Packaged terminal air conditioners and heat pumps (PTACs and PTHPs) are combined heating and cooling assemblies typically found in motels. They are intended for mounting through the wall and include a prime source of refrigeration, separable outdoor louvers, forced ventilation, and heating availability by hot water, steam, or electric resistance heat.
Federal standards for PTACs were established by the Energy Policy Act of 1992. This legislation adopted standards originally set by the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) in 1989. ASHRAE Standard 90.1 is a commercial building energy code that all states must meet or exceed, and it includes minimum efficiency requirements for equipment including PTACs and PTHPs. The Energy Policy and Conservation Act (EPCA) requires that if the equipment efficiency standards in ASHRAE Standard 90.1 are amended, DOE must either establish amended standards for the products at the levels specified in ASHRAE 90.1 or establish more stringent standards if they would result in significant additional energy savings and are technologically feasible and economically justified. In 1999, ASHRAE set modestly higher standards for PTACs and PTHPs, but DOE concluded that higher national standards would likely be justified. DOE published a final rule in October 2008 that established more stringent standards for standard-size PTACs and PTHPs than the ASHRAE 1999 standards, and standards equivalent to the ASHRAE 1999 levels for non-standard-size equipment. The national standards established in the final rule for standard size PTACs and PTHPs will be applicable starting October 8, 2012. The standards for non-standard size PTACs and PTHPs became effective October 7, 2010 (the product timeline below reflects only the 2010 date). The 2010 version of ASHRAE 90.1, which was published in November 2010, contains the EER and COP standards for PTACs and PTHPs that were in the 2008 DOE final rule.
The cooling efficiency of PTACs and PTHPs is measured by the energy efficiency ratio (EER), which is the cooling capacity (in Btu/hr) divide by the power input (in watts). The heating efficiency of PTHPs is measured by the coefficient of performance (COP), which is the heat delivered (in Btu) divided by the energy input (in Btu). The EER and COP standards for PTACs and PTHPs vary by cooling capacity. Cooling capacity represents the amount of heat that an air conditioner or heat pump can remove from an enclosed space per hour.
Technology options for improving the efficiency of PTACs and PTHPs include higher efficiency compressors and increased heat exchanger area.