| Résumé | This paper presents in-situ hygrothermal test results of residential, highly insulated and zero energy ready wall assemblies. A comparison of results of freshly exposed specimens, and results after 3 years of exposure is provided. Three wall specimens were installed and instrumented at the NRC-Construction’s Field Exposure Wall Test Facility (FEWF) in 2016. The wall assemblies consist of 1) a high R-value (R-29) retrofit assembly with continuous external foam insulation (W1- XPS) and poly-ethylene vapor barrier on the interior side; 2) a Passive House (W2- PH), R43 double stud assembly with wood based insulation; and, 3) a stud wall assembly with external insulation (R-29) and wood based oriented strand board vapor control on interior side (W3- OSB). The specimens, installed on a west facing wall of the FEWF were exposed to real climate conditions in Ottawa, Ontario, Canada for the period of 2016 to 2019. Hourly values of temperatures, pressure difference, relative humidity and moisture presence have been monitored and recorded during all four seasons. Temperature, moisture, pressure and heat flux sensors were installed on both interior and exterior sides, as well as within the assemblies at multiple locations where the potential for condensation and mold growth was considered high. The present study reports on the behavior of all three specimens over a three year period of year-round exposure and data monitoring. Some changes in R values were observed. The R value decrease of 12% was calculated for the W1. A 5% decrease in R value was obtained for the W3. The likely reason for this decrease is a combination of material aging (which could be combination of potential off gassing of the XPS and/or settling of the glass fibre insulation) and the potential for increased moisture contents of the components. The presence of moisture was detected at the exterior sheathing board (XPS), corresponding to rain events, however, in each case, the moisture load dried to the exterior, indicating that the risk to deterioration of potentially vulnerable components in the wall assembly is minimal. Comparison of yearly runs of pressures differences, temperatures and humidity results together with dew point calculations results show that after the long-term exposure. |
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