Nowhere is an understanding of building science more important than in designing the building enclosure. To optimize its performance, we must attend to the whole system as well as to the details. Each component plays an important role on its own and in relationship to the others.

It would be hard to find a more critical decision than your choice of insulation. In addition to R-value, you also need to look at these materials’ relationship with the rest of the building envelope. Though the fundamentals of building science are unchanging, new products and evolving best practices allow insulation to play an increasingly important role in whole-house system design.

A comprehensive insulation strategy takes into consideration the products’ efficiency, cost, application techniques, and environmental impact. But we also need to factor in the cost of potential warranty claims, comfort complaints, and durability challenges. Let’s take a closer look at some of the products and practices being used to insulate today’s high-performance homes.

Thermal Resistance Defined

Thermal energy travels from hot to cold, so we lose heat from inside to outside in cold months and lose our cool in the summer as heat tries to move indoors.

Insulation’s job is to slow down that transfer of heat. R-value is a measurement of a material’s ability to resist the transfer of energy; as we all know, the higher the R-value, the more effective the insulation. By doubling the thickness of an insulating material, we can double its R-value, cutting energy transfer in half; however, the law of diminishing returns means that the same resources applied over again yield half the net change. Looking at a complete wall assembly design and its energy analysis is the only way to find the right balance between construction cost, long-term energy savings, and overall environmental impact.