The interface between the interior of the building and the outdoor environment, or the building envelope, plays an important role in determining the amount of energy necessary to maintain a comfortable indoor environment. ZETA's ultra-efficient building envelope design includes high R-value insulation-R-30 roof, R-22 walls R-5 exterior rigid foam, R-22 floor, and R-5 and R-7 Energy Star Rated windows-along with natural daylighting and ventilation.