Independent learnersCompare and estimateExample · 4 steps · 8 min

Find the Hidden Energy Cost

Four short steps with kettle, lamp and router: work out kWh, find the biggest consumer, test a change and price a swap in euros.

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Your example

Three devices in one home

Device	Power	Use per day
Kettle	2,000 W	6 min
Floor lamp	100 W	5 h
Router	20 W	12 h

Kettle: 2,000 W for 6 minutes a day. Floor lamp: 100 W for 5 hours. Router: 20 W for 12 hours.

Step 1 of 4

How many kWh does the kettle use per day?

12 kWh0.2 kWh2 kWh

Show a hint

Turn watts into kilowatts and minutes into hours first.

About this activity

What you practise: You multiplied power by time, kept the units straight and checked a decision in kWh and euros instead of trusting the biggest number.

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How many kWh does the kettle use per day? Kettle: 2,000 W for 6 minutes a day. Floor lamp: 100 W for 5 hours. Router: 20 W for 12 hours. 2,000 W is 2 kW, and 6 minutes is 0.1 h. 2 kW × 0.1 h = 0.2 kWh.