Published: February 18, 2016


One of the factors driving energy cost in commercial buildings is peak electric demand, much of which comes from cooling.

Under normal conditions, peak demand will occur on hot days in the mid-afternoon, when the building cooling load is at its maximum. Methods to reduce peak energy demand due to cooling include reducing the cooling load or increasing the cooling equipment efficiency. Successfully implementing evaporative precooling decreases the ventilation cooling load on the rooftop unit’s (RTU) evaporator coil. Evaporative condensing increases the efficiency of cooling equipment.

Corradini, A., Johnson, K., Karasawa, A., 2012. “Evaporative Retrofit Components For Roof Top Packaged Air-Conditioning Units, Pacific Gas and Electric’s Emerging Technologies Program.

Felts, D., Jump, D., 1998. Energy Savings From Indirect Evaporative Pre-Cooling: Control Strategies and Commissioning, American Council for an Energy Efficient Economy (ACEEE), Summer Study on Energy Efficiency in Buildings.

Woolley, J. 2014. Notes from Presentation on Evaporative Precooling. WCEC.