The immediate impact of the 1973 OPEC oil embargo on the commercial roofing industry was a strong focus on improved thermal insulation materials and stiffer insulation building codes. Today, insulation is an important component of all roofing systems, especially for reducing heat loss by convection in winter months, but also by controlling heat gain through conduction in the summer.
Local building codes typically require minimum thermal resistance properties for specific types of buildings, expressed as an “R-value.” The higher the R-value, the higher the thermal resistance. Many architects and builders often specify roofing insulation with R-values significantly higher than the minimum required to increase energy efficiency.
One study by Lawrence Berkeley National Laboratory found that increasing the R-value on a “typical” roof system in Los Angeles from R-9 to R-15 would reduce average annual energy costs by $2,500 while lowering carbon dioxide emissions by thousands of pounds.
The dominant type of roofing insulation in the U.S. – with more than a 50 percent market share – is polyiscyanurate foam, better known as ISO board. Other leading types of roofing insulation include wood fiberboard, perlite and expanded/extruded polystyrene (EPS).
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