Design and Performance of Walls with SPF

are now making the impact larger than predicted-not because of any single issue, but because of the change in the paradigm of environmental control of buildings (Chapter 8). The holistic approach (systems approach) is now finding its way from academic circles into building codes and material standards. The occupant of a building demands that indoor air be fresh, free ofpollutants, and maintained within a selected temperature range. To ensure that these requirements are fulfilled, the mechanical engineer must use controlled ventilation (with or without air conditioning systems). To this end, the whole building must be airtight and the indoor space divided into controllable compartments. As a starting point, to provide the airtightness ofthe building envelope, one may use air barrier systems. The 1995 edition of the Canadian National Building Code requires doing so.