The National Building Code of Canada (NBC) requires that an "effective" air barrier system be incorporated within the building envelope. Although the NBC addresses the performance characteristics to be considered to demonstrate that an effective air barrier system has been achieved, the NBC does not prescribe any specific test protocols with acceptance criteria to verify compliance of proprietary air barrier systems.

Whole-house tests were developed to compare the airflow resistance of several different materials used to seal the walls of a house at the outer surface. These airflow resistances were measured infield installations and include the effects of interactions with adjacent materials and assemblies. The materials tested were housewrap over fiberboard and foam sheathings, extruded polystyrene foam sheathing with the edges taped, extruded polystyrene sheathing with the edges untaped, and caulking and foaming the inside of the wall cavity.

This paper summarizes the most recent results from an ongoing, multi-year research program to monitor the long-term performance of residential air barrier systems. Airtightness tests were conducted on I 7 houses, located in Winnipeg, Canada, ranging in age from 8 to I I years, for which there was extensive historical data. Eight of the houses used polyethylene air barrier systems and nine used an early version of the airtight drywall approach (ADA). The latest tests were conducted in 1997.

The effect of wall material configuration on dynamic thermal performance is analyzed for six typical wall configurations. Due to different arrangements of concrete and insulation layers, these walls present a wide range of dynamic thermal properties. Newly developed thermal structure factors are used in selection and thermal analysis of these walls. A simple one-room model of the building exposed to diurnal periodic temperature conditions is analyzed to give some basic information about the effect of wall material configuration on thermal stability of the building.

In 1995, the U.S. Department of Energy (DOE) began planning for a new generation of building simulation tools. As part of this planning activity, DOE created an inventory of DOE-sponsored tools in early 1996. By mid-1996, this work had evolved into a web-based directory with information on 50 software tools. Today, the directory contains information on more than 125 tools from around the world. To inform the simulation tool planning efforts, DOE sponsored workshops in August 1995 and June 1996, inviting energy simulation developers and users.

A building's envelope is the product of the choice of framing materials and quality of craftsmanship. Exposed to weather, it may 1101 provide the same airtight conditions in which its insulation material had been tested. Air permeable insulation offers little resistance to pressure driven, or convective, heat loss. Air impermeable insulators can additionally reduce convective, as well as conductive, heat loss by being sprayed into and sealing up sources of infiltration normally addressed by caulks and sealants.

A technique for improving the thermal performance of lightweight steel- and wood-framed building assemblies is introduced in this paper. In this approach, rigid extruded insulation material is applied only to the framing members themselves (studs, plates, doubles, headers, etc.), effectively creating a composite member composed of insulation and structural framing. The depth of the envelope cavity is thereby extended by an amount that is equal to the thickness of the rigid insulation employed.

Modem, massive building envelope technologies (masonry and concrete systems) are gaining acceptance by builders today. All U.S. thermal building standards, including ASHRAE 90.1and90.2 and the Model Energy Code, are linked to the steady-state clear wall R-value. They also have separate requirements for high mass walls. Very often, only steady-state R-value is used as a measure of the steady-state thermal performance of the wall. This value does not reflect the dynamic thermal performance of massive building envelope systems.