Water/steam"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>In the case of heated water or steam, piping is used to transport the heat to the rooms. Most modern hot water boiler heating systems have a circulator, which is a pump, to move hot water through the distribution system (as opposed to older <a href="/wiki/Water_heating#Gravity-fed_system" title="Water heating">gravity-fed systems</a>). The heat can be transferred to the surrounding air using <a href="/wiki/Radiator_(heating)" title="Radiator (heating)">radiators</a>, hot water coils (hydro-air), or other heat exchangers. The radiators may be mounted on walls or installed within the floor to produce floor heat. </p><p>The use of water as the heat transfer medium is known as <a href="/wiki/Hydronics" title="Hydronics">hydronics</a>. The heated water can also supply an auxiliary heat exchanger to supply hot water for bathing and washing. </p> <div class="mw-heading mw-heading4"><h4 id="Air">Air</h4><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Heating,_ventilation,_and_air_conditioning&action=edit&section=9" title="Edit section: Air"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable">Main articles: <a href="/wiki/Room_air_distribution" title="Room air distribution">Room air distribution</a> and <a href="/wiki/Underfloor_air_distribution" title="Underfloor air distribution">Underfloor air distribution</a></div> <p>Warm air systems distribute the heated air through ductwork systems of supply and return air through metal or fiberglass ducts. Many systems use the same ducts to distribute air cooled by an evaporator coil for air conditioning. The air supply is normally filtered through air filters<sup class="noprint Inline-Template" style="white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Accuracy_dispute#Disputed_statement" title="Wikipedia:Accuracy dispute"><span title="The material near this tag is possibly inaccurate or nonfactual. (September 2024)">dubious</span></a> – <a href="/wiki/Talk:Heating,_ventilation,_and_air_conditioning#Dubious" title="Talk:Heating, ventilation, and air conditioning">discuss</a></i>]</sup> to remove dust and pollen particles.<sup id="cite_ref-15" class="reference"><a href="#cite_note-15"><span class="cite-bracket">[</span>15<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading3"><h3 id="Dangers">Dangers</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Heating,_ventilation,_and_air_conditioning&action=edit&section=10" title="Edit section: Dangers"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>The use of furnaces, space heaters, and boilers as a method of indoor heating could result in incomplete combustion and the emission of <a href="/wiki/Carbon_monoxide" title="Carbon monoxide">carbon monoxide</a>, <a href="/wiki/NOx" title="NOx">nitrogen oxides</a>, <a href="/wiki/Formaldehyde" title="Formaldehyde">formaldehyde</a>, <a href="/wiki/Volatile_organic_compound" title="Volatile organic compound">volatile organic compounds</a>, and other combustion byproducts. Incomplete combustion occurs when there is insufficient oxygen; the inputs are fuels containing various contaminants and the outputs are harmful byproducts, most dangerously carbon monoxide, which is a tasteless and odorless gas with serious adverse health effects.<sup id="cite_ref-16" class="reference"><a href="#cite_note-16"><span class="cite-bracket">[</span>16<span class="cite-bracket">]</span></a></sup> </p><p>Without proper ventilation, carbon monoxide can be lethal at concentrations of 1000 ppm (0.1%). However, at several hundred ppm, carbon monoxide exposure induces headaches, fatigue, nausea, and vomiting. Carbon monoxide binds with hemoglobin in the blood, forming carboxyhemoglobin, reducing the blood's ability to transport oxygen. The primary health concerns associated with carbon monoxide exposure are its cardiovascular and neurobehavioral effects. Carbon monoxide can cause atherosclerosis (the hardening of arteries) and can also trigger heart attacks. Neurologically, carbon monoxide exposure reduces hand to eye coordination, vigilance, and continuous performance. It can also affect time discrimination.<sup id="cite_ref-17" class="reference"><a href="#cite_note-17"><span class="cite-bracket">[</span>17<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading2"><h2 id="Ventilation">Ventilation</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Heating,_ventilation,_and_air_conditioning&action=edit&section=11" title="Edit section: Ventilation"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable">Main article: <a href="/wiki/Ventilation_(architecture)" title="Ventilation (architecture)">Ventilation (architecture)</a></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable">See also: <a href="/wiki/Duct_(flow)" title="Duct (flow)">Duct (flow)</a></div> <p>Ventilation is the process of changing or replacing air in any space to control the temperature or remove any combination of moisture, odors, smoke, heat, dust, airborne bacteria, or carbon dioxide, and to replenish oxygen. It plays a critical role in maintaining a healthy indoor environment by preventing the buildup of harmful pollutants and ensuring the circulation of fresh air. Different methods, such as natural ventilation through windows and mechanical <a href="/wiki/Ventilation_(architecture)" title="Ventilation (architecture)">ventilation systems</a>, can be used depending on the building design and air quality needs. Ventilation often refers to the intentional delivery of the outside air to the building indoor space. It is one of the most important factors for maintaining acceptable indoor air quality in buildings. </p><p>Although ventilation is an integral component of maintaining good indoor air quality, it may not be satisfactory alone.<sup id="cite_ref-18" class="reference"><a href="#cite_note-18"><span class="cite-bracket">[</span>18<span class="cite-bracket">]</span></a></sup> A clear understanding of both indoor and outdoor air quality parameters is needed to improve the performance of ventilation in terms of ...<sup id="cite_ref-19" class="reference"><a href="#cite_note-19"><span class="cite-bracket">[</span>19<span class="cite-bracket">]</span></a></sup> In scenarios where outdoor <a href="/wiki/Air_pollution" title="Air pollution">pollution</a> would deteriorate indoor air quality, other treatment devices such as <a href="/wiki/Air_filtration" class="mw-redirect" title="Air filtration">filtration</a> may also be necessary.<sup id="cite_ref-20" class="reference"><a href="#cite_note-20"><span class="cite-bracket">[</span>20<span class="cite-bracket">]</span></a></sup> </p><p>Methods for ventilating a building may be divided into <i>mechanical/forced</i> and <i>natural</i> types.<sup id="cite_ref-21" class="reference"><a href="#cite_note-21"><span class="cite-bracket">[</span>21<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading3"><h3 id="Mechanical_or_forced">Mechanical or forced</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Heating,_ventilation,_and_air_conditioning&action=edit&section=12" title="Edit section: Mechanical or forced"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable">Further information: <a href="/wiki/Ventilation_(architecture)#Mechanical_systems" title="Ventilation (architecture)">Ventilation (architecture) § Mechanical systems</a></div> <figure typeof="mw:File/Thumb"><a href="/wiki/File:HVAC_Ventilation_Exhaust.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/e/e5/HVAC_Ventilation_Exhaust.jpg/350px-HVAC_Ventilation_Exhaust.jpg" decoding="async" width="350" height="233" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/e/e5/HVAC_Ventilation_Exhaust.jpg/525px-HVAC_Ventilation_Exhaust.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/e/e5/HVAC_Ventilation_Exhaust.jpg/700px-HVAC_Ventilation_Exhaust.jpg 2x" data-file-width="5184" data-file-height="3456" /></a><figcaption>HVAC ventilation exhaust for a 12-story building</figcaption></figure> <figure typeof="mw:File/Thumb"><a href="/wiki/File:Industrial_Exhaust_Fan.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/7/78/Industrial_Exhaust_Fan.jpg/350px-Industrial_Exhaust_Fan.jpg" decoding="async" width="350" height="233" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/7/78/Industrial_Exhaust_Fan.jpg/525px-Industrial_Exhaust_Fan.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/7/78/Industrial_Exhaust_Fan.jpg/700px-Industrial_Exhaust_Fan.jpg 2x" data-file-width="6000" data-file-height="4000" /></a><figcaption>An axial belt-drive exhaust fan serving an underground car park. This exhaust fan's operation is interlocked with the concentration of contaminants emitted by internal combustion engines.</figcaption></figure> <p>Mechanical, or forced, ventilation is provided by an <a href="/wiki/Air_handler" title="Air handler">air handler</a> (AHU) and used to control indoor air quality. Excess <a href="/wiki/Humidity" title="Humidity">humidity</a>, odors, and contaminants can often be controlled via dilution or replacement with outside air. However, in humid climates more energy is required to remove excess moisture from ventilation air. </p><p>Kitchens and bathrooms typically have mechanical exhausts to control odors and sometimes humidity. Factors in the design of such systems include the flow rate (which is a function of the fan speed and exhaust vent size) and noise level. <a href="/wiki/Direct_drive_mechanism" class="mw-redirect" title="Direct drive mechanism">Direct drive</a> fans are available for many applications and can reduce maintenance needs. </p><p>In summer, ceiling <a href="/wiki/Fan_(mechanical)" class="mw-redirect" title="Fan (mechanical)">fans</a> and table/floor fans circulate air within a room for the purpose of reducing the perceived temperature by increasing evaporation of perspiration on the skin of the occupants. Because hot air rises, <a href="/wiki/Ceiling_fan" title="Ceiling fan">ceiling fans</a> may be used to keep a room warmer in the winter by circulating the warm stratified air from the ceiling to the floor. </p> <div class="mw-heading mw-heading3"><h3 id="Passive">Passive</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Heating,_ventilation,_and_air_conditioning&action=edit&section=13" title="Edit section: Passive"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable">Main article: <a href="/wiki/Passive_ventilation" title="Passive ventilation">Passive ventilation</a></div> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:N%26AMOV_-_Schoolroom_-_Impulsion.png" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/b/b8/N%26AMOV_-_Schoolroom_-_Impulsion.png/220px-N%26AMOV_-_Schoolroom_-_Impulsion.png" decoding="async" width="220" height="207" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/b/b8/N%26AMOV_-_Schoolroom_-_Impulsion.png/330px-N%26AMOV_-_Schoolroom_-_Impulsion.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/b/b8/N%26AMOV_-_Schoolroom_-_Impulsion.png/440px-N%26AMOV_-_Schoolroom_-_Impulsion.png 2x" data-file-width="468" data-file-height="440" /></a><figcaption>Ventilation on the <a href="/wiki/Downdraught" class="mw-redirect" title="Downdraught">downdraught</a> system, by impulsion, or the <a href="/wiki/Plenum_space" title="Plenum space">'plenum' principle</a>, applied to schoolrooms (1899)</figcaption></figure> <p>Natural ventilation is the ventilation of a building with outside air without using fans or other mechanical systems. It can be via operable windows, louvers, or <a href="/wiki/Trickle_vent" title="Trickle vent">trickle vents</a> when spaces are small and the architecture permits. <a href="/wiki/ASHRAE" title="ASHRAE">ASHRAE</a> defined Natural ventilation as the flow of air through open windows, doors, grilles, and other planned <a href="/wiki/Building_envelope" title="Building envelope">building envelope</a> <a href="/wiki/Penetration_(firestop)" title="Penetration (firestop)">penetrations</a>, and as being driven by natural and/or artificially produced pressure differentials.<sup id="cite_ref-ASHRAE_1-1" class="reference"><a href="#cite_note-ASHRAE-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup> </p><p>Natural ventilation strategies also include <a href="/wiki/Cross_ventilation" title="Cross ventilation">cross ventilation</a>, which relies on wind pressure differences on opposite sides of a building. By strategically placing openings, such as windows or vents, on opposing walls, air is channeled through the space to enhance cooling and ventilation. Cross ventilation is most effective when there are clear, unobstructed paths for airflow within the building. </p><p>In more complex schemes, warm air is allowed to rise and flow out high building openings to the outside (<a href="/wiki/Stack_effect" title="Stack effect">stack effect</a>), causing cool outside air to be drawn into low building openings. Natural ventilation schemes can use very little energy, but care must be taken to ensure comfort. In warm or humid climates, maintaining thermal comfort solely via natural ventilation might not be possible. <a href="/wiki/Air_conditioning" title="Air conditioning">Air conditioning</a> systems are used, either as backups or supplements. Air-side <a href="/wiki/Economizer#HVAC" title="Economizer">economizers</a> also use outside air to condition spaces, but do so using fans, ducts, dampers, and control systems to introduce and distribute cool outdoor air when appropriate. </p><p>An important component of natural ventilation is air change rate or <a href="/wiki/Air_changes_per_hour" title="Air changes per hour">air changes per hour</a>: the hourly rate of ventilation divided by the volume of the space. For example, six air changes per hour means an amount of new air, equal to the volume of the space, is added every ten minutes. For human comfort, a minimum of four air changes per hour is typical, though warehouses might have only two. Too high of an air change rate may be uncomfortable, akin to a <a href="/wiki/Wind_tunnel" title="Wind tunnel">wind tunnel</a> which has thousands of changes per hour. The highest air change rates are for crowded spaces, bars, night clubs, commercial kitchens at around 30 to 50 air changes per hour.<sup id="cite_ref-22" class="reference"><a href="#cite_note-22"><span class="cite-bracket">[</span>22<span class="cite-bracket">]</span></a></sup> </p><p>Room pressure can be either positive or negative with respect to outside the room. Positive pressure occurs when there is more air being supplied than exhausted, and is common to reduce the infiltration of outside contaminants.<sup id="cite_ref-23" class="reference"><a href="#cite_note-23"><span class="cite-bracket">[</span>23<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading3"><h3 id="Airborne_diseases">Airborne diseases</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Heating,_ventilation,_and_air_conditioning&action=edit&section=14" title="Edit section: Airborne diseases"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Natural ventilation <sup id="cite_ref-24" class="reference"><a href="#cite_note-24"><span class="cite-bracket">[</span>24<span class="cite-bracket">]</span></a></sup> is a key factor in reducing the spread of airborne illnesses such as tuberculosis, the common cold, influenza, meningitis or COVID-19. Opening doors and windows are good ways to maximize natural ventilation, which would make the risk of airborne contagion much lower than with costly and maintenance-requiring mechanical systems. Old-fashioned clinical areas with high ceilings and large windows provide the greatest protection. Natural ventilation costs little and is maintenance free, and is particularly suited to limited-resource settings and tropical climates, where the burden of TB and institutional TB transmission is highest. In settings where respiratory isolation is difficult and climate permits, windows and doors should be opened to reduce the risk of airborne contagion. Natural ventilation requires little maintenance and is inexpensive.<sup id="cite_ref-25" class="reference"><a href="#cite_note-25"><span class="cite-bracket">[</span>25<span class="cite-bracket">]</span></a></sup> </p><p>Natural ventilation is not practical in much of the infrastructure because of climate. This means that the facilities need to have effective mechanical ventilation systems and or use Ceiling Level UV or FAR UV ventilation systems. </p> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Alpha_Black_Edition_-_Sirair_Airconditioner_with_UVC_(Ultraviolet_Germicidal_Irradiation).png" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/f/f9/Alpha_Black_Edition_-_Sirair_Airconditioner_with_UVC_%28Ultraviolet_Germicidal_Irradiation%29.png/220px-Alpha_Black_Edition_-_Sirair_Airconditioner_with_UVC_%28Ultraviolet_Germicidal_Irradiation%29.png" decoding="async" width="220" height="124" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/f/f9/Alpha_Black_Edition_-_Sirair_Airconditioner_with_UVC_%28Ultraviolet_Germicidal_Irradiation%29.png/330px-Alpha_Black_Edition_-_Sirair_Airconditioner_with_UVC_%28Ultraviolet_Germicidal_Irradiation%29.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/f/f9/Alpha_Black_Edition_-_Sirair_Airconditioner_with_UVC_%28Ultraviolet_Germicidal_Irradiation%29.png/440px-Alpha_Black_Edition_-_Sirair_Airconditioner_with_UVC_%28Ultraviolet_Germicidal_Irradiation%29.png 2x" data-file-width="5331" data-file-height="3000" /></a><figcaption>Alpha Black Edition - Sirair Air conditioner with UVC (Ultraviolet Germicidal Irradiation)</figcaption></figure> <p>Ventilation is measured in terms of Air Changes Per Hour (ACH). As of 2023, the CDC recommends that all spaces have a minimum of 5 ACH.<sup id="cite_ref-26" class="reference"><a href="#cite_note-26"><span class="cite-bracket">[</span>26<span class="cite-bracket">]</span></a></sup> For hospital rooms with airborne contagions the CDC recommends a minimum of 12 ACH.<sup id="cite_ref-27" class="reference"><a href="#cite_note-27"><span class="cite-bracket">[</span>27<span class="cite-bracket">]</span></a></sup> The challenges in facility ventilation are public unawareness,<sup id="cite_ref-28" class="reference"><a href="#cite_note-28"><span class="cite-bracket">[</span>28<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-29" class="reference"><a href="#cite_note-29"><span class="cite-bracket">[</span>29<span class="cite-bracket">]</span></a></sup> ineffective government oversight, poor building codes that are based on comfort levels, poor system operations, poor maintenance, and lack of transparency.<sup id="cite_ref-30" class="reference"><a href="#cite_note-30"><span class="cite-bracket">[</span>30<span class="cite-bracket">]</span></a></sup> </p><p>UVC or <a href="/wiki/Ultraviolet_germicidal_irradiation" title="Ultraviolet germicidal irradiation">Ultraviolet Germicidal Irradiation</a> is a function used in modern air conditioners which reduces airborne <a href="/wiki/Virus" title="Virus">viruses</a>, <a href="/wiki/Bacteria" title="Bacteria">bacteria</a>, and <a href="/wiki/Fungus" title="Fungus">fungi</a>, through the use of a built-in LED UV light that emits a gentle glow across the evaporator. As the cross-flow fan circulates the room air, any viruses are guided through the sterilization module’s irradiation range, rendering them instantly inactive.<sup id="cite_ref-31" class="reference"><a href="#cite_note-31"><span class="cite-bracket">[</span>31<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading2"><h2 id="Air_conditioning">Air conditioning</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Heating,_ventilation,_and_air_conditioning&action=edit&section=15" title="Edit section: Air conditioning"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable">Main article: <a href="/wiki/Air_conditioning" title="Air conditioning">Air conditioning</a></div> <p>An air conditioning system, or a standalone air conditioner, provides cooling and/or <a href="/wiki/Air_conditioning#Humidity_control" title="Air conditioning">humidity control</a> for all or part of a building. Air conditioned buildings often have sealed windows, because open windows would work against the system intended to maintain constant indoor air conditions. Outside, fresh air is generally drawn into the system by a vent into a mix air chamber for mixing with the space return air. Then the mixture air enters an indoor or outdoor heat exchanger section where the air is to be cooled down, then be guided to the space creating positive air pressure. The percentage of return air made up of fresh air can usually be manipulated by adjusting the opening of this vent. Typical fresh air intake is about 10% of the total supply air.<sup class="noprint Inline-Template Template-Fact" style="white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed"><span title="This claim needs references to reliable sources. (November 2019)">citation needed</span></a></i>]</sup> </p><p>Air conditioning and refrigeration are provided through the removal of heat. Heat can be removed through <a href="/wiki/Thermal_radiation" title="Thermal radiation">radiation</a>, convection, or <a href="/wiki/Thermal_conduction" title="Thermal conduction">conduction</a>. The heat transfer medium is a refrigeration system, such as water, air, ice, and chemicals are referred to as <a href="/wiki/Refrigerant" title="Refrigerant">refrigerants</a>. A refrigerant is employed either in a heat pump system in which a compressor is used to drive thermodynamic <a href="/wiki/Refrigeration_cycle" class="mw-redirect" title="Refrigeration cycle">refrigeration cycle</a>, or in a free cooling system that uses pumps to circulate a cool refrigerant (typically water or a glycol mix). </p><p>It is imperative that the air conditioning horsepower is sufficient for the area being cooled. Underpowered air conditioning systems will lead to power wastage and inefficient usage. Adequate horsepower is required for any air conditioner installed. </p> <div class="mw-heading mw-heading3"><h3 id="Refrigeration_cycle">Refrigeration cycle</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Heating,_ventilation,_and_air_conditioning&action=edit&section=16" title="Edit section: Refrigeration cycle"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable">Main article: <a href="/wiki/Heat_pump_and_refrigeration_cycle" title="Heat pump and refrigeration cycle">Heat pump and refrigeration cycle</a></div> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Heatpump.svg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/7/7d/Heatpump.svg/220px-Heatpump.svg.png" decoding="async" width="220" height="128" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/7/7d/Heatpump.svg/330px-Heatpump.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/7/7d/Heatpump.svg/440px-Heatpump.svg.png 2x" data-file-width="750" data-file-height="438" /></a><figcaption>A simple stylized diagram of the refrigeration cycle: 1) <a href="/wiki/Condensing_coil" class="mw-redirect" title="Condensing coil">condensing coil</a>, 2) <a href="/wiki/Thermal_expansion_valve" title="Thermal expansion valve">expansion valve</a>, 3) <a href="/wiki/Evaporator_coil" class="mw-redirect" title="Evaporator coil">evaporating coil</a>, 4) <a href="/wiki/Gas_compressor" class="mw-redirect" title="Gas compressor">compressor</a></figcaption></figure> <p>The refrigeration cycle uses four essential elements to cool, which are compressor, condenser, metering device, and evaporator. </p> <ul><li>At the inlet of a compressor, the refrigerant inside the system is in a low pressure, low temperature, gaseous state. The <b>compressor</b> pumps the refrigerant gas up to high pressure and temperature.</li> <li>From there it enters a heat exchanger (sometimes called a <b>condensing coil</b> or condenser) where it loses heat to the outside, cools, and condenses into its liquid phase.</li> <li>An <b><a href="/wiki/Thermal_expansion_valve" title="Thermal expansion valve">expansion valve</a></b> (also called metering device) regulates the refrigerant liquid to flow at the proper rate.</li> <li>The liquid refrigerant is returned to another heat exchanger where it is allowed to evaporate, hence the heat exchanger is often called an <b>evaporating coil</b> or evaporator. As the liquid refrigerant evaporates it absorbs heat from the inside air, returns to the compressor, and repeats the cycle. In the process, heat is absorbed from indoors and transferred outdoors, resulting in cooling of the building.</li></ul> <p>In variable climates, the system may include a <a href="/wiki/Reversing_valve" title="Reversing valve">reversing valve</a> that switches from heating in winter to cooling in summer. By reversing the flow of refrigerant, the heat pump refrigeration cycle is changed from cooling to heating or vice versa. This allows a facility to be heated and cooled by a single piece of equipment by the same means, and with the same hardware. </p> <div class="mw-heading mw-heading3"><h3 id="Free_cooling">Free cooling</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Heating,_ventilation,_and_air_conditioning&action=edit&section=17" title="Edit section: Free cooling"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable">Main article: <a href="/wiki/Free_cooling" title="Free cooling">Free cooling</a></div> <p>Free cooling systems can have very high efficiencies, and are sometimes combined with seasonal thermal energy storage so that the cold of winter can be used for summer air conditioning. Common storage mediums are deep aquifers or a natural underground rock mass accessed via a cluster of small-diameter, heat-exchanger-equipped boreholes. Some systems with small storages are hybrids, using free cooling early in the cooling season, and later employing a heat pump to chill the circulation coming from the storage. The heat pump is added-in because the storage acts as a <a href="/wiki/Heat_sink" title="Heat sink">heat sink</a> when the system is in cooling (as opposed to charging) mode, causing the temperature to gradually increase during the cooling season. </p><p>Some systems include an "economizer mode", which is sometimes called a "free-cooling mode". When economizing, the control system will open (fully or partially) the outside air damper and close (fully or partially) the return air damper. This will cause fresh, outside air to be supplied to the system. When the outside air is cooler than the demanded cool air, this will allow the demand to be met without using the mechanical supply of cooling (typically chilled water or a <a href="/w/index.php?title=Direct_expansion&action=edit&redlink=1" class="new" title="Direct expansion (page does not exist)">direct expansion</a> "DX" unit), thus saving energy. The control system can compare the temperature of the outside air vs. return air, or it can compare the <a href="/wiki/Enthalpy" title="Enthalpy">enthalpy</a> of the air, as is frequently done in climates where humidity is more of an issue. In both cases, the outside air must be less energetic than the return air for the system to enter the economizer mode. </p> <div class="mw-heading mw-heading3"><h3 id="Packaged_split_system">Packaged split system</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Heating,_ventilation,_and_air_conditioning&action=edit&section=18" title="Edit section: Packaged split system"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Central, "all-air" air-conditioning systems (or package systems) with a combined outdoor condenser/evaporator unit are often installed in North American residences, offices, and public buildings, but are difficult to retrofit (install in a building that was not designed to receive it) because of the bulky air ducts required.<sup id="cite_ref-32" class="reference"><a href="#cite_note-32"><span class="cite-bracket">[</span>32<span class="cite-bracket">]</span></a></sup> (Minisplit ductless systems are used in these situations.) Outside of North America, packaged systems are only used in limited applications involving large indoor space such as stadiums, theatres or exhibition halls. </p><p>An alternative to packaged systems is the use of separate indoor and outdoor coils in <a href="/wiki/Split-system_air_conditioner" class="mw-redirect" title="Split-system air conditioner">split systems</a>. Split systems are preferred and widely used worldwide except in North America. In North America, split systems are most often seen in residential applications, but they are gaining popularity in small commercial buildings. Split systems are used where ductwork is not feasible or where the space conditioning efficiency is of prime concern.<sup id="cite_ref-33" class="reference"><a href="#cite_note-33"><span class="cite-bracket">[</span>33<span class="cite-bracket">]</span></a></sup> The benefits of ductless air conditioning systems include easy installation, no ductwork, greater zonal control, flexibility of control, and quiet operation.<sup id="cite_ref-34" class="reference"><a href="#cite_note-34"><span class="cite-bracket">[</span>34<span class="cite-bracket">]</span></a></sup> In space conditioning, the duct losses can account for 30% of energy consumption.<sup id="cite_ref-35" class="reference"><a href="#cite_note-35"><span class="cite-bracket">[</span>35<span class="cite-bracket">]</span></a></sup> The use of minisplits can result in energy savings in space conditioning as there are no losses associated with ducting. </p><p>With the split system, the evaporator coil is connected to a remote condenser unit using refrigerant piping between an indoor and outdoor unit instead of ducting air directly from the outdoor unit. Indoor units with directional vents mount onto walls, suspended from ceilings, or fit into the ceiling. Other indoor units mount inside the ceiling cavity so that short lengths of duct handle air from the indoor unit to vents or diffusers around the rooms. </p><p>Split systems are more efficient and the footprint is typically smaller than the package systems. On the other hand, package systems tend to have a slightly lower indoor noise level compared to split systems since the fan motor is located outside. </p> <div class="mw-heading mw-heading3"><h3 id="Dehumidification">Dehumidification</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Heating,_ventilation,_and_air_conditioning&action=edit&section=19" title="Edit section: Dehumidification"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Dehumidification (air drying) in an air conditioning system is provided by the evaporator. Since the evaporator operates at a temperature below the <a href="/wiki/Dew_point" title="Dew point">dew point</a>, moisture in the air condenses on the evaporator coil tubes. This moisture is collected at the bottom of the evaporator in a pan and removed by piping to a central drain or onto the ground outside. </p><p>A <a href="/wiki/Dehumidifier" title="Dehumidifier">dehumidifier</a> is an air-conditioner-like device that controls the humidity of a room or building. It is often employed in basements that have a higher <a href="/wiki/Relative_humidity" class="mw-redirect" title="Relative humidity">relative humidity</a> because of their lower temperature (and propensity for damp floors and walls). In food retailing establishments, large open chiller cabinets are highly effective at dehumidifying the internal air. Conversely, a humidifier increases the humidity of a building. </p><p>The HVAC components that dehumidify the ventilation air deserve careful attention because outdoor air constitutes most of the annual humidity load for nearly all buildings.<sup id="cite_ref-36" class="reference"><a href="#cite_note-36"><span class="cite-bracket">[</span>36<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading3"><h3 id="Humidification">Humidification</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Heating,_ventilation,_and_air_conditioning&action=edit&section=20" title="Edit section: Humidification"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable">Main article: <a href="/wiki/Humidifier" title="Humidifier">Humidifier</a></div> <div class="mw-heading mw-heading3"><h3 id="Maintenance">Maintenance</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Heating,_ventilation,_and_air_conditioning&action=edit&section=21" title="Edit section: Maintenance"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>All modern air conditioning systems, even small window package units, are equipped with internal air filters.<sup class="noprint Inline-Template Template-Fact" style="white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed"><span title="This claim needs references to reliable sources. (September 2024)">citation needed</span></a></i>]</sup> These are generally of a lightweight gauze-like material, and must be replaced or washed as conditions warrant. For example, a building in a high dust environment, or a home with furry pets, will need to have the filters changed more often than buildings without these dirt loads. Failure to replace these filters as needed will contribute to a lower heat exchange rate, resulting in wasted energy, shortened equipment life, and higher energy bills; low air flow can result in iced-over evaporator coils, which can completely stop airflow. Additionally, very dirty or plugged filters can cause overheating during a heating cycle, which can result in damage to the system or even fire. </p><p>Because an air conditioner moves heat between the indoor coil and the outdoor coil, both must be kept clean. This means that, in addition to replacing the air filter at the evaporator coil, it is also necessary to regularly clean the condenser coil. Failure to keep the condenser clean will eventually result in harm to the compressor because the condenser coil is responsible for discharging both the indoor heat (as picked up by the evaporator) and the heat generated by the electric motor driving the compressor. </p> <div class="mw-heading mw-heading2"><h2 id="Energy_efficiency">Energy efficiency</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Heating,_ventilation,_and_air_conditioning&action=edit&section=22" title="Edit section: Energy efficiency"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>HVAC is significantly responsible for promoting <a href="/wiki/Efficient_energy_use" title="Efficient energy use">energy efficiency</a> of buildings as the building sector consumes the largest percentage of global energy.<sup id="cite_ref-37" class="reference"><a href="#cite_note-37"><span class="cite-bracket">[</span>37<span class="cite-bracket">]</span></a></sup> Since the 1980s, manufacturers of HVAC equipment have been making an effort to make the systems they manufacture more efficient. This was originally driven by rising energy costs, and has more recently been driven by increased awareness of environmental issues. Additionally, improvements to the HVAC system efficiency can also help increase occupant health and productivity.<sup id="cite_ref-38" class="reference"><a href="#cite_note-38"><span class="cite-bracket">[</span>38<span class="cite-bracket">]</span></a></sup> In the US, the <a href="/wiki/United_States_Environmental_Protection_Agency" title="United States Environmental Protection Agency">EPA</a> has imposed tighter restrictions over the years. There are several methods for making HVAC systems more efficient. </p> <div class="mw-heading mw-heading3"><h3 id="Heating_energy">Heating energy</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Heating,_ventilation,_and_air_conditioning&action=edit&section=23" title="Edit section: Heating energy"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>In the past, water heating was more efficient for heating buildings and was the standard in the United States. Today, <a href="/wiki/Forced_air" class="mw-redirect" title="Forced air">forced air</a> systems can double for air conditioning and are more popular. </p><p>Some benefits of forced air systems, which are now widely used in churches, schools, and high-end residences, are </p> <ul><li>Better air conditioning effects</li> <li>Energy savings of up to 15–20%</li> <li>Even conditioning<sup class="noprint Inline-Template Template-Fact" style="white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed"><span title="This claim needs references to reliable sources. (June 2009)">citation needed</span></a></i>]</sup></li></ul> <p>A drawback is the installation cost, which can be slightly higher than traditional HVAC systems. </p><p>Energy efficiency can be improved even more in central heating systems by introducing zoned heating. This allows a more granular application of heat, similar to non-central heating systems. Zones are controlled by multiple thermostats. In water heating systems the thermostats control <a href="/wiki/Zone_valve" title="Zone valve">zone valves</a>, and in forced air systems they control <a href="/wiki/Zone_damper" class="mw-redirect" title="Zone damper">zone dampers</a> inside the vents which selectively block the flow of air. In this case, the control system is very critical to maintaining a proper temperature. </p><p><a href="/wiki/Forecasting_(heating)" title="Forecasting (heating)">Forecasting</a> is another method of controlling building heating by calculating the demand for heating energy that should be supplied to the building in each time unit. </p> <div class="mw-heading mw-heading3"><h3 id="Ground_source_heat_pump">Ground source heat pump</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Heating,_ventilation,_and_air_conditioning&action=edit&section=24" title="Edit section: Ground source heat pump"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable">Main article: <a href="/wiki/Geothermal_heat_pump" class="mw-redirect" title="Geothermal heat pump">Geothermal heat pump</a></div> <p>Ground source, or geothermal, heat pumps are similar to ordinary heat pumps, but instead of transferring heat to or from outside air, they rely on the stable, even temperature of the earth to provide heating and air conditioning. Many regions experience seasonal temperature extremes, which would require large-capacity heating and cooling equipment to heat or cool buildings. For example, a conventional heat pump system used to heat a building in Montana's −57 <a href="/wiki/Celsius" title="Celsius">°C</a> (−70 <a href="/wiki/Fahrenheit" title="Fahrenheit">°F</a>) low temperature or cool a building in the highest temperature ever recorded in the US—57 °C (134 °F) in <a href="/wiki/Death_Valley" title="Death Valley">Death Valley</a>, California, in 1913 would require a large amount of energy due to the extreme difference between inside and outside air temperatures. A metre below the earth's surface, however, the ground remains at a relatively constant temperature. Utilizing this large source of relatively moderate temperature earth, a heating or cooling system's capacity can often be significantly reduced. Although ground temperatures vary according to latitude, at 1.8 metres (6 ft) underground, temperatures generally only range from 7 to 24 °C (45 to 75 °F). </p> <div class="mw-heading mw-heading3"><h3 id="Solar_air_conditioning">Solar air conditioning</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Heating,_ventilation,_and_air_conditioning&action=edit&section=25" title="Edit section: Solar air conditioning"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable">Main article: <a href="/wiki/Solar_air_conditioning" title="Solar air conditioning">Solar air conditioning</a></div> <p>Photovoltaic solar panels offer a new way to potentially decrease the operating cost of air conditioning. Traditional air conditioners run using alternating current, and hence, any direct-current solar power needs to be inverted to be compatible with these units. New variable-speed DC-motor units allow solar power to more easily run them since this conversion is unnecessary, and since the motors are tolerant of voltage fluctuations associated with variance in supplied solar power (e.g., due to cloud cover). </p> <div class="mw-heading mw-heading3"><h3 id="Ventilation_energy_recovery">Ventilation energy recovery</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Heating,_ventilation,_and_air_conditioning&action=edit&section=26" title="Edit section: Ventilation energy recovery"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p><a href="/wiki/Energy_recovery" title="Energy recovery">Energy recovery</a> systems sometimes utilize <a href="/wiki/Heat_recovery_ventilation" title="Heat recovery ventilation">heat recovery ventilation</a> or <a href="/wiki/Energy_recovery_ventilation" class="mw-redirect" title="Energy recovery ventilation">energy recovery ventilation</a> systems that employ <a href="/wiki/Heat_exchanger" title="Heat exchanger">heat exchangers</a> or <a href="/wiki/Thermal_wheel" title="Thermal wheel">enthalpy wheels</a> to recover <a href="/wiki/Sensible_heat" title="Sensible heat">sensible</a> or <a href="/wiki/Latent_heat" title="Latent heat">latent heat</a> from exhausted air. This is done by transfer of energy from the stale air inside the home to the incoming fresh air from outside. </p> <div class="mw-heading mw-heading3"><h3 id="Air_conditioning_energy">Air conditioning energy</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Heating,_ventilation,_and_air_conditioning&action=edit&section=27" title="Edit section: Air conditioning energy"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>The performance of vapor compression refrigeration cycles is limited by <a href="/wiki/Second_law_of_thermodynamics" title="Second law of thermodynamics">thermodynamics</a>.<sup id="cite_ref-39" class="reference"><a href="#cite_note-39"><span class="cite-bracket">[</span>39<span class="cite-bracket">]</span></a></sup> These air conditioning and heat pump devices <i>move</i> heat rather than convert it from one form to another, so <i><a href="/wiki/Thermal_efficiency" title="Thermal efficiency">thermal efficiencies</a></i> do not appropriately describe the performance of these devices. The <a href="/wiki/Coefficient_of_performance" title="Coefficient of performance">Coefficient of performance</a> (COP) measures performance, but this dimensionless measure has not been adopted. Instead, the Energy Efficiency Ratio (<i>EER</i>) has traditionally been used to characterize the performance of many HVAC systems. EER is the Energy Efficiency Ratio based on a 35 °C (95 °F) outdoor temperature. To more accurately describe the performance of air conditioning equipment over a typical cooling season a modified version of the EER, the Seasonal Energy Efficiency Ratio (<i>SEER</i>), or in Europe the <a href="/wiki/ESEER" class="mw-redirect" title="ESEER">ESEER</a>, is used. SEER ratings are based on seasonal temperature averages instead of a constant 35 °C (95 °F) outdoor temperature. The current industry minimum SEER rating is 14 SEER. Engineers have pointed out some areas where efficiency of the existing hardware could be improved. For example, the fan blades used to move the air are usually stamped from sheet metal, an economical method of manufacture, but as a result they are not aerodynamically efficient. A well-designed blade could reduce the electrical power required to move the air by a third.<sup id="cite_ref-40" class="reference"><a href="#cite_note-40"><span class="cite-bracket">[</span>40<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading3"><h3 id="Demand-controlled_kitchen_ventilation">Demand-controlled kitchen ventilation</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Heating,_ventilation,_and_air_conditioning&action=edit&section=28" title="Edit section: Demand-controlled kitchen ventilation"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable">Main article: <a href="/wiki/Demand_controlled_ventilation" title="Demand controlled ventilation">Demand controlled ventilation</a></div> <p>Demand-controlled kitchen ventilation (DCKV) is a building controls approach to controlling the volume of kitchen exhaust and supply air in response to the actual cooking loads in a commercial kitchen. Traditional commercial kitchen ventilation systems operate at 100% fan speed independent of the volume of cooking activity and DCKV technology changes that to provide significant fan energy and conditioned air savings. By deploying smart sensing technology, both the exhaust and supply fans can be controlled to capitalize on the <a href="/wiki/Affinity_laws" title="Affinity laws">affinity laws</a> for motor energy savings, reduce makeup air heating and cooling energy, increasing safety, and reducing ambient kitchen noise levels.<sup id="cite_ref-41" class="reference"><a href="#cite_note-41"><span class="cite-bracket">[</span>41<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading2"><h2 id="Air_filtration_and_cleaning">Air filtration and cleaning</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Heating,_ventilation,_and_air_conditioning&action=edit&section=29" title="Edit section: Air filtration and cleaning"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable">Main article: <a href="/wiki/Air_filter" title="Air filter">Air filter</a></div> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Air_handling_unit.JPG" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/0/00/Air_handling_unit.JPG/220px-Air_handling_unit.JPG" decoding="async" width="220" height="146" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/0/00/Air_handling_unit.JPG/330px-Air_handling_unit.JPG 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/0/00/Air_handling_unit.JPG/440px-Air_handling_unit.JPG 2x" data-file-width="1109" data-file-height="738" /></a><figcaption><a href="/wiki/Air_handling_unit" class="mw-redirect" title="Air handling unit">Air handling unit</a>, used for heating, cooling, and filtering the air</figcaption></figure> <p>Air cleaning and filtration removes particles, contaminants, vapors and gases from the air. The filtered and cleaned air then is used in heating, ventilation, and air conditioning. Air cleaning and filtration should be taken in account when protecting our building environments.<sup id="cite_ref-Howard_2003_1–63_42-0" class="reference"><a href="#cite_note-Howard_2003_1–63-42"><span class="cite-bracket">[</span>42<span class="cite-bracket">]</span></a></sup> If present, contaminants can come out from the HVAC systems if not removed or filtered properly. </p><p>Clean air delivery rate (CADR) is the amount of clean air an air cleaner provides to a room or space. When determining CADR, the amount of airflow in a space is taken into account. For example, an air cleaner with a flow rate of 30 cubic metres (1,000 cu ft) per minute and an efficiency of 50% has a CADR of 15 cubic metres (500 cu ft) per minute. Along with CADR, filtration performance is very important when it comes to the air in our indoor environment. This depends on the size of the particle or fiber, the filter packing density and depth, and the airflow rate.<sup id="cite_ref-Howard_2003_1–63_42-1" class="reference"><a href="#cite_note-Howard_2003_1–63-42"><span class="cite-bracket">[</span>42<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading2"><h2 id="Circulation_of_harmful_substances">Circulation of harmful substances</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Heating,_ventilation,_and_air_conditioning&action=edit&section=30" title="Edit section: Circulation of harmful substances"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <style data-mw-deduplicate="TemplateStyles:r1251242444">.mw-parser-output .ambox{border:1px solid #a2a9b1;border-left:10px solid #36c;background-color:#fbfbfb;box-sizing:border-box}.mw-parser-output .ambox+link+.ambox,.mw-parser-output .ambox+link+style+.ambox,.mw-parser-output .ambox+link+link+.ambox,.mw-parser-output .ambox+.mw-empty-elt+link+.ambox,.mw-parser-output .ambox+.mw-empty-elt+link+style+.ambox,.mw-parser-output .ambox+.mw-empty-elt+link+link+.ambox{margin-top:-1px}html body.mediawiki .mw-parser-output .ambox.mbox-small-left{margin:4px 1em 4px 0;overflow:hidden;width:238px;border-collapse:collapse;font-size:88%;line-height:1.25em}.mw-parser-output .ambox-speedy{border-left:10px solid #b32424;background-color:#fee7e6}.mw-parser-output .ambox-delete{border-left:10px solid #b32424}.mw-parser-output .ambox-content{border-left:10px solid #f28500}.mw-parser-output .ambox-style{border-left:10px solid #fc3}.mw-parser-output .ambox-move{border-left:10px solid #9932cc}.mw-parser-output .ambox-protection{border-left:10px solid #a2a9b1}.mw-parser-output .ambox .mbox-text{border:none;padding:0.25em 0.5em;width:100%}.mw-parser-output .ambox .mbox-image{border:none;padding:2px 0 2px 0.5em;text-align:center}.mw-parser-output .ambox .mbox-imageright{border:none;padding:2px 0.5em 2px 0;text-align:center}.mw-parser-output .ambox .mbox-empty-cell{border:none;padding:0;width:1px}.mw-parser-output .ambox .mbox-image-div{width:52px}@media(min-width:720px){.mw-parser-output .ambox{margin:0 10%}}@media print{body.ns-0 .mw-parser-output .ambox{display:none!important}}</style><table class="box-Expand_section plainlinks metadata ambox mbox-small-left ambox-content" role="presentation"><tbody><tr><td class="mbox-image"><span typeof="mw:File"><a href="/wiki/File:Wiki_letter_w_cropped.svg" class="mw-file-description"><img alt="[icon]" src="//upload.wikimedia.org/wikipedia/commons/thumb/1/1c/Wiki_letter_w_cropped.svg/20px-Wiki_letter_w_cropped.svg.png" decoding="async" width="20" height="14" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/1/1c/Wiki_letter_w_cropped.svg/30px-Wiki_letter_w_cropped.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/1/1c/Wiki_letter_w_cropped.svg/40px-Wiki_letter_w_cropped.svg.png 2x" data-file-width="44" data-file-height="31" /></a></span></td><td class="mbox-text"><div class="mbox-text-span">This section <b>needs expansion</b>. You can help by <a class="external text" href="https://en.wikipedia.org/w/index.php?title=Heating,_ventilation,_and_air_conditioning&action=edit&section=">adding to it</a>. <span class="date-container"><i>(<span class="date">October 2024</span>)</i></span></div></td></tr></tbody></table> <p>Poorly maintained air conditioners/ventilation systems can harbor mold, bacteria, and other contaminants, which are then circulated throughout indoor spaces, contributing to ...<sup id="cite_ref-43" class="reference"><a href="#cite_note-43"><span class="cite-bracket">[</span>43<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading2"><h2 id="Industry_and_standards">Industry and standards</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Heating,_ventilation,_and_air_conditioning&action=edit&section=31" title="Edit section: Industry and standards"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>The HVAC industry is a worldwide enterprise, with roles including operation and maintenance, system design and construction, equipment manufacturing and sales, and in education and research. The HVAC industry was historically regulated by the manufacturers of HVAC equipment, but regulating and standards organizations such as HARDI (Heating, Air-conditioning and Refrigeration Distributors International), <a href="/wiki/ASHRAE" title="ASHRAE">ASHRAE</a>, <a href="/wiki/SMACNA" class="mw-redirect" title="SMACNA">SMACNA</a>, ACCA (Air Conditioning Contractors of America), <a href="/wiki/Uniform_Mechanical_Code" title="Uniform Mechanical Code">Uniform Mechanical Code</a>, <a href="/wiki/International_Building_Code" class="mw-redirect" title="International Building Code">International Mechanical Code</a>, and <a href="/wiki/Air_Movement_and_Control_Association" title="Air Movement and Control Association">AMCA</a> have been established to support the industry and encourage high standards and achievement. (<a href="/wiki/United_Laboratories" class="mw-redirect" title="United Laboratories">UL</a> as an omnibus agency is not specific to the HVAC industry.) </p><p>The starting point in carrying out an estimate both for cooling and heating depends on the exterior climate and interior specified conditions. However, before taking up the heat load calculation, it is necessary to find fresh air requirements for each area in detail, as <a href="/wiki/Pressurization" title="Pressurization">pressurization</a> is an important consideration. </p> <div class="mw-heading mw-heading3"><h3 id="International">International</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Heating,_ventilation,_and_air_conditioning&action=edit&section=32" title="Edit section: International"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>ISO 16813:2006 is one of the <a href="/wiki/International_Organization_for_Standardization" title="International Organization for Standardization">ISO</a> building environment standards.<sup id="cite_ref-44" class="reference"><a href="#cite_note-44"><span class="cite-bracket">[</span>44<span class="cite-bracket">]</span></a></sup> It establishes the general principles of building environment design. It takes into account the need to provide a healthy indoor environment for the occupants as well as the need to protect the environment for future generations and promote collaboration among the various parties involved in building environmental design for sustainability. ISO16813 is applicable to new construction and the retrofit of existing buildings.<sup id="cite_ref-iso16813_45-0" class="reference"><a href="#cite_note-iso16813-45"><span class="cite-bracket">[</span>45<span class="cite-bracket">]</span></a></sup> </p><p>The building environmental design standard aims to:<sup id="cite_ref-iso16813_45-1" class="reference"><a href="#cite_note-iso16813-45"><span class="cite-bracket">[</span>45<span class="cite-bracket">]</span></a></sup> </p> <ul><li>provide the constraints concerning sustainability issues from the initial stage of the design process, with building and plant life cycle to be considered together with owning and operating costs from the beginning of the design process;</li> <li>assess the proposed design with rational criteria for indoor air quality, thermal comfort, acoustical comfort, visual comfort, energy efficiency, and HVAC system controls at every stage of the design process;</li> <li>iterate decisions and evaluations of the design throughout the design process.</li></ul> <div class="mw-heading mw-heading3"><h3 id="United_States">United States</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Heating,_ventilation,_and_air_conditioning&action=edit&section=33" title="Edit section: United States"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <div class="mw-heading mw-heading4"><h4 id="Licensing">Licensing</h4><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Heating,_ventilation,_and_air_conditioning&action=edit&section=34" title="Edit section: Licensing"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable">Main article: <a href="/wiki/Section_608_EPA_Certification" class="mw-redirect" title="Section 608 EPA Certification">Section 608 EPA Certification</a></div> <p>In the United States, federal licensure is generally handled by <a href="/wiki/Section_608_EPA_Certification" class="mw-redirect" title="Section 608 EPA Certification">EPA certified</a> (for installation and service of HVAC devices). </p><p>Many U.S. states have licensing for boiler operation. Some of these are listed as follows: </p> <ul><li>Arkansas <sup id="cite_ref-46" class="reference"><a href="#cite_note-46"><span class="cite-bracket">[</span>46<span class="cite-bracket">]</span></a></sup></li> <li>Georgia <sup id="cite_ref-47" class="reference"><a href="#cite_note-47"><span class="cite-bracket">[</span>47<span class="cite-bracket">]</span></a></sup></li> <li>Michigan <sup id="cite_ref-48" class="reference"><a href="#cite_note-48"><span class="cite-bracket">[</span>48<span class="cite-bracket">]</span></a></sup></li> <li>Minnesota <sup id="cite_ref-49" class="reference"><a href="#cite_note-49"><span class="cite-bracket">[</span>49<span class="cite-bracket">]</span></a></sup></li> <li>Montana <sup id="cite_ref-50" class="reference"><a href="#cite_note-50"><span class="cite-bracket">[</span>50<span class="cite-bracket">]</span></a></sup></li> <li>New Jersey <sup id="cite_ref-51" class="reference"><a href="#cite_note-51"><span class="cite-bracket">[</span>51<span class="cite-bracket">]</span></a></sup></li> <li>North Dakota <sup id="cite_ref-52" class="reference"><a href="#cite_note-52"><span class="cite-bracket">[</span>52<span class="cite-bracket">]</span></a></sup></li> <li>Ohio <sup id="cite_ref-53" class="reference"><a href="#cite_note-53"><span class="cite-bracket">[</span>53<span class="cite-bracket">]</span></a></sup></li> <li>Oklahoma <sup id="cite_ref-54" class="reference"><a href="#cite_note-54"><span class="cite-bracket">[</span>54<span class="cite-bracket">]</span></a></sup></li> <li>Oregon <sup id="cite_ref-55" class="reference"><a href="#cite_note-55"><span class="cite-bracket">[</span>55<span class="cite-bracket">]</span></a></sup></li></ul> <p>Finally, some U.S. cities may have additional labor laws that apply to HVAC professionals. </p> <div class="mw-heading mw-heading4"><h4 id="Societies">Societies</h4><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Heating,_ventilation,_and_air_conditioning&action=edit&section=35" title="Edit section: Societies"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable">See also: <a href="/wiki/American_Society_of_Heating,_Refrigerating_and_Air-Conditioning_Engineers" class="mw-redirect" title="American Society of Heating, Refrigerating and Air-Conditioning Engineers">American Society of Heating, Refrigerating and Air-Conditioning Engineers</a></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable">See also: <a href="/wiki/Air_Conditioning,_Heating_and_Refrigeration_Institute" title="Air Conditioning, Heating and Refrigeration Institute">Air Conditioning, Heating and Refrigeration Institute</a></div> <p>Many HVAC engineers are members of the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (<a href="/wiki/ASHRAE" title="ASHRAE">ASHRAE</a>). ASHRAE regularly organizes two annual technical committees and publishes recognized standards for HVAC design, which are updated every four years.<sup id="cite_ref-56" class="reference"><a href="#cite_note-56"><span class="cite-bracket">[</span>56<span class="cite-bracket">]</span></a></sup> </p><p>Another popular society is <a href="/wiki/AHRI" class="mw-redirect" title="AHRI">AHRI</a>, which provides regular information on new refrigeration technology, and publishes relevant <a href="/wiki/AHRI_Standard_700" class="mw-redirect" title="AHRI Standard 700">standards</a> and codes. </p> <div class="mw-heading mw-heading4"><h4 id="Codes">Codes</h4><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Heating,_ventilation,_and_air_conditioning&action=edit&section=36" title="Edit section: Codes"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Codes such as the UMC and IMC do include much detail on installation requirements, however. Other useful reference materials include items from <a href="/wiki/SMACNA" class="mw-redirect" title="SMACNA">SMACNA</a>, <a href="/wiki/ACGIH" class="mw-redirect" title="ACGIH">ACGIH</a>, and technical trade journals. </p><p>American design standards are legislated in the <a href="/wiki/Uniform_Mechanical_Code" title="Uniform Mechanical Code">Uniform Mechanical Code</a> or International Mechanical Code. In certain states, counties, or cities, either of these codes may be adopted and amended via various legislative processes. These codes are updated and published by the International Association of Plumbing and Mechanical Officials (<a href="/wiki/IAPMO" title="IAPMO">IAPMO</a>) or the International Code Council (<a href="/wiki/International_Code_Council" title="International Code Council">ICC</a>) respectively, on a 3-year code development cycle. Typically, local building permit departments are charged with enforcement of these standards on private and certain public properties. </p> <div class="mw-heading mw-heading4"><h4 id="Technicians">Technicians</h4><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Heating,_ventilation,_and_air_conditioning&action=edit&section=37" title="Edit section: Technicians"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <style data-mw-deduplicate="TemplateStyles:r1257001546">.mw-parser-output .infobox-subbox{padding:0;border:none;margin:-3px;width:auto;min-width:100%;font-size:100%;clear:none;float:none;background-color:transparent}.mw-parser-output .infobox-3cols-child{margin:auto}.mw-parser-output .infobox .navbar{font-size:100%}@media screen{html.skin-theme-clientpref-night .mw-parser-output .infobox-full-data:not(.notheme)>div:not(.notheme)[style]{background:#1f1f23!important;color:#f8f9fa}}@media screen and (prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .infobox-full-data:not(.notheme) div:not(.notheme){background:#1f1f23!important;color:#f8f9fa}}@media(min-width:640px){body.skin--responsive .mw-parser-output .infobox-table{display:table!important}body.skin--responsive .mw-parser-output .infobox-table>caption{display:table-caption!important}body.skin--responsive .mw-parser-output .infobox-table>tbody{display:table-row-group}body.skin--responsive .mw-parser-output .infobox-table tr{display:table-row!important}body.skin--responsive .mw-parser-output .infobox-table th,body.skin--responsive .mw-parser-output .infobox-table td{padding-left:inherit;padding-right:inherit}}</style><table class="infobox"><caption class="infobox-title">HVAC Technician</caption><tbody><tr><th colspan="2" class="infobox-header">Occupation</th></tr><tr><th scope="row" class="infobox-label"><div style="display: inline-block; line-height: 1.2em; padding: .1em 0;">Occupation type</div></th><td class="infobox-data"><a href="/wiki/Skilled_trades" class="mw-redirect" title="Skilled trades">Vocational</a></td></tr><tr><th scope="row" class="infobox-label"><div style="display: inline-block; line-height: 1.2em; padding: .1em 0;">Activity sectors</div></th><td class="infobox-data">Construction</td></tr><tr><th colspan="2" class="infobox-header">Description</th></tr><tr><th scope="row" class="infobox-label"><div style="display: inline-block; line-height: 1.2em; padding: .1em 0;">Education required</div></th><td class="infobox-data"><a href="/wiki/Apprenticeship" title="Apprenticeship">Apprenticeship</a></td></tr><tr><th scope="row" class="infobox-label"><div style="display: inline-block; line-height: 1.2em; padding: .1em 0;">Related jobs</div></th><td class="infobox-data"><a href="/wiki/Carpenter" class="mw-redirect" title="Carpenter">Carpenter</a>, <a href="/wiki/Electrician" title="Electrician">electrician</a>, <a href="/wiki/Plumber" title="Plumber">plumber</a>, <a href="/wiki/Welder" title="Welder">welder</a></td></tr></tbody></table> <p>An <b>HVAC technician</b> is a <a href="/wiki/Tradesman" class="mw-redirect" title="Tradesman">tradesman</a> who specializes in heating, ventilation, air conditioning, and refrigeration. HVAC technicians in the US can receive training through formal training institutions, where most earn <a href="/wiki/Associate_degree" title="Associate degree">associate degrees</a>. Training for HVAC technicians includes classroom lectures and hands-on tasks, and can be followed by an apprenticeship wherein the recent graduate works alongside a professional HVAC technician for a temporary period.<sup id="cite_ref-57" class="reference"><a href="#cite_note-57"><span class="cite-bracket">[</span>57<span class="cite-bracket">]</span></a></sup> HVAC techs who have been trained can also be certified in areas such as air conditioning, heat pumps, gas heating, and commercial refrigeration. </p> <div class="mw-heading mw-heading3"><h3 id="United_Kingdom">United Kingdom</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Heating,_ventilation,_and_air_conditioning&action=edit&section=38" title="Edit section: United Kingdom"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>The <a href="/wiki/Chartered_Institution_of_Building_Services_Engineers" title="Chartered Institution of Building Services Engineers">Chartered Institution of Building Services Engineers</a> is a body that covers the essential <a href="/wiki/Service_(systems_architecture)" title="Service (systems architecture)">Service (systems architecture)</a> that allow buildings to operate. It includes the electrotechnical, <a href="/wiki/Heating" class="mw-redirect" title="Heating">heating</a>, <a href="/wiki/Ventilating" class="mw-redirect" title="Ventilating">ventilating</a>, air conditioning, refrigeration and <a href="/wiki/Plumbing" title="Plumbing">plumbing</a> industries. To <a href="/wiki/Train" title="Train">train</a> as a <a href="/wiki/Building_services_engineering" title="Building services engineering">building services engineer</a>, the <a href="/wiki/Academic" class="mw-redirect" title="Academic">academic</a> requirements are GCSEs (A-C) / Standard Grades (1-3) in Maths and Science, which are important in measurements, planning and theory. Employers will often want a <a href="/wiki/Academic_degree" title="Academic degree">degree</a> in a branch of engineering, such as building environment <a href="/wiki/Engineering" title="Engineering">engineering</a>, electrical engineering or mechanical engineering. To become a full member of CIBSE, and so also to be registered by the <a href="/wiki/Engineering_Council_UK" class="mw-redirect" title="Engineering Council UK">Engineering Council UK</a> as a chartered engineer, engineers must also attain an Honours Degree and a master's degree in a relevant engineering subject.<sup class="noprint Inline-Template Template-Fact" style="white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed"><span title="This claim needs references to reliable sources. (December 2019)">citation needed</span></a></i>]</sup> CIBSE publishes several guides to HVAC design relevant to the UK market, and also the Republic of Ireland, Australia, New Zealand and Hong Kong. These guides include various recommended design criteria and standards, some of which are cited within the UK building regulations, and therefore form a legislative requirement for major building services works. The main guides are: </p> <ul><li>Guide A: Environmental Design</li> <li>Guide B: Heating, Ventilating, Air Conditioning and Refrigeration</li> <li>Guide C: Reference Data</li> <li>Guide D: Transportation systems in Buildings</li> <li>Guide E: Fire Safety Engineering</li> <li>Guide F: Energy Efficiency in Buildings</li> <li>Guide G: Public Health Engineering</li> <li>Guide H: Building Control Systems</li> <li>Guide J: Weather, Solar and Illuminance Data</li> <li>Guide K: Electricity in Buildings</li> <li>Guide L: Sustainability</li> <li>Guide M: Maintenance Engineering and Management</li></ul> <p>Within the <a href="/wiki/Construction" title="Construction">construction</a> sector, it is the job of the building services engineer to <a href="/wiki/Design" title="Design">design</a> and oversee the installation and maintenance of the essential services such as gas, <a href="/wiki/Electricity" title="Electricity">electricity</a>, water, heating and <a href="/wiki/Lighting" title="Lighting">lighting</a>, as well as many others. These all help to make buildings comfortable and healthy places to live and work in. Building Services is part of a sector that has over 51,000 businesses and employs represents 2–3% of the <a href="/wiki/GDP" class="mw-redirect" title="GDP">GDP</a>. </p> <div class="mw-heading mw-heading3"><h3 id="Australia">Australia</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Heating,_ventilation,_and_air_conditioning&action=edit&section=39" title="Edit section: Australia"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>The Air Conditioning and Mechanical Contractors Association of Australia (AMCA), Australian Institute of Refrigeration, Air Conditioning and Heating (AIRAH), Australian Refrigeration Mechanical Association and CIBSE are responsible. </p> <div class="mw-heading mw-heading3"><h3 id="Asia">Asia</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Heating,_ventilation,_and_air_conditioning&action=edit&section=40" title="Edit section: Asia"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Asian architectural temperature-control have different priorities than European methods. For example, Asian heating traditionally focuses on maintaining <a href="/wiki/Underfloor_heating#History" title="Underfloor heating">temperatures of objects such as the floor</a> or furnishings such as <a href="/wiki/Kotatsu" title="Kotatsu">Kotatsu</a> tables and directly warming people, as opposed to the Western focus, in modern periods, on designing air systems. </p> <div class="mw-heading mw-heading4"><h4 id="Philippines">Philippines</h4><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Heating,_ventilation,_and_air_conditioning&action=edit&section=41" title="Edit section: Philippines"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>The Philippine Society of Ventilating, Air Conditioning and Refrigerating Engineers (PSVARE) along with Philippine Society of Mechanical Engineers (PSME) govern on the codes and standards for HVAC / MVAC (MVAC means "mechanical ventilation and air conditioning") in the Philippines. </p> <div class="mw-heading mw-heading4"><h4 id="India">India</h4><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Heating,_ventilation,_and_air_conditioning&action=edit&section=42" title="Edit section: India"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>The Indian Society of Heating, Refrigerating and Air Conditioning Engineers (ISHRAE) was established to promote the HVAC industry in India. ISHRAE is an associate of ASHRAE. ISHRAE was founded at <a href="/wiki/New_Delhi" title="New Delhi">New Delhi</a><sup id="cite_ref-58" class="reference"><a href="#cite_note-58"><span class="cite-bracket">[</span>58<span class="cite-bracket">]</span></a></sup> in 1981 and a chapter was started in Bangalore in 1989. Between 1989 & 1993, ISHRAE chapters were formed in all major cities in India.<sup class="noprint Inline-Template Template-Fact" style="white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed"><span title="This claim needs references to reliable sources. (November 2019)">citation needed</span></a></i>]</sup> </p> <div class="mw-heading mw-heading2"><h2 id="See_also">See also</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Heating,_ventilation,_and_air_conditioning&action=edit&section=43" title="Edit section: See also"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <style data-mw-deduplicate="TemplateStyles:r1184024115">.mw-parser-output .div-col{margin-top:0.3em;column-width:30em}.mw-parser-output .div-col-small{font-size:90%}.mw-parser-output .div-col-rules{column-rule:1px solid #aaa}.mw-parser-output .div-col dl,.mw-parser-output .div-col ol,.mw-parser-output .div-col ul{margin-top:0}.mw-parser-output .div-col li,.mw-parser-output .div-col dd{page-break-inside:avoid;break-inside:avoid-column}</style><div class="div-col" style="column-width: 20em;"> <ul><li><a href="/wiki/Air_speed_(HVAC)" class="mw-redirect" title="Air speed (HVAC)">Air speed (HVAC)</a></li> <li><a href="/wiki/Architectural_engineering" title="Architectural engineering">Architectural engineering</a></li> <li><a href="/wiki/ASHRAE_Handbook" title="ASHRAE Handbook">ASHRAE Handbook</a></li> <li><a href="/wiki/Auxiliary_power_unit" title="Auxiliary power unit">Auxiliary power unit</a></li> <li><a href="/wiki/Cleanroom" title="Cleanroom">Cleanroom</a></li> <li><a href="/wiki/Electric_heating" title="Electric heating">Electric heating</a></li> <li><a href="/wiki/Fan_coil_unit" title="Fan coil unit">Fan coil unit</a></li> <li><a href="/wiki/Glossary_of_HVAC_terms" title="Glossary of HVAC terms">Glossary of HVAC terms</a></li> <li><a href="/wiki/Head-end_power" title="Head-end power">Head-end power</a></li> <li>Hotel electric power</li> <li><a href="/wiki/Mechanical_engineering" title="Mechanical engineering">Mechanical engineering</a></li> <li><a href="/wiki/Outdoor_wood-fired_boiler" title="Outdoor wood-fired boiler">Outdoor wood-fired boiler</a></li> <li><a href="/wiki/Radiant_cooling" class="mw-redirect" title="Radiant cooling">Radiant cooling</a></li> <li><a href="/wiki/Sick_building_syndrome" title="Sick building syndrome">Sick building syndrome</a></li> <li><a href="/wiki/Uniform_Codes" title="Uniform Codes">Uniform Codes</a></li> <li><a href="/wiki/Uniform_Mechanical_Code" title="Uniform Mechanical Code">Uniform Mechanical Code</a></li> <li><a href="/wiki/Ventilation_(architecture)" title="Ventilation (architecture)">Ventilation (architecture)</a></li> <li><a href="/wiki/World_Refrigeration_Day" title="World Refrigeration Day">World Refrigeration Day</a></li> <li><a href="/wiki/Wrightsoft" title="Wrightsoft">Wrightsoft</a></li></ul> </div> <div class="mw-heading mw-heading2"><h2 id="References">References</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Heating,_ventilation,_and_air_conditioning&action=edit&section=44" title="Edit section: References"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <style data-mw-deduplicate="TemplateStyles:r1239543626">.mw-parser-output .reflist{margin-bottom:0.5em;list-style-type:decimal}@media screen{.mw-parser-output .reflist{font-size:90%}}.mw-parser-output .reflist .references{font-size:100%;margin-bottom:0;list-style-type:inherit}.mw-parser-output .reflist-columns-2{column-width:30em}.mw-parser-output .reflist-columns-3{column-width:25em}.mw-parser-output .reflist-columns{margin-top:0.3em}.mw-parser-output .reflist-columns ol{margin-top:0}.mw-parser-output .reflist-columns li{page-break-inside:avoid;break-inside:avoid-column}.mw-parser-output .reflist-upper-alpha{list-style-type:upper-alpha}.mw-parser-output .reflist-upper-roman{list-style-type:upper-roman}.mw-parser-output .reflist-lower-alpha{list-style-type:lower-alpha}.mw-parser-output .reflist-lower-greek{list-style-type:lower-greek}.mw-parser-output .reflist-lower-roman{list-style-type:lower-roman}</style><div class="reflist reflist-columns references-column-width" style="column-width: 30em;"> <ol class="references"> <li id="cite_note-ASHRAE-1"><span class="mw-cite-backlink">^ <a href="#cite_ref-ASHRAE_1-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-ASHRAE_1-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text"><a rel="nofollow" class="external text" href="https://www.ashrae.org/advertising/handbook-advertising/fundamentals/ventilation-and-infiltration">Ventilation and Infiltration chapter</a>, Fundamentals volume of the <i><a href="/wiki/ASHRAE_Handbook" title="ASHRAE Handbook">ASHRAE Handbook</a></i>, ASHRAE, Inc., Atlanta, GA, 2005</span> </li> <li id="cite_note-Rock_and_Zhu-2"><span class="mw-cite-backlink"><b><a href="#cite_ref-Rock_and_Zhu_2-0">^</a></b></span> <span class="reference-text"><i>Designer's Guide to Ceiling-Based Air Diffusion</i>, Rock and Zhu, <a href="/wiki/ASHRAE" title="ASHRAE">ASHRAE</a>, Inc., <a href="/wiki/New_York_(state)" title="New York (state)">New York</a>, 2002</span> </li> <li id="cite_note-3"><span class="mw-cite-backlink"><b><a href="#cite_ref-3">^</a></b></span> <span class="reference-text"><style data-mw-deduplicate="TemplateStyles:r1238218222">.mw-parser-output cite.citation{font-style:inherit;word-wrap:break-word}.mw-parser-output .citation q{quotes:"\"""\"""'""'"}.mw-parser-output .citation:target{background-color:rgba(0,127,255,0.133)}.mw-parser-output .id-lock-free.id-lock-free a{background:url("//upload.wikimedia.org/wikipedia/commons/6/65/Lock-green.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-limited.id-lock-limited a,.mw-parser-output .id-lock-registration.id-lock-registration a{background:url("//upload.wikimedia.org/wikipedia/commons/d/d6/Lock-gray-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-subscription.id-lock-subscription a{background:url("//upload.wikimedia.org/wikipedia/commons/a/aa/Lock-red-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output 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R. 5225.0550 - EXPERIENCE REQUIREMENTS AND DOCUMENTATION FOR LICENSURE AS AN OPERATING ENGINEER"</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=Minn.+R.+5225.0550+-+EXPERIENCE+REQUIREMENTS+AND+DOCUMENTATION+FOR+LICENSURE+AS+AN+OPERATING+ENGINEER&rft_id=https%3A%2F%2Fwww.law.cornell.edu%2Fregulations%2Fminnesota%2FMinn-R-5225-0550&rfr_id=info%3Asid%2Fen.wikipedia.org%3AHeating%2C+ventilation%2C+and+air+conditioning" class="Z3988"></span></span> </li> <li id="cite_note-50"><span class="mw-cite-backlink"><b><a href="#cite_ref-50">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://www.law.cornell.edu/regulations/montana/department-24/chapter-24.122/subchapter-24.122.5">"Subchapter 24.122.5 - Licensing"</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=Subchapter+24.122.5+-+Licensing&rft_id=https%3A%2F%2Fwww.law.cornell.edu%2Fregulations%2Fmontana%2Fdepartment-24%2Fchapter-24.122%2Fsubchapter-24.122.5&rfr_id=info%3Asid%2Fen.wikipedia.org%3AHeating%2C+ventilation%2C+and+air+conditioning" class="Z3988"></span></span> </li> <li id="cite_note-51"><span class="mw-cite-backlink"><b><a href="#cite_ref-51">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://www.law.cornell.edu/regulations/new-jersey/title-12/chapter-90">"Chapter 90 - BOILERS, PRESSURE VESSELS, AND REFRIGERATION"</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=Chapter+90+-+BOILERS%2C+PRESSURE+VESSELS%2C+AND+REFRIGERATION&rft_id=https%3A%2F%2Fwww.law.cornell.edu%2Fregulations%2Fnew-jersey%2Ftitle-12%2Fchapter-90&rfr_id=info%3Asid%2Fen.wikipedia.org%3AHeating%2C+ventilation%2C+and+air+conditioning" class="Z3988"></span></span> </li> <li id="cite_note-52"><span class="mw-cite-backlink"><b><a href="#cite_ref-52">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://www.law.cornell.edu/regulations/north-dakota/title-33.1/article-33.1-14">"Article 33.1-14 - North Dakota Boiler Rules"</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=Article+33.1-14+-+North+Dakota+Boiler+Rules&rft_id=https%3A%2F%2Fwww.law.cornell.edu%2Fregulations%2Fnorth-dakota%2Ftitle-33.1%2Farticle-33.1-14&rfr_id=info%3Asid%2Fen.wikipedia.org%3AHeating%2C+ventilation%2C+and+air+conditioning" class="Z3988"></span></span> </li> <li id="cite_note-53"><span class="mw-cite-backlink"><b><a href="#cite_ref-53">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://www.law.cornell.edu/regulations/ohio/Ohio-Admin-Code-1301-3-5-10">"Ohio Admin. 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Retrieved <span class="nowrap">2023-06-22</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=www.bls.gov&rft.atitle=Heating%2C+Air+Conditioning%2C+and+Refrigeration+Mechanics+and+Installers+%3A+Occupational+Outlook+Handbook%3A+%3A+U.S.+Bureau+of+Labor+Statistics&rft_id=https%3A%2F%2Fwww.bls.gov%2Fooh%2Finstallation-maintenance-and-repair%2Fheating-air-conditioning-and-refrigeration-mechanics-and-installers.htm%23tab-4&rfr_id=info%3Asid%2Fen.wikipedia.org%3AHeating%2C+ventilation%2C+and+air+conditioning" class="Z3988"></span></span> </li> <li id="cite_note-58"><span class="mw-cite-backlink"><b><a href="#cite_ref-58">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://ishrae.in/Home/about_ishrae">"About ISHRAE"</a>. ISHRAE<span class="reference-accessdate">. Retrieved <span class="nowrap">2021-10-11</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=About+ISHRAE&rft.pub=ISHRAE&rft_id=https%3A%2F%2Fishrae.in%2FHome%2Fabout_ishrae&rfr_id=info%3Asid%2Fen.wikipedia.org%3AHeating%2C+ventilation%2C+and+air+conditioning" class="Z3988"></span></span> </li> </ol></div> <div class="mw-heading mw-heading2"><h2 id="Further_reading">Further reading</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Heating,_ventilation,_and_air_conditioning&action=edit&section=45" title="Edit section: Further reading"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <ul><li><i><a rel="nofollow" class="external text" href="https://web.archive.org/web/20150308003244/http://publicecodes.cyberregs.com/icod/imc/2012/index.htm">International Mechanical Code</a></i> (2012 (Second Printing)) by the International Code Council, Thomson Delmar Learning.</li> <li><i><a rel="nofollow" class="external text" href="https://archive.org/details/ModernRefrigerationAndAirConditioning">Modern Refrigeration and Air Conditioning</a></i> (August 2003) by Althouse, Turnquist, and Bracciano, Goodheart-Wilcox Publisher; 18th edition.</li> <li><i><a rel="nofollow" class="external text" href="https://www.nytimes.com/2012/08/19/sunday-review/air-conditioning-is-an-environmental-quandary.html?_r=0">The Cost of Cool.</a></i></li> <li><i><a rel="nofollow" class="external text" href="https://www.youtube.com/watch?v=Ky8y2jDk6i8&list=RDCMUCRPcR5JV-lRttH-b6iSgjNA&start_radio=1&rv=Ky8y2jDk6i8&t=0">Whai is LEV?</a></i></li></ul> <div class="mw-heading mw-heading2"><h2 id="External_links">External links</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Heating,_ventilation,_and_air_conditioning&action=edit&section=46" title="Edit section: External 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.navbar{display:none!important}}</style><div class="navbar plainlinks hlist navbar-mini"><ul><li class="nv-view"><a href="/wiki/Template:HVAC" title="Template:HVAC"><abbr title="View this template">v</abbr></a></li><li class="nv-talk"><a href="/wiki/Template_talk:HVAC" title="Template talk:HVAC"><abbr title="Discuss this template">t</abbr></a></li><li class="nv-edit"><a href="/wiki/Special:EditPage/Template:HVAC" title="Special:EditPage/Template:HVAC"><abbr title="Edit this template">e</abbr></a></li></ul></div><div id="Heating,_ventilation,_and_air_conditioning" style="font-size:114%;margin:0 4em"><a class="mw-selflink selflink">Heating, ventilation, and air conditioning</a></div></th></tr><tr><th scope="row" class="navbox-group" style="width:1%">Fundamental <br />concepts</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0;text-align: middle;"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Air_changes_per_hour" title="Air changes per hour">Air changes per hour</a></li> <li><a href="/wiki/Bake-out" title="Bake-out">Bake-out</a></li> <li><a href="/wiki/Building_envelope" title="Building envelope">Building envelope</a></li> <li><a href="/wiki/Convection" title="Convection">Convection</a></li> <li><a href="/wiki/Dilution_(equation)" title="Dilution (equation)">Dilution</a></li> <li><a href="/wiki/Domestic_energy_consumption" title="Domestic energy consumption">Domestic energy consumption</a></li> <li><a href="/wiki/Enthalpy" title="Enthalpy">Enthalpy</a></li> <li><a href="/wiki/Fluid_dynamics" title="Fluid dynamics">Fluid dynamics</a></li> <li><a href="/wiki/Gas_compressor" class="mw-redirect" title="Gas compressor">Gas compressor</a></li> <li><a href="/wiki/Heat_pump_and_refrigeration_cycle" title="Heat pump and refrigeration cycle">Heat pump and refrigeration cycle</a></li> <li><a href="/wiki/Heat_transfer" title="Heat transfer">Heat transfer</a></li> <li><a href="/wiki/Humidity" title="Humidity">Humidity</a></li> <li><a href="/wiki/Infiltration_(HVAC)" title="Infiltration (HVAC)">Infiltration</a></li> <li><a href="/wiki/Latent_heat" title="Latent heat">Latent heat</a></li> <li><a href="/wiki/Noise_control" title="Noise control">Noise control</a></li> <li><a href="/wiki/Outgassing" title="Outgassing">Outgassing</a></li> <li><a href="/wiki/Particulates" title="Particulates">Particulates</a></li> <li><a href="/wiki/Psychrometrics" title="Psychrometrics">Psychrometrics</a></li> <li><a href="/wiki/Sensible_heat" title="Sensible heat">Sensible heat</a></li> <li><a href="/wiki/Stack_effect" title="Stack effect">Stack effect</a></li> <li><a href="/wiki/Thermal_comfort" title="Thermal comfort">Thermal comfort</a></li> <li><a href="/wiki/Thermal_destratification" title="Thermal destratification">Thermal destratification</a></li> <li><a href="/wiki/Thermal_mass" title="Thermal mass">Thermal mass</a></li> <li><a href="/wiki/Thermodynamics" title="Thermodynamics">Thermodynamics</a></li> <li><a href="/wiki/Vapour_pressure_of_water" title="Vapour pressure of water">Vapour pressure of water</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Technology</th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0;text-align: middle;"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Absorption-compression_heat_pump" title="Absorption-compression heat pump">Absorption-compression heat pump</a></li> <li><a href="/wiki/Absorption_refrigerator" title="Absorption refrigerator">Absorption refrigerator</a></li> <li><a href="/wiki/Air_barrier" title="Air barrier">Air barrier</a></li> <li><a href="/wiki/Air_conditioning" title="Air conditioning">Air conditioning</a></li> <li><a href="/wiki/Antifreeze" title="Antifreeze">Antifreeze</a></li> <li><a href="/wiki/Automobile_air_conditioning" class="mw-redirect" title="Automobile air conditioning">Automobile air conditioning</a></li> <li><a href="/wiki/Autonomous_building" title="Autonomous building">Autonomous building</a></li> <li><a href="/wiki/Building_insulation_material" title="Building insulation material">Building insulation materials</a></li> <li><a href="/wiki/Central_heating" title="Central heating">Central heating</a></li> <li><a href="/wiki/Central_solar_heating" title="Central solar heating">Central solar heating</a></li> <li><a href="/wiki/Chilled_beam" title="Chilled beam">Chilled beam</a></li> <li><a href="/wiki/Chilled_water" title="Chilled water">Chilled water</a></li> <li><a href="/wiki/Constant_air_volume" title="Constant air volume">Constant air volume</a> (CAV)</li> <li><a href="/wiki/Coolant" title="Coolant">Coolant</a></li> <li><a href="/wiki/Cross_ventilation" title="Cross ventilation">Cross ventilation</a></li> <li><a href="/wiki/Dedicated_outdoor_air_system" title="Dedicated outdoor air system">Dedicated outdoor air system</a> (DOAS)</li> <li><a href="/wiki/Deep_water_source_cooling" title="Deep water source cooling">Deep water source cooling</a></li> <li><a href="/wiki/Demand_controlled_ventilation" title="Demand controlled ventilation">Demand controlled ventilation</a> (DCV)</li> <li><a href="/wiki/Displacement_ventilation" title="Displacement ventilation">Displacement ventilation</a></li> <li><a href="/wiki/District_cooling" title="District cooling">District cooling</a></li> <li><a href="/wiki/District_heating" title="District heating">District heating</a></li> <li><a href="/wiki/Electric_heating" title="Electric heating">Electric heating</a></li> <li><a href="/wiki/Energy_recovery_ventilation" class="mw-redirect" title="Energy recovery ventilation">Energy recovery ventilation</a> (ERV)</li> <li><a href="/wiki/Firestop" title="Firestop">Firestop</a></li> <li><a href="/wiki/Forced-air" title="Forced-air">Forced-air</a></li> <li><a href="/wiki/Forced-air_gas" title="Forced-air gas">Forced-air gas</a></li> <li><a href="/wiki/Free_cooling" title="Free cooling">Free cooling</a></li> <li><a href="/wiki/Heat_recovery_ventilation" title="Heat recovery ventilation">Heat recovery ventilation</a> (HRV)</li> <li><a href="/wiki/Hybrid_heat" title="Hybrid heat">Hybrid heat</a></li> <li><a href="/wiki/Hydronics" title="Hydronics">Hydronics</a></li> <li><a href="/wiki/Ice_storage_air_conditioning" title="Ice storage air conditioning">Ice storage air conditioning</a></li> <li><a href="/wiki/Kitchen_ventilation" title="Kitchen ventilation">Kitchen ventilation</a></li> <li><a href="/wiki/Mixed-mode_ventilation" title="Mixed-mode ventilation">Mixed-mode ventilation</a></li> <li><a href="/wiki/Microgeneration" title="Microgeneration">Microgeneration</a></li> <li><a href="/wiki/Passive_cooling" title="Passive cooling">Passive cooling</a></li> <li><a href="/wiki/Passive_daytime_radiative_cooling" title="Passive daytime radiative cooling">Passive daytime radiative cooling</a></li> <li><a href="/wiki/Passive_house" title="Passive house">Passive house</a></li> <li><a href="/wiki/Passive_ventilation" title="Passive ventilation">Passive ventilation</a></li> <li><a href="/wiki/Radiant_heating_and_cooling" title="Radiant heating and cooling">Radiant heating and cooling</a></li> <li><a href="/wiki/Radiant_cooling" class="mw-redirect" title="Radiant cooling">Radiant cooling</a></li> <li><a href="/wiki/Radiant_heating" class="mw-redirect" title="Radiant heating">Radiant heating</a></li> <li><a href="/wiki/Radon_mitigation" title="Radon mitigation">Radon mitigation</a></li> <li><a href="/wiki/Refrigeration" title="Refrigeration">Refrigeration</a></li> <li><a href="/wiki/Renewable_heat" title="Renewable heat">Renewable heat</a></li> <li><a href="/wiki/Room_air_distribution" title="Room air distribution">Room air distribution</a></li> <li><a href="/wiki/Solar_air_heat" title="Solar air heat">Solar air heat</a></li> <li><a href="/wiki/Solar_combisystem" title="Solar combisystem">Solar combisystem</a></li> <li><a href="/wiki/Solar_cooling" class="mw-redirect" title="Solar cooling">Solar cooling</a></li> <li><a href="/wiki/Solar_heating" class="mw-redirect" title="Solar heating">Solar heating</a></li> <li><a href="/wiki/Thermal_insulation" title="Thermal insulation">Thermal insulation</a></li> <li><a href="/wiki/Thermosiphon" title="Thermosiphon">Thermosiphon</a></li> <li><a href="/wiki/Underfloor_air_distribution" title="Underfloor air distribution">Underfloor air distribution</a></li> <li><a href="/wiki/Underfloor_heating" title="Underfloor heating">Underfloor heating</a></li> <li><a href="/wiki/Vapor_barrier" title="Vapor barrier">Vapor barrier</a></li> <li><a href="/wiki/Vapor-compression_refrigeration" title="Vapor-compression refrigeration">Vapor-compression refrigeration</a> (VCRS)</li> <li><a href="/wiki/Variable_air_volume" title="Variable air volume">Variable air volume</a> (VAV)</li> <li><a href="/wiki/Variable_refrigerant_flow" title="Variable refrigerant flow">Variable refrigerant flow</a> (VRF)</li> <li><a href="/wiki/Ventilation_(architecture)" title="Ventilation (architecture)">Ventilation</a></li> <li><a href="/wiki/Water_heat_recycling" title="Water heat recycling">Water heat recycling</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Components</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0;text-align: middle;"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Air_conditioner_inverter" class="mw-redirect" title="Air conditioner inverter">Air conditioner inverter</a></li> <li><a href="/wiki/Air_door" title="Air door">Air door</a></li> <li><a href="/wiki/Air_filter" title="Air filter">Air filter</a></li> <li><a href="/wiki/Air_handler" title="Air handler">Air handler</a></li> <li><a href="/wiki/Air_ioniser" title="Air ioniser">Air ionizer</a></li> <li><a href="/wiki/Air-mixing_plenum" title="Air-mixing plenum">Air-mixing plenum</a></li> <li><a href="/wiki/Air_purifier" title="Air purifier">Air purifier</a></li> <li><a href="/wiki/Air_source_heat_pump" title="Air source heat pump">Air source heat pump</a></li> <li><a href="/wiki/Attic_fan" title="Attic fan">Attic fan</a></li> <li><a href="/wiki/Automatic_balancing_valve" title="Automatic balancing valve">Automatic balancing valve</a></li> <li><a href="/wiki/Back_boiler" title="Back boiler">Back boiler</a></li> <li><a href="/wiki/Barrier_pipe" title="Barrier pipe">Barrier pipe</a></li> <li><a href="/wiki/Blast_damper" title="Blast damper">Blast damper</a></li> <li><a href="/wiki/Boiler" title="Boiler">Boiler</a></li> <li><a href="/wiki/Centrifugal_fan" title="Centrifugal fan">Centrifugal fan</a></li> <li><a href="/wiki/Ceramic_heater" title="Ceramic heater">Ceramic heater</a></li> <li><a href="/wiki/Chiller" title="Chiller">Chiller</a></li> <li><a href="/wiki/Condensate_pump" title="Condensate pump">Condensate pump</a></li> <li><a href="/wiki/Condenser_(heat_transfer)" title="Condenser (heat transfer)">Condenser</a></li> <li><a href="/wiki/Condensing_boiler" title="Condensing boiler">Condensing boiler</a></li> <li><a href="/wiki/Convection_heater" title="Convection heater">Convection heater</a></li> <li><a href="/wiki/Compressor" title="Compressor">Compressor</a></li> <li><a href="/wiki/Cooling_tower" title="Cooling tower">Cooling tower</a></li> <li><a href="/wiki/Damper_(flow)" title="Damper (flow)">Damper</a></li> <li><a href="/wiki/Dehumidifier" title="Dehumidifier">Dehumidifier</a></li> <li><a href="/wiki/Duct_(flow)" title="Duct (flow)">Duct</a></li> <li><a href="/wiki/Economizer" title="Economizer">Economizer</a></li> <li><a href="/wiki/Electrostatic_precipitator" title="Electrostatic precipitator">Electrostatic precipitator</a></li> <li><a href="/wiki/Evaporative_cooler" title="Evaporative cooler">Evaporative cooler</a></li> <li><a href="/wiki/Evaporator" title="Evaporator">Evaporator</a></li> <li><a href="/wiki/Exhaust_hood" class="mw-redirect" title="Exhaust hood">Exhaust hood</a></li> <li><a href="/wiki/Expansion_tank" title="Expansion tank">Expansion tank</a></li> <li><a href="/wiki/Fan_(machine)" title="Fan (machine)">Fan</a></li> <li><a href="/wiki/Fan_coil_unit" title="Fan coil unit">Fan coil unit</a></li> <li><a href="/wiki/Fan_filter_unit" title="Fan filter unit">Fan filter unit</a></li> <li><a href="/wiki/Fan_heater" title="Fan heater">Fan heater</a></li> <li><a href="/wiki/Fire_damper" title="Fire damper">Fire damper</a></li> <li><a href="/wiki/Fireplace" title="Fireplace">Fireplace</a></li> <li><a href="/wiki/Fireplace_insert" title="Fireplace insert">Fireplace insert</a></li> <li><a href="/wiki/Freeze_stat" title="Freeze stat">Freeze stat</a></li> <li><a href="/wiki/Flue" title="Flue">Flue</a></li> <li><a href="/wiki/Freon" title="Freon">Freon</a></li> <li><a href="/wiki/Fume_hood" title="Fume hood">Fume hood</a></li> <li><a href="/wiki/Furnace_(house_heating)" class="mw-redirect" title="Furnace (house heating)">Furnace</a></li> <li><a href="/wiki/Gas_compressor" class="mw-redirect" title="Gas compressor">Gas compressor</a></li> <li><a href="/wiki/Gas_heater" title="Gas heater">Gas heater</a></li> <li><a href="/wiki/Gasoline_heater" title="Gasoline heater">Gasoline heater</a></li> <li><a href="/wiki/Grease_duct" title="Grease duct">Grease duct</a></li> <li><a href="/wiki/Grille_(architecture)" title="Grille (architecture)">Grille</a></li> <li><a href="/wiki/Ground-coupled_heat_exchanger" title="Ground-coupled heat exchanger">Ground-coupled heat exchanger</a></li> <li><a href="/wiki/Ground_source_heat_pump" title="Ground source heat pump">Ground source heat pump</a></li> <li><a href="/wiki/Heat_exchanger" title="Heat exchanger">Heat exchanger</a></li> <li><a href="/wiki/Heat_pipe" title="Heat pipe">Heat pipe</a></li> <li><a href="/wiki/Heat_pump" title="Heat pump">Heat pump</a></li> <li><a href="/wiki/Heating_film" title="Heating film">Heating film</a></li> <li><a href="/wiki/Heating_system" title="Heating system">Heating system</a></li> <li><a href="/wiki/HEPA" title="HEPA">HEPA</a></li> <li><a href="/wiki/High_efficiency_glandless_circulating_pump" title="High efficiency glandless circulating pump">High efficiency glandless circulating pump</a></li> <li><a href="/wiki/High-pressure_cut-off_switch" class="mw-redirect" title="High-pressure cut-off switch">High-pressure cut-off switch</a></li> <li><a href="/wiki/Humidifier" title="Humidifier">Humidifier</a></li> <li><a href="/wiki/Infrared_heater" title="Infrared heater">Infrared heater</a></li> <li><a href="/wiki/Inverter_compressor" title="Inverter compressor">Inverter compressor</a></li> <li><a href="/wiki/Kerosene_heater" title="Kerosene heater">Kerosene heater</a></li> <li><a href="/wiki/Louver" title="Louver">Louver</a></li> <li><a href="/wiki/Mechanical_room" title="Mechanical room">Mechanical room</a></li> <li><a href="/wiki/Oil_heater" title="Oil heater">Oil heater</a></li> <li><a href="/wiki/Packaged_terminal_air_conditioner" title="Packaged terminal air conditioner">Packaged terminal air conditioner</a></li> <li><a href="/wiki/Plenum_space" title="Plenum space">Plenum space</a></li> <li><a href="/wiki/Pressurisation_ductwork" title="Pressurisation ductwork">Pressurisation ductwork</a></li> <li><a href="/wiki/Process_duct_work" title="Process duct work">Process duct work</a></li> <li><a href="/wiki/Radiator_(heating)" title="Radiator (heating)">Radiator</a></li> <li><a href="/wiki/Radiator_reflector" title="Radiator reflector">Radiator reflector</a></li> <li><a href="/wiki/Recuperator" title="Recuperator">Recuperator</a></li> <li><a href="/wiki/Refrigerant" title="Refrigerant">Refrigerant</a></li> <li><a href="/wiki/Register_(air_and_heating)" title="Register (air and heating)">Register</a></li> <li><a href="/wiki/Reversing_valve" title="Reversing valve">Reversing valve</a></li> <li><a href="/wiki/Run-around_coil" title="Run-around coil">Run-around coil</a></li> <li><a href="/wiki/Sail_switch" title="Sail switch">Sail switch</a></li> <li><a href="/wiki/Scroll_compressor" title="Scroll compressor">Scroll compressor</a></li> <li><a href="/wiki/Solar_chimney" title="Solar chimney">Solar chimney</a></li> <li><a href="/wiki/Solar-assisted_heat_pump" title="Solar-assisted heat pump">Solar-assisted heat pump</a></li> <li><a href="/wiki/Space_heater" title="Space heater">Space heater</a></li> <li><a href="/wiki/Smoke_canopy" title="Smoke canopy">Smoke canopy</a></li> <li><a href="/wiki/Smoke_damper" title="Smoke damper">Smoke damper</a></li> <li><a href="/wiki/Smoke_exhaust_ductwork" title="Smoke exhaust ductwork">Smoke exhaust ductwork</a></li> <li><a href="/wiki/Thermal_expansion_valve" title="Thermal expansion valve">Thermal expansion valve</a></li> <li><a href="/wiki/Thermal_wheel" title="Thermal wheel">Thermal wheel</a></li> <li><a href="/wiki/Thermostatic_radiator_valve" title="Thermostatic radiator valve">Thermostatic radiator valve</a></li> <li><a href="/wiki/Trickle_vent" title="Trickle vent">Trickle vent</a></li> <li><a href="/wiki/Trombe_wall" title="Trombe wall">Trombe wall</a></li> <li><a href="/wiki/TurboSwing" title="TurboSwing">TurboSwing</a></li> <li><a href="/wiki/Turning_vanes_(HVAC)" title="Turning vanes (HVAC)">Turning vanes</a></li> <li><a href="/wiki/Ultra-low_particulate_air" title="Ultra-low particulate air">Ultra-low particulate air</a> (ULPA)</li> <li><a href="/wiki/Whole-house_fan" title="Whole-house fan">Whole-house fan</a></li> <li><a href="/wiki/Windcatcher" title="Windcatcher">Windcatcher</a></li> <li><a href="/wiki/Wood-burning_stove" title="Wood-burning stove">Wood-burning stove</a></li> <li><a href="/wiki/Zone_valve" title="Zone valve">Zone valve</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Measurement<br />and control</th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0;text-align: middle;"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Air_flow_meter" title="Air flow meter">Air flow meter</a></li> <li><a href="/wiki/Aquastat" title="Aquastat">Aquastat</a></li> <li><a href="/wiki/BACnet" title="BACnet">BACnet</a></li> <li><a href="/wiki/Blower_door" title="Blower door">Blower door</a></li> <li><a href="/wiki/Building_automation" title="Building automation">Building automation</a></li> <li><a href="/wiki/Carbon_dioxide_sensor" title="Carbon dioxide sensor">Carbon dioxide sensor</a></li> <li><a href="/wiki/Clean_air_delivery_rate" title="Clean air delivery rate">Clean air delivery rate</a> (CADR)</li> <li><a href="/wiki/Control_valve" title="Control valve">Control valve</a></li> <li><a href="/wiki/Gas_detector" title="Gas detector">Gas detector</a></li> <li><a href="/wiki/Home_energy_monitor" title="Home energy monitor">Home energy monitor</a></li> <li><a href="/wiki/Humidistat" title="Humidistat">Humidistat</a></li> <li><a href="/wiki/HVAC_control_system" title="HVAC control system">HVAC control system</a></li> <li><a href="/wiki/Infrared_thermometer" title="Infrared thermometer">Infrared thermometer</a></li> <li><a href="/wiki/Intelligent_buildings" class="mw-redirect" title="Intelligent buildings">Intelligent buildings</a></li> <li><a href="/wiki/LonWorks" title="LonWorks">LonWorks</a></li> <li><a href="/wiki/Minimum_efficiency_reporting_value" title="Minimum efficiency reporting value">Minimum efficiency reporting value</a> (MERV)</li> <li><a href="/wiki/Normal_temperature_and_pressure" class="mw-redirect" title="Normal temperature and pressure">Normal temperature and pressure</a> (NTP)</li> <li><a href="/wiki/OpenTherm" title="OpenTherm">OpenTherm</a></li> <li><a href="/wiki/Programmable_communicating_thermostat" title="Programmable communicating thermostat">Programmable communicating thermostat</a></li> <li><a href="/wiki/Programmable_thermostat" title="Programmable thermostat">Programmable thermostat</a></li> <li><a href="/wiki/Psychrometrics" title="Psychrometrics">Psychrometrics</a></li> <li><a href="/wiki/Room_temperature" title="Room temperature">Room temperature</a></li> <li><a href="/wiki/Smart_thermostat" title="Smart thermostat">Smart thermostat</a></li> <li><a href="/wiki/Standard_temperature_and_pressure" title="Standard temperature and pressure">Standard temperature and pressure</a> (STP)</li> <li><a href="/wiki/Thermographic_camera" class="mw-redirect" title="Thermographic camera">Thermographic camera</a></li> <li><a href="/wiki/Thermostat" title="Thermostat">Thermostat</a></li> <li><a href="/wiki/Thermostatic_radiator_valve" title="Thermostatic radiator valve">Thermostatic radiator valve</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Professions,<br />trades,<br />and services</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0;text-align: middle;"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Architectural_acoustics" title="Architectural acoustics">Architectural acoustics</a></li> <li><a href="/wiki/Architectural_engineering" title="Architectural engineering">Architectural engineering</a></li> <li><a href="/wiki/Architectural_technologist" title="Architectural technologist">Architectural technologist</a></li> <li><a href="/wiki/Building_services_engineering" title="Building services engineering">Building services engineering</a></li> <li><a href="/wiki/Building_information_modeling" title="Building information modeling">Building information modeling</a> (BIM)</li> <li><a href="/wiki/Deep_energy_retrofit" title="Deep energy retrofit">Deep energy retrofit</a></li> <li><a href="/wiki/Duct_cleaning" class="mw-redirect" title="Duct cleaning">Duct cleaning</a></li> <li><a href="/wiki/Duct_leakage_testing" title="Duct leakage testing">Duct leakage testing</a></li> <li><a href="/wiki/Environmental_engineering" title="Environmental engineering">Environmental engineering</a></li> <li><a href="/wiki/Hydronic_balancing" title="Hydronic balancing">Hydronic balancing</a></li> <li><a href="/wiki/Kitchen_exhaust_cleaning" title="Kitchen exhaust cleaning">Kitchen exhaust cleaning</a></li> <li><a href="/wiki/Mechanical_engineering" title="Mechanical engineering">Mechanical engineering</a></li> <li><a href="/wiki/Mechanical,_electrical,_and_plumbing" title="Mechanical, electrical, and plumbing">Mechanical, electrical, and plumbing</a></li> <li><a href="/wiki/Mold_growth,_assessment,_and_remediation" class="mw-redirect" title="Mold growth, assessment, and remediation">Mold growth, assessment, and remediation</a></li> <li><a href="/wiki/Refrigerant_reclamation" title="Refrigerant reclamation">Refrigerant reclamation</a></li> <li><a href="/wiki/Testing,_adjusting,_balancing" title="Testing, adjusting, balancing">Testing, adjusting, balancing</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Industry <br />organizations</th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0;text-align: middle;"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Air_Conditioning,_Heating_and_Refrigeration_Institute" title="Air Conditioning, Heating and Refrigeration Institute">AHRI</a></li> <li><a href="/wiki/Air_Movement_and_Control_Association" title="Air Movement and Control Association">AMCA</a></li> <li><a href="/wiki/ASHRAE" title="ASHRAE">ASHRAE</a></li> <li><a href="/wiki/ASTM_International" title="ASTM International">ASTM International</a></li> <li><a href="/wiki/Building_Research_Establishment" title="Building Research Establishment">BRE</a></li> <li><a href="/wiki/BSRIA" title="BSRIA">BSRIA</a></li> <li><a href="/wiki/Chartered_Institution_of_Building_Services_Engineers" title="Chartered Institution of Building Services Engineers">CIBSE</a></li> <li><a href="/wiki/Institute_of_Refrigeration" title="Institute of Refrigeration">Institute of Refrigeration</a></li> <li><a href="/wiki/International_Institute_of_Refrigeration" title="International Institute of Refrigeration">IIR</a></li> <li><a href="/wiki/Leadership_in_Energy_and_Environmental_Design" class="mw-redirect" title="Leadership in Energy and Environmental Design">LEED</a></li> <li><a href="/wiki/Sheet_Metal_and_Air_Conditioning_Contractors%27_National_Association" title="Sheet Metal and Air Conditioning Contractors' National Association">SMACNA</a></li> <li><a href="/wiki/Uniform_Mechanical_Code" title="Uniform Mechanical Code">UMC</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Health and safety</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0;text-align: middle;"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Indoor_air_quality" title="Indoor air quality">Indoor air quality</a> (IAQ)</li> <li><a href="/wiki/Passive_smoking" title="Passive smoking">Passive smoking</a></li> <li><a href="/wiki/Sick_building_syndrome" title="Sick building syndrome">Sick building syndrome</a> (SBS)</li> <li><a href="/wiki/Volatile_organic_compound" title="Volatile organic compound">Volatile organic compound</a> (VOC)</li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">See also</th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0;text-align: middle;"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/ASHRAE_Handbook" title="ASHRAE Handbook">ASHRAE Handbook</a></li> <li><a href="/wiki/Building_science" title="Building science">Building science</a></li> <li><a href="/wiki/Fireproofing" title="Fireproofing">Fireproofing</a></li> <li><a href="/wiki/Glossary_of_HVAC_terms" title="Glossary of HVAC terms">Glossary of HVAC terms</a></li> <li><a href="/wiki/Warm_Spaces" title="Warm Spaces">Warm Spaces</a></li> <li><a href="/wiki/World_Refrigeration_Day" title="World Refrigeration Day">World Refrigeration Day</a></li> <li><a href="/wiki/Template:Home_automation" title="Template:Home automation">Template:Home automation</a></li> <li><a href="/wiki/Template:Solar_energy" title="Template:Solar energy">Template:Solar energy</a></li></ul> </div></td></tr></tbody></table></div> <div class="navbox-styles"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1129693374"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236075235"></div><div role="navigation" class="navbox" aria-labelledby="Home_automation" style="padding:3px"><table class="nowraplinks hlist mw-collapsible autocollapse navbox-inner" style="border-spacing:0;background:transparent;color:inherit"><tbody><tr><th scope="col" class="navbox-title" colspan="3"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1129693374"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1239400231"><div class="navbar plainlinks hlist navbar-mini"><ul><li class="nv-view"><a href="/wiki/Template:Home_automation" title="Template:Home automation"><abbr title="View this template">v</abbr></a></li><li class="nv-talk"><a href="/wiki/Template_talk:Home_automation" title="Template talk:Home automation"><abbr title="Discuss this template">t</abbr></a></li><li class="nv-edit"><a href="/wiki/Special:EditPage/Template:Home_automation" title="Special:EditPage/Template:Home automation"><abbr title="Edit this template">e</abbr></a></li></ul></div><div id="Home_automation" style="font-size:114%;margin:0 4em"><a href="/wiki/Home_automation" title="Home automation">Home automation</a></div></th></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Home_automation#System" title="Home automation">System</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:1%">Elements</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Actuator" title="Actuator">Actuators</a></li> <li><a href="/wiki/Programmable_logic_controller" title="Programmable logic controller">Hardware controllers</a></li> <li><a href="/wiki/Sensor" title="Sensor">Sensors</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Home_automation#Interconnection" title="Home automation">Interconnection <br />type</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Wire" title="Wire">Wired</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li>Cable (<a href="/wiki/Digital_subscriber_line" title="Digital subscriber line">xDSL</a>)</li> <li><a href="/wiki/Optical_fiber" title="Optical fiber">Optical fiber</a></li> <li><a href="/wiki/Power-line_communication" title="Power-line communication">Powerline</a> <ul><li><a href="/wiki/PLCBUS" title="PLCBUS">PLCBUS</a></li> <li><a href="/wiki/Universal_powerline_bus" title="Universal powerline bus">Universal powerline bus</a> (UPB)</li> <li><a href="/wiki/X10_(industry_standard)" title="X10 (industry standard)">X10</a></li></ul></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Wireless" title="Wireless">Wireless</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Radio_frequency" title="Radio frequency">Radio frequency</a> <ul><li><a href="/wiki/Bluetooth" title="Bluetooth">Bluetooth</a></li> <li><a href="/wiki/Bluetooth_Low_Energy" title="Bluetooth Low Energy">Bluetooth Low Energy</a></li> <li><a href="/wiki/Digital_Enhanced_Cordless_Telecommunications" class="mw-redirect" title="Digital Enhanced Cordless Telecommunications">DECT</a></li> <li><a href="/wiki/EnOcean" title="EnOcean">EnOcean</a></li> <li><a href="/wiki/General_Packet_Radio_Service" title="General Packet Radio Service">GPRS</a></li> <li><a href="/wiki/MyriaNed" title="MyriaNed">MyriaNed</a></li> <li><a href="/wiki/One-Net" title="One-Net">One-Net</a></li> <li><a href="/wiki/Thread_(network_protocol)" title="Thread (network protocol)">Thread</a></li> <li><a href="/wiki/UMTS" title="UMTS">UMTS</a></li> <li><a href="/wiki/Wi-Fi" title="Wi-Fi">Wi-Fi</a></li> <li><a href="/wiki/Zigbee" title="Zigbee">Zigbee</a></li> <li><a href="/wiki/Z-Wave" title="Z-Wave">Z-Wave</a></li></ul></li> <li><a href="/wiki/Infrared" title="Infrared">Infrared</a> (<a href="/wiki/Consumer_IR" title="Consumer IR">Consumer IR</a>)</li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Both</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Insteon" title="Insteon">Insteon</a></li> <li><a href="/wiki/KNX" title="KNX">KNX</a></li> <li><a href="/wiki/Matter_(standard)" title="Matter (standard)">Matter</a></li></ul> </div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Home_automation#Classifications_of_domestic_network_technologies" title="Home automation">Network<br />technologies,<br />by function</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:1%">Device<br />interconnection</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Bluetooth" title="Bluetooth">Bluetooth</a></li> <li><a href="/wiki/Bluetooth_Low_Energy" title="Bluetooth Low Energy">Bluetooth Low Energy</a></li> <li><a href="/wiki/IEEE_1394" title="IEEE 1394">FireWire</a></li> <li><a href="/wiki/Infrared_Data_Association" title="Infrared Data Association">IrDA</a></li> <li><a href="/wiki/USB" title="USB">USB</a></li> <li><a href="/wiki/Zigbee" title="Zigbee">Zigbee</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Control and<br />automation</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/AllJoyn" title="AllJoyn">AllJoyn</a></li> <li><a href="/wiki/Bus_SCS" title="Bus SCS">Bus SCS</a> with <a href="/wiki/OpenWebNet" title="OpenWebNet">OpenWebNet</a></li> <li><a href="/wiki/C-Bus_(protocol)" title="C-Bus (protocol)">C-Bus (protocol)</a></li> <li><a href="/wiki/CEBus" title="CEBus">CEBus</a></li> <li><a href="/wiki/EnOcean" title="EnOcean">EnOcean</a></li> <li><a href="/wiki/European_Home_Systems_Protocol" title="European Home Systems Protocol">EHS</a></li> <li><a href="/wiki/Insteon" title="Insteon">Insteon</a></li> <li><a href="/wiki/IP500_Alliance" title="IP500 Alliance">IP500</a></li> <li><a href="/w/index.php?title=Luxom&action=edit&redlink=1" class="new" title="Luxom (page does not exist)">Luxom</a></li> <li><a href="/wiki/KNX_(standard)" class="mw-redirect" title="KNX (standard)">KNX</a></li> <li><a href="/wiki/LonWorks" title="LonWorks">LonWorks</a></li> <li><a href="/wiki/One-Net" title="One-Net">One-Net</a></li> <li><a href="/wiki/Universal_powerline_bus" title="Universal powerline bus">Universal powerline bus</a></li> <li><a href="/wiki/X10_(industry_standard)" title="X10 (industry standard)">X10</a></li> <li><a href="/wiki/Zigbee" title="Zigbee">Zigbee</a></li> <li><a href="/wiki/Z-Wave" title="Z-Wave">Z-Wave</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Data<br />networking</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Ethernet" title="Ethernet">Ethernet</a></li> <li><a href="/wiki/HomePlug" title="HomePlug">HomePlug</a></li> <li><a href="/wiki/HomePNA" title="HomePNA">HomePNA</a></li> <li><a href="/wiki/Wi-Fi" title="Wi-Fi">Wi-Fi</a></li></ul> </div></td></tr></tbody></table><div></div></td></tr></tbody></table><div></div></td><td class="noviewer navbox-image" rowspan="3" style="width:1px;padding:0 0 0 2px"><div><span typeof="mw:File"><a href="/wiki/File:Patch_Panel.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/b/b9/Patch_Panel.jpg/155px-Patch_Panel.jpg" decoding="async" width="155" height="207" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/b/b9/Patch_Panel.jpg/233px-Patch_Panel.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/b/b9/Patch_Panel.jpg/310px-Patch_Panel.jpg 2x" data-file-width="2448" data-file-height="3264" /></a></span></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Home_automation#Tasks" title="Home automation">Tasks</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Home_automation#Audio_and_video" title="Home automation">Audio and video</a></li> <li><a class="mw-selflink selflink">Heating, ventilation, and air conditioning</a></li> <li><a href="/wiki/Lighting_control_system" title="Lighting control system">Lighting control system</a></li> <li><a href="/wiki/Home_automation#Other_systems" title="Home automation">Other systems</a></li> <li><a href="/wiki/Home_automation#Robotics" title="Home automation">Robotics</a></li> <li><a href="/wiki/Home_automation#Security" title="Home automation">Security</a></li> <li><a href="/wiki/Programmable_communicating_thermostat" title="Programmable communicating thermostat">Thermostat automation</a></li> <li><a href="/wiki/Residential_gateway" title="Residential gateway">Gateway</a></li> <li><a href="/wiki/Smart_home_hub" title="Smart home hub">Smart home hub</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Other</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Home_automation#Costs" title="Home automation">Costs</a></li> <li><a href="/wiki/Mesh_networking" title="Mesh networking">Mesh networking</a></li> <li><a href="/wiki/Home_automation#Organizations" title="Home automation">Organizations</a></li> <li><a href="/wiki/Smart_grid" title="Smart grid">Smart grid</a></li></ul> </div></td></tr><tr><td class="navbox-abovebelow" colspan="3"><div> <dl><dt>See also</dt> <dd><a href="/wiki/Home_of_the_future" title="Home of the future">Home of the future</a></dd> <dd><a href="/wiki/Building_automation" title="Building automation">Building automation</a></dd> <dd><a href="/wiki/Floor_plan" title="Floor plan">Floor plan</a></dd> <dd><a href="/wiki/Home_automation" title="Home automation">Home automation</a></dd> <dd><a href="/wiki/Home_energy_monitor" title="Home energy monitor">Home energy monitor</a></dd> <dd><a href="/wiki/Home_network" title="Home network">Home network</a></dd> <dd><a href="/wiki/Home_server" title="Home server">Home server</a></dd> <dd><a href="/wiki/Robotic_mapping" title="Robotic mapping">House navigation system</a></dd> <dd><a href="/wiki/INTEGER_Millennium_House" title="INTEGER Millennium House">INTEGER Millennium House</a></dd> <dd><a href="/wiki/House_for_the_Future,_Cardiff" title="House for the Future, Cardiff">The House for the Future</a></dd> <dd><a href="/wiki/Ubiquitous_computing" title="Ubiquitous computing">Ubiquitous computing</a></dd> <dd><a href="/wiki/Xanadu_Houses" 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