[Equest-users] ASHRAE 62.1 cfm/person

Glenn Haynes glenn.haynes at rlw.com
Tue Mar 31 10:03:14 PDT 2009

What I am about to say may be controversial, but I am a conservation program impact evaluator, an avid DOE2 user, and feel strongly about excessive OA ventilation requirements, especially in colder climates.  The ASHRAE minimum, when translated into air changes per hour (ACH) requires over 0.8 ACH for a 10x10 office with an 8 foot ceiling and one occupant.  On the other hand, the EPA claims that Energy Star homes must have an energy recovery ventilator because they often end up with natural infiltration rates under the threshold of safety, about 0.32 ACH.

If, as they believe, 0.32 or higher is safe enough for residential occupants, why, then, does the ASHRAE standard require almost three times that for office spaces?  This high requirement is, of course, safe enough, but it is costing commercial building operators in cold climates a fortune in heating costs, often accounting for 50% to 80% of the total heating energy consumption.  In hot climates it translates into excessive cooling energy use.  Is it time for some of us to question the ASHRAE standard, or is the EPA threshold (it isn't a law) safe enough?

With the current emphasis on LEEDS design are we overlooking a huge energy savings potential here?  We strive very hard to save as much energy as possible, but then we are required to impose a questionable ventilation standard that often overshadows all else.

I just want to hear some other professional thoughts on this.

Glenn C. Haynes, PE
Middletown, CT

-----Original Message-----
From: equest-users-bounces at lists.onebuilding.org [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Min-Hwan Yang
Sent: Tuesday, March 31, 2009 12:08 PM
To: equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] ASHRAE 62.1 cfm/person

I think what Pravin did was correct.

Eric, according to DOE2.2 Dictionary, only the maximum value of oa-flow/area and oa-flow/per will be used, not summed together.  
Please let me know if I am wrong.

Min-Hwan Yang, CPD, LEED AP
Mechanical Engineer | yangm at kjww.com

200 West Jackson Boulevard, Suite 1200 | Chicago, Illinois 60606
312-294-0501 | Direct: 312-356-3750 | Fax: 312-294-0003


I'm attaching a screen capture from a building I modeled (yes, that system setup was heinous and produced terrible results - it wasn't my doing) that shows the OA settings based on 62.1 requirements. 

Let me know if that doesn't simplify your process.


From: equest-users-bounces at lists.onebuilding.org [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Pravin Wakode
Sent: Tuesday, March 31, 2009 4:50 AM
To: equest-users at lists.onebuilding.org
Subject: [Equest-users] ASHRAE 62.1 cfm/person

Hi All,
        This query is related to HVAC Ventilation used in equest. As per ASHRAE 62.1 Ventilation rates are specified based on per person and per sqft basis for example if I consider a office area the ventilation rates would be 5 cfm/person + 0.06 cfm/sqft.
Equest doesnt allow you to enter the ventilation rate based on sqft basis.
I  am calculating the ventilation rate manully (using per-person + per-sqft basis) and then dividing it by total occupancy and arriving at the cfm/person value which is to be entered in Equest.
Is this procedure correct???
Pravin Wakode

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