Humans radiate energy at a net rate of roughly 100W; this is essentially waste heat from various chemical processes needed for bodily functioning. Consider four humans in a roughly square hut measuring 5m ? 5m, with a flat roof at 3m height. The exterior walls of the hut are maintained at 0 ^?C by the external environment. For each of the following construction materials for the walls and ceiling, ?

(i) compute the R-value (?T/q) for the material,?

(ii) compute the equilibrium temperature in the hut when the four people are in it:?

(a) 0.3m (1 foot) concrete walls/ceiling;?

(b) 10 cm (4") softwood walls/ceiling; and?

(c) 2.5 cm (1") softwood, with 0.09m (3.5") fiberglass insulation on interior of walls and ceiling. Take thermal conductivities and/or R-values from Tables 6.1

?and Table 6.3.

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Thermal Thermal diffusivity conductivity k Material a (10-7 m²/s) (W/m K) Air (NTP) 0.026 205* Argon (NTP) 0.018 190 Кrуpton (NTP) 0.0094 100 Xenon (NTP) 0.0057 61 Water 0.57 1.4 Hardwood (white oak) 0.18 0.98