Keep Temperatures Cool for Less

If money were no object, you could keep your plant and warehouse so cool that productivity sizzles during hot weather -- rather than employees. But there may be a cheaper option for your company than simply using air conditioning: roof mist cooling.

Used by itself, roof mist cooling can make interior conditions bearable. Used as a supplement, it can drive down the costs of operating existing air-conditioning systems and allow the use of smaller, more economical units.

Roof mist systems lower roof temperatures by 40 to 60 degrees through a process of sprayed water and evaporation. Sensors and controllers regulate the process by zones, misting any part of the roof that reaches a predetermined temperature, typically 90 degrees Fahrenheit. For a large plant or warehouse, water pressure may not be strong enough to mist the entire roof, so the system can be programmed to mist zones in a sequence.

Interior heat discomfort is caused mainly by the transfer of solar heat from the roof. In addition, the physics principle of "warm seeks cool" applies, meaning that heat from lighting, machinery and body temperature is trapped inside because the hot roof cannot absorb it. Misting allows the roof to act as a cooling panel to absorb much of the internal heat.

One company installed a roof misting system to supplement an inadequate air-conditioning system in its 60,000-square-foot machine shop. The company's operating maintenance costs related to the system average less than $2,500 a year. In addition, roofing materials last longer because of the lower and more consistent temperatures.