90.1 Lab MakeUp Air unit flow

asked 2017-03-09 14:00:24 -0500

970 ●1 ●8

updated 2017-08-07 13:36:07 -0500

__AmirRoth__

4436 ●5 ●17 http://bleedinggreenna...

From 90.1 Appendix G, it says"Systems serving laboratory spaces shall reduce the exhaust and makeup air volume during unoccupied periods to the largest of 50% of zone peak air flow, the minimum outdoor air flow rate, or the air flow rate required to comply with applicable codes or accreditation standards. "

How to model the 50% peak air flow in the Openstudio ? I can set up a Max fraction OA schedule in the outdoor air controller, but I don't think that's code's intent. I have baseline system 5, which has no damper control in the terminal unit.

Any one knows how to do this in OS or energyplus ?

answered 2017-03-09 17:16:21 -0500

TaylorRoberts

2903 ●1 ●2 ●13 http://www.group14eng.com/

updated 2017-03-09 17:16:31 -0500

In OS, under the Space Types tab there is the "Design Specification Outdoor Air" object. The object has an input for a fractional schedule called "Outdoor Air Flow Rate Fraction Schedule Name". Create a schedule that is 1 during occupied hours and 0.5 during unoccupied hours and OS will reduce the amount of outdoor air for the zone by 50%.

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Thank you for the help. But I think the code means the total air flow not OA, is my understanding correct ?

BL ( 2017-03-10 08:23:44 -0500 )edit

My interpretation of the code is to reduce exhaust and "makeup air" by 50%. Makeup air is outdoor air or transfer air, so I just assumed it was outdoor air. Also, the exhaust fan object has a similar schedule input that will reduce the exhaust at night by the fraction of the schedule as well.

TaylorRoberts ( 2017-03-10 08:50:08 -0500 )edit

Thanks Taylor !

BL ( 2017-03-10 09:05:24 -0500 )edit

I can't answer specifically how to handle this in OS/e+, however I believe 90.1 is referencing 50% of peak design flow (as driven by cooling or heating conditioning needs) in that specific clause. The next two parts of the sentence mean you must also meet minimum ventilation (62.1) and you must maintain minimum air change rates as required for laboratories. ACH rates can vary between lab types/usage, and is determined ultimately by (with) the owner/operator, who might not permit reducing ACH rates during unoccupied periods. Can you specify separate schedules for each requirement?