Revise GCSE Physics

Question:What is meant by Pay-Back Time?

When some form of home insulation (or any energy saving device) is installed in a house, the cost of heating the home (paying for electricity or gas) is reduced once the insulation is installed.

The payback time is the length of time, in years, that it takes for the annual savings due to the same energy saving installation made in a home to equal the cost of that installation.

The most common mistake when students answer questions about payback time is that they mistakenly think it has something to do with paying off a debt or bill for the cost of the insulation.