> UK housing has really high insulation requirements for new builds. Your body heat will keep it warm most of the year. They are starting to require retrofit

> UK housing has really high insulation requirements for new builds. Your body heat will keep it warm most of the year. They are starting to require retrofits for old buildings too. UK housing is mostly quite old - an average age of 50 years or so. Modern insulation requirements only became law in the last 20 years. Most houses aren't particularly well insulated - and most houses haven't had much retrofit work done. The UK is really far behind most of Northern Europe in this regard. I think the rest of your reasons are valid. Average floor area is probably half that of a US house. Domestic air conditioning is almost unheard of. Almost everyone heats with natural gas. Heating is a huge part of energy demand - around 25% of UK total energy goes into space heating - so if you're not doing that via electricity then average energy consumption per house will be much lower.