Built structures have evolved over centuries from basic shelter to the advanced buildings we design and construct today. The materials with which humans have erected these structures have also evolved and changed. And similarly, the manner in which materials get assembled together to form the enclosure of buildings has altered. We have morphed from uninsulated mass walls of natural materials in their native form to highly insulated cavity walls of engineered materials. With this change in construction assembly and materials has come improved energy performance and incorporation of recyclable materials. We can take waste wood and form it into sheets for sheathing. Plastic bottles can be transformed into decking. Petroleum can be fashioned into rigid insulation and glass spun into fibers that insulate. Solid stone blocks and timber logs stacked upon each other to form a structure’s division between interior and exterior are ways of the past. An uninsulated wall is inconceivable today. But, what are the unintended consequences of these improved, highly insulated, framed walls of engineered materials? Has durability been replaced in favor of insulation? Is resiliency an afterthought? Have building science issues been created that make moisture and mold an unwelcomed challenge? Are assemblies unable to breath and made of engineered materials that degrade with increased speed if wetted? Have modern construction methods developed a world of building pathology? How do we promote the technology of highly insulated buildings but minimize the associated pathology that can be an unintended consequence?
The study of building science, and practices such as hygrothermal analysis, are helping to advance enclosure design. Developments in material science have produced technologies such as smart membranes that actively control vapor movement. And verification processes such as building enclosure commissioning have strengthened oversight and help validate performance.
A well insulated and air sealed assembly is an obvious target for any designer. But where the assembly is insulated and how it is allowed to breathe are equally important. And we must not forget about the age old mass of a wall and how that can contribute to performance, durability, and resiliency.
