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NC-2009 EAp2:Minimum Energy Performance

Unconditioned vs conditioned space

Hello everyone, I know this topic has been addressed in several threads below, but I just want to try to have a better understanding of the subject. A conditioned space would be a space with a cooling or heating system installed, and ASHRAE 90.1 defines the minimum cooling or heating capacity that the system must have to be considered conditioned. I have a project with no air conditioning designed nor required, and the owner is completely positive that it won't be installed in the future. The reviewer suggests that the project must be modeled with cooling and heating, even if it does not exists (as stated in ASHRAE for conditioned spaces); and if I do this, the energy savings percent drops considerably. The equipment capacity estimated in the energy model does exceed the 5 btu/h/sf, so under ASHRAE, it would be considered a cooled space. How can I explain that this is an unconditioned space? Do I have to somehow prove that the space is comfortable without HVAC? It does comply with ASHRAE 62.1 with natural ventilation.

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Marcus Sheffer
LEED Fellow
7group / Energy Opportunities
LEEDuser Expert
4454 thumbs up

Thu, 06/04/2015 - 21:27

If it has no heating or cooling system it is an unconditioned space. Does it have a heating system? If not it is unconditioned. If it does you can model the Baseline as a system 9 or 10 according to Addendum dn. Since you have already done the model, you can also adjust the cooling temperature set points so high that the system never operates. As long as the set points are the same in both models Appendix G allows this. You only have to prove comparable comfort if you are claiming any savings related to natural ventilation.

Thu, 06/04/2015 - 21:58

Thank you very much for your response. We do not have heating here in Costa Rica, so i'll definitely consider it to be unconditioned. I will adjust temperature set points in the baseline and proposed case. We did mentioned in the first review that there would not be any HVAC system installed but the reviewer insists in including it in the model. If we adjust set points, and there is 0 energy consumption in cooling, would it be the same if we just don't model the equipment? Is there any specific document that I should make reference in the response narrative?
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Marcus Sheffer
LEED Fellow
7group / Energy Opportunities
LEEDuser Expert
4454 thumbs up

Thu, 06/04/2015 - 22:20

If the space has no heating or cooling then it is unconditioned and the reviewer is wrong. It happens. You could send a project team inquiry through GBCI's web site to seek clarification pointing out the definition of an unconditioned space. The effect of the equipment running should be the same as no equipment, zero energy use. I would just tell the reviewer the set points and indicate they are identical. See Table G3.1-b.

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