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Unformatted text preview: Heat Gain Coeﬃcient = _____________ Correct A ) Light to Solar Gain LSG = V T / S HGC Solar Heat Gain Coeﬃcient (SHGC) is expressed as number between 0 and __________ Correct A ) 1 Solar Heat Gain Coeﬃcient is expressed as a number between 0 and 1. The lower a window's SHGC, the less solar heat it transmits We have a window with S HGC=0.33 and V T=0.52. What is the L SG? Correct D ) 1.58 LSG = V T / S HGC
LSG = 0.52/0.33 = 1.58 Heat loss and gain occur by inﬁltra*on through cracks in the window assembly by _________ Correct A ) Convec*on
Air leaks into or outside through cracks. Thus, heat is transfered by convec*on. A house in State College, PA consists of the following: 12 single pane windows (each 7 i by 5 i with an R value of 1). Calculate the total number of Btus lost for one season through these 12 windows. HDD for State College are 6,000 Correct B ) 60480000 Btus Area os windows = 12 x 7 x 5 = 420 sq.i
Heat lost = 420 x 6000 x 24 / 1 = 6,048,000 BTUs On a summer aiernoon you should keep the draperies closed on all west facing windows to block out the hot sun. Correct A ) T RUE On a summer aiernoon you should keep the draperies closed on all west facing windows to block out the hot sun ______________ measures how well a window blocks heat from the sunlight Correct A ) Solar Heat Gain Coeﬃcient (SHGC) SHGC measures how well a window blocks heat from the sunlight Windows can be designed not only to prevent heat loss but also for heat gain. Correct A ) T RUE Windows can be designed not only to prevent heat loss but also for heat gain Condensa*on Resistance (CR) is expressed as number between 0 and __________ Correct A ) 100 Condensa*on Resistance is expressed as a number between 0 and 100 The heat loss through a window (U value = 1) is 10 MMBTU/year. Calculate the payback period (in years) if Argon is ﬁlled in the window to increase the eﬀec*ve U value of the window to 0.1111. Assume hea*ng price to be $10/MMBTU and the cost for ﬁlling Argon is $20. Correct A ) 0.22 years R value of new window = 1/0.1111 = 9 Heat lost through new window per year = (10 x 1) / 9 = 1.11 MMBTUs/yr
Reduc*on in heat lost per year = 10  1.11 = 8.89 M MBTUs/yr
Savings in energy cost per year = 8.89 x 10 = $88.9
Payback period = 20 / 88.9 = 0.22 yrs Spacer materials used in a window reduce Correct A ) conduc*on losses Spaces material usually has a high R value and is used to reduce conduc*on losses in a window The heat loss through a window (U value = 0.5) is 10 MMBTU/year. Calculate the payback period (in years) if Argon is ﬁlled in the window to increase the eﬀec*ve U value of the window to 0.1429. Assume hea*ng price to be $10/MMBTU and the cost for ﬁlling Argon is $20. Correct D ) 0.28 years R value of new window = 1/0.1429 = 7 Heat lost through new window per year = (10 x 2) / 7 = 2.84 MMBTUs/yr
Reduc*on in heat lost per year = 10  2.84 = 7.16 M MBTUs/yr
Savings in energy cost per year = 7.16 x 10 = $71.6
Payback period = 20 / 71.6 = 0.28 yrs...
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 Spring '07
 PISUPATI,SARMAVE

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