Rating System

LEED BD+C: New Construction, LEED BD+C: New Construction, LEED BD+C: Schools, LEED BD+C: Schools, LEED ID+C: Commercial Interiors, LEED BD+C: Core and Shell

Rating System Version

v2 - LEED 2.2, v3 - LEED 2009, v2 - Schools 2007, v3 - LEED 2009, v3 - LEED 2009, v3 - LEED 2009

Inquiry

The project consists of a single story 6,300 sf office building attached to a 160,000 sf manufacturing facility. The issue is how to model the heated only manufacturing area. The requirements from ASHRAE 90.1-2004, Appendix G state, "all conditioned spaces in the proposed design shall be simulated as being both heated and cooled even if no heating or cooling system is to be installed." Furthermore, "where no cooling system exists or no cooling system has been specified, the cooling system shall be identical to the system modeled in the baseline building design." These ASHRAE 90.1 requirements indicate that the proposed Constant Volume, 100% Outdoor Air, Gas-Fired, Make-Up Air Unit would need to include the baseline Variable Volume, 100% Outdoor Air, Chilled Water, Packaged Rooftop Unit for cooling. Current industry energy modeling software, approved by ASHRAE 90.1, cannot model this system for a single space. It also is unrealistic to compare the proposed Make-Up Air Units to a VAV w/Reheat System in a manufacturing facility. Our design team suggests that any heated only space should be modeled as heated only (no cooling) for the proposed and baseline model. This is mainly because if it were possible to model the "imaginary" cooling system for heated only spaces it would provide the project with unwarranted energy credit or debit. Specifically, if the loads were reduced between each simulation, for reasons such as improved insulation, the project could use less electricity and therefore gain energy credit from a cooling system that does not exist. Please advise if our recommended procedure to model "heated only" spaces is acceptable, and if not, what is the USGBC\'s recommended method to comply with ASHRAE 90.1-2004 requirements in this instance?