Executive Summary

National Bank of Arizona’s 144,000-square-foot headquarters complex in Phoenix, built in 1987 for a previous owner, contains a beautiful amenity:  Some 18,000 square feet of skylights allow natural light to flood the premises, nurturing an abundance of plant life as well as the busy employees and customers on the floor some 30 feet below the glass.  

But in a city where the daily average high temperature in mid-summer is 102 degrees Fahrenheit, and monthly rainfall averages under one inch, a vast amount of unimpeded sunlight is a serious detriment to efficient, cost-effective cooling. So when the bank decided to take advantage of a comprehensive energy-efficiency rebate program being offered by its local electric utility, Salt River Project (SRP), finding a solution to the skylight problem became one of its high-priority objectives. 

According to Dennis Calik, National Bank of Arizona’s senior vice president of corporate properties, the bank’s energy-efficiency makeover included the installation of a new 250-ton chiller to supplement the old one, together with the addition of lighting censors and new lighting technology. However, the full advantages of these upgrades would not be realized unless something was done to address the heat transmitted through the skylights.  

3M Sun Control Window Film was installed in the relatively short span of two weeks, with no interior disruption. The film is estimated to be saving the bank 249,000 kilowatt hours of electricity per year, which is enough energy to power approximately 17 average-size homes, according to SRP. Equally important, Mr. Calik noted that visibility in the lobby immediately improved.  

“The total program has been a great success, saving us about 747,000 kilowatt hours a year,” said Mr. Calik. Instead of running two chillers, the bank has found that, with the addition of direct digital controls, it can operate the new chiller at about 75-to-80-percent of capacity, even on the hottest days. According to SRP, the bank is saving more than $74,000 per year in electricity costs.