Page 24 - Zero Net Energy Case Study Buildings-Volume 2

CASE STUDY NO. 7 DPR CONSTRUCTION OFFICE BUILDING
For design reasons, namely to avoid the “pillowing” appearance of insulation added to the underside of the roof sheathing, the insulation was applied to the exterior in the form of a spray foam roofing system. The overall thickness is 4”, providing an R-value of 24. The foam also has a UV reflective coating with a solar reflectance of 83% to provide a “cool roof” effect where exposed to the sun.
In addition, structural reinforcement was done with new steel components that resemble the original steel trusswork. These two design approaches for the roof systems preserved the original appearance of the roof structure from the interior while providing the optimum thermal characteristics for that large part of the building envelope.
The concrete building walls, on the other hand, were left untouched and uninsulated. This decision was based on the cost of ret- rofitting with insulation, which would have to be done from the interior since there is no access to the exterior lot-line walls, versus
12 Zero Net Energy Case Study Buildings: Volume 2