What counts as energy-efficient renovation?

To count as energy-efficient renovation, thermal renovation measures should be of such high quality that heat loss from the building is reduced by up to 90 percent.

Heat loss from the building consists of: transmission heat loss through the building envelope (heat conduction through building components) and ventilation heat loss (heat convection through openings and leaks in the building envelope).

What is the building envelope?

The building envelope consists of all building components which surround the (used and heated) interior. These are: external walls, roof or top-floor ceiling, and floor slab or basement ceiling.