Spreadsheetman

Planning? Some of the recent monobloc systems are over the 0.6m3 allowed under permitted development, so add extra hurdles to the process.

As I understand it the EPC (with all its faults) is meant to reflect total energy consumption, of which lighting is certainly a part. The house I am buying was marked down on its EPC (done 9 years ago) due to the large number of 50w halogen downlighters - now it will all be LED, so a big power saving.

Hi GLPinxit, size of the install is a tricky one. A lot of the pics of ASHP installs on the web look like they are in a boiler room of a ship rather than in a normal domestic house with limited space. I'm in a similar situation to you, although my house purchase hasn't completed yet and my house to-be is only 145m2 built in 2001/2 (epc is a high D). Practically speaking, there is room for an exterior unit up to the permitted development 0.6m3 volume, the space where the floor-mounting oil boiler currently lives (about the size of a washing machine) and a compact airing cupboard where an unvented HW cyclinder lives. Any HP solution has to fit in that space and work with radiators (albeit larger if necessary). I plan to live with the oil system for a winter while I do as much insulation as practical (loft, improved windows and doors, draftproofing) and work out the heat losses for all the rooms. At that point I'll have hopefully learnt enough and have enough data to be able to sense-check anything that HP installers say. Maybe in a year's time they will have also fixed the EPC criteria which currently scores heat pumps like conventional inefficient electrical heating and could actually result in a worse rating after a more efficient system is installed.