This commercial tower has an atypical roof configuration. The weather-protective surface of the roof is located approximately 100 feet below the top of the parapet (the parapet is an architectural feature). About 80 feet above this roof surface (approximately 20 feet below the parapet), there is a metal grating with 50% open area. The parapet is constructed of opaque metal panels on the interior side and glass on the exterior side. This parapet permanently shades approximately 33% the weather-protecting roof surface at noon on June 21. The metal grating further shades the weather-protecting roof surface. The team believes that there are two potential interpretation of defining the roof area for this project: 1. The weather-protecting roof is considered the roof for the purposes of SSc7.2, and all area that is permanently shaded by the parapet and the metal grating should be excluded from the roof area calculation. 2. The metal grating is considered the roof for the purposes of SSc7.2, and the open area of the grating, as well as the area permanently shaded by the parapet, should be excluded from the roof area calculation. Please confirm which of these two interpretations is correct.
Roof design, including associated architectural features, contributes in varying degrees to heat island effect. While permanent shading of direct solar gain meets the intent of SSc7.2, CIR ruling dated 9/20/04 notes that the shading device is effectively part of the roofing system as it relates to reflectivity. This also extends to architectural features. Apply credit requirements to the area of non-shaded weather protection combined with the area of the metal grating and architectural feature. Weighted averages can be calculated in accordance with SSc7.2 CIR ruling dated 1/23/06.