EGEE Exam 4
A 80 watt incandescent light bulb is operated for 22 hours, and a 15 watt fluorescent light bulb is operated for the same period of time. At 11 cents per kWh, what is the cost savings of the fluorescent bulb?
$ 0.16
A 150-watt light bulb is left on for 40 hours. How much did it cost to operate the light bulb if electricity costs 11 cents per kWh?
$ 0.66
Natural gas is sold in the US at $14.40 per MCF. 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.
$ 14.40/MMBTU
Natural gas is sold in the US at $1.29 per CCF. The efficiency of the natural gas furnace is 81.8%. What is the actual 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.
$ 15.77/MMBTU
To save energy and money, Jackie Smith replaced the 150 Watt incandescent light bulb in her house with a 32 Watt CFL bulb. The expected life of incandescent and CFL bulbs is 1000 and 8000 hours respectively. The purchase price of an incandescent bulb is $0.70 and for the CFL it is $6.46. The cost of electricity is 7 cents per kWh. What is her total savings over the life time of the CFL?
$ 65.22
A 100 watt incandescent light bulb is operated for 120 hours, and a 15 watt fluorescent light bulb is operated for the same period of time. At 10 cents per kWh, what is the cost savings of the fluorescent bulb?
$1.02 Energy = Power x duration, 100W x 120h = 12,000Wh = 12 kWh 15W x 120h =1,800 Wh = 1.8 kWh Energy savings is the difference (12-1.8) kWh = 10.2 kWh; at the rate of 10 cents per kWh this amounts to $1.02
Heat loss through a window (R-1) is 10 MMBTU/year. Calculate the payback period if Argon is filled in the window. Assume heating price to be $10/MMBTU. Additional cost for filling Argon is $20 and that gives an effective R value of 9
0.22 years
Visual Transmittance (VT) is expressed as number between 0 and __________
1
One calorie is defined as the amount of energy that is required to raise the temperature of ____
1 g of water by 1 degree C
We have a window with SHGC=0.61 and VT=0.67. What is the LSG?
1.1
If the owner replaces his old 3 ton air conditioner (SEER=8) with a new 3 ton air conditioner (SEER=13), which costs $500 more, what is the payback period? Assume that he operates his air conditioner for about 2000 hrs in a yr and cost of electricity is 9.2 cents per kwh.
1.57 years
A 100-watt light bulb produces 10 watts of radiant energy and 90 watts of heat energy. What is its efficiency?
10 %
The stratosphere begins at what altitude?
10 miles
Condensation Resistance (CR) is expressed as number between 0 and __________
100
One food calorie is equal to how many calories?
1000
An old refrigerator consumes 247 W of power. Assuming that the refrigerator operates for 19 hours everyday, what is the annual operating cost of the refrigerator, if the cost of electricity is $0.06 per kWh?
102.78 $ Annual operating cost = 247 / 1000 * 19 * 0.06 * 365 = $102.78.
A freezer maintains a temperature of 30ºF while the outside temperature is 75ºF. What is the COP of the freezer cooling system?
11.8
In general, air conditioners are rated in tons. A ton of refrigeration transfers _______
12,000 BTUs/hr
Water heaters are typically set to _____degrees F.
120 Degrees F
The useful output from a heat engine is 230 cal. The energy that is wasted is 5672 J? What is the Carnot efficiency of the engine?
14.55 % Efficiency = ((useful energy output) / (useful energy output + waste energy output))*100
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)?
16.6 Years 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
At the current rate of consumption approximately how long will the US coal reserves last?
164 years
The following step efficiencies apply to the use of gasoline in a car: Crude production: 91%, Refining 88%, Transportation 98%, Engine efficiency 22.3%. What is the total efficiency of the process?
17.5 %
The following step efficiencies apply to the use of gasoline in a car: Crude production: 94%, Transportation 95%, Refining 90%, Distribution of gasoline 84%, Engine efficiency 26%. What is the overall efficiency of the process?
17.6
Three energy conversion processes take place in succession. The first has an efficiency of 51%, the second is 50% efficient, and the third 10%. What is the efficiency of the entire process?
2.55 %
Coal reserves for the World at the present rate of consumption will last for about ________.
200 years
Energy use in a developing country is projected to increase at the rate of 1.9% per year for the next few decades. How long will it take that country to double its current usage of 10 quadrillion BTUs per year?
36.8
A house in State College (HDD=6000), PA has 283 ft2 of windows with R value = 2.3, 1904 ft2 of walls with R value = 19, and 1201 ft2 of roof with an R-value = 32. What is the total heat loss from the house for the season?
37553076.66 BTUs
A water heater heats 151 gal of water from 54oF to 137oF every day. What is the annual energy requirement of the water heater?
37968723.5 Btus Annual energy requirement = 151 * (137 - 54) * 8.3 * 365 = 37968723.5 BTUs.
A house in State College, PA consists of the following: 12 single pane windows (each 6 ft by 5 ft with an R value of 1.2). Calculate the total number of Btus lost for one season through these 12 windows. HDD for State College are 6,000
43200000 Btus
Approximately what percentage of electricity does an incandescent light bulb convert into visible light?
5%
Your old high school pal Mike Errington wants to upgrade an old 1976 vintage room air conditioner that is believed to operate at an EER of 6.5. He is considering a room air conditioner with an EER of 13. He wants to know by what percentage is electricity consumption would reduce? Can you help find it?
50 %
The coefficient of performance for a single heat pump in heating mode is greatest at which temperature?
50 F
What is the minimum amount of illumination that is required for reading?
50 fc
A family of four, each showering for five minutes a day, uses 700 gallons of water every week. Installing a low-flow non-aerating showerhead can cut this consumption by how much?
50%
The flame temperature in an automobile engine is 1699 °F, and the exhaust is emitted at 229 °F. What is the Carnot efficiency of the engine?
68.09 %
The flame temperature in an automobile engine is 1012 °C, and the exhaust is emitted at 74 °C. What is the Carnot efficiency of the engine?
73%
Calculate the amount of heat energy required to heat 126 lbs of water from 62oF to 121oF.
7434 BTUs Amount of heat energy required = 126 * (121 - 62) = 7434 BTUs.
If the energy input of a system is 87 calories and its output is 69 calories, what is the efficiency of the system?
79.31 % System Efficiency = (useful energy output) / (total energy input) * 100
John Jankomsky has an air conditioner that is rated at 8000 BTUs/h with an EER of 10 what is the power consumption of the air conditioner?
800 watts
An old refrigerator which is rated at 409 Watts and runs for 12 hours everyday is replaced by a new energy efficient refrigerator which is rated at 217 Watts and is expected to run 8 hours everyday. If electricity costs 9.4 cents per kWh, what are the energy savings in the month of December?
9.24
In State College, PA the average outside temperature during the month of January was 34 degrees F. Calculate the HDD for the month of January.
961 degree days
A 19 watt compact fluorescent lamp produces 1869 lumens of light. What is the efficacy of the CFL (in lumens/watt)?
98.37 lumens/watt
Compared to a house built in the 1960's, a house built today has _____.
A greater R-value
Normally dishwashers require a water temperature of
A) 140 F
Jane uses a water heater that is rated at 2391 watts for 6 hours everyday. The cost of electricity in her region is 8.3 cents per kWh. Calculate the annual operating cost for the water heater.
A) 434612.07 Dollars Annual Energy Consumption = 2391 / 1000 x 6 x 365 = 5236.29kWh Annual Operating Cost = 5236.29 x 8.3 / 100 = $434.61
In a typical residential or commercial lighting installation, _____ energy is wasted by obsolete equipment, inadequate maintenance, or inefficient use.
A) 50 % or more
The flame temperature in an automobile engine is 1071oC, and the exhaust is emitted at 187oC. What is the maximum possible efficiency of this engine?
A) 65.8 % Carnot's Efficiency = (1 - (Tcold / Thot)) x 100Thot = 1071 + 273 = 1344 KTcold = 187 + 273 = 460 KCarnot's Efficiency = (1 - (460 / 1344)) x 100 = 65.77%
Katy is planning on adding additional insulation to her roof, which costs $2929. It is estimated that she can save $364/year on energy costs from this modification. What is the pay back period in years?
A) 8 Years Pay back period = 2929/364 = 8.04 yrs
Kimonoski takes a 8-minute shower every day. The shower uses about 1.7 gal per minute of water. He also uses 20 gallons of hot water per day for clothes and dish washers. The hot water heats the water from 60 to 110 F. What is the total energy required per week for hot water?
A) 97608 BTUs
Which gases contribute to the acid rain formation? (select all that apply)
A) Carbon dioxide B) Carbon monoxide C) Sulfur dioxide D) Nitrogen Oxides
Which one of the following accounts for some of the differences in the energy intensity of various countries or regions?
A) Climate B) Geography C) Type and/or nature of the products produced *D) All the above*
Modified Energy Factor is used for
A) Clothes Washers
Carnot Efficiency is the energy efficiency of a __________.
A) Heat engine
A higher HDD indicates _____.
A) Higher heat loss B) Higher fuel requirements C) Higher temperature difference between inside and outside of the house *D) All the above*
Bleeding air from the pipes of a hydronic radiant baseboard heating system will _____.
A) Increase efficiency
Placing your clothes dryer in a cold basement will make the dryer _____.
A) Less efficient
Compact fluorescent light usually has a _____ compared to an incandescent bulb producing the same number of lumens.
A) Longer life
Kate is remodeling her kitchen. She goes shopping for a refrigerator. She finds three models that suit her needs. Model A - Price $306, estimated energy cost per yr $32 Model B - Price $402, estimated energy cost per yr $39 Model C - Price $483, estimated energy cost per yr $31 All three models have an estimated lifetime of 10 yrs. She needs help in deciding which one to buy. Which model would you recommend to Kate that makes most economical sense?
A) Model A Model A: Lifecycle cost = $306 + $32/yr x 10yrs = $626 Model B: Lifecycle cost = $402 + $39/yr x 10yrs = $792 Model C: Lifecycle cost = $483 + $31/yr x 10yrs = $793
Refrigerators are heat _____.
A) Movers
Energy Factor for Dish Washers is expressed as
A) Number of washes per kWh
Which of the following is a form mechanical energy?
A) Potential energy
The largest ozone hole is located over:
A) The Antarctic circle.
Results of recent climate models suggest that projected greenhouse gas emission patterns may lead to a global warming of 1.4 to 5.8 degrees Celsius during _____.
A) The next 100 years
Which of the following is NOT true about energy conversion devices?
A) Total Energy Input = Energy Dissipated to the surroundings
Smog is a secondary pollutant caused by the burning of fossil fuels.
A) True
The primary source for nitrogen oxide emissions in the US is from industries
A) True
Which one of the following countries has the highest carbon dioxide emissions?
A) United States
A higher CRI means _____.
A) better color rendering
In heating mode, when the refrigerant liquid moves past the expansion valve it ______.
A) evaporates, absorbing heat from the outside
A footcandle (fc) is the standard unit of measure for illumination on a surface. It is calculated as _____.
A) fc = Lumens of Light / Area in sq. ft
Which of the following is/are true about a geothermal heat pump? (Select all that applies)
A) it provides reduced or free hot water B) it requires little maintenance C) it saves energy and is evironmentally friendly
Light bulb labels should contain what kind of information?
A) light output B) energy used C) life of the bulb *D) all of the above*
Acid rain damages trees in which of the following manners?
A) removes soil nutrients
The R-value of thermal insulation depends on _____.
A) the type of material B) the thickness C) density *D) all the above*
For energy-efficient operation of a dishwasher _____.
A) wash only full loads B) use the no-heat air dry feature C) don't pre-rinse dishes before putting them in the dishwasher *D) all of the above*
What steps can lead to an energy efficient operation of a dishwasher?
A) wash only full loads B) use the no-heat air dry feature C) don't pre-rinse dishes before putting them in the dishwasher *D) all of the above*
_______ gas is used in gas filled windows to improve thermal performance
Argon
What percentage of the U.S. petroleum demand is met by imports?
Around 50%
The International Energy Outlook 2004 projects strong growth for worldwide energy demand over the 26-year projection period from 2004 to 2030. Most of the growth in the energy is likely to be in
Asia
After a house is built, the easiest way to insulate it, is by insulating the _____.
Attic
In State College, PA the average outside temperature during the month of January was 42 oF. Calculate the HDD for the month of January.
B) 713 HDD
Which of the following appliances uses modified energy factor to express energy efficiency?
B) Clothes washer
Which form of energy is the byproduct from most of the energy conversion devices?
B) Heat
The overall efficiency of a system will always be _____ than the _____ step efficiency.
B) Higher, Lowest
When does acid rain directly damage your skin?
B) It does not damage directly
Currently which fuel meets most of the world's energy needs?
B) Petroleum
Ozone is a _____.
B) Secondary pollutant
Stratospheric ozone layer is good for us because it prevents harmful ________ radiation from reaching the earth
B) UV
The circulation of air due to temperature differences in a room is called a _____.
B) convective loop
The compressor of a heat pump system ___________ the pressure of the refrigerant, ________ its temperature.
B) increases, raising
The Greenhouse Effect occurs because carbon dioxide absorbs _____.
B) infrared radiation
The largest ozone hole _____.
B) is over Antarctica
Which one of the following sustainable energy sources is producing significant amount of renewable energy in the US?
Biomass
_________ relative humidity feels uncomfortable
Both very high and very low
Which one of the following is a unit of power?
Btu/h
An old refrigerator consumes 187 W of power. Assuming that the refrigerator operates for 17 hours every day, what is the annual operating cost of the refrigerator, if the cost of electricity is $0.06 per kWh?
C) $ 69.62
The average cost of electricity in the US is ______.
C) $80/MWh
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.
C) 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
The clothes washer in your house consumes 423 kWh of energy per year. Price of the washer is $311 and the lifetime of the washer is 10 yrs. Energy price in your city is 12 cents per kWh. What is the lifecycle cost of the clothes washer? (assumes a maintenance cost of $20 per year)
C) 1018.60 $
John purchased 13985 kWh of electricity and 2216 CCF of natural gas in a year. The cost of electricity is 6.8 cents/kWh and that of natural gas is 1 dollars per CCF. Assuming that 1 CCF of natural gas has 100,000 BTUs and 1 kWh has 3412 BTUs, what is the average cost of 1 MMBTUs for John. (4 points)
C) 16.6 Dollars
A room has a wall with an R value of 14 F sq.ft. hr/BTU. The room is 17 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)?
C) 23314.3 BTUs Total area of walls = 2 ((17 x 8) + (8 x 8)) = 400 sq.ft HDD = 65-31 = 34 oF Heat transferred = 400 x 34 x 24 / 14 = 23314.28 BTUs
A house in State College, PA (HDD=6000) has 344 ft2 of windows with R value = 2.5, 1804 ft2 of walls with R value = 18, and 1101 ft2 of roof with an R-value = 28. What is the total heat loss from the house for the season (in BTUs)?
C) 39908685.71 BTUs eat lost through windows = 344 x 6000 x 24 / 2.5 = 19814400 BTUs Heat lost through walls = 1804 x 6000 x 24 / 18 = 14432000 BTUs Heat lost through roof = 1101 x 6000 x 24 / 28 = 5662285.71 BTUs Total heat loss from the house = 19814400 + 14432000 + 5662285.71 = 39908685.71 BTUs
17 million Joules of chemical energy are supplied to a boiler in a power plant. 7 x 106 Joules of energy are lost through unburnt fuel. The boiler radiates 2 million Joules to the atmosphere. What is the efficiency of the boiler?
C) 47.1 % Energy efficiency = Useful energy output / Total energy input Useulf energy output = 17 - 7 - 2 = 8 million Joules Efficiency of the boiler = 8 / 17 x 100 = 47.05%
The kitchen in your house measures 10 ft by 10 ft. You need to have 50 footcandles of illumination in the room. How many 60 watt bulbs will be required if one bulb emits 834 lumens. (1 footcandle = 1 lumen/sq.ft)
C) 6 bulbs
Buying an expensive energy efficient water heater will most likely save _____ in the long-term.
C) Both money and energy
Which of the following air systems is the most commonly used type of central heating and cooling system?
C) Forced Air Duct
Ozone forms by the reaction of nitrogen oxides and _____.
C) VOCs
What forms of energy are emitted by a glowing bulb?
C) radiation and thermal
Sulfates and nitrates that form in the atmosphere from sulfur dioxide (SO2) and nitrogen oxides (NOx) emissions contribute to _____.
C) visibility reduction
From the following, pick the odd set of pollutants:
CO, SO2, NOx
The energy in fossil fuels such as petroleum is stored as _____.
Chemical
At the present rate of consumption, reserves for which one of the following fuels will last the longest time?
Coal
Which energy source accounts for the greatest proportion of electricity generation in the US?
Coal
Which natural resource is the United States richest in?
Coal
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 _____.
Conduction
A spoon that is placed in a cup of hot coffee gets hot over time due to _____.
Conduction
Heat is lost through the walls, windows and the roof of a house. What is the primary mechanism by which this heat loss occurs?
Conduction
When you place a spoon into a cup of cocoa it gets hot over time. What is this due to?
Conduction
One of the heating systems we talked about in this course comprises of a system of ducts. What is the process by which heating occurs in this system?
Convection
You feel the heat of a wood stove when you stand next to it. What is this due to?
Convection
What is the function of a generator in a power plant?
Convert mechanical energy to electrical energy.
Of the following sources, where does the most heat loss occur for a typical home?
Cracks in walls, windows and doors
Ms. Hugger after taking the EGEE 102 class, added more insulation to her attic (500 sq. ft) at a cost of 1095 dollars. After the addition, she noticed that her heat loss from the entire house went down from 48 million BTUs to 27 million BTUs. She heats her home with natural gas at a cost of $8.3 per MCF. What is her pay back period?
D) 6.3 Years
Which gases contribute to ozone formation at the ground level?
D) Nitrogen Oxides
In a conventional oven, brownies bake in a glass pan using these two methods.
D) Radiation and conduction
Methane and nitrous oxide have what impact on the atmosphere?
D) Trap heat
Of the following sources, where does a typical home lose most of its heat?
E) Cracks in walls, windows and doors
Which term is used to define the energy efficiency of a room air conditioner?
EER
In a power plant, chemical energy is finally converted into_______energy.
Electrical
What kind of label do highly energy efficient appliances have?
Energy Star label
Growth in the World's energy consumption can be mathematically represented by which one of the following functions?
Exponential
Size of air conditioner doesn't depend on how much air leaks into you home from the outside.
FALSE
A heat mover speeds up a natural heating process.
False
Carbon dioxide is the only product when burning coal.
False
Coal accounts for the highest amount of carbon dioxide emissions in the US.
False
Doubling time is the time in which the rate of growth is doubled.
False
Due to convection, a house with an electric radiant system and floors with a high thermal mass can reduce heating costs if the electric company offers "time-of-use" rates.
False
Energy can be created when we burn fossil fuels.
False
For an Incandescent bulb, initial cost may be high but the energy costs will be low over its life time.
False
Fossil fuels are hydrocarbons comprised of primarily sulfur and hydrogen and some carbon, nitrogen, oxygen, and mineral matter.
False
Ground level ozone is produced directly by combustion.
False
If the air did not contain carbon dioxide, the planet would be hotter.
False
In the next 20 years, it is expected that renewable energy sources will supply more than half of the U.S. energy requirements.
False
Joule is a unit of power.
False
Most of the projected increase in the renewable energy use in the world over next two decades is from the industrialized world.
False
Most of the synthetic insulation products are poor insulation materials.
False
Natural gas water heaters are cheaper to install than electric water heaters.
False
Room air conditioners have a higher efficiency than central air conditoners
False
SO2 is a secondary pollutant.
False
Size of the air conditioner doesn't depend on how much shade is on your home's windows, walls and roofs.
False
Solar and GHP heating systems have absolutely no impact on the environment.
False
The U.S. has highest crude oil reserves in the world.
False
To produce one dollar worth of goods and services, the U.S. uses less energy than any other country in the world.
False
Where there is limited space, a hydronic heating system can be installed vertically.
False
In a baseboard radiator, _________increase(s) the surface area, which in turn leads to more efficient heat transfer.
Fins
Which one of the following is a type of fuel formed from the remains of plants or sea creatures millions of years ago?
Fossil fuel
Normal light bulbs (incandescent) give off much more ________ than fluorescent light bulbs.
Heat
One BTU of energy is enough to do what?
Heat one pound of water by one degree Fahrenheit.
Thermosiphon systems are most efficient in areas with ____ levels of solar radiation.
High
The _________ the CR rating, the better that product is at resisting condensation formation
Higher
Low-e coatings reduce ________ transfer by 5 to 10 times
IR heat
Which one of the following energy conversion devices has the lowest energy efficiency?
Incandescent light bulb
The word insolation is a combination of which of the following words:
Incident solar radiation
Carnot efficiency is lowered if we _____.
Increase Tcold
Which one of the following is an odd set of units?
J/s, Watt, BTU/s, kW/h
At the present rate of consumption, how long are the U.S. petroleum reserves expected to last?
Less than 10 years
What percentage of the U.S. energy demand is met by renewable energy sources?
Less than 10%
Compact fluorescent light usually has a ___________ compared to incandescent bulb producing the same amount of lumens.
Longer life
Windows _________ more heat per square foot of area in winter and _____ more heat in summer than any other surface in the home.
Loose, Gain
Which one of the following light bulbs produces highest lumens per watt?
Low pressure sodium
Typically, windows have an R-value ________ the wall.
Lower than
In a windmill, _____ energy is finally converted to _____energy.
Mechanical, electrical
In which of the following regions of the world is the per capita energy consumption the highest in the world?
North America
From the following, identify the list where all energy sources are non-renewable energy sources.
Nuclear Fission, Petroleum
Which one of the following will have a negative impact on the home heating efficiency?
Open front door in winter to filter and clean warm air.
In a __________ air conditioner, the evaporator, condenser and compressor are all located in one cabinet.
Packaged central
The time it takes to recover the additional cost through savings is called _____.
Pay Back Period
Which fuel supplies the greatest proportion of primary energy in the U.S.?
Petroleum
Units of energy when divided by time of usage give units of _____.
Power
Which one of the following is a list of devices from the most efficient to least efficient?
Power Plant (thermal), Automobile Engine, Light-bulb (Fluorescent), Light-bulb (Incandescent)
From a computer, the useful energy output is in the form of _____ energy.
Radiant
On cloudless nights, heat escapes from our planet and goes into space by _____.
Radiation
We are warmed by the sun. This is an example of heat transfer by _____.
Radiation
What is the form of useful energy output in the case of a computer screen?
Radiation
Which mechanism of heat transfer does not need any medium (molecules or atoms)?
Radiation
Solar water heating systems _____ the amount of heat that must be provided by conventional energy sources like electricity generated from fossil fuels.
Reduces
Which is more efficient, an air conditioner with EER 8.0 or an air conditioner with SEER 9.7?
SEER 9.7
Which of the following is not needed to produce ground level ozone?
SO2
If Peter expends 1,000 calories running a mile in one hour and Samantha burns 1000 calories riding a bike in forty-five minutes. Which one of the two exerted more power?
Samantha Power = Energy / Time Peter:Power = 1000 / 1 = 1000 cal/hr Samantha:Power = 1000 / 0.75 = 1333.33 cal/hr
Air conditioner is a heat pump
TRUE
Horizontal axis (front loading) clothes washer are more efficient compared to top loading models.
TRUE
Size of air conditioner depends on how much heat the accupants and appliances in your home generate.
TRUE
From an energy efficient point of view, an air conditioner should be mounted on _______
The shady side of the house
In a heat engine what type of energy is converted to mechanical energy?
Thermal
In a heat engine, ________ energy is converted into mechanical energy.
Thermal
Which one of the following is not an advantage of forced air heating systems?
They usually have a very high efficiency (80-90%)
Which one of the following is true about energy conversion devices?
Total Energy Input = Total Energy Output
A BTU has more energy than a calorie.
True
Analysis of ice cores provides the composition of the past air, which can be used to determine the past temperatures for approximately hundreds of thousands of years.
True
Earth is a natural greenhouse.
True
Effective shading can be provided by trees and other vegetation
True
Energy can be converted from one form to another.
True
Global climate change critics argue that due to increased concentration of CO2 we are seeing more forestation and that climate change is not a serious problem.
True
Greenhouse gas concentrations in the atmosphere are steadily increasing.
True
Greenhouse gases trap the infrared radiation in the atmosphere which is radiated back from the Earth.
True
HDD is used to estimate the amount of energy required for residential space heating during a cool season.
True
HDD is used to estimate the amount of energy required for residential space heating during heating season.
True
Heat pumps can cool your home
True
Home heating is the single highest energy expense for a household.
True
Horizontal axis (front loading) washing machines are more efficient compared to top loading models.
True
Insulating hot water pipes reduces the energy consumption for water heating.
True
Minerals in fossil fuels turn into ash when oxidized (burnt).
True
Most of the synthetic insulation products are very effective insulation materials.
True
Nitric oxide (NO) and nitrogen dioxide (NO2) together are represented by NOx.
True
Nuclear fusion is a renewable source of energy.
True
Oceans are vital in the energy balance of the earth. The great ocean conveyer belt slowdown or stoppage could lead to a potential catastrophe.
True
Potential Global Warming can lead to melting polar ice caps.
True
Resources represent the portion of the energy that is known to exist or even suspected to exist, regardless of technical or economic viability.
True
Short-term exposures to low levels of NO2 may lead to changes in airway responsiveness and lung function in individuals with preexisting respiratory illnesses.
True
Slowdown or stoppage of the great ocean conveyer belt could lead to a potential catastrophe.
True
The US has reserves of petroleum that will last about 11 years at the current rate of consumption and if we keep importing at the current rate.
True
The United States has less than 5 percent of the world's oil and natural gas
True
Using kitchen and bath exhaust fans may adversely affect the heating and cooling requirements
True
When all forms of energy coming out of an energy conversion device are added up, it will be equal to the energy input into the device.
True
When you insulate the attic of a home the R-value of insulation increases at the same rate as its thickness.
True
Wind energy can be converted to electricity.
True
Windows can be designed not only to prevent heat loss but also for heat gain.
True
With strong growth in GDP, demand for energy in developing Asia doubles over the forecast period from 2004 to 2030.
True
Energy can be converted to which of the following?
Work Heat Radiation All of the above
The R-value of a composite wall is calculated by _____.
adding the R-values of all layers
Insulation of a house helps reduce
both heating and cooling costs
Reserves represent the portion of demonstrated resources that _____.
can be recovered economically with the application of extraction technology available currently or in the foreseeable future.
Fluorescent light is produced by _____.
converting UV to visible light
In heating mode when the refrigerant liquid moves past the expansion valve it_____.
evaporates, absorbing heat from the outside evaporates, absorbing heat from the outside evaporates, absorbing heat from the outside
Which of the following kind of bulb requires a ballast?
fluorescent
What kind of washer is most efficient?
front loading
An energy source is nonrenewable if _____.
if the source cannot be regenerated in a reasonable time period.
Which one of the following is true about global temperatures in the last century?
increased about 1 degrees F
When warm outside air is cooled by an air conditioner, its relative humidity
increases
Cooling costs are ________ for the basement (in ground) compared to the upper floors.
lower
Which of these is not responsible for increasing atmospheric CO2?
photosynthesis
Most low-e coatings __________ the amount of visible light transmitted through the glazing relative to clear glass.
slightly reduce
PM2.5 describes the "fine" particles that are _____ 2.5 µm (micro meter) in diameter.
smaller than or equal to
Window coatings that only let through certain types of light are called
spectrally selective coatings
Global warming occurs when _____.
the total energy arriving at the earth is more than the energy leaving.
What is the impact of methane and nitrous oxide on the atmosphere?
trap heat
Energy and work have the same units.
true
The collector's efficiency increases as ______.
useful energy delivered increases (insolation remains constant)
A heat mover_____.
uses work to move heat from a low temperature reservoir to a high temperature reservoir
Water heater consumes energy _____.
whether we use hot water or not