For decades, judging a home’s energy performance meant asking one question: how much does it use? Labels such as energy performance certificates still ask only that.
But homes are changing. Add solar panels, a battery or an electric car, and a house starts to generate, store and sell electricity. Meanwhile, what that electricity costs depends more and more on the clock. Since June 2026, Ireland’s largest suppliers have had to offer tariffs that change every half hour. In the UK, households pay about 26p for each unit they buy, but solar owners can be paid as little as a few pence for each unit they sell.
