3.3 THERMAL INSULATION
Thermal insulation serves several purposes in building envelopes: controlling heat flow, serving as
a component of the condensation control system, contributing to the maintenance of thermal
comfort by controlling interior surface temperatures, reducing thermally induced movement of
structural elements, and protecting envelope materials from temperature cycling. The ASHRAE
Handbook of Fundamentals discusses the fundamentals and application of thermal insulation.
The discussion of thermal insulation in these guidelines does not address the determination of
appropriate levels of insulation, but rather the manner in which this insulation is incorporated in the
thermal envelope at the design and construction stages. There are two keys issues regarding
thermal insulation systems, the first being the insulation material. The other issue is how the
insulation is positioned and attached to obtain effective and long-lasting performance.