Designing HVAC to resist harmful microorganisms - Revision history

Editor at 18:35, 14 January 2022

2022-01-14T18:35:14Z

← Older revision		Revision as of 18:35, 14 January 2022
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	* Building ventilation and COVID-19 transmission risk.		* Building ventilation and COVID-19 transmission risk.
	* Clean indoor air for healthy living - New air filter standards.		* Clean indoor air for healthy living - New air filter standards.
		+	* High efficiency particulate arrestance HEPA.
	* Humidity.		* Humidity.
	* HVAC.		* HVAC.

Editor at 19:04, 13 December 2021

2021-12-13T19:04:34Z

← Older revision		Revision as of 19:04, 13 December 2021
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	* Air conditioning.		* Air conditioning.
		+	* Air filtration.
	* Air filtration and clean indoor air quality standards.		* Air filtration and clean indoor air quality standards.
	* Air pressure drop APD.		* Air pressure drop APD.

Editor at 16:10, 3 December 2021

2021-12-03T16:10:02Z

← Older revision		Revision as of 16:10, 3 December 2021
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	* Air conditioning.		* Air conditioning.
	* Air filtration and clean indoor air quality standards.		* Air filtration and clean indoor air quality standards.
		+	* Air pressure drop APD.
	* Back to the workplace: are you prepared?		* Back to the workplace: are you prepared?
	* BSRIA completes 2021 World Air Conditioning market studies.		* BSRIA completes 2021 World Air Conditioning market studies.

Editor at 18:36, 2 December 2021

2021-12-02T18:36:23Z

← Older revision		Revision as of 18:36, 2 December 2021
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	This article was written by Muhammad is an MEP consultant, LEED Green Associate. He has experience in the design and development of commercial and residential buildings. He currently lives in Dubai and he loves to write about construction in general and MEP in particular.		This article was written by Muhammad is an MEP consultant, LEED Green Associate. He has experience in the design and development of commercial and residential buildings. He currently lives in Dubai and he loves to write about construction in general and MEP in particular.

−	= Related articles on Designing Buildings ~~Wiki~~ =	+	= Related articles on Designing Buildings =

	* Air conditioning.		* Air conditioning.
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	* HVAC.		* HVAC.
	* IAQ developments accelerated by COVID-19 pandemic.		* IAQ developments accelerated by COVID-19 pandemic.
		+	* Minimum efficiency reporting value MERV.
	* SAGE EMG guidance on ventilation and COVID-19.		* SAGE EMG guidance on ventilation and COVID-19.
	* UV disinfection of building air to remove harmful bacteria and viruses.		* UV disinfection of building air to remove harmful bacteria and viruses.

Editor at 10:56, 24 September 2021

2021-09-24T10:56:03Z

← Older revision		Revision as of 10:56, 24 September 2021
Line 63:		Line 63:
	* Air conditioning.		* Air conditioning.
	* Air filtration and clean indoor air quality standards.		* Air filtration and clean indoor air quality standards.
		+	* Back to the workplace: are you prepared?
	* BSRIA completes 2021 World Air Conditioning market studies.		* BSRIA completes 2021 World Air Conditioning market studies.
	* Building ventilation and COVID-19 transmission risk.		* Building ventilation and COVID-19 transmission risk.

Editor at 12:11, 13 April 2021

2021-04-13T12:11:56Z

← Older revision		Revision as of 12:11, 13 April 2021
Line 64:		Line 64:
	* Air filtration and clean indoor air quality standards.		* Air filtration and clean indoor air quality standards.
	* BSRIA completes 2021 World Air Conditioning market studies.		* BSRIA completes 2021 World Air Conditioning market studies.
		+	* Building ventilation and COVID-19 transmission risk.
	* Clean indoor air for healthy living - New air filter standards.		* Clean indoor air for healthy living - New air filter standards.
	* Humidity.		* Humidity.

Editor at 12:27, 24 March 2021

2021-03-24T12:27:55Z

← Older revision		Revision as of 12:27, 24 March 2021
Line 63:		Line 63:
	* Air conditioning.		* Air conditioning.
	* Air filtration and clean indoor air quality standards.		* Air filtration and clean indoor air quality standards.
		+	* BSRIA completes 2021 World Air Conditioning market studies.
	* Clean indoor air for healthy living - New air filter standards.		* Clean indoor air for healthy living - New air filter standards.
	* Humidity.		* Humidity.

Editor at 16:59, 11 March 2021

2021-03-11T16:59:48Z

← Older revision		Revision as of 16:59, 11 March 2021
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	= Introduction =		= Introduction =

−	The presence of airborne particles (such as dust), harmful pathogenic microorganisms (such as bacteria), viruses (such as COVID-19 and other forms of influenza is inevitable in occupied closed spaces/buildings. Heating, ventilation and air conditioning (HVAC) plays a vital role in making those buildings habitable. Other than providing comfort, it can also impact the wellbeing of occupants by maintaining a healthy indoor environment.	+	The presence of airborne particles (such as dust), harmful pathogenic microorganisms (such as bacteria) and viruses (such as COVID-19 and other forms of influenza) is inevitable in occupied closed spaces/buildings. Heating, ventilation and air conditioning (HVAC) plays a vital role in making those buildings habitable. Other than providing comfort, it can also impact the wellbeing of occupants by maintaining a healthy indoor environment.

	One of the benefits of a well-designed HVAC system is control over harmful pathogenic microorganisms. There are many methods building owners can put in place, including:		One of the benefits of a well-designed HVAC system is control over harmful pathogenic microorganisms. There are many methods building owners can put in place, including:
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	The viruses responsible for the most common cold, influenza and COVID-19 spread more easily when the air is dry as viruses and airborne particles stay longer in the air when there is low humidity. For example, people in the Middle East spend most of their time indoors in closed spaces with the air conditioning working, which means viruses spread more easily.		The viruses responsible for the most common cold, influenza and COVID-19 spread more easily when the air is dry as viruses and airborne particles stay longer in the air when there is low humidity. For example, people in the Middle East spend most of their time indoors in closed spaces with the air conditioning working, which means viruses spread more easily.

−	A U.S. Centers for Disease Control and Prevention study states that “At humidity levels of 23%, 70% to 77% of the flu virus particles were still able to cause an infection an hour after the coughing simulation. But when humidity levels were raised to 43%, just 14% of the virus particles had the ability to infect. Most of the flu particles became inactive 15 minutes after they were released into the humid air. The virus just' falls apart' at high humidity levels.”	+	A U.S. Centers for Disease Control and Prevention study states that “At humidity levels of 23%, 70% to 77% of the flu virus particles were still able to cause an infection an hour after the coughing simulation. But when humidity levels were raised to 43%, just 14% of the virus particles had the ability to infect. Most of the flu particles became inactive 15 minutes after they were released into the humid air. The virus just 'falls apart' at high humidity levels.”

−	~~Though~~ raising the humidity of an entire building is a challenge, it could be beneficial in hospitals, clinics and the places where there is a high risk of flu transmission. However, the humidity levels should not be higher than 30% to 40% because then moulds etc. may start to grow.	+	Although raising the humidity of an entire building is a challenge, it could be beneficial in hospitals, clinics and the places where there is a high risk of flu transmission. However, the humidity levels should not be higher than 30% to 40%, because then moulds etc. may start to grow.

	= Increased ventilation =		= Increased ventilation =
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	= High efficiency (HEPA) filters =		= High efficiency (HEPA) filters =

−	HEPA filters are particulate absorbing filters. To qualify as a HEPA filter, the device must remove 99.95% (EU standard) and 99.97% (ASME, US DOE) of 0.3 micrometers sized debris from the air that passes through it. This value is used for filter classification, because it is close to the most penetrating particle size (MPPS) of approximately 0.2-0.3 μm. ([https://ntrs.nasa.gov/citations/20170005166 NASA)]. Particles that are larger or smaller than the MPPS are filtered more efficiently than the rated efficiency, although in some circumstances particles below the MPPS may act as nucleation sites and form particles close to the MPPS.	+	HEPA filters are particulate absorbing filters. To qualify as a HEPA filter, the device must remove 99.95% (EU standard) and 99.97% (ASME, US DOE) of 0.3 micrometers sized debris from the air that passes through it. This value is used for filter classification, because it is close to the most penetrating particle size (MPPS) of approximately 0.2-0.3 μm ([https://ntrs.nasa.gov/citations/20170005166 NASA)]. Particles that are larger or smaller than the MPPS are filtered more efficiently than the rated efficiency, although in some circumstances particles below the MPPS may act as nucleation sites and form particles close to the MPPS.

	Since COVID-19 is 50 to 200 nanometre in size, it is smaller than the MPPS of HEPA filters, and thus the filter will be able to remove it with at least the rated efficiency. Contrary to common misconception, there is no need to produce special filters for blocking smaller viruses.		Since COVID-19 is 50 to 200 nanometre in size, it is smaller than the MPPS of HEPA filters, and thus the filter will be able to remove it with at least the rated efficiency. Contrary to common misconception, there is no need to produce special filters for blocking smaller viruses.
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	Ultraviolet (UV) radiation is a type of energy produced by the sun and some artificial sources, such as black lights and UV lasers.		Ultraviolet (UV) radiation is a type of energy produced by the sun and some artificial sources, such as black lights and UV lasers.

−	Introducing UV lamps in the return AC duct and near to the filter can have a significant effect on the indoor air quality since it may help to kill harmful viruses and deter the growth of moulds inside ducts. Since lamps prevent the build-up of particles both in the system and in the ducts, they may also improve airflow and contribute to energy savings.	+	Introducing UV lamps in the return AC duct and near to the filter can have a significant effect on the indoor air quality, since it may help to kill harmful viruses and deter the growth of moulds inside ducts. Since lamps prevent the build-up of particles both in the system and in the ducts, they may also improve airflow and contribute to energy savings.

	= Conclusion =		= Conclusion =
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	<li>Increased ventilation (to avoid mould making and regulate the previously increased humidity).</li>		<li>Increased ventilation (to avoid mould making and regulate the previously increased humidity).</li>
	<li>Intake fresh air (which is then recirculated and passed through specially design HEPA filters).</li>		<li>Intake fresh air (which is then recirculated and passed through specially design HEPA filters).</li>
−	<li>UV lights installed inside the air ducts, preferably close to air filters, to kill any residual bacteria and viruses</li></ol>	+	<li>UV lights installed inside the air ducts, preferably close to air filters, to kill any residual bacteria and viruses.</li></ol>

−	~~About the Author:~~ Muhammad is an MEP consultant, LEED Green Associate ~~and~~ has ~~years of~~ experience in the design and development of commercial and residential buildings. He currently lives in Dubai and he loves to write about construction in general and MEP in particular.	+	-----
		+	This article was written by Muhammad is an MEP consultant, LEED Green Associate. He has experience in the design and development of commercial and residential buildings. He currently lives in Dubai and he loves to write about construction in general and MEP in particular.

	= Related articles on Designing Buildings Wiki =		= Related articles on Designing Buildings Wiki =

Editor at 20:24, 27 January 2021

2021-01-27T20:24:40Z

← Older revision		Revision as of 20:24, 27 January 2021
Line 66:		Line 66:
	* HVAC.		* HVAC.
	* IAQ developments accelerated by COVID-19 pandemic.		* IAQ developments accelerated by COVID-19 pandemic.
		+	* SAGE EMG guidance on ventilation and COVID-19.
	* UV disinfection of building air to remove harmful bacteria and viruses.		* UV disinfection of building air to remove harmful bacteria and viruses.
	* Ventilation.		* Ventilation.

Editor at 16:46, 19 January 2021

2021-01-19T16:46:17Z

← Older revision		Revision as of 16:46, 19 January 2021
Line 61:		Line 61:

	* Air conditioning.		* Air conditioning.
−	* Air filtration and clean ~~Indoor~~ air quality standards.	+	* Air filtration and clean indoor air quality standards.
−	* Budget 2020.	+
	* Clean indoor air for healthy living - New air filter standards.		* Clean indoor air for healthy living - New air filter standards.
−	* Coronavirus and force majeure.
−	* Coronavirus impact survey.
−	* Coronavirus job retention scheme.
−	* Health effects of indoor air quality on children and young people.
	* Humidity.		* Humidity.
	* HVAC.		* HVAC.