Comparing Retrofit Wall Performance Predicted from Hygrothermal Simulations to Measurements

Over the past few years ORNL has been showing that WUFI® can be used to predict the moisture performance of walls when exposed to diffusion of water vapor, convection of moist air through the wall, and solar driven moisture. This is accomplished by comparing the hygrothermal simulation results to carefully instruments walls exposed to these phenomena in a climate chamber. In FY 2018, three stick-built walls were succumbed to typical Chicago, Illinois weather conditions in Oak Ridge National Laboratory’s Heat, Air and Moisture chamber. The measured temperature, relative humidity, and moisture content within these walls were compared with WUFI hygrothermal simulation results. In FY 2019, similar experiments and comparisons with WUFI results were completed with two walls, a structural insulated panel-based wall and a concrete masonry unit-based wall. In FY 2020, experiments were completed for a probable exterior retrofit of a wall which included adding cavity and continuous insulation. Two pairs of walls were tested by exposing them to Chicago winter weather with a positive pressure pushing outside air into the wall. The results from the FY 2020 experiments are reported here.