In order to reduce CO2 emissions in line with UK policy, existing UK homes need to be retrofitted to high thermal standards. A large proportion of these homes have traditional or aesthetically pleasing features which people are reluctant to compromise for the sake of thermal efficiency. A minority of such dwellings are protected by statute, but millions are not. There is a dearth of structured discussion on the issues owners of such homes face when planning thermal retrofits. This study begins with a literature review of sustainable development, heritage and aesthetics. It then reports the results of qualitative interviews with retrofitting owners of such homes in Cambridge, UK. It finds homeowners struggling to balance thermal issues against a range of heritage and aesthetic concerns which often overlap or clash. Homeowners develop their own logic in working these through, and their aesthetic convictions strongly influence what happens with retrofitting. The interviews suggest that concern for the heritage embodied in the housing stock can be one reason current policy does not always engage homeowners in retrofitting.