Building envelopes serve as our barrier between the ever-changing exterior climate and the mechanically-controlled environment of our interiors. This presents a challenge for architects, because while personal comfort is generally constant and narrowly defined, the outside environment can present a wide range of conditions, from day to night and from season to season. Insulation is one of the most important considerations to prevent the thermal heat transfer through the building envelope, maintaining our interior comfort while ultimately lowering the cost of heating and cooling to do so.