Performance Evaluation Protocol for Full-Scale Wood-Frame Building Envelopes

Abstract

A protocol to evaluate the overall performance of the building envelope is not yet available in North America. Consequently neither the manufacturer nor the client can be sure of the performance of the unit over time. In the Canadian climate, the performance of wood-frame building envelopes is directly affected by moisture management, as well as by the quality of design, construction workmanship, and maintenance. Trapped moisture reduces the thermal performance of the envelope and can lead to mould growth that deteriorates building materials and contaminates the indoor-air. The means to evaluate the impact of these factors on the overall performance of the envelope are limited. The computer models that exist are still, for the most part, reserved for researchers or have not been validated to a sufficient comfort level for the designer. Large scale testing that would provide realistic results have been limited due to the lack of facilities and the lack of evaluation procedures. At this time under development is a protocol for the evaluation of performance of wood-frame building envelopes, which is intended to evaluate building envelopes as integrated systems with emphasis on durability characteristics. This protocol establishes an overall performance of the wood-frame building envelope as a system. Specifically, it focuses on hygrothermal factors; it develops a strategy to evaluate durability of wood-frame building envelopes and sets the internal and external limiting conditions to maintain performance.