The A-G scale is designed to be easy to use and is very similar to that used for electrical goods and cars. It quickly allows people to judge the relative energy costs associated with properties. To quote the EPC:
"A building with a rating of 100 would cost almost nothing to heat and light and would cause almost no carbon emissions. The potential ratings ... describe how close this building could get to 100 if all the cost effective recommended improvements were implemented."
So for a home to reach the top of the scale it would need to be heavily insulated and use its own sources of renewable energy for heating and electricity. By 2016 all new buildings constructed in England and Wales will need to be zero carbon, achieving 100.
Answer these questions about EPCs: