Are current EPC ratings failing Heat Pumps?

Chris Flaherty – Plumbing and Heating Specialist and owner of Vietec Heating Ltd – questions whether EPC ratings are giving an accurate view of the efficiency of heat pump installs.

This article is NOT criticising heat pumps, but the EPC system for energy ratings.

I completed a flat refurbishment in December 2023, where the whole flat was upgraded, with a new and improved layout, all external solid walls had IWI added, the loft had large amounts of insulation added, under the floor was insulated, all new double glazing, new plumbing including new bathroom, and new kitchen etc.

For the new heating system, I advised the client to consider an Air Source Heat Pump (ASHP) and underfloor heating (UFH), and the client was happy to take my advice.

I installed a Vaillant aroTHERM plus with a Joule Heat Pump cylinder. I had the UFH system designed by the manufacturer based on the calculated heat loss for each room, for the system control I opted to stick with Vaillant controls, using the sensoCOMFORT and weather compensation control.

As this is a relatively small flat all on one level I did not use a buffer, so the only pump is the one in the aroTHERM ASHP. I did not feel micromanaging each individual room with temperature control would be of any benefit been a flat, so just used the Comfort control for full weather-compensated control of the entire property.

All pipes internally and externally have been well insulated, the system was up and running and heating the flat nicely, flow temperature was set to a maximum of 45 degrees C.

19mm wall External pipe insulation
13mm wall internal insulation

So the property requires an EPC, this is for me where the problem lies with persuading people to switch to heat pumps.

On the EPC for this job, the walls, windows, roof all have ‘Good’ to ‘Very Good’ ratings. What did the ASHP and UFH get? ‘Average’. And the hot water was given ‘Poor’, and the weather compensated control was given ‘Average’.

Mainly I think because I put it down as a programmable room stat and not a weather-compensated control. I would like to know what system apart from an ASHP and UFH should I have installed to get a ‘Good’ or ‘Very Good’ rating for the heating system, it makes no sense.

Is anyone else paying attention to the EPC ratings of their systems? I most likely would have achieved a similar rating had I opted for a gas combi boiler and radiators. How are these EPC ratings supposed to encourage the uptake of heat pumps?

In my opinion, the EPC system needs updating and will do damage to the heat pump industry, and it would be great to hear what other engineers think.