Canadian Consulting Engineer

U.S. tightens energy standards for rooftop air conditioners by 30%

The U.S. Department of Energy (DOE) has proposed new efficiency standards that would cut the energy used by rooftop air conditions by approximately 30%.

September 23, 2014   Canadian Consulting Engineer

The U.S. Department of Energy (DOE) has proposed new efficiency standards that would cut the energy used by rooftop air conditions by approximately 30%.

The proposed standards would result in more energy savings than those achieved by any standard ever issued by the U.S. Department of Energy, according to the American Council for an Energy-Efficient Economy (ACEEE).

ACEEE points out that current efficiency standards for rooftop air conditioners measure efficiency at full capacity, although air conditioners rarely operate at that level except on the hottest days.

The new proposed standards are instead based on a metric called IEER (integrated energy efficiency ratio) which captures efficiency at 25, 50, 75, and 100% of full capacity and better reflects real-world performance.

The DOE estimates that over the lifetime of units sold over 30 years, the proposed standards would reduce electricity consumption by about 1.3 trillion kilowatt-hours, or enough energy to cool all the commercial buildings in the U.S. for 7 years. Air conditioners account for about 10 per cent of a typical commercial building’s electricity cost.

Typical new rooftop air conditioners that just meet the commercial building energy code have efficiency levels of about 9.5 to 11.5. However, more efficient equipment is available on the market that reaches IEER levels as high as 21. Today’s proposed standards would set minimum efficiency levels of 12.3 to 14.8, depending on the equipment type and capacity.

The DOE is scheduled to issue a final rule for rooftop air conditions by the end of 2015. The Department is now about 70% of the way to reaching President Obama’s 2013 goal of reducing carbon dioxide emissions by 3 billion metric tons by 2030 through energy efficiency standards.

Meanwhile the Air-Conditioning, Heating and Refrigeration Institute (AHRI) in the U.S. has just announced that it will spend $5 billion on research and development over the next decade to develop new refrigerants for air-conditioning and refrigeration equipment.


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