
Energy Use of Home Appliances
How much electricity do our appliances use? You can usually find the wattage of most appliances on the nameplate on the back or bottom of the appliance. The wattage listed is the maximum power drawn by the appliance. Wattage = current X voltage. Often you will see the letters UL on the nameplate, which means the product has been tested to safety standards. Adjusting volume or changing settings can affect the actual amount of power consumed. Many appliances draw small amounts of power even when they are turned off. These "phantom loads" occur in VCR's, televisions, stereos, computers and increase the appliance's energy consumption a few watts per hour. Below is a list of some common household items and the wattage used for each.




















microwave  7501100  refrigerator  1725 












APPLIANCE  VOLTAGE  CURRENT  WATTAGE  COST  HOURS/YEAR  ANNUAL COST 
copier  115V  11A  1265W  $0.08kWh  120  $12.00 
printer  120V  5.5A  
monitor  120V  2.0A  
computer  200240V  3.0A  
fax machine  1.0A  45W  
TV  120V  75W  
microwave  120V  1500W  
scanner  100240V  2.0A 
American homes contain over 3 billion light fixtures. It takes about 138 billion kilowatthours of energy per year to operate these lights. 610% of our electricity bills are spent on lighting costs. The most common light bulbs in our homes today are incandescent or halogen bulbs. There are also Compact Fluorescent Lights (CFLs). Compact Fluorescent lights contain gas instead of a wire filament. The electric current makes the gas glow, which produces very little heat. CFLs last up to 10 times longer and use 70% less energy. Using energy efficient bulbs can both save money and natural resources.
How much energy/money can be saved by replacing our light bulbs with Compact Fluorescent Lights?
Number of lights Number of hours Lights X hours = TOTAL Living Room ______________ ______________ _____________ Dining Room ______________ _____________ ______________ Kitchen ______________ ______________ ______________ Bedrooms ______________ ______________ ______________ Bathrooms ______________ ______________ ______________ Hallways ______________ ______________ ______________ Family Room ______________ ______________ ______________ Outside Lights ______________ ______________ ______________ TOTAL ______________
Each energy efficient CFL bulb saves 50 watts, how many watthours could you save if you replaced all bulbs with CFLs?
Total hours of operation X 50 watts = _________Watt hours you would save each day
Divide your answer by 1,000 since there are 1,000 watthours in a Kilowatthour (which is how your utility bills you)
Watt hours / 1,000 = _______________ kilowatthours you would save
Take this answer and multiply it by 365 (the days in a year) to calculate the Kilowatthours saved in a year.
Kilowatt hours X 365 = __________Kilowatthours saved in a year
To calculate the amount of money your family could save in a year, take the Kilowatthours saved in a year times the cost per Kilowatthour ( in Denver it is $.089).
Kilowatthours saved X $.089 = ______________Amount saved per year!
In addition to saving money, we use less electricity! Using less electricity means producing less greenhouse gases. If we assume that every kilowatthour saved removes 2 pounds of carbon dioxide from the air, how much greenhouse gases could be prevented?
Kilowatthours saved in a year X 2 pounds = _______________pounds of greenhouse gas prevented
Reading Electric Meters
Understanding how we use energy can help us better conserve energy. Many different energy sources are used to generate electricitybut more than half of the electricity in the United States is generated by coalfired power plants. Electricity enters a home through a distribution line that passes through a meter that measures the amount of electricity consumed in kilowatthours.
Reading an electric meter is easy. The face of the meter has five dials with the numbers 09 on each dial. The dials are not identical though. On the first dial, the numbers increase in a clockwise direction. On the next meter, the numbers increase in the opposite direction, in a counterclockwise direction. Each dial alternates from clockwsie to counterclockwise as shown. To read a meter, you read the dials from right to left and record the numbers. If the pointer is between two numbers, you always record the smaller number.
EXAMPLE
Monday morning the meter looked like this:
Friday morning the meter looked like this:
The meter reading Monday would be 40565 and on Friday it would be 41615
To figure out how much electricity was used, subtract Monday's reading from Friday's reading like this:
41,615  40,565 = 1,050 kilowatthours
Based on electricity costs in Denver of $.089 per kilowatthour, the total cost would be: 1,050 X $.089 = $93.45
PROBLEM TO SOLVE
On January 1, the meter looked like this:
On January 31, the meter looked like this:
How many kilowatthours of electricity were used during January?
If the cost of electricity in Denver is $.089 per kWh, how much did electricity cost for January?
What is the average cost of electricity per day during January?
Monitor home energy use by reading the electric meter each morning for a week and determine the cost per week of electricity in your own home.
Turn off the power for just one hour. Monitor electricity during a normal hour at home and then turn off as many electrical devices as possible for an hour and record the difference in electrical use.
How To Read Utility Bills
Electric companies monitor electric consumption with meters that measure the amount of electricity consumed in buildings. Electricity is measured in kilowatthourskWh. The average cost of electricity in the US is approximately eight cents.
Utilities usually read meters once a month, although some utilities read meters every other month and estimate readings for teh months inbetween. Bills are sent to customers monthly, providing detailed information on the amount of energy consumed and the rate structure for billing.
Many customers can opt for a budget plan, in which they pay the same amount to the utilities each month, regardless of the actual amount of energy they use. This spreads out the seasonal fluctuations in energy usehigh heating costs in winter and high cooling costs in summer.
Look at the sample electric bill below. Use the information provided to answer the questions that follow.
BUZZ LITE ENERGY COMPANY
DATE METER READING DECEMBER 1 970 DECEMBER 8 1040 DECEMBER 15 1230 DECEMBER 22 1410 DECEMBER 29 1640 JANUARY 2 2260 JANUARY 9 2370 JANUARY 16 2680 JANUARY 22 2920
1. Using the meter readings from January 9th and December 8th, what was the total kilowatt hour usage?
2. Calculate the actual cost by using the rate schedule. Show your work for each step:
UTILITY RATES:
basic charge(your cost to be connected to the Utility company) ($7.00) +
kWh first 800 ($.06) +
kWh over 800 ($.08) = (your cost) =$ ___________
Students: Click on the button at the left to connect to the Measurement Worksheet
Authors: Sue Emmons, Powell Middle School, Littleton, CO; Kevin Lindauer, John F. Kennedy High School, Denver, CO; Linda Lung, National Renewable Energy Laboratory, Golden, CO; John Sepich, Scott Carpenter Middle School, Westminster, CO; ; Janet Stellema, Monarch K8, Louisville, CO. Created: September 9, 1998  Updated: October 3, 2001. URL: /ntep/f98/projects/nrel_energy_2/measurement.html