We are working on a 10 story mixed use building consisting of approx. 11,705 SF of conditioned retail, office and support areas, common lobbies and utility areas on level1 and clubroom and fitness areas on level 10; 56,242 SF of conditioned residential condominium spaces located on levels 5 thru 9; 9,885 SF of conditioned residential corridors and elevator lobbies located on levels 5 thru 10; 2,998 SF of unconditioned stairwell throughout the building; and 64,524 SF of parking garages extending from level 1 through level 4. The building's total area is approximately 145,354 SF.
We intend to clearly treat the conditioned residential condo spaces (56,242 SF) separately in our energy model as residential system 2 units, in accordance with ASHRAE 90.1-2007 user's manual and exception (a) to section G3.1.1 of Appendix G.
According to table 3.1.1A & B of Appendix G, however, the conditioned non-residential portion of the building (21,590 SF) should be treated as a System 8, not because of the total conditioned floor area (1st FL. & 10th of 11,705 SF + 5 thru 10th FL. corridors & Elev. Lobbies of 9,885 SF = 21,590 SF
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5916 thumbs up
November 2, 2014 - 6:51 pm
Residential is the predominant system so none of the exceptions apply to it at all. Any exceptions must be to the residential since it is predominant. You cannot claim exceptions relative to non-predominant parts of the building (like you are trying to do to justify the separation of systems to avoid a system 8).
Here is a suggestion - Include all spaces associated with the residential (lobbies, corridors, etc.) as residential. Then apply exception b to the areas on the 1st and 10th based on a difference in schedule.