Issue link: http://cp.revolio.com/i/1121626
Polystyrene Foam Insulation in Long-Term Building Applications – Effective R-values Page 11 Temperature Adjustment Factor The performance of polystyrene foam insulation is well documented in ASTM C578. The R-value of both EPS and XPS increases at mean temperatures colder than 75°F (24°C) and decreases at mean temperatures warmer than 75°F (24°C). Table 5 provides the recognized R-values at 75°F (24°C) for EPS and XPS in compliance with ASTM C578 as well as the R-values at 110°F (43°C), 40°F (4°C), and 25°F (-4°C) mean temperatures. Temperature ASTM C578 Material Type EPS XPS II IX X IV R-value RSI R-value RSI R-value RSI R-value RSI 110°F (43°C) 3.65 0.64 3.85 0.69 4.65 0.82 4.65 0.82 75°F (24°C) 4.0 0.70 4.2 0.74 5.0 0.88 5.0 0.88 40°F (4°C) 4.4 0.77 4.6 0.81 5.4 0.95 5.4 0.95 25°F (-4°C) 4.6 0.81 4.8 0.84 5.6 0.99 5.6 0.99 Table 5. ASTM C578/CAN S701.1 R-values at Various Mean Temperatures Plotting the various R-values in ASTM C578 in Figure 6 shows that there is a linear relationship of R-value with a temperature that allows the prediction of R-value at other temperatures. 6 5.5 5 4.5 4 3.5 3 10 30 50 70 90 110 130 Temperature, °F Figure 6. R-value vs. Mean Temperature for EPS Type II, IX and XPS Type IV, X EPS Type II EPS Type IX XPS Types IV and X 1.10 1.0 0.90 0.80 0.70 0.60 0.50 R-value (°F•ft 2 •h/BTU) RSI (°C•m 2 /W)