The radiant energy incident on the earth's surface on a sunny day is roughly 900W/m2. Collecting and focusing sunlight and using the focused beam to heat a fluid is an old idea, and as the environmental costs of fossil fuel combustion mount, solar heating becomes an increasingly attractive alternative. Suppose a house is to be designed that will have a circulating forced air central heating system, and solar energy is contemplated as a heat source (backed up with conventional furnace to be used on cloudy days). If the air is to be fed at a rate of 1,000 m3/min at 30 C and 1 atm, and the air is to be heated to 55 ?C before being discharged into the living space, what is the required area of the solar collector plates? Assume 30% of the radiant energy incident on the plates is used to heat the air.