Hello everyone,
According to ASHRAE 90.1-2010 and 2016 the following assumptions are described for the Baseline path definition (Appendix G):
- Building Envelope is defined as EXTERIOR (conditioned - to exterior) plus SEMIEXTERIOR (conditioned - unconditioned/semiheated) according to 3. Definitions
- In Table G3.1 section 1 Design Model it is said that building conditioned area must be the same in proposed and baseline (nothing said about uncoditioned area)
- In Table G3.1 section 5 Envelope it is said that building envelope must have the same are in proposed and baseline (nothing said about the exterior surfaces of unconditioned spaces)
Due to it I understand the following, which I wanted to confirm it with evidences:
- Baseline can be modelled with only the conditioned and semiheated spaces by removing unconditioned spaces (that complies with above 2nd and 3rd point). This will result in a model with what ASHRAE 90.1 define as building envelope (below 2nd point)
- In case unconditioned spaces are maintained they can have the construction you decide, as there are no requirements and it makes no sense of having high insulated fabric for non assesed spaces.
For me makes sense to follow this criteria, as this unconditioned spaces are design options like local design shadings, that are deleted on the baseline. Furthermore in the Spanish regulations for modelling an EPC these uncoditioned spaces are removed from the baseline.
Happy to see your opinion and how it should be modelled.
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5898 thumbs up
September 6, 2024 - 11:33 am
1. Maybe. You still need to include in your models any other energy use associated with the unconditioned spaces like lighting or ventilation for example. If the unconditioned space is adjacent to conditioned or semi-conditioned spaces it will have an effect on the energy use in those condtioned spaces and should be modeled to simulate that effect. That does not mean the area needs to be identical but uncondtioned spaces are very easy to include in your models so not sure why you are trying to eliminate them? This is not the same as fenestration shading IMO.
2. The baseline envelop of uncondtioned spaces should be modeled identically to the proposed design.