Describe the scope of "energy-efficient" windows in residential code.

The scope of "energy-efficient" windows within the residential code emphasizes their performance characteristics, particularly in terms of energy conservation. These windows are required to meet defined standards regarding U-factor and Solar Heat Gain Coefficient (SHGC) ratings. The U-factor measures the rate of heat transfer, indicating how well windows retain heat; a lower U-factor signifies better insulating properties. The SHGC quantifies how much solar radiation passes through the window, with lower values indicating reduced solar heat gain, helping to keep homes cooler in warm climates.

The inclusion of specific ratings ensures that the windows contribute positively to the overall energy efficiency of residential buildings, aiding in minimizing energy consumption for heating and cooling. This focus on performance standards is what distinguishes energy-efficient windows from standard options, which may not adhere to the same energy-saving measures.