I have a project I am trying to model. the overall building is just over 25,000sf. The is an office area that is about 11,000sf and enclosed parking area, and an enclosed utility space. The office area is conditioned by a heat pumps system. the enclosed parking and other spaces are heat only with radaint heaters or hw unit heaters depending on the space. The enclosed parking also has a ventilation system.
We originally submitted the building modeling it against a baseline system #4 Packaged heat pumps. the reviewer came back and said that since the building was over 25,000sf that we should be using system #5 Packaged VAV with reheat as baseline. So we re-modeled the building using system #5 as a baseline with a couple exceptions. Appendix G says that if you are using system #5 there is an exception to use a system #3 or 4 for areas that differ significantly from the rest of the building. We used that excepttion for the garage area and utility spaces.
The reviewers still did not like that and came back and said that we need to model the garage and other utility spaces as semi heated. Looking at appendix G I do not see where it says we can model as a semi heated space. Appendix G also states that where attirbutes make the building eligible for more than one system that the most predominant system shall apply.
Any one have any thoughts on what system I should be modleing as baseline? Where in appendix G does it talk about semi heated spaces?
thomas beal
41 thumbs up
July 6, 2011 - 5:22 pm
Check the heating capacity per square foot for the parking garage. ASHRAE defines a conditioned as being heated if it has a heating capacity that exceeds a defined value. There is a table in the definition section of 90.1 that lists the criteria for "conditioned - heated" for every climate zone (ASHRAE 90.1-2007 page 13). Below the conditioned space definition is also the semi-heated definition. If your space is considered "conditioned" follow the guidelines of Appendix G table G3.1 number 10 (hVAC Systems).