A structure has no active heating when there is no specially generated or specially channeled energy source set up to provide warmth to its interior. This includes buildings with no heating system whatsoever, as well as buildings which use passive heating.

The absence concerns an active supply of heat. A building can still retain environmental heat through deliberate passive heating measures.

No heating has the narrower meaning of no special mechanism or technology for warmth. Both that case and deliberate passive heating belong to the absence of active heating.