Chapter 11 Fundamentals of Thermal Radiation 11-71 The net annual cost savings due to installing reflective coating on the West windows of a building and the simple payback period are to be determined. Assumptions 1 The calculations given below are for an average year. 2 The unit costs of electricity and natural gas remain constant. Analysis Using the daily averages for each month and noting the number of days of each month, the total solar heat flux incident on the glazing during summer and winter months are determined to be Q solar, summer = 4.24 × 30+ 4.16 × 31+ 3.93 × 31+3.48 × 30 = 482 kWh/year Q solar, winter = 2.94 × 31+ 2.33 × 30+2.07 × 31+2.35 × 31+3.03 × 28+3.62 × 31+4.00 × 30 Air space Glass Reflective film Sun Transmitted Reflected = 615 kWh/year Then the decrease in the annual cooling load and the increase in the annual heating load due to reflective film become Cooling load decrease = Q solar, summer A glazing (SHGC without film- SHGC with film ) = (482 kWh/year)(60 m
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This note was uploaded on 01/24/2012 for the course PHY 4803 taught by Professor Dr.danielarenas during the Fall '10 term at UNF.