We are modelling a Major Renovation Project under the ASHRAE 90.1-2007 - APPENDIX G. The building existing conditions prior to this project renovation includes solar shading devices on all facades which greatly contributes to the building energy performance. The project team is currently evaluating at LEED point-of-view if the shading should be maintained or removed. It is not clear if the baseline building should consider the shading devices as in TABLE G3.1 - Baseline Building Performance states:
a. The building shall be modeled so that it does not shade itself; and also
f. For existing building envelope, the baseline building shall reflect existing conditions prior to any revisions that are part of the scope of work being evaluated.
I understand that the baseline model should reflect the solar shading contribution otherwise the benefit of a well-designed shading device would not be valued by ASHRAE standard.
Does anyone have an answer on this issue?
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Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5899 thumbs up
September 27, 2011 - 12:58 pm
Technically it appears as if Table G3.1.5 Baseline (f) should be followed so there would be external shading in both models.
Our interpretation is based on the fact that G3.1.5 Baseline (a) does not apply to existing buildings and G3.1.5 Baseline (c) only appies to new buildings.
Fabiano Castro
CTE23 thumbs up
September 28, 2011 - 3:54 pm
Thank you very much for your reply. That is also what we understand. A further thinking on this issue raised another question:
According to your interpretation, I understand the baseline model should be simulated only with its actual orientation and the 90, 180 and 270 degrees rotated models can de discarded from the simulation. Is that right?
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5899 thumbs up
September 28, 2011 - 8:45 pm
Yes existing building do not have to be rotated for LEED.
Morteza Kasmaei
PrincipalClimatic Design Inc.
22 thumbs up
September 30, 2011 - 4:55 pm
Marcus,
Don't you think it is depend on the percentage of renovation of the existing building? "Advanced Energy Modeling for LEED" states "Existing buildings with less than 50% renovations do not have to be rotated". (Page 7)
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5899 thumbs up
September 30, 2011 - 7:53 pm
That statement is not correct in my opinion. The Guide is trying to summarize 90.1 and in this case does so in a confusing manner. It does not even make any logical sense. The reason you rotate a building is to capture energy savings associated with orientation. Whether a building was 25% renovated or 100% renovated it would make no difference since an existing building can't be rotated.
I believe that in the case where there is new and existing building if more than 50% is new it would need to be rotated. I think this is what they were trying to get say.
Morteza Kasmaei
PrincipalClimatic Design Inc.
22 thumbs up
October 1, 2011 - 11:01 am
I'm very glad that you mention that. Is there any way to request GBCI reviewer's point of view about that statement. I would like to know their opinion before submitting my LEED documents.
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5899 thumbs up
October 1, 2011 - 12:32 pm
There are only two official means - a project specific CIR or an Interpretation.
You can write to GBCI on their web site and ask but the response is not technically official.
Expect dealys in the response either way since Greenbuild is next week.