[Bldg-sim] ASHRAE 90.1 system type in maintenance garage / office

[Nathan Miller]

On a recent LEED project I received a review comment that stated:

"The exception [it was exception G3.1.1b in my case] should be applied to lesser portion of building served by the system." The reviewer's interpretation was that the primary system selection applied to the LARGER BY AREA portion of the project, and the break-out system per the exception goes to the lessor by area portion of the project, which in your case sounds like you would end-up with a bizzaro switch on system types between the baseline and proposed model.

I guess this is just another one of those examples to file away when you end up with outlandish baseline systems per the Appendix G prescribed methodology that seems counter-intuitive.

Nathan Miller - PE, LEED®AP BD+C, CEM
Mechanical Engineer/Senior Energy Analyst
RUSHING | D 206-788-4577 | O 206-285-7100
www.rushingco.com<http://www.rushingco.com/>

From: bldg-sim-bounces at lists.onebuilding.org [mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Adam Barker
Sent: Friday, November 22, 2013 2:17 PM
To: 'bldg-sim at lists.onebuilding.org'
Subject: [Bldg-sim] ASHRAE 90.1 system type in maintenance garage / office

All,

A (hopefully) simple ASHRAE 90.1 baseline system question.

I have a building which is part office, part maintenance/storage garage.  The garage/maintenance portion is about ¾ of the total GFA.  Appendix G system type is #5 - Packaged VAV w RH.  However, I want to apply G3.1.1c as an exception, which states that system 3 or 4 should be used for zones which have special pressurization relationships, cross contamination requirements or code-required airflow rates. This is definitely the case.

My question is do I use system 3 or 4 for the garage/maintenance zones (both the predominant condition and the zones with the special requirements) or the office zones?  The wording leads me to believe its actual the office zones which need to be system type 3, but this seems backwards, and it's essentially the reverse of what is installed, which is VAV in the office, PSZ in the garage.

Regards,

Adam


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