On October 29, 2010, the American Society of Heating, Refrigeration, and Air-Conditioning Engineers (ASHRAE) officially released ASHRAE Standard 90.1-2010, which sets efficiency levels for certain types of equipment, including commercial package air conditioning and heating equipment. Such equipment can include air-cooled, evaporatively-cooled, water-cooled, or water source (not including ground water source) electrically operated, unitary central air conditioners and central air conditioning heat pumps for commercial use. Commercial-sized water-cooled and evaporatively cooled air conditioners cool commercial facilities, using water instead of ambient air (as is used in air-cooled equipment) to cool the condensing coil. In the case of a water-cooled air conditioner, the condensing coil is submerged in circulating water; in the case of an evaporatively cooled air conditioner, the condensing coil is sprayed with water that evaporates as air passes over the coil. Both systems utilize the high heat capacity of water to optimize the heat transfer from the refrigerant in the condensing coil. Water-cooled air conditioners can be used effectively in any type of environment, while evaporatively cooled air conditioners are most effective in hot-dry climate regions (i.e., the southwestern United States).

ASHRAE Standard 90.1-2010 recently expanded its scope to include air conditioners and condensing units serving computer rooms. These units operate similarly to other types of commercial packaged air conditioners in that they provide space conditioning using a refrigeration cycle consisting of a compressor, condenser, expansion valve, and evaporator. However, air conditioners and condensing units serving computer rooms are typically designed to maintain the temperature in the conditioned space at 72 degrees Fahrenheit, and maintain a specific relative humidity.

Current Rulemaking Activities: The Energy Policy and Conservation Act (EPCA) established Federal energy conservation standards for commercial heating, air conditioning, and water heater equipment that generally correspond to the levels set in the American Society of Heating, Refrigeration, and Air-Conditioning Engineers (ASHRAE) Standard 90.1. EPCA also directs the U.S. Department of Energy (DOE) to consider amending the existing Federal energy efficiency standard for each type of equipment listed, each time ASHRAE Standard 90.1 is amended with respect to such equipment. For each type of equipment, EPCA directs that DOE must adopt amended standards at the new efficiency level in ASHRAE Standard 90.1, unless clear and convincing evidence supports a determination that adoption of a more stringent level as a national standard would produce significant additional energy savings and be technologically feasible and economically justified.

 In a Notice of Data Availability (NODA), which DOE published in May 2011, DOE determined that ASHRAE Standard 90.1-2010 increased the efficiency level (in comparison to the Federal standard) or added new efficiency standards for the following equipment classes:

·         Small, Large, and Very Large Water-Cooled Air Conditioners;

·         Small, Large, and Very Large Evaporatively Cooled Air Conditioners;

·         Certain Small (only those with cooling capacity < 17,000 Btu/h) and Large Variable Refrigerant Flow (VRF) Water-Source Heat Pumps; and

·         Air Conditioners and Condensing Units Serving Computer Rooms.

In addition, although ASHRAE Standard 90.1-2010 did not increase the efficiency level for single-package vertical air conditioners (SPVACs) and single-package vertical heat pumps (SPVHPs), DOE is required by EPCA, as amended by the Energy Independence and Security Act of 2007 (EISA 2007), to consider increasing the energy conservation standards for these equipment classes.

In the May 2011 NODA, DOE published the energy savings potential for water-cooled and evaporatively cooled air conditioners and SPVACs and SPVHPs (for sizes where equipment is available on the market). At the time of the NODA, DOE did not have enough information available to analyze the energy-savings potential for VRFs and computer room air conditioners. After obtaining sufficient information, DOE undertook these analyses for the Notice of Proposed Rulemaking (NOPR), which is expected to be published in January 2012.

Because of the significant potential for energy savings for SPVACs and SPVHPs, and because the Federal standards are currently the same as the efficiency levels in ASHRAE Standard 90.1-2010, DOE is conducting further analysis to determine if efficiency levels higher than those in ASHRAE are justified. A NOPR for these products is expected later in 2012.

Efficiency Rating: The efficiency descriptor for most commercial air conditioners is the energy efficiency ratio (EER). In the U.S., the EER is a steady-state efficiency rating which is determined by dividing the cooling capacity (in Btu/hr) by the electrical input (in watts). For commercial heat pump equipment, the coefficient of performance (COP) is an additional efficiency metric.

The efficiency descriptor for computer room air conditioners is the sensible coefficient of performance as defined in ASHRAE Standard 127 (SCOP-127). This is a ratio calculated by dividing the net sensible cooling capacity (in watts) by the total power input (in watts; excluding re-heaters and humidifiers) at conditions defined in ASHRAE Standard 127.

Analyses: Under contract to DOE, LBNL's Energy Efficiency Standards (EES) group conducted analyses for the NODA and for the NOPR, including:

• Shipments Analysis
• National Impact Analysis (National Energy Savings and Net Present Value)
• Emissions Analysis

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