[Bldg-sim] Modeling Laboratory DCV and ASHRAE 62?

[Sami, Vikram]

Also - when you switch from a standard VAV system to a chilled beam system in a heat gain driven lab there is some reduction. For instance if your EHS mandated ACH is 6ACH, and thermal loads require you to go up to 8ACH to meet the cooling needs, that 8ACH has to be 100% OA (sine you cannot return lab air). A Chilled beam system would allow you to hold the air changes at 6ACH.


Vikram Sami, LEED AP BD+C
Sustainable Design Analyst
1315 Peachtree St. NE, Atlanta, GA 30309
t: 404-443-7462    f: 404.892.5823       e: vikram.sami at perkinswill.com   www.perkinswill.com<http://www.perkinswill.com/>
Perkins+Will.  Ideas + buildings that honor the broader goals of society


From: bldg-sim-bounces at lists.onebuilding.org [mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Bishop, Bill
Sent: Monday, February 04, 2013 4:05 PM
To: James Hansen; Building SimForum
Subject: Re: [Bldg-sim] Modeling Laboratory DCV and ASHRAE 62?

James,

See this thread for some background on the subject:
http://lists.onebuilding.org/pipermail/equest-users-onebuilding.org/2011-October/010327.html

Most likely, you are correct in thinking that you will have to model the Baseline with ASHRAE minimum requirements if you model the Proposed with DCV. Potentially, you could justify modeling the baseline using a local (or campus?) OA requirement if it is more stringent that ASHRAE 62.1.

If you keep the OA requirement identical between the baseline and proposed models, there are still opportunities for energy savings:

*         from energy recovery (if it is not required in the Baseline per G3.1.2.10)

*         from increased baseline fan power due to pressure drop adjustments (Return and/or exhaust airflow control devices, others in Table 6.5.3.1.1B)

*         from VAV hoods (this is trickier, but if the baseline system type is not variable, such as System 3 or 4 per G3.1.1 exception c., the baseline flow might be autosized at a higher CFM that the proposed design, and will not be 100% OA. If you model a reduced OA requirement at night, which is typical and also required in G3.1.1 exception d., the baseline will still have to run at 100% design flow but with a lower OA%, while the proposed model can ramp down to save fan energy.)

Regards,
Bill

[cid:image001.jpg at 01CE03C2.59381730]<mailto:wbishop at pathfinder-ea.com>

From: bldg-sim-bounces at lists.onebuilding.org [mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of James Hansen
Sent: Monday, February 04, 2013 3:20 PM
To: Building SimForum
Subject: Re: [Bldg-sim] Modeling Laboratory DCV and ASHRAE 62?

Sorry, that last sentence didn't make any sense (thanks Bill).  Should read:

We have a client that wants a specific ACH rate (100% OA, once-thru system) that is well above the ASHRAE 62.1 OA requirements for laboratory space in Table 6-1.  We would like to use VAV hoods, occupancy-based exhaust modulation, etc.  But since this is considered DCV, is GBCI really going to require us to bring the lab OA volume down to ASHRAE 62.1 minimum requirements for the baseline model?  Or will we be allowed to set the baseline OA flow for the laboratory at the minimum prescribed rates (say 8 ACH), and take credit for flow reduction in the proposed system?


GHT Limited
James Hansen, P.E., LEED AP
Senior Associate
1010 N. Glebe Road, Suite 200
Arlington, VA  22201-4749
703-243-1200 (office)
703-338-5754 (cell)
703-276-1376 (fax)
www.ghtltd.com<http://www.ghtltd.com/>

From: James Hansen
Sent: Monday, February 04, 2013 3:06 PM
To: Building SimForum
Subject: Modeling Laboratory DCV and ASHRAE 62?

Hi All,

Does anyone have clarity on modeling OA flow rates in laboratory spaces, specifically how they relate to the LEED baseline requirement for OA flow when the proposed model has DCV?

We have a client that wants a specific ACH rate (100% OA, once-thru system) that is well above the ASHRAE 62.1 OA requirements for laboratory space in Table 6-1.  We would like to use VAV hoods, occupancy-based exhaust modulation, etc.  But since this is considered DCV, is GBCI really going to require us to bring the lab OA volume(flow reduction) in the proposed system?

Thanks for any advice!

GHT Limited
James Hansen, P.E., LEED AP
Senior Associate
1010 N. Glebe Road, Suite 200
Arlington, VA  22201-4749
703-243-1200 (office)
703-338-5754 (cell)
703-276-1376 (fax)
www.ghtltd.com<http://www.ghtltd.com/>

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