More and more people are using heat pumps to stay warm.
The latest figures from the Federal Statistics office show their use has climbed five-fold since the year 2000.
The vast majority of buildings built in the last 10 years use a heat pump – but also homeowners have been installing them, especially in detached houses.
Despite the improving popularity, still two thirds of homes use fossil fuel for heating – either oil or gas - 18% have a heat pump.