Estimate the R-values for a 5-cm-thick fiberglass board and a 2.5-cm-thick polyurethane foam layer. Then, compare their respective conductivity times- density products if the density for fiberglass is 50 kg/m³ and the density of polyurethane is 30 kg/m³. Use the units given in Figure 1.31.

Data from in  Figure 1.31

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Mineral wool Cellulose Fiberglass (resin bonded) Phenolic Polyurethane Expanded polystyrene Urea formaldehyde Cellular glass 0.02 200°C 150°C 120°C 50°C 200°C 75°C 230°C Fibrous Cellular 0.04 0.06 Effective thermal conductivity keff (W/m K) 0.08 480°C 0.10