1
Activity 2
Electricity Use
Key words and definitions for you to know
Kilowatt (kW) - A unit for measuring electrical electricity.
• 1,000 watts = 1 kilowatt.
Kilowatt Hour (kWh) - The use of 1,000 watts of electricity for one full hour.
• 1 kWh = ten 100 watt bulbs all burning at the same time for one hour.
• 10 bulbs x 100 watts each x 1 hour = 1,000 watts hours or 1kWh.
Megawatt - One million watts, or 1,000 kW.
Meter - An instrument that records or regulates the amount of something passing through it,
like electricity, water, or gas.
Watt - A unit for measuring electric power.
• 1 Kilowatt = 1000 watts. 1 Megawatt = 1,000,000 watts.
Like to surf? Learn more about this topic at…….
Wikipedia- electricity generation definition
http://en.wikipedia.org/wiki/Electricity_generation
EIA Energy Kids - Electricity
http://www.eia.gov/kids/energyfacts/sources/electricity
Electricity for kids... and everyone else
http://www.explainthatstuff.com/electricity
The Power Kids - Glossary - Choptank Electric Cooperative
http://www.choptankelectric.com/kids/glossary
City of Cape Town’s Global Change - Green Audit Toolkit.
http://www.capetown.gov.za/en/EnvironmentalResourceManagement/yes/YESEduNet/Do
cuments/Green%20Audit%20Toolkit_Learners%20Booklet_01_2009.pdf
Eskom Energy Calculator
http://www.eskomidm.co.za/powerCalculator/?q=energy_calculator
Eskom Comprehensive Energy audit
http://www.eskomidm.co.za/?q=user/register
Activity Sheet
2
ACTIVITY 2A: UNDERSTANDING ELECTRICITY CONSUMPTION AND ASSOCIATING A COST TO
THIS UTILITY
Activity Instructions:
1. In preparation for the lesson bring an electricity bill or a prepaid
electricity token slip to class.
2. With the bill or slip in front of you read through the paragraph blow on how
electricity is measured.
Measuring electric power
Watt - A unit for measuring electric power.
Kilowatt (kW) - A unit for measuring electrical electricity.
1,000 watts = 1 kilowatt= 1 unit
Kilowatt Hour (kWh) - The use of 1,000 watts of electricity for one full hour.
• 1 kWh = ten 100 watt bulbs all burning at the same time for one hour.
• 10 bulbs x 100 watts each x 1 hour = 1,000 watts hours or 1kWh.
Exercise:
Look at the example of a bill or prepaid slip that you have in front of you,
you can even swop with a friend, try and find the account number, the
units consumed and total amount of money due on your bill using the
information on the other side of this page.
Did you know?
To make 1 kWh of electricity it takes, 0.5 kg coal , 1.3 litres water of
water, 1.2 kg CO₂ and lots of ash, SO2 & NOx ……consider this
when playing your playstation for hours, or using a heater.
Activity Sheet
3
1
Account Number
Total Due
1
Shows a domestic electricity bill for a resident in Cape Town. Everyone has their own unique account
number and is charged for their use of electricity. The table below the bill shows how much you are
charged for the service and for the electricity. This is shown in Rands and cents. Where electricity use
does not go over 400 kWh per month (on average), you will receive a free basic amount of
electricity up to 50 kWh. This brings the total electricity received up to a maximum of 450 kWh per
month. If you use more than 400 kWh per month (on average), then the free electricity amount will
not be available to you. This average of 400 kWh per month is an average measured over twelve
months. If you use a prepaid meter you do not receive the free basic allocation in months in which
you do not buy electricity unless this is especially claimed at your local shop.
2
Unique Number code
2
Shows a prepaid meter and an example of the slip that is given to you when you buy electricity from
the shops. It has a number code on it. Each number code is unique. You type these numbers onto
the keypad on the prepaid meter and your meter is charged with the amount of electricity that you
have bought. This is a good way of keeping track of how much electricity you use.
Activity Sheet
4
ACTIVITY 2B: CLASSROOM ELECTRICTY AUDIT
Activity Instructions:
1. Listen to the ‘Electricity Facts’ introduction from your educator.
2. Work in groups of 4. Elect a leader for your group as well as
someone who will record the results of your audit on the worksheet. Walk around the
classroom/ passage/ hall (whatever area you are allocated by the teacher) and
answer the questions.
Exercise:
Electricity Audit:
• What items use electricity in the room?
__________________________________________________________________________________
__________________________________________________________________________________
•
Count how many of the following items are present in the room
Old
fashioned
bulbs
CFL’s
Fans/ air
conditioners
North
facing
window
s
Computers,
Printers and
Photocopier
s
Heaters
other
Room
•
How many hours is the room used each week?
__________________________________________________________________________________
•
Does the room have insulation in the walls and ceiling?
__________________________________________________________________________________
•
Are there overhangs over the windows to shade windows from the sun in warm
weather, and allow the slanted rays of the sun in winter to enter?
__________________________________________________________________________________
•
What kind of heating system is used in the room?
__________________________________________________________________________________
What kind of cooling system is used in the room?
__________________________________________________________________________________
•
Activity Sheet
5
•
•
•
•
•
•
What kind of lighting is used in the room (CFLs, incandescent lights, florescent lights)?
__________________________________________________________________________________
Does the room make use of natural lighting, i.e. could you turn the lights off and still
work there?
__________________________________________________________________________________
Does the room make use of natural airflow for cooling or does it rely on air
conditioning or a fan?
__________________________________________________________________________________
Do you think you could do without any of these items i.e. lights, aircon?
__________________________________________________________________________________
Do you think you could save electricity by not having these items?
__________________________________________________________________________________
Are there ways in which you can save electricity in the room? What are they? Write
them down.
__________________________________________________________________________________
Group Work:
In your group, discuss the following questions:
• Why do you think it is important to know how much electricity we use?
• What do you think electricity use at the school will look like in the
•
future?
How do you think the school can improve its electricity saving?
Take it Home:
•
• Why not do an electricity audit of your home?
Use the same questions that you used in this electricity audit to investigate the
amount of electricity used in your house.
Are there ways that you can reduce the amount of energy used in your home?
Did you know?
Cape Town water bylaws limit shower flow rates to no more than 10
litres per minute. To test this at home, hold a bucket under the
showerhead for 12 seconds. If there is more than 2 litres in the bucket,
then your showerhead is inefficient. …consider replacing it with a
more efficient one. ….. Activity Sheet
6
ACTIVITY 2C ELECTRICITY USE
Activity Instructions:
1. Listen to the ‘Electricity Facts’ introduction from your educator.
Exercise:
2. Match up Column 1 with the correct number of watts that the item
uses in Column 2. An example has been provided for you.
Activity Sheet
7
Group Work:
In your groups:
• Your educator has the correct answers to the ‘match the columns’
exercise. Swop your worksheet with the person sitting on your left and mark
their activity. How many did they get right?
Discuss the following questions:
• Were you surprised at how much electricity some things use?
• Efficient appliances are usually more expensive to buy than less efficient models, but
the life cycle cost of efficient appliances is usually much less than the less expensive
models. Do you think it is worth spending money on electricity saving appliances
now so that you save money in the future?
• Do you think that the government should pass a law that all appliances should carry
labels telling us how much electricity they use? Why?
• Do you practice electricity saving at home? Tell the group how?
Take it Home:
Walk around your house and see how many of the appliances in your home
are electricity efficient. Some have labels telling you how much electricity
they use. Look out for these labels and write down how much electricity each appliance
uses. Think about this consumption as a whole and think of ways you could save by not
using these appliances.
•
How many of the appliances in your home are on ‘stand-by’ mode.
Did you know?
Even after switching off your television, computer,
DVD and CD players with the remote control,
many of them continue to use electricity. To
reduce standby power, turn off these appliances
at the wall socket.
Activity Sheet
8
Fun exercise: Lets work out how much electricity your bedside lamp uses in a month
•
•
•
•
•
•
•
Look at the type of lightbulb you have.
Remember from class that a CFL lighbulb uses 18 watts and an old fashioned
lighbulb uses 60 watts.
Work out how many hours you use the light a day.
Multiply this by 30 to find out how many hours it is on per month.
Take the Wattage and multiply this by the hours used per month ÷ 1000.
This would equal the monthly Kilowatt-hour (kWh) consumption.
You can then calculate the monthly cost to run the light by multiplying the kWh per
month by the current tarriff per kWh consumed (ask your caregiver to help you
here).
Use this space for your sums:
Having done this, if you have an old fashioned lightbulb, why not consider replacing it with
a CFL when it breaks as they use less electricity?
Tell your parents, relatives and community about what you have learnt about appliances
and their use of electricity during this Activity.
Did you know?
•
•
Activity Sheet
•
Compact fluorescent lamps (CFLs) or electricitysaving light bulbs use up to 80% less electricity
than incandescent light bulbs to produce the
same amount of light, and they can last up to 10
times longer!
Remember: Broken CFL’s should be picked up
using gloves and must be disposed of properly, in
a special bin – not your household waste that
goes to landfill, see
http://www.capetown.gov.za/solidwaste for a list
of disposal sites in your area.