Reflective Roofing

Dark roofs absorb a tremendous amount of solar radiation and become extremely hot. Hot roof surfaces translate to higher utility and equipment costs and contribute to elevated air temperatures. Reflective or cool roof applications can reduce air conditioning energy use, level of roof insulation required, and chiller equipment size. The Lawrence Berkeley National Laboratory estimates that reflective roofing for commercial and residential structure could alone save $27 million a year in Houston and $20 million a year in the Dallas/Fort Worth areas in energy costs.

Courtesy of LBNL

According to EPA, $40 billion is spent annually in the US to air condition buildings – one-sixth of all electricity generated in a year! Qualified roof products substantially reduce air conditioning needs thus reducing energy bills. In most of Texas, reducing the heat entering buildings is a prime requirement to reducing cooling costs. This is true for both residential and commercial structures (link here to the commercial roofing section).

Florida Solar Energy Center has sponsored testing on over 60 samples of common roofing materials, providing data on spectral reflectance characteristics. The results suggest the following conclusions:

• All colors of asphalt shingles evidence poor solar reflectance (3 - 26%)
  
  
• An improved white asphalt shingle using the conventional process showed only modest improvement (31% reflectance)
  
  
• White elastomeric coatings showed high solar reflectance (65-78%)
  
  
• Other white roofing systems showed high solar reflectance:
  • White concrete tile: 73%
    
  • White metal roof: 67%

courtesy of Everest Coatings

Based upon preliminary analysis done by Lawrence Berkeley National Laboratory (S. Konopacki and H. Ackbari, 2002), the residential sector for the Houston region could achieve up to 8% annual electric energy savings from cool roof applications not including indirect benefits or shading.