Hygrothermal = moisture + heat
Hygrothermal modeling uses a computer program to model the long-term effects of heat and moisture within and through construction assemblies. All building envelope assemblies routinely have some heat and moisture transfer through them as the seasons change and time progresses. Typically, many roofing and exterior wall assemblies, will “load up” with moisture during the winter months and “dry out” during the summer months. Hygrothermal modeling allows us to analyze this cycling and predict if it will become an issue or if it is acceptable.
The industry-accepted Hygrothermal modeling tool is WUFI. WUFI is a German acronym which stands for Wärme Und Feuchte Instationär, which translated means heat and moisture transiency. We use WUFI Pro 6.0 as a tool to model and predict how building envelope assemblies reached the condition they are in and to predict how new assemblies will perform. As with the use of any tool, use of WUFI requires training, experience in the building envelope, and a lot of common sense.
In addition to WUFI, we use traditional dew point and condensation analysis tools to validate WUFI models and existing conditions. We are also familiar with THERM which was developed by the Lawrence Berkeley National Laboratory to model heat transfer in building components.