Basic 9 · Social Studies · Environmental Issues
Measuring Energy and the Value of Conservation
In this topic you will describe the processes and devices used for measuring and metering energy, and describe the advantages of energy conservation while educating others about it.
By the end of these notes you should be able to:
- Describe devices that measure energy
- Read and interpret energy use
- Explain and promote energy conservation
What you already know
- Global energy sources
Copy everything that has a blue line on its left into your notebook. The other parts are for reading.
Lesson 1
- Strand
- Environment
- Sub-strand
- Environmental Issues
- Indicator
- B9.1.1.2.1 – Assess global sources and the means of conserving energy
Introduction
You cannot manage what you do not measure. Energy meters tell us how much we use and what we must pay.
1. Units of Energy
| Energy type | Unit | Device |
|---|---|---|
| electricity | kilowatt-hour (kWh) | electricity meter |
| LPG | kilograms | scale at the filling point |
| petrol and diesel | litres | fuel pump |
| charcoal | bags or kilograms | scale |
| solar | watts, watt-hours | charge controller |
2. Electricity Meters
| Type | How it works |
|---|---|
| postpaid | usage is read and billed monthly |
| prepaid | customers buy units in advance |
| smart meter | sends readings to the company |
An old postpaid meter has a set of number dials. To find the units used, subtract the previous reading from the current one. A prepaid meter shows how many units remain, and customers can buy more at vending points or by using a mobile app. In Ghana, the ECG and NEDCo distribute electricity to customers, while the Public Utilities Regulatory Commission sets tariffs.
3. Reading a Bill
Reading a meter
A meter read 4,350 kWh last month and 4,560 kWh this month. If each unit costs GH₵2, find the cost.
- Units used: 4,560 − 4,350 = 210 kWh.
- Cost: 210 × 2.
Answer: GH₵420
The price here is only for practice, because tariffs change. Electricity tariffs are often higher for those who use more. Customers may also pay service charges and levies.
4. Measuring at the National Level
Countries measure energy on a large scale. Power stations are rated in megawatts (MW). The Akosombo Dam can generate about 1,020 MW. Ghana's Energy Commission publishes statistics on energy supply and demand, helping the government to plan. Knowing how much is used at peak times tells planners how much generating capacity is needed.
5. Using Meter Data
A household that studies its meter may spot waste. If units fall quickly at night, a device could be wasting energy. Schools can compare their monthly use. Smart meters can show patterns in detail. Careful measuring is the first step towards saving. Meter tampering is illegal and dangerous, and it passes costs on to honest customers.
New words
- meter
- A device that measures use.
- prepaid
- Paid for in advance.
- tariff
- The price of electricity.
- megawatt
- A million watts.
Summary
- Different energy types have different units and devices.
- Prepaid and postpaid meters record electricity.
- Measuring helps with planning and saving.
Class activity: Meter Reading
- Read a meter at home or school.
- Read it again after a week.
- Calculate the units used.
You need: Sample ECG electricity-meter photograph, Printed appliance wattage labels, Calculator
Exercises
Answer in your exercise book first, then check your answers.
1. Electricity is measured in…
- A. kilowatt-hours
- B. litres
- C. kilograms
- D. metres
Show answer
Answer: kilowatt-hoursUnit.2. Who sets tariffs in Ghana?
- A. PURC
- B. WAEC
- C. GES
- D. NCCE
Show answer
Answer: PURCRegulator.3. Prepaid meters are paid for in advance.
- A. True
- B. False
Show answer
Answer: TrueTerm.4. A million watts is a ______.
Show answer
Answer: megawattUnit.5. Find the units used if a meter goes from 2,100 to 2,250.
Show answer
Answer: 150 kWhSubtract.6. Why is meter tampering wrong?
Show answer
Answer: It is illegal, dangerous and passes costs to honest customers.Moral.
Lesson 2
- Strand
- Environment
- Sub-strand
- Environmental Issues
- Indicator
- B9.1.1.2.1 – Assess global sources and the means of conserving energy
Introduction
Saving energy is one of the simplest ways to help your family and your country.
1. Advantages
| Level | Advantage |
|---|---|
| household | lower bills, more money for food and school |
| business | lower costs, higher profits |
| nation | less fuel imported, less pressure on the grid |
| environment | less pollution, fewer forests cut |
| global | fewer greenhouse gases |
2. Conservation in Numbers
Saving with bulbs
A school replaces 100 bulbs of 60 W with bulbs of 10 W. They are used 5 hours a day for 20 days per month. How many kWh are saved in a month?
- Saving per bulb: 60 − 10 = 50 W = 0.05 kW.
- For 100 bulbs: 0.05 × 100 = 5 kW.
- Per month: 5 × 5 × 20.
Answer: 500 kWh a month
At GH₵2 per kWh, this saves about GH₵1,000 a month. A simple change can pay for itself within a short time, and the money can be spent on other needs.
3. Educating Others
| Method | Example |
|---|---|
| posters | "Switch off when you leave" |
| drama | a play about wasting electricity |
| radio | a talk on a local station |
| social media | short messages |
| demonstrations | showing how much a device uses |
| home visits | helping neighbours |
When you educate others, keep your messages short, clear and positive. Show people how they will benefit. "Save GH₵50 a month" may work better than "Stop wasting". Use local languages for your audience. Lead by example: people notice what you do more than what you say.
4. Barriers
Some people believe that saving energy will not make any difference. Others leave lights on in public buildings because they do not pay the bill. Efficient appliances may cost more at first. Campaigns must address such attitudes and costs. Governments can give incentives, such as lower duties on efficient appliances, and they can require public buildings to set an example.
5. Making It a Habit
Habits are built by repetition. Put reminders by light switches, and appoint class monitors. Check your progress and celebrate success. A school that saves energy for a term can use the money for books or computers. Small steps add up, and your generation can help to build a culture of care for energy.
New words
- campaign
- Organised action for a goal.
- incentive
- Something that encourages action.
- slogan
- A short, memorable phrase.
- habit
- A regular way of behaving.
Summary
- Conservation helps families, businesses and the nation.
- Short, positive messages educate others.
- Habits and incentives overcome barriers.
Class activity: Energy Awareness Week
- Plan an energy campaign.
- Create posters and a slogan.
- Carry it out at school.
You need: LED bulb, Switchable power strip, Printed energy-conservation action cards
Exercises
Answer in your exercise book first, then check your answers.
1. Saving energy lowers…
- A. bills
- B. marks
- C. prices of books
- D. rainfall
Show answer
Answer: billsBenefit.2. A short, memorable phrase is a…
- A. slogan
- B. tariff
- C. meter
- D. census
Show answer
Answer: sloganTerm.3. People notice what you do.
- A. True
- B. False
Show answer
Answer: TrueExample.4. Organised action for a goal is a ______.
Show answer
Answer: campaignTerm.5. State three advantages of conservation.
Show answer
Answer: Lower bills, less pollution and less pressure on the grid.Any three.6. Replacing 10 bulbs saves 0.05 kW each. How much is saved in 4 hours?
Show answer
Answer: 2 kWh0.5 kW × 4.
Homework
- Carry out a one-week energy saving plan at home.