How are HVAC systems rated for energy efficiency?

HVAC systems are commonly rated for energy efficiency using the Energy Efficiency Ratio (EER) and the Seasonal Energy Efficiency Ratio (SEER). In this context, the correct answer focuses on the evaluation of energy efficiency under specific operating conditions.

The EER measures the cooling output in BTUs divided by the energy consumption in watt-hours at a specific operating condition, typically at 95°F outside ambient temperature and 80°F indoor temperature with 50% relative humidity. This value helps consumers understand the efficiency of air conditioning units under peak operational conditions. A higher EER indicates a more efficient system, meaning it provides more cooling for each watt of electricity consumed.

While SEER is also an important rating used for air conditioning units and provides an average efficiency over a cooling season, it is often considered separate from the immediate assessment that the EER offers. SEER is ideal for evaluating the overall seasonal performance rather than the performance at specific conditions.

BTU ratings indicate the capacity of the unit but don’t directly measure efficiency, and tonnage is a measure of cooling capacity (1 ton = 12,000 BTUs per hour), not efficiency. Therefore, focusing on EER offers a precise understanding of how effectively a system uses energy at peak performance, establishing it