Designing a hygrothermally-stable wall featuring multiple evaporative air cavities

The concept of using multiple cavities walls systems (MCWS) and redistributed insulation in providing high thermal efficiency in walls while enhancing its capacity to control with intruded moisture was tested through four wall system designs. Twelve walls having fixed number of cavities were tested simultaneously with a reference wall for summer temperature and humidity conditions. Results show lower heat flow rates for MCWS walls with equally distributed polyisocyanurate insulation panels (50mm on both sides of a central cavity) as compared to the reference wall with RSI 2.29 (R-13) despite the evaporative air cavities present in the MCWS walls. Reduction in the indoor insulation to 25 mm resulted wider variation in recorded heat flow rate but still thermally efficient than the reference wall. MCWS walls with balanced but only 25 mm PIR insulation on both sides of the wall cavity showed variable performance. When PIR insulations (50mm) were placed only at the outer portion of the central wall cavity, the reference wall showed lower (better) flow rate than MCWS.