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NC-v4 EAp2:Minimum energy performance

Minimum OA and makeup air

Hello,

We are working on a residential project with a central laundry room with a 2200 cfm exhaust rate (each dryer has a dedicated exhaust fan). Per ASHRAE 62.1-2010, this space requires a minimum outdoor air rate of 60 cfm; however, per Florida Building Code Mechanical section 504.6, the space requires an equal or similar makeup air rate as exhaust. 


Is it possible to increase the minimum OA rate for that space in the baseline model according to the makeup air rate? So, we would model 2200 cfm of OA in the baseline instead of 60 cfm and 2250 cfm of OA in the proposed model as designed.

Thank you,

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Tue, 02/28/2023 - 16:55

Hello, Could anyone help me?
Profile picture for user cory.duggin
Cory Duggin
Senior Energy Wizard
TLC Engineering Solutions
LEEDuser Premium Member
44 thumbs up

Tue, 02/28/2023 - 17:12

Yes, the OA is allowed to be the greater of the ventilation requirement or the exhaust make-up air requirement for the space.  Since exhaust only spaces are not always included int he minimum ventilation calculator, it would be a good idea to include a note saying that the ventilation has been increased for make-up air requirements.

Wed, 03/01/2023 - 23:31

Thanks for your reply Cory.
Do you have any source or reference documents to support this methodology? We want to make sure we have all the necessary information and avoid any potential review comments.
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Moses Chong
Mechanical Engineer
WSP
LEEDuser Basic Member
2 thumbs up

Thu, 03/02/2023 - 15:23

The LEED minimum indoor air quality prerequisite states that the ventilation shall be based on ASHRAE 62.1 or a local equivalent, whichever is more stringent. The local equivalent in your case is the Florida Building Code. You can upload a narrative and/or portion of the building code as suppport document. Does your code requires some kind of control, or is there any common practice in your area? I would model the same ventilation rate and control in both proposed and baseline. 

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