The R-value is a measure that is expressed in what units?

The R-value is indeed expressed in British Thermal Units (BTUs). Specifically, it quantifies thermal resistance, indicating how well a material resists heat flow. A higher R-value means better insulation properties, meaning that the material can keep heat in during winter and out during summer more effectively.

To put it into context, when evaluating energy efficiency in buildings, understanding the R-value is critical for materials such as insulation. It helps builders and homeowners make informed choices about the types of insulation to use based on climate and thermal needs.

The other units provided do not relate to the R-value. Pascals are a unit of pressure, pounds per square foot measure weight per area, and cubic feet measure volume, none of which pertain to thermal resistance. Thus, the correct choice focuses on the unit that directly ties to the concept of heat transfer and energy efficiency.