[Equest-users] LEED modeling- Unit heaters‏

[Nikola Kravik]

Ana,

I agree with Bill Bishop’s comments using PTAC’s or PTHP for residential (depending on heating source.)
Not sure why the LEED reviewer says System type #5 or #7. Exceptions to G3.1.1 may apply-not sure if you’re conditioning the stairs.
I had similar problem a while back (heating only by design proposed res bld, that per AHSRAE Appx G requirements needed cooling added the same as the baseline PTAC)

It’s been a while since I’ve worked on residential, but I remember the baseline PTAC fan power was coming too high using table G.3.1.2.9 and the lighting savings were substantial compared to baseline (I used the dormitory lighting at 1.1w/sf for the baseline, proposed was much lower LPD and how to justify it?….)

I have same understanding for serving identical areas, but we may be wrong.
Any other comments from the users? Anyone with res experience and LEED situation like this, so we can all learn?

Thanks,
Nikola

From: equest-users-bounces at lists.onebuilding.org [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Ana N.
Sent: Thursday, March 11, 2010 2:34 PM
To: equest-users at lists.onebuilding.org
Subject: [Equest-users] LEED modeling- Unit heaters‏


Thank you for your suggestions.

 I am actually revising the model after it was reviewed by GBCI.
The model that was submitted had these spaces attached to PTAC systems (chilled water and hot water coils). My first thought was just to change a hot water coil to heat resistance in proposed. However, one of the reviewers comments was that all non-residential spaces should be modeled as system type #5 ( if the total conditioned building area is less than 150,000sf)  or system type #7 (exceeds 150,000 sf).  They also gave me an option of using system type #3 ( PSZ) for spaces where load varies substantially from other non-residential units. The model was done by someone else, but even if I had built this model I would not use VAV systems. I would probably go with PTAC for stairs and PSZ for mechanical rooms. Now, I am completely confused.


Besides, when I model for LEED, I usually make my HVAC systems so that they serve identical areas in baseline and proposed design. Is this good understanding of Appendix G?
Any thoughts and suggestions are appreciated.


Ana

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