Realdania Byg has studied the limits to energy preservation measures set by the historical settings of a specific, listed 18th C property in Copenhagen, Denmark. The findings of that study are currently being carried out in practice. In collaboration with the Danish Heritage Authorities Realdania Byg organized a series of workshops where all possible technical solutions were discussed. In the end a combination of simple, low-tech solutions and some high-tech consumption control systems were chosen. Altogether, the measures taken will reduce the CO2-emission of the property by about 20%. Most of these measures are economically realistic and can thus be replicated by others. The project has been selected as a case study in 3ENCULT, a EU 7th Framework Programme entitled “Efficient Energy for EU Cultural Heritage”.