There are two thin plates with the length of 2 m and width of 1 m, placed in parallel with the distance of 1 m inside a large room. the ambient temperature is 27℃. we can assume that the backsides of the plates are well insulated and have no heat loss. temperature and emissivity for plate 1 are t1 = 827℃ and ε1 = 0.2; temperature and emissivity for plate 2 are t2 = 327℃ and ε2 = 0.5. calculate the net radiation heat losses per unit time for plate 1 and plate 2, respectively; and calculate the radiation energy absorbed by the large room in a unit time.

Determine the time of the day and month of the year at which the peak sensible cooling load occurs for a top floor, north-eastern corner room of an office building in durban for the following conditions: floor area: 8 x 8 x 3 m east and north walls: 115 mm face brick (outside), 20 mm air space, 115 mm ordinary brick (inside) with 15 mm plaster roof construction: suspended plasterboard ceiling, 450 mm air space, 150 mm concrete, 75mm screed, waterproofing no heat transfer across other surfaces window area 3x 1,5 m high in north wall only. ordinary glass with venetian blinds. lights and occupants : from 07: 00 to 18: 00 average light density: 25 w/m2 number of occupants : 5 seated, light office work room temperature 24°c