Why does COMcheck 3.1 include all below-grade walls with above-grade walls when calculating window-to-wall ratio (WWR)?
ASHRAE approved an interpretation in June 2005 for including basement walls in the WWR calculation based on the definitions of “building envelope”, “wall”, and “gross wall area” in Section 3.2 of Standard 90.1-2004. The interpretation states that in buildings with conditioned space below-grade, the gross wall area extends from the top of the surface of the floor of the lowest conditioned space to the bottom of the roof of the highest conditioned space. This interpretation was deemed to also affect 90.1-1999 and 90.1-2001. Therefore, with the release of COMcheck 3.1, below-grade walls are included with above-grade walls when calculating WWR when 90.1-1999, 90.1-2001, or 90.1-2004 is the selected code.
