Personal Energy Audit

Personal Energy Audit

You are going to estimate the amount of energy that your household uses per day. To do this, you must go around to each and every appliance in your house. This means every light bulb, every computer, every tv, etc. Nothing that uses electricity is off limits. Be thorough and make sure that every appliance is included.

Some appliances may only be used every few days, weeks or months. This is fine, but they should still be included in your audit. Simply figure out how many hours they’re used every week or month and divide by the number of days in a week or month to figure out the average use per day.

In order to perform this audit, you will need to find out the power rating of each appliance. How much power does it use? Most appliances have a label somewhere on them indicating their power rating. For others, you may need to check the manual or look up information on their model number online.

For each appliance, fill in the following table. If you run out of room in your table, make a new one for yourself, don’t just stop when you run out of spots. It’s important to get every appliance. Note that the energy used per day is measured in kilowatt-hours, rather than joules. You’ll have to convert your appliances’ power ratings to [kW] then multiply by the number of hours per day to determine the energy used per day.

Appliance / Power [W] / Power [kW] / Hours Used Per Day [h/day] / Energy Used Per Day [kW-h/day]

How much total energy (in kilowatt-hours) does your household use in a day?

Residential power in Westchester County costs about $0.164 per kilowatt-hour. How much does your household’s daily energy use cost? How much, on average, does your household energy use cost per month?

Ask your parents how much the monthly power bill is, on average. Compare their figure to yours. Is there a discrepancy? What your parents actually pay may be more than what you calculated if you missed some appliances and because this audit doesn’t really take into account things like electric heat or electric water heaters. The power bill also varies depending on the time of year. Generally, people spend more in the summer due to air conditioning.

Estimating Environmental Impact

The percent of electric power generated by each fuel type in the United States can be found at

Burning one pound of bituminous coal generates 3.52 [kW-h].
Burning one barrel of oil generates 1.64 x 103 [kW-h].
Burning one cubic foot of natural gas generates 0.30 [kW-h].
The fusion of one gram of uranium 235 generates 1.17 x 104 [kW-h].

Let’s assume that the power production for Westchester County follows the same percentages as listed on the Department of Energy website given above. Using the data given, calculate how much of each fossil fuel is consumed to power your household for a day.

For every cubic foot of natural gas burned, 0.122 [lb] of carbon dioxide is produced.
For every pound of coal burned, 8.1 [lb] of carbon dioxide is produced.

Using the amount of coal and natural gas that your home consumers per day, calculate how much carbon dioxide is released into the atmosphere producing the power used by your home in a single day.

Examining Alternative Methods

Natural gas costs $4.67 per 1000 cubic feet.
Coal costs $24.38 per ton (2000 pounds).
Uranium 235 costs $0.022 per gram.

Assume that burning natural gas produces all of the power needed by your home. How much does it cost for the fuel used to power your home for a single day?

Now, assume that burning coal produces all of the power needed by your home. How much does it cost for the fuel used to power your home for a single day?

Finally, assume that the fusion of uranium 235 produces all of the power needed by your home. How much does it cost for the fuel used to power your home for a single day?

If uranium fusion is a more cost-effective method of producing power, why do you think we use so little of it?