What does "R-value" measure in glazing?

R-value measures the thermal resistance of materials, including glazing. In the context of glazing, R-value quantifies how well a window or glass unit resists heat transfer. A higher R-value indicates better insulation properties, meaning that the glazing can effectively reduce heat loss during colder months and minimize heat gain in warmer months. This is critical for energy efficiency in buildings, as effective glazing can lead to reduced heating and cooling costs.

The concept of R-value specifically pertains to thermal performance, making it an important factor for architects, builders, and glazing contractors when selecting materials for energy-efficient designs. Understanding R-value helps professionals assess how different glazing options compare and identify the most suitable choice for a specific climate or building application.