Commercial CAC and HP (Air-Cooled)

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THE PRODUCT:

Commercial air-cooled central air conditioners (CACs) and heat pumps (HPs) reject heat to the atmosphere by blowing outside air over the condenser coil. Commercial CACs and HPs can either be “single package” systems, where the evaporator coil and the condensing unit are combined into a single physical unit, or “split systems,” where the condensing unit is typically placed outdoors while the evaporator is indoors. Commercial CACs and HPs are often called roof-top units (RTUs) and are typically used for small- to mid-sized commercial buildings. RTUs may also contain a heating section.

THE STANDARD:

The Energy Policy Act (EPAct) of 2005 included efficiency standards for commercial air-cooled CACs and HPs, which vary by cooling capacity (in Btu/hr). Cooling capacity represents the amount of heat that an air conditioner or heat pump can remove from an enclosed space per hour. The EPAct standards, which went into effect January 1, 2010, cover equipment with capacities ranging from 65,000 Btu/hr up to 760,000 Btu/hr. The cooling efficiency of commercial air-cooled CACs and HPs is measured by the energy efficiency ratio (EER), which is the cooling capacity (in Btu/hr) divided by the power input (in watts). The heating efficiency of air-cooled HPs is measured by the coefficient of performance (COP), which is the heat delivered (in Btu) divided by the energy input (in Btu). This standard level is the same as that published in the the commercial building energy code, ASHRAE (American Society of Heating, Refrigerating and Air-Conditioning Engineers) 90.1 in November 2010.

The 2012 ASAP/ACEEE report, The The Efficiency Boom, analyzed the Consortium for Energy Efficiency's (CEE) Tier 2 standard for commercial air-cooled CACs and HPs, which represents energy savings of about 9%. A standard at this level would result in annual savings of 9.7 TWh in 2035 and generate net present value savings of $2.4 billion for consumers. The incremental cost of $1,200 for an average-sized unit would have a payback period of less than 6 years.

KEY FACTS:

Technology options for improving the efficiency of commercial air-cooled CACs and HPs include higher efficiency compressors, larger and better heat exchangers, and higher efficiency fans and fan blades.