Thermal and Hygrothermal Analysis in Building Envelope Commissioning

As the focus of new building construction shifts towards sustainability with emphasis on energy efficient design, more importance is placed on performance of the building envelope. Ensuring the envelope performs up to specifications is, at least in part, the purview of whole building commissioning. Government developments in Canada and the United States have been commissioning the building envelope for many years. Commissioning is becoming more common in the commercial sector, as developers require more specific project targets, either to meet enhanced building code requirements or earn LEED certification.

However, no amount of physical testing or field observation can compensate for an envelope design that was flawed from the outset. It is therefore important for building scientists to support a project’s design with quantitative data, prior to construction commencing. Computer simulation programs aid in this respect, giving building scientists the ability to model simulations that would be difficult to calculate otherwise. Simulations provide the ability to quickly verify a design’s expected performance, highlight problem areas for revision by the principal designers, or predict potential long term problems in novel, un-tried assemblies.

This paper focuses on several case studies where thermal analysis and hygrothermal simulation software aided in the evaluation and adjustment of several building envelope designs. The software aided the commissioning process in several ways:

1. They helped determine whether or not an assembly would function as required by project targets.
2. They pinpointed potential or unforeseen problems of new design concepts.
3. They provided clear graphical outputs that could be easily related to the client.
4. They quickly assessed the effect of a minor change to an assembly.

The push towards green building design marks an important step in the building science industry. Being able to verify the quality of the building envelope design is equally important. Many programs exist that can model a building assembly’s performance. The software can be used to verify a traditional method or test a new design concept. The results offer an effective way to certify a building envelope’s performance and help clients reach their project targets.