Legal
Where each figure on a postcode page comes from, how we count it, and what it can't tell you.
A postcode page shows facts about the homes at one postcode, worked out from official records. Each figure is about the postcode's homes together - never a value for one home, and never advice about one. This page says how each figure is worked out, so you can check it against its source.
We read every energy certificate on the Energy Performance of Buildings Register, the government's public list of energy certificates for homes in England and Wales. We treat certificates for the same address as one home, and count each home once, by its newest certificate that gives a band. A postcode shows its energy ratings only where 5 homes or more are certified. Some owners keep their certificate off the public list, and a home that has never been sold or let since certificates began may have none, so fewer homes can be certified than there are at the postcode.
For each certified home rated below C, we add up the rough costs the assessor gave for the steps they suggest, in the order they listed them, up to the first step that takes the home to C. A home whose steps never reach C, or where a step on the way has no cost, is left out. The figure on the page is the middle of those homes' costs - half of them cost less, half cost more - taken for the low end and the high end of the assessors' estimates. These are rough costs from when each certificate was made, not a quote.
We rebuild every postcode's figures once a month from the latest records. A certificate lodged since then shows at the next update.
If a figure looks wrong, email hi@owlsby.com with the postcode. We check it against its source and put our record right.
Owlsby answers for these figures. The company's registered details are on our Company information page. Nobody can pay to change what we show.