Hi,

Trying to figure out the minimal insulation required following Table 5.5.6 of ASHRAE 90.1-2007 for a fully underground space? (roof, slab, walls)

Our project includes an underground occupied spaces joining an existing building. The top of the concrete slab (roof) is always deeper than 2 feet below final grade.

Following MNECB (Canada) and EE4 modeling guidelines, the roof could be counted as a Below-grade wall but it's not as clear in ASHRAE 90.1.

Anyone has some input on this?

Thanks all!

GUILLAUME MARTEL

SUSTAINABILITY COORDINATION
M.ARCH, PA LEED BD+C