[Bldg-sim] Ventilation rates in industrial buildings

[Matthew Dubrovich]

Hi Lizzy, here is a great answer from David on a similar topic that was posted to the list last November.  Be sure to search the archives, you might find the rest of the conversation helpful also.

Quick answer:

90.1 does not care if you are pursuing EQC2, use the same OA quantities in baseline and proposed for EAC1.


Long answer:

These are separate credits - the modeling takes place based on the proposed design in comparison to a baseline that is only restricted by 90.1.  The OA requirement should be the same in both models subject to any DCV or exceptional calcs or technologies.  This is not affected by other LEED credits.

The credit for increased ventilation takes place "before" modeling starts.  This is besides the many cases for laboratories or hospitals where the local code ventilation requirements are much greater than ASHRAE 62.1 already - the proposed design is in effect already taking the EAC1 penalty but earning the credit for increased ventilation under the best practice design.  You wouldn't relax the baseline ventilation to less than 30% in these cases!

I'm sure there are some proposed buildings out there that condition OA very effectively, and may gain EAC1 gross energy cost savings by having increased ventilation, but even where that effect occurs there is  the question of percentage savings applying to a larger energy consumption and cost.

Overall if you gain EAC1 points by pursuing increased ventilation, I think you have worked well within the system - good for you in designing a system to condition outside air so effectively.  For many projects (other than labs or hospitals which may have to use that quantity of OA anyway) I would expect EQC2 could be trading for an EAC1 credit, so you'll have to prioritize.  Both are rewarded from USGBC, but EAC1 is also rewarded in lower utility bills.

David
http://www.grummanbutkus.com

Sincerely,

Matt Dubrovich, P.E.
LEED AP

EMC Engineers, Inc.
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From: bldg-sim-bounces at lists.onebuilding.org [mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Lizzy Guhl
Sent: Monday, March 22, 2010 6:39 AM
To: bldg-sim at lists.onebuilding.org
Subject: [Bldg-sim] Ventilation rates in industrial buildings

Dear All,

I am modeling an industrial building for Leed compliance and I have some doubts about how to model the proposed and baseline building:

The ventilation rates defined by the user for most of the zones are much higher than the required rates. The point is that we just can´t reach the necessary savings due to the high ventilation rates and therefore we recommended to reduce them.  Now my question is how to model this for Leed compliance. Is it necessary to model both the baseline and proposed building with the same ventilation rates? Or do I need to model the baseline building with the required rates according to Ashrae 90.1 and the proposed building with the defined rates? Suggestions are highly appreciated.

Regards,
Lizzy

LIZZY GUHL
Dipl. Ing. (FH) Mechanical Engineering | Sustainable Design Consultant

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