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The Vacaville Home Base home
improvement store was in trouble - the evaporative coolers used to condition
the air weren't large enough to keep the store cool! Store temperatures
reached 85°F and higher on the hottest summer afternoons, making for
a very uncomfortable shopping experience. The only alternative seemed to
be adding more cooling capacity, which would not only cost a lot of money
up front, but would increase energy bills (and emissions!) for years to
come.
Before making this investment, the facilities managers at Home Base decided to try something different - applying a cool white coating to their roof. In theory, this coating lowers the roof's temperature by reflecting away solar energy. A lower roof temperature means less heat is transferred to the store below, keeping it cooler. But the Home Base staff was skeptical - how much would the coating really improve their store's comfort? To find out, Home Base turned to Scholten Roofing in Mission Viejo, California to add a white elastomeric roof coating, and Dr. Lisa Gartland of Oakland's PositivEnergy to monitor the store's comfort and energy use before and after the roof was coated.
Initially the light gray capsheet roof reflected away only 31% of the sun's energy and heated up to 170°F. With the cool coating from National Coatings the roof reflects away 74% of the sun's energy and only reaches a peak temperature of 120°F - a reduction of 50°F! More importantly, temperatures inside the store stay below 85°F, and fell within optimal comfort levels (below about 79°F and 60% relative humidity) for 10 more hours a week. The building also used 10% less energy, since the evaporative coolers didn't run as often in the morning and at night.
Adding the roof coating
didn't solve all of the store's problems, but it was the most effective
way to reduce the store's cooling loads. Summer cooling loads on this typical
flat-roofed, skylit warehouse were cut by 24%. There are other energy efficiency
measures Home Base can take to further reduce their cooling loads, like
adding spectrally selective films to the skylights, and using fans for night
time ventilation. But if they decide instead to add to their cooling system,
the extra capacity they'll need is much smaller - which should cut down
on their equipment expenditures.
Adding a cool roof coating also made sense from a roof maintenance perspective. A 50¢ to 75¢ per square foot investment in a cool coating protects your roof from solar UV rays and thermal fatigue. Coating a roof every 10 years can help avoid the expense and hassle of replacement.
Home Base came out ahead on all counts - a more comfortable building, lower cooling energy bills, a longer-lasting roof, potentially lower capital expenditures - plus they made an environmentally responsible choice to reduce future energy use and emissions.
For more information about how cool coatings can help your building, contact Mark C'DeBaca of Scholten Roofing (949) 951-9984, National Coatings (800) 423-9557, or Dr. Lisa Gartland of PositivEnergy (510) 595-PNRG, lisa@pstvnrg.com.