How will the concept of higher reflectivity roofing be sold in colder climates?
(Savings in Chicago going worst to best for 1500 ft2 building is approx. $23/year according to LBNL report) In cold climates like Chicago, both the cooling and heating loads must be considered. ORNL computer modeling for Chicago shows that for year-round energy efficiency, a highly reflective, low emissivity roof may give the lowest energy cost. The negative impact of high reflectivity in the winter months is minimized by the low angle of the sun and short daylight hours. If one were concerned strictly with the urban heat island effect, and disregarded energy efficiency, the choice would be high reflectivity, high emissivity.
