Here, it's my job to compare different appliances to each other and pick the one that is the most energy efficient. The contractor for my house has given me specifications for each refridgerator, dishwasher, water heater, and clothes washer that we need. The one given will be named "A" in each section. I need to find appliances on the internet like similar or higher capacities for each appliance. The energy price in the area is 0.08 $/kWh for electricity and 11 $/MMBTU for gas. Lifetime for all appliances is assumed to be 10 years.
SOURCE: All of the refridgerators, dishwashers, water heaters, and clothes washers named "B" and "C" were found on sears.com in the appliances section. The appliances named "A" were given on the course website.
1. Energy Cost for 1 year = Energy Consumption x Energy Price in the area
For Refridgerator A = 442 kWh/yr x 0.08 $/kWh = $35.36 /yr
2. Energy Cost for 10 years = Energy Cost of 1 year x 10 yrs
For Refridgerator A = $35.36 /yr x 10 yrs = $353.60 /10 yrs
3. Total Cost = Purchase Price + Energy Cost for 10 years
For Refridgerator A = $750 + $353.60 = $1103.60
NOTE: THESE SAME, EXACT CALCULATIONS FOLLOW THROUGH TO THE rest of the REFRIDGERATORS, DISHWASHERS, WATER HEATER, and CLOTHES WASHER sections.
A 18.8-18.9 ft^3 Top Mount Kitchen Aid $750 442 kWh/yr
B 20.6 ft^3 Top Mount Kenmore $549 432 kWh/yr
C 18.9 ft^3 Top Mount Whirlpool $829.99 417 kWh/yr
Purchase Price $750 $549 $829.99
Energy Consumption 442 kWh/yr 432 kWh/yr 440 kWh/yr
Energy Cost for 1 year $35.36 /yr $34.56 /yr $35.20 /yr
Energy Cost for 10 years $353.60 /10 yrs $345.60 /10 yrs $352.00 /10 yrs
Total Cost $1103.60 $894.60 $1181.99
Also, it is the cheapest appliance to buy intially at $549 and over 10 years at $894.60.
A 24 inch Built In GE $500 387 kWh/yr
B 24 inch Built In Kenmore $199.99 347 kWh/yr
C 24 inch Built In Frigidaire $269.99 374 kWh/yr
Purchase Price $500 $199.99 $269.99
Energy Consumption 387 kWh/yr 347 kWh/yr 374 kWh/yr
Energy Cost for 1 year $30.96 /yr $27.76 /yr $29.92 /yr
Energy Cost for 10 years $309.60 /10 yrs $277.60 /10 yrs $299.20 /10 yrs
Total Cost $809.60 $477.59 $569.19
Also, it is the cheapest appliance to buy initially at $199.99 and over 10 years at $477.59.
A 50 gallon Electric Kenmore $250 4879 kWh/yr
B 50 gallon Electric Kenmore $229.99 4721 kWh/yr
C 55 gallon Electric Kenmore $329.00 4622 kWh/yr
Purchase Price $250 $229.99 $329.99
Energy Consumption 4879 kWh/yr 4721 kWh/yr 4622 kWh/yr
Energy Cost for 1 year $390.32 /yr $377.68 /yr $369.76 /yr
Energy Cost for 10 years $3903.20 /10 yrs $3776.80 /10 yrs $3697.60 /10 yrs
Total Cost $4153.20 $4076.79 $4027.59
Also, it is the cheapest appliance over 10 years at $4027.59. However, this appliance does have the highest intial cost, but we do see that it is the most economical over the 10 year life span. (We will pay $329.99-$250 = $79.99 more initially.)
A 3.1 ft^3 Front Load GE $730 260 kWh/yr
B 3.1 ft^3 Front Load Kenmore $599.98 246 kWh/yr
C 3.3 ft^3 Front Load Maytag $699.99 296 kWh/yr
Purchase Price $730 $599.98 $699.99
Energy Consumption 260 kWh/yr 246 kWh/yr 296 kWh/yr
Energy Cost for 1 year $20.80 /yr $19.68 /yr $23.68 /yr
Energy Cost for 10 years $208.00 /10 yrs $196.80 /10 yrs $236.80 /10 yrs
Total Cost $938 $796.78 $936.79
Also, it is the cheapest appliance to buy intially at $599.98 and over 10 years at $796.78.
Refridgerator: No additional money is needed, initially. The most energy efficient appliance is $549 and the original appliance (which is less efficient) is $750. We would actually be saving $750-$549 = $201.00 by buying the energy efficient appliance initially.
Dish Washer: No additional money is needed, initially. The most energy efficient appliance is $199.99 and the original appliance (which is less efficient) is $500. We would actually be saving $500-$199.99 = $300.01 by buying the energy efficient appliance initially.
Water Heater: The most energy efficient appliance is $329.99 and the original appliance (which is less efficient) costs less, at $250. We would have to invest an additional $329.99-$250 = $79.99 by buying the energy efficient appliance initially.
Clothes Washer: No additional money is needed, initially. The most energy efficient appliance is $599.98 and the original appliance (which is less efficient) is $730. We would actually be saving $730-$599.98 = $130.02 by buying the energy efficient appliance initially.
ALL APPLIANCES: Overall, we would be saving a total of $631.03 ($201 + $300.01 + $130.02) by buying the more efficient fridge, dish washer, and clothes washer. We would have to invest an additional $79.99 for the most efficient water heater. Our net savings = $631.03 - $79.99 = $551.04.
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2. What will the total energy savings (kWh) per year be if you replace the appliances with the energy efficient appliances?
Total Energy Savings (kWh) per year = Energy consumption of given appliance ("A") - Energy Consumption of most energy efficient appliance ("B" or "C")
Refridgerator: 442 kWh/yr - 432 kWh/yr = 10 kWh/yr
Dish Washer: 387 kWh/yr - 347 kWh/yr = 40 kWh/yr
Water Heater: 4879 kWh/yr - 4622kWh/yr = 257 kWh/yr
Clothes Washer: 260 kWh/yr - 246 kWh/yr = 14 kWh/yr
ALL APPLIANCES: The overall energy savings for all appliances would be the total of the above energy savings for each appliance, which is 10 kWh/yr + 40 kWh/yr + 257 kWh/yr + 14 kWh/yr = 321 kWh/yr.
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3. How much money will you save per year if you replace the appliances with the energy efficient appliances?
Money saved per year = Energy cost for 1 year for given appliance ("A") - Energy cost for 1 year for most energy efficient appliance ("B" or "C")
(Energy cost for 1 year equation given at top, in explanation of calculations section.)
Refridgerator: $35.36/yr - $34.56/yr = $0.80 /yr
Dish Washer: $30.96/yr - $27.76/yr = $3.20 /yr
Water Heater: $390.32/yr - $369.76/yr = $20.56 /yr
Clothes Washer: $20.80/yr - $19.68/yr = $1.12 /yr
ALL APPLIANCES: The overall savings per year for all appliances would be the total of the above savings for each appliance per year, which is $0.80 /yr + $3.20 /yr + $20.56 /yr + $1.12 /yr = $25.68 /yr.
We can confirm this number by using our answer from #2, above. The total energy savings for all appliances in one year is 321 kWh/yr. 321 kWh/yr x 0.08 $/kWh = $25.68 /yr, which is what we got.
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4. What will be the overall (all appliances together) payback period?
Payback Period = The amount of time it takes to recover your additional investments by savings.
Payback Period =
[ The prices of the most energy efficient appliances ("B" or "C") - The prices of given appliances ("A") ] /
{[Energy Cost for 10yrs of given appliances ("A") - Energy Cost for 10yrs of most energy efficient appliances ("B" or "C")]/10yrs}
a) Initial Prices of most energy efficient appliances = Price of Refridgerator "B" + Price of Dishwasher "B" + Price of Water Heater "C" + Price of Clothes Washer "B" = $549 + $199.99 + $329.99 + $599.98 = $1678.96
b) Initial Prices of given appliances = Price of Refridgerator "A" + Price of Dishwasher "A" + Price of Water Heater "A" + Price of Clothes Washer "A" = $750 + $500 + $250 + $730 = $2230
c) Energy Cost for 10 yrs of given appliances = Energy Cost for 10 yrs of Refridgerator "A" + Energy Cost for 10 yrs of Dishwasher "A" + Energy Cost for 10 yrs of Water Heater "A" + Energy Cost for 10 yrs of Clothes Washer "A" = $353.60 + $309.60 + $3903.20 + $208.00 = $4774.40
d) Energy Cost for 10 yrs of most efficient energy appliances = Energy Cost for 10 yrs of Refridgerator "B" + Energy Cost for 10 yrs of Dishwasher "B" + Energy Cost for 10 yrs of Water Heater "C" + Energy Cost for 10 yrs of Clothes Washer "B" = $345.60 + $277.60 + $3697.60 + $196.80 = $4517.60
Payback Period = [$1678.96 - $2230]/{[$4774.40 - $4517.60]/10yrs} = -21.46 years
****Here, we are disregarding the payback period because our more energy efficient appliances cost less than the original appliances given on the webpage, so the payback is negative. It is irrelevant here.
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5. How much money will you save over a period of 10 years?
Money saved over 10 years = Energy cost for 10 years for given appliance ("A") - Energy cost for 10 years for most energy efficient appliance ("B" or "C")
(Energy cost for 10 years equation given at top, in explanation of calculations section.)
Refridgerator: $1103.60 - $894.60 = $209.00 /10 yrs
Dish Washer: $809.60 - $477.69 = $332.01 /10 yrs
Water Heater: $4153.20 - $4027.59 = $125.61 /10 yrs
Clothes Washer: $938 - $796.78 = $141.22 /10 yrs
ALL APPLIANCES: The overall monetary savings over 10 years for all of the appliances would be the sum of the savings for each appliance listed above. The overall monetary savings over 10 years for all appliances is $209 /10yrs + $332.01 /10yrs + $125.61 / 10yrs + $141.22 / 10yrs = $807.84 /10yrs.
However, this isn't very common. With the water heater, which is the more common situation, we saw that we'd pay the most intially for the model that ended up using the least amount of energy and ended up costing us the least over 10 years. So, it'd be worth it to invest the extra money up front for a substantial amount of savings over 10 years.
As you can see above, I have made recommendations for which appliance to buy out of the refridgerators, dish washers, water heaters, and clothes washers. I have made these decisions based on the energy consumption (choosing the appliance that consumes the least amount of energy) and based on the cost over 10 years (choosing the appliance with the lowest cost). These two factors always correlated well and the decision for which model to pick was pretty obvious for each appliance.
After clicking on the link at the bottom of the appliances assignment, I found that by saving 321 kWh/yr (for all appliances in total) I would be saving an estimated 31 $/yr. I would also have a reduction of 649 lb/yr of greenhouse gases (carbon dioxide), reduction of 1 lb/yr of nitrogen oxides, reduction of 5 lb/yr sulfur dioxide, and a reduction of 12 mg/yr of mercury. So, besides the monetary savings we'd get my using more efficient appliances, there are also benefits involving pollutants in the air!