A building has a gypsum wall of 13 mm and fiber glass of 13 cm. The inside and outside temperatures are 20C and 6C, respectively. The wind speed is 7m/s. The area of the wall is 25 m. The fiberglass thermal conductivity is 0.04 W/mC. Find the heat transfer. 25-watt 20 fluorescent lamps are replaced with LED lamp that save 12% to give the same output. The cost of one LED lamp is $ 2. Provide your opinion regarding this measure using NPV. The required IRR is 25%. Hours of operation are 4900 hr. the lamp life is 3yr. KWh cost is 0.1$/kWh.