Okay, so you installed a cool roofing system, but since the building already had so much insulation you haven’t noticed any energy savings. What’s the point?
True. High reflectivity is a key characteristic that helps keep buildings cooler and can reduce energy usage. As much as 40% less cooling energy may be needed for buildings that have highly-reflective roofs. But even if a building is very well insulated, here are some other valuable benefits from cool roofing:
Insulation can be 25%-50% more effective
Studies have shown that extremely high temperatures reduce the effective R-value of the most widely used types of insulation (Leonard & Leonard, 2005). Cooler surfaces help preserve and keep rooftop insulation materials cooler.
HVAC equipment can operate more efficiently
Inlet air temperatures can be 5-15 degrees cooler 30 inches above a cool roofing surface compared to a black surface. Most rooftop HVAC units are designed with efficiency ratings evaluated at 95°F (York International, 2005); rooftop temperatures on a black surface can reach 160°F or higher, meaning that HVAC units will not operate at peak efficiency.
Substrate deterioration may be slowed by as much as 75%
Ultraviolet and infrared radiation and moisture penetration accelerate substrate deterioration. A cool roofing system will reflect this radiation and help protect the substrate (Kirn et. Al., 1994).
Ambient interior temperatures can be up to 20°F cooler than outside
Studies of worker performance with machine operation and high physical activity reveal that productivity drops 10% at 84°F and 38% at 95°F (Schweisheimer, W., 1962). So even if a building is not air conditioned occupants will still notice improved comfort on hot days.
