Rating System

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

Rating System Version

v2 - LEED 2.2, v3 - LEED 2009, v2 - Schools 2007, v3 - LEED 2009, v2 - LEED 2.0, v3 - LEED 2009

Inquiry

The project in question is an existing office building of which everything was demolished with the exception of the structure, slabs and roof. The building\'s skin was reconstructed and the mechanical systems were redesigned. The question is regarding the baseline model calculations used in the Energy and Atmosphere Credit 1 - Optimize Energy Performance. The credit requirements for Whole Building Energy Simulation say to use the Performance Rating Method in Appendix G of ASHRAE/IESNA 90.1-2004 to establish baseline building performance. One of the requirements of this standard (G4.1A - Baseline Building Envelope Orientation) states that "the baseline building performance shall be generated by simulating the building with it\'s actual orientation and again after rotating the entire building 90, 180, 270 degrees, then averaging the results." This requirement makes sense when talking about a building in new construction because you have the option to orient the building in such a way as to take maximum advantage of passive solar design, wind currents, etc. With an existing building the existing orientation is already determined so it doesn\'t make sense to establish a baseline off of the average of four orientations. When we model it this way we lose 6% of our energy reduction compared to the design case. We would like to ask if based on the fact that this building\'s orientation was already set because it is a rennovation project, that we can establish the baseline energy model solely off of that building orientation, not the average of all 4.