Egee 3 Test Answers
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A room has a wall with an R value of 13 F sq.ft. hr/BTU. The room is 13 feet long and 12 feet wide with walls that are 8 ft high. On a particular day the average outside temperature is 25 degrees F. How much heat is transferred through the walls on that day (in BTUs)?
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29538.5 BTUs Total area of walls = 2 ((13 x 8) + (12 x 8)) = 400 sq.ft HDD = 65-25 = 40 oF Heat transferred = 400 x 40 x 24 / 13 = 29538.46 BTUs
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A process by which energy is transferred as the vibrations of one molecule are passed on to the next, but there is no movement of energetic atoms or molecules themselves is called _____.
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Conduction
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In State College, PA the average outside temperature during the month of January was 28 oF. Calculate the HDD for the month of January.
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1147 HDD = (65-28) x 31 = 1147 degree-days
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To calculate the heating degree days for a particular day, the day's outside temperature is calculated by _____.
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Subtracting the outside temperature from the inside temperature
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What is the process by which energy is transferred by the bulk motion of the fluids?
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Convection
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Most of the synthetic insulation products are poor insulation materials.
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false
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A thermos bottle has a shiny interior. What type of heat transfer does this prevent?
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Radiation
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Dave has a home in Pittsburgh, PA (HDD = 6,000) with a roof area of 1004 ft2. He is considering upgrading the insulation from R-16 to R-28. The estimate for this job from the contractor is $757. Dave's home is heated with natural gas. Last year, the average price he paid for natural gas was $10.3/MCF. Assuming an AFUE of 87.5%, how long will it take Dave to recover his investment (in years)?
answer
Cost of insulation = 757 / 1004 = 0.7539 $/sq.ft Cost of energy = 10.3 / 1,000,000 = 0.0000103 $/BTU Time to recover investment = (0.7539 x 16 x 28 x 0.875) / (0.0000103 x (28 - 16) x 6000 x 24) = 16.6 yrs
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Which one of the following provides the most insulation?
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6 inches of Cellulose
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The number of degrees the mean outside temperature falls below 65 oF for a given day is given by _____.
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HDD
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A higher HDD indicates
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All the above
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Compared to a house built in the 1960's, a house built today has ______.
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A greater R-value
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Natural materials like stone and bricks are not good insulation materials.
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TRUE
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A thermos bottle has a shiny interior. What type of heat transfer does this prevent?
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Radiation
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Heat in the room moves with the warm currents from warmer areas to cooler areas due to _____.
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Convection
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A wall consists of 0.5\" wood siding (R = 0.81), 0.75\" plywood (R = 0.94), 1.2\" of fiberglass (R = 3.7 per inch) and 0.5\" plasterboard (R = 0.45). What is the composite R-value of the wall?
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6.64 Composite R-value = 0.81 + 0.94 + (1.2 x 3.7) + 0.45 = 6.64
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The higher the R-value, the greater the insulating effectiveness.
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true R-value is a measure of insulating effectiveness of a material. The higher the R-value, the greater the insulating efectiveness
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On cloudless nights, heat escapes from our planet and goes into space. What is this due to?
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Radiation
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Brownies bake in a glass pan using these 2 methods.
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Radiation and conduction
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Thermal-lined draperies and outdoor awnings can significantly reduce the energy required for air conditioning.
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true
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Most of the synthetic insulation products are very effective insulation materials.
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true
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How many degree days are accumulated in a seven day period where the average outside temperature is 30 degrees Fahrenheit?
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245 HDD = (65 - 30) x 7 = 245 degree-days
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When you insulate the attic of a home the R-value of insulation increases at the same rate as its thickness.
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TRUE
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140 CCF of natural gas is equivalent to how many kWh of Electricity?
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4103.17 KWH We know that, 1 CCF = 100,000 BTU & 1 KWH = 3412 BTU ' 140 CCF = 140 CCF x 100,000 BTU / 1 CCF x 1 KWH / 3412 BTU = 4103.165 KWH
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To calculate the heating degree days for a particular day, the day's average outside temperature is calculated by _____.
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adding the high and low temperatures and then dividing by two.
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135 CCF of natural gas is equivalent to how many kWh of Electricity?
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3956.62 KWH We know that, 1 CCF = 100,000 BTU & 1 KWH = 3412 BTU ' 135 CCF = 135 CCF x 100,000 BTU / 1 CCF x 1 KWH / 3412 BTU = 3956.623 KWH
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When you insulate the attic of a home the R-value of insulation increases at the same rate as its thickness.
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true
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What is the process in which heat is transferred through electromagnetic radiation?
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Radiation
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You are warmed by the sun. This is an example of heat transfer by ____
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Radiation
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The R-value of a composite wall is calculated by _____.
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adding the R-values of all layers
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What is the typical cost of natural gas per million BTUs?
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5
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The heat loss through a window (R-3) is 10 MMBTU/year. Calculate the payback period (in years) if Argon is filled in the window to increase the effective R-value of the window to 8. Assume heating price to be $10/MMBTU and the cost for filling Argon is $20.
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0.32 years Heat lost through new window per year = (10 x 3) / 8 = 3.75 MMBTUs/yr Reduction in heat lost per year = 10 - 3.75 = 6.25 MMBTUs/yr Savings in energy cost per year = 6.25 x 10 = $62.5 Payback period = 20 / 62.5 = 0.32 yrs
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The heat loss through a window (R-1) is 10 MMBTU/year. Calculate the payback period (in years) if Argon is filled in the window to increase the effective R-value of the window to 7. Assume heating price to be $10/MMBTU and the cost for filling Argon is $20.
answer
0.23 years Heat lost through new window per year = (10 x 1) / 7 = 1.42 MMBTUs/yr Reduction in heat lost per year = 10 - 1.42 = 8.58 MMBTUs/yr Savings in energy cost per year = 8.58 x 10 = $85.8
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Of the following sources, where does the most heat loss occur for a typical home?
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Cracks in walls, windows and doors
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A house in State College, PA (HDD=6000) has 323 ft2 of windows with R value = 2.5, 1970 ft2 of walls with R value = 18, and 1266 ft2 of roof with an R-value = 28. What is the total heat loss from the house for the season (in BTUs)?
answer
40875657.14 BTUs Heat lost through windows = 323 x 6000 x 24 / 2.5 = 18604800 BTUs Heat lost through walls = 1970 x 6000 x 24 / 18 = 15760000 BTUs Heat lost through roof = 1266 x 6000 x 24 / 28 = 6510857.14 BTUs Total heat loss from the house = 18604800 + 15760000 + 6510857.14 = 40875657.14 BTUs
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A house in State College, PA (HDD=6000) has 314 ft2 of windows with R value = 2.5, 1882 ft2 of walls with R value = 18, and 1132 ft2 of roof with an R-value = 28. What is the total heat loss from the house for the season (in BTUs)?
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...
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How many degree days are accumulated in a seven day period when the average outside temperature is 30 oF?
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245 HDD = 65 - outside temperature HDD for 7 days = 7 x (65-30) = 7 x 35 = 245 degree-days
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A wall consists of 0.5\" wood siding (R = 0.81), 0.75\" plywood (R = 0.94), 1.6\" of fiberglass (R = 3.7 per inch) and 0.5\" plasterboard (R = 0.45). What is the composite R-value of the wall?
answer
8.12 Composite R-value = 0.81 + 0.94 + (1.6 x 3.7) + 0.45 = 8.12
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Dave has a home in Pittsburgh, PA (HDD = 6,000) with a roof area of 1017 ft2. He is considering upgrading the insulation from R-16 to R-28. The estimate for this job from the contractor is $616. Dave's home is heated with natural gas. Last year, the average price he paid for natural gas was $15.6/MCF. Assuming an AFUE of 88.1%, how long will it take Dave to recover his investment (in years)?
answer
8.9 Years Cost of insulation = 616 / 1017 = 0.6057 $/sq.ft Cost of energy = 15.6 / 1,000,000 = 0.0000156 $/BTU Time to recover investment = (0.6057 x 16 x 28 x 0.881) / (0.0000156 x (28 - 16) x 6000 x 24) = 8.86 yrs
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Katy is planning on adding additional insulation to her roof, which costs $2491. It is estimated that she can save $426/year on energy costs from this modification. What is the pay back period in years?
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) 5.8 Years Pay back period = 2491/426 = 5.84 yrs
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What is the mechanism by which heat is transferred without the help of any medium (molecules or atoms)?
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Radiation
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Most of the energy used at home is used for _____.
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heating
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In State College, PA the average outside temperature during the month of January was 28 oF. Calculate the HDD for the month of January.
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1147 HDD = (65-28) x 31 = 1147 degree-days
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What is the process by which energy is passed as the vibrations of one molecule are passed to the next, but there is no movement of energetic atoms or molecules?
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Conduction
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Dave has a home in Pittsburgh, PA (HDD = 6,000) with a roof area of 1821 ft2. He is considering upgrading the insulation from R-16 to R-28. The estimate for this job from the contractor is $810. Dave's home is heated with natural gas. Last year, the average price he paid for natural gas was $14.5/MCF. Assuming an AFUE of 80.9%, how long will it take Dave to recover his investment (in years)?
answer
6.4 Years Cost of insulation = 810 / 1821 = 0.4448 $/sq.ft Cost of energy = 14.5 / 1,000,000 = 0.0000145 $/BTU Time to recover investment = (0.4448 x 16 x 28 x 0.809) / (0.0000145 x (28 - 16) x 6000 x 24) = 6.43 yrs
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Thermal-lined draperies and outdoor awnings can significantly reduce the energy required for air conditioning.
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true
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Dave has a home in Pittsburgh, PA (HDD = 6,000) with a roof area of 1894 ft2. He is considering upgrading the insulation from R-16 to R-28. The estimate for this job from the contractor is $902. Dave's home is heated with natural gas. Last year, the average price he paid for natural gas was $14.1/MCF. Assuming an AFUE of 87.5%, how long will it take Dave to recover his investment (in years)?
answer
7.7 Years Cost of insulation = 902 / 1894 = 0.4762 $/sq.ft Cost of energy = 14.1 / 1,000,000 = 0.0000141 $/BTU Time to recover investment = (0.4762 x 16 x 28 x 0.875) / (0.0000141 x (28 - 16) x 6000 x 24) = 7.66 yrs
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A wall consists of 0.5\" wood siding (R = 0.81), 0.75\" plywood (R = 0.94), 3.1\" of fiberglass (R = 3.7 per inch) and 0.5\" plasterboard (R = 0.45). What is the composite R-value of the wall?
answer
13.67 Composite R-value = 0.81 + 0.94 + (3.1 x 3.7) + 0.45 = 13.67
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Katy is planning on adding additional insulation to her roof, which costs $2882. It is estimated that she can save $397/year on energy costs from this modification. What is the pay back period (in years)?
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7.3 Pay back period = 2882/397 = 7.25 yrs
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The circulation of air due to temperature differences in a room is called a _____.
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convective loop The circulation of air due to temperature differences in a room is called a convective loop
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What is the typical cost of natural gas per million BTUs?
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5
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Warm water rises in a lake and cold water descends. What is this due to?
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Convection Convection is a process by which energy is transferred by the bulk motion of the fluids (gases or liquids).
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Dave has a home in Pittsburgh, PA (HDD = 6,000) with a roof area of 1004 ft2. He is considering upgrading the insulation from R-16 to R-28. The estimate for this job from the contractor is $757. Dave's home is heated with natural gas. Last year, the average price he paid for natural gas was $10.3/MCF. Assuming an AFUE of 87.5%, how long will it take Dave to recover his investment (in years)?
answer
16.6 Cost of insulation = 757 / 1004 = 0.7539 $/sq.ft Cost of energy = 10.3 / 1,000,000 = 0.0000103 $/BTU Time to recover investment = (0.7539 x 16 x 28 x 0.875) / (0.0000103 x (28 - 16) x 6000 x 24) = 16.6 yrs
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In State College, PA the average outside temperature during the month of January was 42 oF. Calculate the HDD for the month of January.
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713 HDD HDD = (65-42) x 31 = 713 degree-days
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In State College, PA the average outside temperature during the month of January was 51 oF. Calculate the HDD for the month of January. Correct B ) 434 HDD HDD = (65-51) x 31 = 434 degree-days
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...
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A room has a wall with an R value of 13 F sq.ft. hr/BTU. The room is 18 feet long and 8 feet wide with walls that are 8 ft high. On a particular day the average outside temperature is 31 degrees F. How much heat is transferred through the walls on that day (in BTUs)?
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26112 BTUs Total area of walls = 2 ((18 x 8) + (8 x 8)) = 416 sq.ft HDD = 65-31 = 34 oF Heat transferred = 416 x 34 x 24 / 13 = 26112 BTUs
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The heat loss through a window (R-2) is 10 MMBTU/year. Calculate the payback period (in years) if Argon is filled in the window to increase the effective R-value of the window to 7. Assume heating price to be $10/MMBTU and the cost for filling Argon is $20.
answer
0.28 years Heat lost through new window per year = (10 x 2) / 7 = 2.84 MMBTUs/yr Reduction in heat lost per year = 10 - 2.84 = 7.16 MMBTUs/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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What is the most common fuel for home heating in the US?
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Natural Gas
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When using a fire place, most of the heated air is lost through the chimney.
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TRUE
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Heat is lost through walls, windows and roof of a house. What is the primary mechanism of such heat loss?
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conduction
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A house in State College, PA (HDD=6000) has 339 ft2 of windows with R value = 2.5, 1843 ft2 of walls with R value = 18, and 1241 ft2 of roof with an R-value = 28. What is the total heat loss from the house for the season (in BTUs)?
answer
40652685.71 BTUs Heat lost through windows = 339 x 6000 x 24 / 2.5 = 19526400 BTUs Heat lost through walls = 1843 x 6000 x 24 / 18 = 14744000 BTUs Heat lost through roof = 1241 x 6000 x 24 / 28 = 6382285.71 BTUs Total heat loss from the house = 19526400 + 14744000 + 6382285.71 = 40652685.71 BTUs
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When you place a spoon into a cup of cocoa it gets hot over time. What is this due to?
answer
Conduction
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In State College, PA the average outside temperature during the month of January was 20 oF. Calculate the HDD for the month of January.
answer
1395 HDD HDD = (65-20) x 31 = 1395 degree-days
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The heat loss through a window (R-3) is 10 MMBTU/year. Calculate the payback period (in years) if Argon is filled in the window to increase the effective R-value of the window to 8. Assume heating price to be $10/MMBTU and the cost for filling Argon is $20.
answer
0.32 years Heat lost through new window per year = (10 x 3) / 8 = 3.75 MMBTUs/yr Reduction in heat lost per year = 10 - 3.75 = 6.25 MMBTUs/yr Savings in energy cost per year = 6.25 x 10 = $62.5 Payback period = 20 / 62.5 = 0.32 yrs
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On cloudless nights, heat escapes from our planet and goes into space by _____.
answer
Radiation
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Natural gas is sold in the US at $1.50 per CCF. What is the cost of heating per MMBTU? Recall that 1 MCF = 1,000 Cu. Ft and has 1,000,000 BTU; 1 CCF = 100 Cu. Ft and has 100,000 BTU.
answer
$ 15.00/MMBTU ($1.50/CCF) x (1 CCF/100 cu.ft) x (100 cu.ft/100,000 BTU) x (1,000,000 BTU/ 1 MMBTU) = $15.00/MMBTU
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What is the name of the process by which energy is transferred by the bulk motion of the fluids?
answer
Convection
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A room has a wall with an R value of 18 F sq.ft. hr/BTU. The room is 15 feet long and 11 feet wide with walls that are 9 ft high. On a particular day the average outside temperature is 40 degrees F. How much heat is transferred through the walls on that day (in BTUs)?
answer
15600 BTUs Total area of walls = 2 ((15 x 9) + (11 x 9)) = 468 sq.ft ' HDD = 65-40 = 25 oF ' Heat transferred = 468 x 25 x 24 / 18 = 15600 BTUs
question
The heat loss through a window (R-1) is 10 MMBTU/year. Calculate the payback period (in years) if Argon is filled in the window to increase the effective R-value of the window to 9. Assume heating price to be $10/MMBTU and the cost for filling Argon is $20.
answer
0.22 years Heat lost through new window per year = (10 x 1) / 9 = 1.11 MMBTUs/yr Reduction in heat lost per year = 10 - 1.11 = 8.89 MMBTUs/yr Savings in energy cost per year = 8.89 x 10 = $88.9 Payback period = 20 / 88.9 = 0.22 yrs
question
Katy is planning on adding additional insulation to her roof, which costs $2882. It is estimated that she can save $397/year on energy costs from this modification. What is the pay back period in years?
answer
7.3 Years Pay back period = 2882/397 = 7.25 yrs
question
165 CCF of natural gas is equivalent to how many kWh of Electricity?
answer
4835.87 KWH We know that, 1 CCF = 100,000 BTU & 1 KWH = 3412 BTU ' 165 CCF = 165 CCF x 100,000 BTU / 1 CCF x 1 KWH / 3412 BTU = 4835.873 KWH
question
A house in State College, PA (HDD=6000) has 333 ft2 of windows with R value = 2.5, 1840 ft2 of walls with R value = 18, and 1106 ft2 of roof with an R-value = 28. What is the total heat loss from the house for the season (in BTUs)?
answer
39588800 BTUs Heat lost through windows = 333 x 6000 x 24 / 2.5 = 19180800 BTUs Heat lost through walls = 1840 x 6000 x 24 / 18 = 14720000 BTUs Heat lost through roof = 1106 x 6000 x 24 / 28 = 5688000 BTUs Total heat loss from the house = 19180800 + 14720000 + 5688000 = 39588800 BTUs
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Dave has a home in Pittsburgh, PA (HDD = 6,000) with a roof area of 1310 ft2. He is considering upgrading the insulation from R-16 to R-28. The estimate for this job from the contractor is $716. Dave's home is heated with natural gas. Last year, the average price he paid for natural gas was $12.7/MCF. Assuming an AFUE of 88%, how long will it take Dave to recover his investment (in years)?
answer
9.8 Years Cost of insulation = 716 / 1310 = 0.5465 $/sq.ft Cost of energy = 12.7 / 1,000,000 = 0.0000127 $/BTU Time to recover investment = (0.5465 x 16 x 28 x 0.88) / (0.0000127 x (28 - 16) x 6000 x 24) = 9.81 yrs
question
A house in State College, PA (HDD=6000) has 314 ft2 of windows with R value = 2.5, 1882 ft2 of walls with R value = 18, and 1132 ft2 of roof with an R-value = 28. What is the total heat loss from the house for the season (in BTUs)?
answer
38964114.29 Heat lost through windows = 314 x 6000 x 24 / 2.5 = 18086400 BTUs Heat lost through walls = 1882 x 6000 x 24 / 18 = 15056000 BTUs Heat lost through roof = 1132 x 6000 x 24 / 28 = 5821714.28 BTUs Total heat loss from the house = 18086400 + 15056000 + 5821714.28 = 38964114.28 BTUs
question
Brownies bake in a glass pan using these 2 methods.
answer
Radiation and conduction
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140 CCF of natural gas is equivalent to how many kWh of Electricity?
answer
4103.17 KWH We know that, 1 CCF = 100,000 BTU & 1 KWH = 3412 BTU ' 140 CCF = 140 CCF x 100,000 BTU / 1 CCF x 1 KWH / 3412 BTU = 4103.165 KWH
question
The R-value of a composite wall is calculated by _____.
answer
adding the R-values of all layers
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You feel the heat of a wood stove when you stand next to it. What is this due to?
answer
Radiation and convection
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Which mechanism of heat transfer does not need any medium (molecules or atoms)?
answer
Radiation
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Oil is sold in a particular region at $1.10/gal and natural gas at $11.47 per MCF. Given that the oil has a heating value of 140,000 Btus/gal and natural gas of 1 MMBtu/MCF, which fuel is cheaper to use?
answer
Oil Oil: (1.10/gal) / (140,000 BTU/gal) = (1.10 / 140,000) BTU (1.10 / 140,000) BTU x (1 MMBTU / 1,000,000 BTU) = $7.86/MMBTU Natural Gas: ($11.47/MCF) x (1 MMBTU/1 MCF) = $11.47/MMBTU
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What is the average cost of electricity in the US?
answer
$80/MWh Average cost of electricity in the US is $0.08 per kWh. This is same as $80 per MWh
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Home heating is the single highest energy expense for a household.
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true
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You are warmed by the sun. This is an example of heat transfer by _____
answer
Radiation
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106 CCF of natural gas is equivalent to how many kWh of Electricity?
answer
3106.68 KWH We know that, 1 CCF = 100,000 BTU & 1 KWH = 3412 BTU ' 106 CCF = 106 CCF x 100,000 BTU / 1 CCF x 1 KWH / 3412 BTU = 3106.68 KWH
question
Most of the synthetic insulation products are very effective insulation materials.
answer
true
question
A spoon that is placed in a cup of hot coffee gets hot over time due to
answer
Conduction
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On cloudless nights, heat escapes from our planet and goes into space. What is this due to?
answer
radiation
question
Dave has a home in Pittsburgh, PA (HDD = 6,000) with a roof area of 1182 ft2. He is considering upgrading the insulation from R-16 to R-28. The estimate for this job from the contractor is $638. Dave's home is heated with natural gas. Last year, the average price he paid for natural gas was $12.9/MCF. Assuming an AFUE of 94.6%, how long will it take Dave to recover his investment (in years)?
answer
10.3 Years Cost of insulation = 638 / 1182 = 0.5397 $/sq.ft Cost of energy = 12.9 / 1,000,000 = 0.0000129 $/BTU Time to recover investment = (0.5397 x 16 x 28 x 0.946) / (0.0000129 x (28 - 16) x 6000 x 24) = 10.26 yrs
question
A house in State College, PA (HDD=6000) has 323 ft2 of windows with R value = 2.5, 1970 ft2 of walls with R value = 18, and 1266 ft2 of roof with an R-value = 28. What is the total heat loss from the house for the season (in BTUs)?
answer
40875657.14 BTUs Heat lost through windows = 323 x 6000 x 24 / 2.5 = 18604800 BTUs Heat lost through walls = 1970 x 6000 x 24 / 18 = 15760000 BTUs Heat lost through roof = 1266 x 6000 x 24 / 28 = 6510857.14 BTUs Total heat loss from the house = 18604800 + 15760000 + 6510857.14 = 40875657.14 BTUs
question
The heat loss through a window (R-2) is 10 MMBTU/year. Calculate the payback period (in years) if Argon is filled in the window to increase the effective R-value of the window to 7. Assume heating price to be $10/MMBTU and the cost for filling Argon is $20.
answer
0.28 years Heat lost through new window per year = (10 x 2) / 7 = 2.84 MMBTUs/yr Reduction in heat lost per year = 10 - 2.84 = 7.16 MMBTUs/yr Savings in energy cost per year = 7.16 x 10 = $71.6 Payback period = 20 / 71.6 = 0.28 yrs
question
A wall is made up of 7 inches of stone (R=0.08/inch), 4 inches of polyurethane board (R value=5.25/inch), and 0.75 inches of plywood (R value= 0.94). Calculate the composite R-value for the wall.
answer
A ) 22.5 F sq.ft. h/BTU Composite R-value = 7x0.08 + 4*5.25 + 0.94 = 22.5
question
A wall consists of 0.5\" wood siding (R = 0.81), 0.75\" plywood (R = 0.94), 3.6\" of fiberglass (R = 3.7 per inch) and 0.5\" plasterboard (R = 0.45). What is the composite R-value of the wall?
answer
15.52 Composite R-value = 0.81 + 0.94 + (3.6 x 3.7) + 0.45 = 15.52
question
The heat loss through a window (R-2) is 10 MMBTU/year. Calculate the payback period (in years) if Argon is filled in the window to increase the effective R-value of the window to 10. Assume heating price to be $10/MMBTU and the cost for filling Argon is $20.
answer
0.25 years Heat lost through new window per year = (10 x 2) / 10 = 2 MMBTUs/yr Reduction in heat lost per year = 10 - 2 = 8 MMBTUs/yr Savings in energy cost per year = 8 x 10 = $80 Payback period = 20 / 80 = 0.25 yrs
question
A room has a wall with an R value of 16 F sq.ft. hr/BTU. The room is 16 feet long and 8 feet wide, with walls that are 9 ft high. On a particular day the average outside temperature is 34 degrees F. How much heat is transferred through the walls on that day (in BTUs)?
answer
20088 BTUs Total area of walls = 2 ((16 x 9) + (8 x 9)) = 432 sq.ft HDD = 65-34 = 31 oF Heat transferred = 432 x 31 x 24 / 16 = 20088 BTUs
question
A wall consists of 0.5\" wood siding (R = 0.81), 0.75\" plywood (R = 0.94), 3.1\" of fiberglass (R = 3.7 per inch) and 0.5\" plasterboard (R = 0.45). What is the composite R-value of the wall?
answer
Composite R-value = 0.81 + 0.94 + (3.1 x 3.7) + 0.45 = 13.67
question
A house in State College, PA (HDD=6000) has 339 ft2 of windows with R value = 2.5, 1843 ft2 of walls with R value = 18, and 1241 ft2 of roof with an R-value = 28. What is the total heat loss from the house for the season (in BTUs)?
answer
40652685.71 BTUs Heat lost through windows = 339 x 6000 x 24 / 2.5 = 19526400 BTUs Heat lost through walls = 1843 x 6000 x 24 / 18 = 14744000 BTUs Heat lost through roof = 1241 x 6000 x 24 / 28 = 6382285.71 BTUs Total heat loss from the house = 19526400 + 14744000 + 6382285.71 = 40652685.71 BTUs
question
Which of the following indicates the heating requirement at a particular location?
answer
Heating Degree Days
question
A wall consists of 0.5\" wood siding (R = 0.81), 0.75\" plywood (R = 0.94), 1.2\" of fiberglass (R = 3.7 per inch) and 0.5\" plasterboard (R = 0.45). What is the composite R-value of the wall?
answer
6.64 Composite R-value = 0.81 + 0.94 + (1.2 x 3.7) + 0.45 = 6.64
question
A house in State College, PA (HDD=6000) has 347 ft2 of windows with R value = 2.5, 1926 ft2 of walls with R value = 18, and 1212 ft2 of roof with an R-value = 28. What is the total heat loss from the house for the season (in BTUs)?
answer
41628342.86 BTUs Heat lost through windows = 347 x 6000 x 24 / 2.5 = 19987200 BTUs Heat lost through walls = 1926 x 6000 x 24 / 18 = 15408000 BTUs Heat lost through roof = 1212 x 6000 x 24 / 28 = 6333142 BTUs Total heat loss from the house = 19987200 + 15408000 + 6233142.85 = 41628342.85 BTUs
