Household Electricity Use Worksheet

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Dina Bradford
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1 Household Electricity Use Worksheet Evaluation of Household Appliance Electricity Use Part 1: Calculating operating cost for an appliance In order to calculate the average operating cost for any electrical appliance you can use the following formula: kwh = (watts/1,000) x hours of operation Cost = rate (cost/kwh) x kwh Watts can usually be found on the appliance name plate. If the name plate lists amps: volts x amps = watts Example: How much does it cost to operate a portable electric heater? An electric heater wattage is usually given on the unit itself, or with the literature that comes with it. An example is 1000 watts. If you use the heater an average of 45 hours during winter months (1 /2 hour per day for the three winter months). If the electric rate during the winter is $0.068 per kwh. So kwh = 1,000 watts/ 1,000 x 45 hours = 45 kwh cost = 45 kwh x.068/hour = $3.06 Now, if you have an 8 amp heater, the calculation changes just a bit: 8 amps x 120 volts household current = 960 watts price =.96 kw x 45 hours x S.068/kWh = $ Chose an electrical appliance in your house, either a computer or a television set. Look at the back of the appliance. You will either find the power in Watts, or the current in amps. Appliance: = amps power = watts or current 2. Unless you know otherwise, assume that the appliance is receiving 120 volts of household current. In Los Angeles at this time the electric rate is $0.10 per kwh 3. Estimate the number of hours that the appliance is used in one month: hours 4. Calculate the energy in kwh that is used to run your appliance for one month. Show your calculations below

2 5. Calculate the cost per month of using the appliance. Part 2 -Calculating Household Appliance Energy Use Listed below are some common appliances, their wattage, and average monthly use. Determine your household energy use by estimating your average hourly use of each appliance, and then the cost per month. Many of the appliances your family will not use, while there will be other appliances, such as a computer, that your family may use which you must list at the end. For some appliances, you l1 also have to indicate the number of each appliance used (light bulbs and clocks for example). Appliance Watts U.S. average hours/month Air Conditioner (Room) 6,000 BTU Air Conditioner (Room) 9,000 Air Conditioner (Central) 2.5 Can Opener Ceiling Fan Clock Clothes Dryer (Elec) Clothes Dryer (gas) Clothes Washer Coffee Maker Computer (printer and monitor) Dehumidifier Dishwasher Electric Blanket Portable electric heater Portable fan Food blender Food freezer (1.5ft3) Frying pan/waffle maker Furnace fan motor # in house Your personal ave. hours/month Your cost ($) per month

3 Hairdryer Single lamp Compact fluorescent 2 tubes fluorescent Microwave oven Electric stove Refrigerator Stereo receiver (on) Setero receiver (standby) TV on TV standby Toaster Electric toothbrush Vacuum cleaner VCR/DVD player on VCR/DVD player standby TOTALS-- Part 2: Your assignment is to decrease your electricity use by at least 7% for one week. First determine what you would use in a normal week then conserve energy for the second week. Describe in detail what changes you made and how you obtained the data. The Report: It is important that you make some kind of measurement so that you can quantify the savings. The most direct way to do this is to read your electricity meter. If this is not possible, then you need to consult with your instructor about an alternative. In addition to reading the meter, you are asked to calculate the savings in energy expected from your conservation plan. This requires that you decide what appliances you will replace or restrict, then find the power they use, and finally estimate the number of hours of saving which you have accomplished. The report comes in FOUR parts (A, B, C, D). Your Electric Meter Read the dials from left to right and write down, in the same order, the last number that the pointer has passed. The result is your meter reading.

4 If the pointer is directly on a number, record the next lower number unless the pointer on the dial to the right has passed 0. The reading at the right is 7025 A. READING YOUR METER - Due on To be certain that you are reading the electrical meter correctly, you are to make a first reading and report the result. You are to record here the appearance of the 4 or 5 dials on your meter. Then 1. WRITE in all of the numbers on the dials, 2. use arrows to show the direction each pointer moves, 3. and show the positions of the pointers as they appear. 4. Then write down the number of kilowatt hours that this reports, and finally record the time and date upon which this reading was made. DIALS: 1. Reading = kwh Time: ; Date: B. NORMAL USAGE - Due on Record the second reading of your electrical meter DIALS: 2. Reading = kwh Time: ; Date: Report here the number of kilowatt-hours used during a week of normal electrical usage. If the time between your meter readings was not one week (to

5 within about four hours) then you will need to calculate what would be used in a day, and then change it to a week. Show your work 3. Amount of electricity used during the first week = C. PLANNED SAVINGS - Due on Here you are to indicate how you expect to save electrical energy usage, and the quantity that you expect to save. You may change more than one thing. 4. How you plan to change your use of electricity?: How to Estimate your savings For the appliances, light fixtures, or motors that are to be used for a reduced amount of time during the test week, you need to find out (a) the power each appliance uses and (b) an estimate of how many hours it is normally used in a day or week, and how many hours this will be reduced in a day or week. You will then calculate the saving expected in a week. Examples:

6 For the electric motor on the washing machine the data might be 400 watts used 5 hours a week to be reduced (by using larger loads) to 3.5 hours. The savings would be Savings = (0.400 kw) x (1.5 hrs) = kwh For appliances that are replaced by others requiring lower electrical power you need to find out (a) the power used by your appliance, (b) the savings in power from the new appliance, and (c) an estimate of the number of hours this appliance is used in a week. You then calculate the savings expected in a week. For a light fixture with three 75 watt bulbs that that is replaced with three 20 watt compact fluorescent bulbs which are used two hours a day, the savings would be calculated as Power difference = (75-20) x 3 = 165 watts =0.165 kw Energy savings = (0.165 kw) x (2 hrs/day) x (7 days/wk) = 2.31 kwh Estimate of Savings- (show work) D. FINAL REPORT - Due on Record the third reading of your electrical meter DIALS: Reading = kwh Time: ; Date: Amount of energy used during the second week =

7 CALCULATIONS: Show all work (There are 101 million households in the United States) (The cost of 1 kwh is approximately $0.10, and one KWH produces 1.5 lbs of CO 2 ) 1. Energy savings from the first week to the second week (as determined by meter readings) 2. % decrease in energy use 3. Energy savings in one year 4. Money savings in one week 5. Money savings in one year 6. Energy saved if 10% of the households in the United States did the same for one year 7. A typical coal-burning power plant produces 3.5 billion kwh per year. How many power plants could shut down if 10% of the U.S. households did the same you did?

8 8. Lbs of CO 2 saved if 10% of the households in the United States did the same for one year.

THE ELECTRIC HOOKUP. 1. Determine the wattage of various household appliances. 2. Calculate the number of kilowatt-hours used by appliances.

THE ELECTRIC HOOKUP. 1. Determine the wattage of various household appliances. 2. Calculate the number of kilowatt-hours used by appliances. Objectives: The student will do the following: THE ELECTRIC HOOKUP 1. Determine the wattage of various household appliances. 2. Calculate the number of kilowatt-hours used by appliances. 3. Identify the