What property of insulation is crucial for evaluating its efficiency?

The R-value is a critical measure of insulation efficiency, as it quantifies the insulation's resistance to heat flow. A higher R-value indicates better insulating performance, meaning it can effectively reduce heat loss in winter and heat gain in summer. This property is essential for determining how well an insulation material will perform in a given climate and for specific building applications.

While thickness does influence the R-value to some extent, the R-value itself is a more comprehensive measure because it accounts for the type and quality of the insulation material. Color does not impact the insulation's thermal properties; it may affect aesthetic choices but does not contribute to efficiency. Similarly, while the material type can offer varying R-values, the rated R-value is the definitive standard for assessing insulation performance and making comparisons between different materials. Understanding R-value allows home inspectors to evaluate insulation effectiveness accurately and recommend improvements where necessary.