New air conditioner standards would reduce cooling costs for modular classrooms and offices

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Joanna Mauer

The Department of Energy (DOE) issued proposed new standards today for certain types of specialized air conditioners that would reduce cooling costs for many schools as well as other buildings. The new standards would cut energy use by about 18% relative to the current standards.

The standards proposed today cap a busy week for new DOE efficiency standards. DOE completed new standards for commercial clothes washers on Monday and released proposed updates to the residential dishwasher standards yesterday.

The proposal issued today would set new minimum efficiency levels for single-package vertical air conditioners and heat pumps, which are commonly used to cool modular classrooms and offices and telecommunications shelters housing electronic equipment. These air conditioners are installed on external building walls.

DOE estimates that over the lifetime of units sold over 30 years, the proposed standards would net customers $110-440 million in savings and reduce electricity consumption by about 26 billion kilowatt-hours (kWh), an amount equal to the annual electricity use of 2.4 million U.S. households.

Vertical heat pumps can reverse the refrigeration cycle to provide heating to schools or offices in the winter in addition to cooling during the summer, while vertical air conditioners can also provide heating using gas or electricity, for example. Unlike schools and offices, telecommunications shelters often require year-round cooling due to the high internal heat load from the electronic equipment housed inside.

DOE estimates that a single vertical air conditioner just meeting the current standards consumes about 6,800 kWh per year on average, while a vertical heat pump consumes more than 20,000 kWh per year. By comparison, an average U.S. household consumes about 11,000 kWh annually.

The cooling efficiency of vertical air conditioners and heat pumps is measured by the energy efficiency ratio (EER), where higher values indicate higher efficiency. The current standards for vertical air conditioners and heat pumps require a minimum EER of 9 for the most common equipment. The latest version of ASHRAE 90.1, a commercial building energy code, specifies a minimum EER of 10 for vertical air conditioners and heat pumps. The new proposed standards would raise the minimum national efficiency level to 11 EER for the most common equipment.

DOE is scheduled to publish a final rule by May 2015, and the new standards would take effect four years later.