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NC-2009 IEQp1:Minimum IAQ Performance

Breathing Zone definition

Hello everyone, I'm confused by a substantial discrepancy between two different definitions that I have come across in regards to Breathing Zone. 1) LEED Definition: "The breathing zone is the region within an occupied space between 3 and 6 feet above the floor and more than 2 feet from walls or fixed air-conditioning equipment. (AHSRAE 62.1-–2007)" 2) ASHRAE 62.1-2007 Standard Definition: "The region within an occupied space between planes 3 and 72 in. (75 and 1800 mm) above the floor and more than 2 ft (600 mm) from the walls or fixed air-conditioning equipment." The LEED Definition as well as countless sources (including the LEEDuser Glossary) refer to the Breathing Zone as beginning 3 feet above the floor; yet the ASHRAE Standard defines it as beginning 3 inches above the floor. Am I missing something? Can someone please clarify? Regards, Gabriel

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Tue, 04/02/2013 - 21:15

The 3-inches above the floor is the correct breathing zone per ASHRAE. The 3 feet above the floor is supposed to be a minimum location for CO2 sensors above the floor. I was vice-chair of the LEED EQ Technical Advisory Group (TAG) when the CO2 sensor position requirement was added to LEED v2.2. For LEED v2.0 and v2.1 the breathing zone was defined as between 3-inches and 6-feet above the floor. I have no explanation for why the v2.2 Reference Guide authors decided to make the breathing zone for LEED 3-feet instead of 3-inches. The EQ TAG had nothing to do with the development of the guide.

Wed, 04/03/2013 - 20:29

Thank you for your concise response Hernando. I checked version 2.0 and 2.2 and saw the difference in definition which you talked about. The new definition persisted into version 3.0. I imagine version 4.0 will have it as well. Thanks again,

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