1.6 Exercise 32

Many decisions are made on the basis of the payback period: the time it will take through savings to equal the capital cost of an investment. Acceptable payback times depend upon the business or philosophy one has. (For some industries, a payback period is as small as 2 years.) Suppose you wish to install the extra insulation in the preceding problem. If energy cost $\$ 1.00$ per million joules and the insulation was $4.00 per square meter, then calculate the simple payback time. Take the average $\Delta T$ for the 120-day heating season to be $15.0 ° \text{C} .$