Minimum efficiency reporting value MERV - Revision history

Editor at 18:36, 14 January 2022

2022-01-14T18:36:07Z

← Older revision		Revision as of 18:36, 14 January 2022
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	* Designing HVAC to resist harmful microorganisms.		* Designing HVAC to resist harmful microorganisms.
	* Growing focus on IAQ challenges for specifiers and HVAC manufacturers.		* Growing focus on IAQ challenges for specifiers and HVAC manufacturers.
		+	* High efficiency particulate arrestance HEPA.
	* HVAC.		* HVAC.
	* Indoor air quality.		* Indoor air quality.

Editor at 19:02, 17 December 2021

2021-12-17T19:02:59Z

← Older revision		Revision as of 19:02, 17 December 2021
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	* At a glance - Indoor air quality.		* At a glance - Indoor air quality.
	* Building ventilation and COVID-19 transmission risk.		* Building ventilation and COVID-19 transmission risk.
		+	* Clean air delivery rate CADR
	* Clean indoor air for healthy living - New air filter standards.		* Clean indoor air for healthy living - New air filter standards.
	* Designing HVAC to resist harmful microorganisms.		* Designing HVAC to resist harmful microorganisms.

Editor at 19:08, 13 December 2021

2021-12-13T19:08:47Z

← Older revision		Revision as of 19:08, 13 December 2021
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	= Related articles on Designing Buildings =		= Related articles on Designing Buildings =

		+	* Air filtration.
	* Air pressure drop APD.		* Air pressure drop APD.
	* Arrestance.		* Arrestance.

Editor at 17:43, 8 December 2021

2021-12-08T17:43:00Z

← Older revision		Revision as of 17:43, 8 December 2021
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	* Air pressure drop APD.		* Air pressure drop APD.
		+	* Arrestance.
	* At a glance - Indoor air quality.		* At a glance - Indoor air quality.
	* Building ventilation and COVID-19 transmission risk.		* Building ventilation and COVID-19 transmission risk.

Editor at 16:12, 3 December 2021

2021-12-03T16:12:44Z

← Older revision		Revision as of 16:12, 3 December 2021
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	= Related articles on Designing Buildings =		= Related articles on Designing Buildings =

		+	* Air pressure drop APD.
	* At a glance - Indoor air quality.		* At a glance - Indoor air quality.
	* Building ventilation and COVID-19 transmission risk.		* Building ventilation and COVID-19 transmission risk.

Editor at 11:36, 3 December 2021

2021-12-03T11:36:58Z

← Older revision		Revision as of 11:36, 3 December 2021
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	Sample rating ranges include:		Sample rating ranges include:

−	* MERV 1 to 4. These filters are made from materials such as fibreglass and aluminium mesh. They can be used to remove large particles and protect equipment. They can remove substances such as pollen, dust mites and carpet fibres and are suitable for light industrial and some residential applications.	+	* MERV 1 to 4. These filters are made from materials such as fibreglass and aluminium mesh. They can be used to remove large particles and protect equipment. They can remove substances such as pollen, dust mites, cockroach debris and carpet fibres and are suitable for light industrial and some residential applications including residential window air conditioning units.
−	* MERV 5 to 8. These are disposable filters that can be used to remove substances such as mould spores and other particulate material commonly found in residential environments.	+	* MERV 5 to 8. These are disposable filters that can be used to remove substances such as mould spores, pet dander and other particulate material commonly found in residential environments and some light industrial and commercial environments.
−	* MERV 9 to 13. These are higher quality filters used to remove fine household dust particles (such as flour) as well as ~~those~~ found in workshop fumes.	+	* MERV 9 to 12. These are higher quality filters used to remove fine household dust particles (such as flour), and Legionella as well as some particles found in workshop fumes. These can be used in more demanding residential, commercial and healthcare environments.
−	* MERV 14 to 16 are designed for high levels of filtration and are suitable for commercial applications with extreme filtration requirements. These filters are not suitable for residential HVAC applications or furnaces.	+	* MERV 13 to 16. These are designed for high levels of filtration for substances such as bacteria, smoke dust and other extremely fine particles. They are suitable for commercial and healthcare applications with extreme filtration requirements. These filters are not suitable for residential HVAC applications or furnaces.

	Originally, MERV values ranged from 1 to 20, but ASHRAE stopped recognising MERV values from 17 to 20 in January 2009. This range is instead represented by HEPA and ULPA filters, which are capable of removing extremely high levels of dust particles as well as some viruses and other dangerous airborne particulates.		Originally, MERV values ranged from 1 to 20, but ASHRAE stopped recognising MERV values from 17 to 20 in January 2009. This range is instead represented by HEPA and ULPA filters, which are capable of removing extremely high levels of dust particles as well as some viruses and other dangerous airborne particulates.

Designing Buildings at 09:10, 3 December 2021

2021-12-03T09:10:46Z

Editor at 18:33, 2 December 2021

2021-12-02T18:33:45Z

← Older revision		Revision as of 18:33, 2 December 2021
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	= Related articles on Designing Buildings =		= Related articles on Designing Buildings =

		+	* At a glance - Indoor air quality.
		+	* Building ventilation and COVID-19 transmission risk.
		+	* Clean indoor air for healthy living - New air filter standards.
	* Designing HVAC to resist harmful microorganisms.		* Designing HVAC to resist harmful microorganisms.
	* Growing focus on IAQ challenges for specifiers and HVAC manufacturers.		* Growing focus on IAQ challenges for specifiers and HVAC manufacturers.
		+	* HVAC.
		+	* Indoor air quality.
		+	* Mechanical ventilation of buildings.
		+
		+	[[Category:DCN_Definition]] [[Category:DCN_Guidance]] [[Category:DCN_Product_Knowledge]] [[Category:DCN_Standard]] [[Category:Definitions]] [[Category:Standards_/_measurements]] [[Category:Products_/_components]]

Editor at 18:27, 2 December 2021

2021-12-02T18:27:55Z

← Older revision		Revision as of 18:27, 2 December 2021
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−	~~[[File:BSRIAIAQTable3.jpg]]~~
−
	= Introduction =		= Introduction =

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	In general, mid-range rated filters (from 7 to 13) are typically recommended for commercial buildings. During the new construction phase, MERV 8 filters may be advisable, with MERV 13 filters generally recommended once the building is operational.		In general, mid-range rated filters (from 7 to 13) are typically recommended for commercial buildings. During the new construction phase, MERV 8 filters may be advisable, with MERV 13 filters generally recommended once the building is operational.
		+
		+	{\|
		+	\|width="100%"\|
		+	[[File:BSRIAIAQTable3.jpg\|link=File:BSRIAIAQTable3.jpg]]
		+
		+	(NB: MERV 17-20 ratings are no longer acknowledged by ASHRAE.)
		+	\|}

	Sample rating ranges include:		Sample rating ranges include:

Editor at 18:25, 2 December 2021

2021-12-02T18:25:08Z

← Older revision		Revision as of 18:25, 2 December 2021
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		+	[[File:BSRIAIAQTable3.jpg]]
		+
	= Introduction =		= Introduction =

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	Originally, MERV values ranged from 1 to 20, but ASHRAE stopped recognising MERV values from 17 to 20 in January 2009. This range is instead represented by HEPA and ULPA filters, which are capable of removing extremely high levels of dust particles as well as some viruses and other dangerous airborne particulates.		Originally, MERV values ranged from 1 to 20, but ASHRAE stopped recognising MERV values from 17 to 20 in January 2009. This range is instead represented by HEPA and ULPA filters, which are capable of removing extremely high levels of dust particles as well as some viruses and other dangerous airborne particulates.

−	= The ~~impace~~ of air resistance on MERV =	+	= The impact of air resistance on MERV =

	In a furnace or air handler, the queuing up of air to pass through a high-MERV filter creates resistance. Referred to in HVAC language as a pressure drop, this condition decreases airflow on the downstream side of the air filter.		In a furnace or air handler, the queuing up of air to pass through a high-MERV filter creates resistance. Referred to in HVAC language as a pressure drop, this condition decreases airflow on the downstream side of the air filter.
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	* Designing HVAC to resist harmful microorganisms.		* Designing HVAC to resist harmful microorganisms.
		+	* Growing focus on IAQ challenges for specifiers and HVAC manufacturers.

← Older revision		Revision as of 09:10, 3 December 2021
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	= Introduction =		= Introduction =

−	~~Minimum~~ efficiency reporting value (MERV) ~~is a rating system that~~ can be used to evaluate the effectiveness of air filters in heating, ventilation and air conditioning (HVAC) components.	+	The minimum efficiency reporting value (MERV) can be used to evaluate the effectiveness of air filters in heating, ventilation and air conditioning (HVAC) components.

	= Background =		= Background =
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	The rating system was developed in the 1980s by the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE). ASHRAE develops standards related to refrigeration processes and the design and maintenance of indoor environments. The purpose of the organisation's standards is to establish consensus for test use in commerce as well as performance criteria for use as facilitators.		The rating system was developed in the 1980s by the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE). ASHRAE develops standards related to refrigeration processes and the design and maintenance of indoor environments. The purpose of the organisation's standards is to establish consensus for test use in commerce as well as performance criteria for use as facilitators.

−	This rating system ~~is an industry standard that~~ is used in the US for ~~the purpose of~~ comparing air filters made by different manufacturers. ~~The system~~ assigns a single number air filter designation based on how well it captures and holds dust.	+	This MERV rating system is used in the US for comparing air filters made by different manufacturers. It assigns a single number air filter designation based on how well it captures and holds dust. MERV rated filters may be used in place of high efficiency particulate arrestance (HEPA) or ultra low particulate air (ULPA) filters in certain circumstances (such as when central air conditioning systems are in place).
−		+
−	MERV rated filters may be used in place of high efficiency particulate arrestance (HEPA) or ultra low particulate air (ULPA) filters in certain circumstances (such as when central air conditioning systems are in place).	+

	= MERV testing =		= MERV testing =

−	The MERV rating system is based on ASHRAE Standard 52.2-2007~~. This standard established~~ the testing protocol ~~to ensure testing of~~ air filtration performance.	+	The MERV rating system is based on ASHRAE Standard 52.2-2007, the testing protocol for air filtration performance.

−	~~The rating system~~ reflects a measurement of the filter’s arrestance - or its ability to remove dust from the air - relative to how many of a specific size dust particle (within the range of 0.3 to 10 micrometers) need to be removed to keep HVAC equipment clean.	+	It reflects a measurement of the filter’s arrestance - or its ability to remove dust from the air - relative to how many of a specific size dust particle (within the range of 0.3 to 10 micrometers) need to be removed to keep HVAC equipment clean.

−	The test extends over six cycles and begins with a clean filter. During each cycle, a measured amount of particles (broken down into three size categories) is released into the test airstream. These three arrestances ~~include~~:	+	The test extends over six cycles and begins with a clean filter. During each cycle, a measured amount of particles (broken down into three size categories) is released into the test airstream. These three arrestances are:

	* E1 for small particles such as tobacco smoke and bacteria.		* E1 for small particles such as tobacco smoke and bacteria.
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	* E3 for larger particles such as dirt, lint, hair and dust.		* E3 for larger particles such as dirt, lint, hair and dust.

−	The number of particles trapped and missed is measured. This procedure is repeated five additional times and the MERV rating is calculated based on the poorest performance rating ~~through the course of~~ the six tests.	+	The number of particles trapped and missed is measured. This procedure is repeated five additional times and the MERV rating is calculated based on the poorest performance rating during the six tests.

	The MERV number corresponds to the filter’s efficiency in its clean, least efficient state (which is why the rating is referred to as ‘minimum efficiency’). A filter increases in efficiency as it loads.		The MERV number corresponds to the filter’s efficiency in its clean, least efficient state (which is why the rating is referred to as ‘minimum efficiency’). A filter increases in efficiency as it loads.
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	MERV values range from 1 (minimal filtering) to 16 (maximum filtering).		MERV values range from 1 (minimal filtering) to 16 (maximum filtering).

−	~~In general, mid~~-range rated filters (from 7 to 13) are typically recommended for commercial buildings. During the new construction phase, MERV 8 filters may be advisable, with MERV 13 filters generally recommended once the building is operational.	+	Mid-range rated filters (from 7 to 13) are typically recommended for commercial buildings. During the new construction phase, MERV 8 filters may be advisable, with MERV 13 filters generally recommended once the building is operational.

	{\|		{\|
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	* MERV 5 to 8. These are disposable filters that can be used to remove substances such as mould spores and other particulate material commonly found in residential environments.		* MERV 5 to 8. These are disposable filters that can be used to remove substances such as mould spores and other particulate material commonly found in residential environments.
	* MERV 9 to 13. These are higher quality filters used to remove fine household dust particles (such as flour) as well as those found in workshop fumes.		* MERV 9 to 13. These are higher quality filters used to remove fine household dust particles (such as flour) as well as those found in workshop fumes.
−	* MERV 14 to 16 are designed for high levels of filtration and suitable for commercial applications with extreme filtration requirements. These filters are not suitable for residential HVAC applications or furnaces.	+	* MERV 14 to 16 are designed for high levels of filtration and are suitable for commercial applications with extreme filtration requirements. These filters are not suitable for residential HVAC applications or furnaces.

	Originally, MERV values ranged from 1 to 20, but ASHRAE stopped recognising MERV values from 17 to 20 in January 2009. This range is instead represented by HEPA and ULPA filters, which are capable of removing extremely high levels of dust particles as well as some viruses and other dangerous airborne particulates.		Originally, MERV values ranged from 1 to 20, but ASHRAE stopped recognising MERV values from 17 to 20 in January 2009. This range is instead represented by HEPA and ULPA filters, which are capable of removing extremely high levels of dust particles as well as some viruses and other dangerous airborne particulates.
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	In a furnace or air handler, the queuing up of air to pass through a high-MERV filter creates resistance. Referred to in HVAC language as a pressure drop, this condition decreases airflow on the downstream side of the air filter.		In a furnace or air handler, the queuing up of air to pass through a high-MERV filter creates resistance. Referred to in HVAC language as a pressure drop, this condition decreases airflow on the downstream side of the air filter.

−	Pressure drop may increase as the MERV number increases. As contaminants load on the filter, pressure in the system rises and can have a negative impact on airflow. This may cause systems to operate for longer periods of time in order to reach certain temperature settings. In extreme cases, decreased airflow over the part of the system that heats (in winter) or cools (in summer) ~~the air~~ can lead to overheating and an automated system shutdown or icing over of the coil~~, respectively~~.	+	Pressure drop may increase as the MERV number increases. As contaminants load on the filter, pressure in the system rises and can have a negative impact on airflow. This may cause systems to operate for longer periods of time in order to reach certain temperature settings. In extreme cases, decreased airflow over the part of the system that heats (in winter) or cools (in summer) can lead to overheating and an automated system shutdown or icing over of the coil.

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