Seasonal Energy Efficiency Ratio (SEER) is the only legal way to rate energy efficiency of central air conditioners in the U.S. SEER 13 replaced SEER 10 as the minimum in January, 2006. SEER is a national average rating. There is growing concern that the SEER's test conditions do not reflect installations in real houses (based on field data). There is also concern that SEER does not reflect regional performance concerns, including peak performance in hot regions or moisture control in humid climates. Achieving the next large national savings increase with today's metrics would require complex and expensive machinery. We support two changes. (1) Adjust test parameters, such as external static pressure levels and default fan power values, that materially affect the gap between laboratory ratings and field experience. Equipment optimized for real-world conditions will be more efficient in actual use. (2) Adopt rating methods that reflect regional needs.

Manufacturers already make regionally differentiated models (of furnaces), so regional products are feasible as well as desirable for comfort and efficiency. We discuss ways to modify and complement the current SEER test to address these issues.