There has been much talk that warehouses with heating-only (no cooling) must still model a cooling system in the baseline and proposed case, since the space is defined as conditioned. Adding this fictional system then dilutes your energy savings (since cooling a warehouse is a big energy hog). I have seen it mentioned that you can adjust your temperature range on the cooling system to ensure it doesn't turn on in either the baseline or proposed case, which resolves this issue. Has anyone done this? Is it allowed? Any other ideas or approved ways to address this conflict?
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Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5867 thumbs up
April 1, 2011 - 4:30 pm
It is most definitely allowed. Appendix G simply requires that the temperature setting be the same in both models. It does not dictate what those temperature setting are set to.
We have done it several times.
Curt Pascoe
P.E., LEED AP BD+CRyan Companies US, Inc.
123 thumbs up
April 5, 2011 - 9:21 am
Have you discovered a way to accurately model the air distribution system? I am not an energy modeler, but the ones I use tell me that App G requires them to use a standard VAV system for the warehouse space (even though it would never be built this way) which also dilutes any energy savings in the rest of the building.
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5867 thumbs up
April 5, 2011 - 9:50 am
The baseline VAV system can easily be accurately modeled. Your modelers have it right - don't confuse an Appendix G baseline building with reality. The purpose behind Appendix G is to create a uniform baseline. It is extrordinarily hard to come up with a system that works perfectly for all building types in all climates. Sounds like you assume a VAV system uses less energy than design but in our expereince that is not always the case. Fan power allowances in the baseline are pretty high so you should still be able to show savings in most cases.
Jeremy Poling
Senior ConsultantGoby
39 thumbs up
April 5, 2011 - 11:27 am
Is it also correct that a warehouse space that qualifies as a semi-heated space is not subject to the requirement for modeling an air-conditioning system? It clearly affects the envelope requirements but for the baseline HVAC systems this nuance is less specific.
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5867 thumbs up
April 5, 2011 - 12:08 pm
Yes that is correct.
Semi-heated is not conditioned. To interpret how to deal with the baseline HVAC you need to take a detour through the 90.1 definitions.
Curt Pascoe
P.E., LEED AP BD+CRyan Companies US, Inc.
123 thumbs up
April 11, 2011 - 10:35 am
Continuing discussion: A baseline warehouse will use a VAV system, while the proposed will model the real warehouse air distribution system. We are running into the problem that the GBCI reviewers are requesting that the proposed model bumps up the fan power to match the baseline VAV system, because otherwise you get a big (and arguably false) savings since a real warehouse design has very low fan power.
Of course, the flip side to this is that adding that much fan power to a large warehouse dilutes any real savings you have in the office portion of an office/warehouse, especially if the floor area ratio is 50:1 (warehouse:office) or higher. It makes it difficult to get points for the office/warehouse product.
This appears to be a Catch 22, but I was wondering if anyone has ideas/approved methods to address this?