Dear All,
This has probably been discussed before, but we are about to finalize a
LEED application and do not want to make any costly mistakes. If we are
dealing with the major renovation of an existing building, do 4 separate
orientations of the baseline model still need to be simulated?
Thank you,
?mer Moltay
Omer,
If the building can only be located one way because of being connected to an existing building or if the building is existing that your modeling, then you only need to model the building as it is. No parametric runs of rotation are needed.
James M. Newman, EIT, LEED AP
Hi,
Thanks for the reply. Following up on this: ASHRAE 90.1 also says that
baseline building shall be modelled so that it does not shade itself.
This allows for earning credit for innovative design where shading is
beneficial. However, since there is no design possibility for an
existing building, does the same logic follow to the conclusion that the
baseline building for an existing building should be allowed to shade
itself?
Thanks,
?mer Moltay
Hi ?mer,
I think your inquiry is rooted around the idea that this mandate is tied to the orientation-neutralizing procedure (and it is), but the "no self-shading" requirement serves its own distinct purpose... Building & site self-shading are not always inherently beneficial (solar loads blocked in the summer generally coincide with solar loads blocked in the winter - a bad thing for a heating-dominated building), so 90.1's mandate to disallow self-shading in a baseline model in practice does as much to "reward" good static shading design as it does to "punish" detrimental self-shading caused by building massing / static shade design. This is distinct from the intent to "reward/punish" building/glazing orientation with respect to the site, which is the clear intent of the 90/180/270 parametric runs.
As a result, my interpretation of the intent would cause me to not model self-shading in a 90.1 baseline, whether running at 4 orientations or at one. If the existing-to-remain / revised static shading elements and building masses result in a net benefit, then you get a credit for that in your proposed model, and on the flip side you might be "penalized" for adding new shading or leaving existing shading that influences the envelope gains in a negative fashion over the course of a year.
It would behoove me to mention this is only my personal interpretation being shared for consideration. In the end, we modelers have to make the calls regarding issues like this and reviewers out there may ultimately disagree with whatever we find most logical. As long as you feel comfortable defending and explaining your position, it's as "right" as it's going to get =).
Best of luck,
~Nick
PS: For future reference, such inquiries not specific to eQuest will reach a broader audience using the [bldg-sim] list (not sure about the demographics - [eQuest-users] may have more subscribers?).
NICK CATON, E.I.T.