Which factor primarily determines the efficiency of an HVAC system?

The Seasonal Energy Efficiency Ratio (SEER) rating is a critical measure of an HVAC system's efficiency, representing the ratio of cooling output during a typical cooling-season to the total electric energy input during the same period. A higher SEER rating indicates a more efficient system, capable of delivering greater cooling output for less energy consumption. This efficiency is particularly relevant in determining long-term operational costs and energy savings for the end-user.

In contrast, while the type of refrigerant used in an HVAC system can influence its overall performance and environmental impact, it does not directly reflect efficiency in the same way that SEER rating does. Similarly, other factors such as the color of the HVAC unit or the type of construction materials used may have indirect effects on the system's performance or energy consumption but are not primary determinants of the system's efficiency rating. Focusing on SEER is essential for evaluating and comparing the energy efficiency of different HVAC systems effectively.