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Home Energy Magazine Online March/April 2000
trends
in energy
Improving Air Conditioning Efficiency
Last November, the U.S. Department of Energy (DOE) announced that it was
planning to raise minimum efficiency standards for home central air conditioners
and heat pumps. The current air conditioner standard is a seasonal energy
efficiency rating (SEER) of 10. The new standards are likely to range from
11 to 13 SEER. The higher standards would represent an increase in efficiency
of 10%-30% over today's central air conditioners. What the final standards
will be, and the effective date for implementing them, was still up for
negotiation at press time.
Meanwhile, in Europe, where until recently cooling needs have been met
largely through a building's architectural features, sales of room air
conditioners have been growing by 12% annually since 1996. Energy consumption
in Europe from room air conditioners reached 12 TWh in 1996, but this usage
is projected to climb to more than 44 TWh per year by 2020 under a business-as-usual
scenario. A recent European Union study recommended the imposition of two
tiers of minimum energy efficiency standards for room air conditioners
to help contain the rising electricity consumption of these appliances.
The first tier would be implemented in 2003; the second by 2010 at the
latest. The technical changes needed to improve the efficiency of room
air conditioners are well understood (see Table 1).
Mary James is editor/publisher of Home Energy.
| Table 1. Methods for Improving the Energy Efficiency
of Room Air Conditioners |
| Technological Improvements |
Increase in Energy Efficiency Ratio* |
| 30% increase in frontal coil (heat exchanger) area |
8% |
| 45% increase in frontal coil (heat exchanger) area |
11% |
| Addition of one extra row of refrigerant tubing in frontal coil |
10% |
| Addition of two extra rows of refrigerant tubing in frontal coil |
16% |
| 20% increase in coil fin density |
16% |
| Improved coil fin design (modified fin pattern) |
11% |
| Improved refrigerant tubing heat transfer |
8% |
| 15% more efficient compressor |
8% |
| Use of variable speed compressor |
10%-40% |
Source: "Hungry Cooling: Room Air-Conditioners," Appliance
Efficiency 3, no. 3, (1999) p. 6-10.
*Energy Efficiency Ratio = cooling capacity of air conditioner in watts/electrical
input power in watts |
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