Year 9 Science · Unit 3 · Lesson 23
Foundation Worksheet
Learning Goals
Order the steps: a school energy audit
Number the steps from 1 (first) to 6 (last).
1. Put the six steps of the audit in order.
| Order (1–6) | Step |
|---|---|
| Calculate each appliance’s energy use in kWh with E = P × t | |
| Write recommendations to cut the school’s energy use | |
| Walk through the school and list every appliance and system that uses energy | |
| Rank the appliances by yearly running cost to find the biggest users | |
| Find each appliance’s power rating and how many hours a day it runs | |
| Work out each appliance’s yearly running cost |
Fill the gap: the Energy Rating Label
Choose the correct word from the word bank. Each word is used once. Two words will not be used.
The Energy Rating Label shows a number of and the energy the appliance uses in per year. Each model is tested in a laboratory and compared with a for appliances of the same type and . More stars means the appliance is more for its size. To find the yearly running cost, multiply the kWh per year by the of each kWh of electricity.
Investigation: auditing the staffroom
A student audit team recorded three appliances in the staffroom. The school is open 200 days a year, and electricity costs 25 cents per kWh.
| Appliance | Power (kW) | Time on each school day (h) |
|---|---|---|
| Hot-water urn | 2.0 | 4 |
| Microwave oven | 1.2 | 0.5 |
| Lights (six 25 W tubes) | 0.15 | 9 |
Source: sample audit results.
2. Use E = P × t to find the energy each appliance uses in one school day.
Urn kWh
Microwave oven kWh
Lights kWh
3. Find the urn’s energy use for the whole school year, and its yearly running cost.
Urn yearly kWh
Urn cost dollars
Data: two televisions for the library
The library needs a new television. Table 2 shows the Energy Rating Labels of two models.
| Television | Star rating | Energy use (kWh per year) |
|---|---|---|
| A: 75-inch screen | 7 stars | 260 |
| B: 43-inch screen | 4 stars | 120 |
Source: sample labels for this worksheet.
4. Which television is cheaper to run, and by how much each year? Use the staffroom’s electricity price.
Cheaper by dollars
5. Television A has more stars but uses more electricity. Explain how both can be true.
Scenario: the school library
Your class must cut the library’s power bill. It has lights, computers, a printer, air conditioning and a drinks fridge.
6. Plan the library audit. Describe what you would list and measure, how you would calculate each appliance’s energy use and cost, and how you would decide which change to recommend first.