Hello we´ve submitted a project to review in which we have no conditioned spaces in the proposed case but we modelled the HVAC system the same way in baseline and proposed cases since we dont comply with the criteria for non-conditioned spaces these is the review comment we got:
1. It appears from the narrative provided under PIf4 (Schedules and Overview documents) that no HVAC systems except for ventilation fans are provided for the project building and therefore the building spaces meeting the criteria for un-conditioned space.
As per the ASHRAE 90.1-2007 Users Manual, unconditioned space is not cooled and has a heating system smaller than 3.4 Btu/h#sq.ft. Note that for unconditioned spaces, the envelop does not necessarily need to be modeled, but the electric loads from the lighting and fans shall be included in the energy calculations per LEED Interpretation 2028 dated 1/29/2008.
I don´t know if they´re telling us not to model any HVAC systems or that we have to install one if we dont comply with the criteria.
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5909 thumbs up
October 21, 2013 - 2:22 pm
If the space is unconditioned (i.e. meets the definition they state) you do not have to model heating or cooling equipment. It is only if you have one or the other that you need to model the one you do not have.
Jorge Lopez de Obeso
Architect / Environmental advisereosis Consulting
20 thumbs up
October 22, 2013 - 2:02 pm
The spaces in the model have a range of 30-50 Btu/hsf does this means I have to model both heating and cooling in my model or do I have to install the equipment physically in the building and model it?
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5909 thumbs up
October 23, 2013 - 12:01 pm
The 3.4 refers to the heating system capacity. Since you have no heating system your capacity is less than 3.4 and you do not need to model heating or cooling. Your space is unconditioned.
Jorge Lopez de Obeso
Architect / Environmental advisereosis Consulting
20 thumbs up
October 23, 2013 - 5:09 pm
Thanks a lot Marcus you´ve been really helpful..