New AC Standards Would Rank as Biggest Energy Saver in DOE History

September 22, 2014 By Karen Henry

rooftopac-energy-manageThe US Department of Energy (DOE) has proposed new efficiency standards that would slash commercial rooftop air conditioner energy use by about 30 percent. The proposed standards would achieve the largest national energy savings of any standard ever issued by DOE.

Rooftop air conditioners, commonly used in low-rise buildings such as schools, restaurants, big-box stores and small office buildings, cool about half of the total commercial floor space in the United States.

Air conditioners account for about 10 percent of a typical commercial building’s electricity costs, according to the American Council for an Energy-Efficient Economy. DOE estimates that the new standards would net a typical building owner between $3,500 and $16,500 over the life of a single commercial rooftop air conditioner. Overall savings will often be higher since most buildings have multiple units.

Over the lifetime of units sold over 30 years, the proposed standards would save businesses between $16 and $50 billion and reduce electricity consumption by about 1.3 trillion kilowatt-hours, DOE projects.

The current efficiency standards for rooftop air conditioners measure efficiency at full capacity despite the fact that air conditioners rarely operate at that level except on the hottest days. The new proposed standards are instead based on a metric called integrated energy efficiency ratio (IEER), which captures efficiency at 25, 50, 75, and 100 percent of full capacity and better reflects real-world performance. Typical new rooftop air conditioners that just meet the commercial building energy code have efficiency levels of about 9.5 to 11.5. However, DOE’s High Performance Rooftop Unit Challenge has helped spur several manufacturers to develop and bring to market high-efficiency rooftop air conditioners. Equipment on the market today achieves IEER levels as high as 21. The proposed standards would set minimum efficiency levels of 12.3 to 14.8 depending on equipment type and capacity.

DOE is scheduled to publish a final rule for rooftop air conditioners by the end of 2015.

Photo via Shutterstock.

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