You may see something when the domestic RHI is introduced next year. The reasoning behind the EPC for PV is the old saying 'insulate before you generate'. Greater savings can be made through reducing enregy consumption in the first place. The difficulty is that EPCs are a bit of a blunt instrument and do not take in to account what is practical for any given property. In time alignment with the Green Deal assessment instead may be a way forward.
With regard to heat technologies, if they are being used for space heating, improving the thermal efficiency of a building first is a no brainer. Where they are being used for water heating, the case is a little different. The thermal efficiency of the building does not affect hot water usage. Hot water usage should be the same for a tent or a passivhaus of similar size and occupancy levels. It is hoped that DECC can be persuaded to concentrate on the efficiency of the hot water system itself by ensuring high levels of tank and pipe insulation, and properly regulated flow rates in showers. Time will tell.
