EPC rated air pump as "poor"

Jemma01

Hi

I'm looking at putting an offer on a house, I don't know much about heat pumps, so naturally nervous about it. I checked the EPC for rough estimate on how much it costs to run the property per year, it says 1.4k. The rating it gave the heat pump is poor, so is water heating. Any thoughts? I don't understand any of this 😩  

Thanks

sammyjammy

Heat pump is in with electric under floor heating, its that thats probably causing the poor rating - very expensive to run in general.

matelodave

Its a stupid quirk of the EPC rules which base the rating on the thermal energy required to heat the house rather than the actual energy input to the house, against the costs. As electricity costs around 4-5 times more than gas per kwh then it skews the EPC in favour of gas and penalises houses using electric heating and hot water without taking into account how the heat is derived from the fuel input.

 There's been a lot of mumbling over the years to try and sort it out but I don't know whether it ever got resolved. Hopefully someone with a heatpump and recent EPC could 

Dunno how the EPC works nowadays as it's over ten years since we had one done but we got the same daft result that you have noticed, but put simply, my EPC is based on the amount of energy the house needs to heat it in kwh times the cost, rather than the actual energy input the house requires. Even with fairly decent insulation, underfloor heating, and double glazing having a heatpump only gets us an D rating with "poor" for heating and hot water. (it is, however better than the F it had with storage heaters)

eg if the house needs 12,000kwh then based on gas at say 5p/kwh then the cost would be £600 but based on leccy at say 20p/kwh then the cost would be £2400 .

It doesn't take into account the COP of the heat source which in our case is about 3, meaning that we get 12,000kwh of heat out of 4000kwh of leccy costing 4000x20p = £800

Others may have better info on how their EPCs have fared since heatpumps have become more widespread. 

Here is a Which? article from 2022 that explains it - https://www.which.co.uk/news/article/why-epcs-arent-ready-for-low-carbon-heating-aA1Es0m1LUX7

Jemma01

sammyjammy said:

Heat pump is in with electric under floor heating, its that thats probably causing the poor rating - very expensive to run in general.

That's one thing I'm worried about. The maintenance cost. Never had underfloor heating, so I don't know how often it fails, how often I need to replace anything or service anything 😔. The house is 2009 build, not too old, and it was built with the air pump. It's epc rating overall is C at 71.

Jemma01

matelodave said:

Its a stupid quirk of the EPC rules which base the rating on the thermal energy required to heat the house rather than the actual energy input to the house, against the costs. As electricity costs around 4-5 times more than gas per kwh then it skews the EPC in favour of gas and penalises houses using electric heating and hot water without taking into account how the heat is derived from the fuel input.

 There's been a lot of mumbling over the years to try and sort it out but I don't know whether it ever got resolved. Hopefully someone with a heatpump and recent EPC could 

Dunno how the EPC works nowadays as it's over ten years since we had one done but we got the same daft result that you have noticed, but put simply, my EPC is based on the amount of energy the house needs to heat it in kwh times the cost, rather than the actual energy input the house requires. Even with fairly decent insulation, underfloor heating, and double glazing having a heatpump only gets us an D rating with "poor" for heating and hot water. (it is, however better than the F it had with storage heaters)

eg if the house needs 12,000kwh then based on gas at say 5p/kwh then the cost would be £600 but based on leccy at say 20p/kwh then the cost would be £2400 .

It doesn't take into account the COP of the heat source which in our case is about 3, meaning that we get 12,000kwh of heat out of 4000kwh of leccy costing 4000x20p = £800

Others may have better info on how their EPCs have fared since heatpumps have become more widespread. 

Here is a Which? article from 2022 that explains it - https://www.which.co.uk/news/article/why-epcs-arent-ready-for-low-carbon-heating-aA1Es0m1LUX7

Thank you so much

The EPC is recent, 2 April 2024. Guess they haven't moved anywhere with this 😭

Are you content with yours? If you had a choice for a brand new installation, would you keep it over a gas boiler?

What detailed questions should I be asking the seller to help me form an opinion? How do I determine if it is efficient or not, and whether or not it heats up the water well and warms up the rooms?

Sorry too many questions, woke up at 6am today researching this, but without background in electricity costs and kWhs and these things that I'm clueless about, I feel like I'm not progressing 😭

Netexporter

Potentially a heat pump with underfloor heating can be extremely efficient in energy use. However, the system needs to have been designed correctly to achieve a good SCOP (seasonal coefficient of performance). A well designed system, with a SCOP of around 5 will be cheaper to run than a gas boiler.

If you are otherwise keen on the house I'd suggest employing an expert to look at the system and see if it is, or can be made, to perform acceptably.

Have a look at this video of a newish development of houses where the systems have not been correctly specified.

https://www.youtube.com/watch?v=r70Pt6roE0o

It may be a bit technical but it will give you an idea of the sort of questions to ask and the sort of people who can help you out.

Reed_Richards

They were saying that this widely acknowledged failing of the EPC rating system was being reviewed two years ago.  I thought something had come of this but apparently not.  How ridiculous!  

cannugec5

We have an ASHP installed 2023 and an EPC immediately afterwards. 

We have a star rating (Scotland) and we were given 4 out of a possible 5 for our heating, with 3 for hot water. 

I find it odd that a comment was that we “should” install TRVs and have zoned thermostatic control. We have both, but clearly the assessor did not notice! 

Netexporter

I find it odd that a comment was that we “should” install TRVs and have zoned thermostatic control. We have both, but clearly the assessor did not notice! 

The current wisdom is that you shouldn't have zones or any other obstructions. Best SCOPs are achieved by having  correctly sized emitters but relying on weather compensation to regulate the flow temperature.

Reed_Richards

Netexporter said:

I find it odd that a comment was that we “should” install TRVs and have zoned thermostatic control. We have both, but clearly the assessor did not notice! 

The current wisdom is that you shouldn't have zones or any other obstructions. Best SCOPs are achieved by having  correctly sized emitters but relying on weather compensation to regulate the flow temperature.

That's the current wisdom for the most economical operation of a heat pump; it's not necessarily what gives you the most comfort.  I don't believe any installer will have enough time to properly balance a set of radiators to match each room to the temperature you want it to be so TRVs are a quick fix.  They are mandated because before people had them, rooms tended to get overheated, wasting money and energy.  Anyway, TRVs shut off gradually so if you are trying to achieve a constant temperature 24/7 then it doesn't make much odds whether you have these or just carefully throttled valves.

Jemma01

Netexporter said:

Potentially a heat pump with underfloor heating can be extremely efficient in energy use. However, the system needs to have been designed correctly to achieve a good SCOP (seasonal coefficient of performance). A well designed system, with a SCOP of around 5 will be cheaper to run than a gas boiler.

If you are otherwise keen on the house I'd suggest employing an expert to look at the system and see if it is, or can be made, to perform acceptably.

Have a look at this video of a newish development of houses where the systems have not been correctly specified.

https://www.youtube.com/watch?v=r70Pt6roE0o

It may be a bit technical but it will give you an idea of the sort of questions to ask and the sort of people who can help you out.

I def will get someone to check before I buy the house, I couldn't walk into a very expensive home without understanding what I'm paying for. Thanks a lot.