This is an artificial artefact of the EPC assessment that is imposed on the process of getting the Renewable Heat Incentive and other aspects of grant funding. It is a ridiculous situation that will and does (I’m sure) put people off. The real energy consumption will more than likely be a fraction of the EPC rated energy consumption. Exactly how much your real space heating consumption is likely to be is impossible for me to say, but maybe someone within the CarbonCoop people powered retrofit team can help. Again it boils down to having realistic heat loss calcs, but in this instance the methodology of the quoted “fuel bill” element is just plain wrong for most households and is best ignored.
I have attached an extract from our quote with the EPC Running Costs. As you will see the EPC estimates are typically 3x the likely electricity consumption and ~2.3x higher than our likely bills (if you ignore our PV and 3.6x worse if you factor in our PV).
Oh it is also worth me pointing out that the SCOP is “inverted” so should read 1.42 (ie 1/0.704, so the 0.704 is a “mistake”). Even this is hugely pessimistic; you can generally expect SCOP around ~2.5 to 3.5 and so far our ASHP is providing an SCOP ~3.3. This better SCOP (than in the EPC assessment) will further reduce electricity consumption and hence also running costs. In the end our ASHP may well end up costing us ~£450/year in running costs (ie lower still than the estimates I have posted on the annotated screenshot). I will report our actual running costs on here as the occur, but it will take until April 2022 until I have a full year of bills to quote.
It’s great you’re sharing this information Dom @zapaman .
Which heat pump model do you have Dom?
When you procured it ,what credentials did you check out for the pump and choosing the installer?
I know having a high COP is the thing to look out for.
And MCS register model for eligibility of Renewable Heat Incentives
As well as an MCS registered installer.
I’m keen to understand how they will look at our energy usage too.
I noticed on the MCS registration site their list of installers seem to have different credentials from various bodies. NEICIS and NAPIT etc More research needed here for us
Re mis information
You are right about how off putting these inaccurate EPCs, bill / usage forecasts are - especially as the grant is being aimed at low income households like ours.
It will definitely affect uptake.
We have just had a retrofit survey with PPR - it didn’t factor in a heat pump - but I think it does factor in the heat loss. I’m keen to know how this is worked out now and how accurate it’s likely to be if it was worked out from our EPC.
There is a feeling that the uptake of the grant for greening our homes is failing when considering all the misinformation putting the most likely users off.
Ourselves, we’re more determined to make the grant work and hope it will work better with feedback like ours and the much needed guidance from the likes of Carbon Coop. It’s good that they are on the taskforce at least.
We have a NIBE F2040-6 air-source heat pump. This is rated at 6kW and has an official sCOP ~3.5.
In terms of checking credentials: for my installer I chose a company who had done some previous work for us (Ecopartners) and yes I researched a fair bit what makes / models of ASHP would suit our house (heat loss and hot water use).
What did you use to work out your heat loss, heat and hot water usage Dom?
This technical stuff is new to me, but I feel I need to get onboard in understanding it now!!
“What did you use to work out your heat loss, heat and hot water usage Dom?”
Oh this is a long(ish) story. I would separate out energy monitoring from energy modelling.
Starting with energy monitoring I have been tracking our utility bills for 20+yrs and also recording meter readings both by hand initially and now by smart metering.
Then I have done various heat loss calculators including most particularly the CarbonCoop calculator.
I describe some of that in this video. Gervase Mangwana also does a very good job of describing the heat loss assessment process. Also John Cantor does an excellent introduction to heat pumps.
I went to visit a low carbon social housing scheme yesterday (semi detached 2/3/4 bed homes). They’re being built to Passive House Low Energy Building standards. No gas, heating provided by 2 electric panel heaters (in 2 bed house), ASHP for hot water and MVHR.
The hot water tank and what looked like a condenser(?) above it was in a cupboard in the middle of the ground floor (not next to an external wall). The MVHR kit was in a similar sized cupboard upstairs. When I asked to see the ASHP unit itself, I was eventually told that it was in the loft. There were 2 pairs of what looked like 2 air vents on the gable wall, and I got the impression that one pair was for the MVHR and the other for the ASHP. Is that usual?
I looked seriously into an exhaust air heat pump taking air from my MVHR’s output. On the surface it seems to make sense. There must be more heat in the exhaust than in the atmosphere unless the heat exchanger is 100 efficient. The problem is that the airflow rate for the heat pump is far greater than the balanced MVHR could deliver, so two independent systems are installed, each with their own inlet and outlet vents.
It does also mean that if one system fails the other can continue to operate.
I didn’t even think about the ASHP and MVHR being connected in any way Tim. Maybe they are? It’s just that I thought ASHPs were big white boxes fixed to the wall, I’ve never heard of them being sited within the building before!
There are various monoblock ASHP available. They are often used for properties without a ground floor or where the noise of the system would exceed permissible limits.
Yes as Tim says these (exhaust air hot water ASHP systems) are becoming increasingly common especially in apartment schemes where developers try to avoid gas heating altogether. What Tim says about the airflow associated with MVHR and the exhaust air ASHP systems also makes sense.
There are also 1 or 2 such systems which can handle space heating as well; but only typically suited to small properties although could potentially also work with PH where heat loss is very low. Small Home and Apartment Heat Pump | Ground Sun
Heat pumps seem to be quite versatile. Just the fact they can be installed into your radiator system impressed me when I first enquired via the Green Grant.
As an aside - do any of you know of any heat pump engineers who would service a Misubishi Ecodan ASHP in the South Manchester Area - a person on the Freecycle community made a random enquiry.
Thanks all for the info. I was just on a visit to see what Housing Associations are building for their tenants, and how they arrived at decisions on the heating/hot water systems. Noone who was there on the day seemed to really understand how it all worked, and it looked ‘different’ from what I’ve seen elsewhere.
Peak daily cost would be interesting. Cop X demand X electrical price on variable tariff. Have you seen ways this has been presented well? I’ve been meaning to look into it.
I’m not sure what you mean by “peak daily cost” or why that might be a useful measure.
I will provide a full annual running cost breakdown when we have clocked up a full 12months with our ASHP, ie in about 4 weeks from now.
Here is a somewhat delayed reply containing a full break-down of our household electricity & gas use for the 12months before and 12months after we had our ASHP installed. As you will observe in very simple terms it effectively is a pretty much break-even result (actually saving 10p but hey).
NB these costs do not include revenue from PV exported (on a deemed export tariff) or revenue from the Renewable Heat Incentive which we also receive.
Oh and more importantly the ASHP has resulted in a 64.5% reduction in the carbon emissions associated with our heating and hot water relative to the 12months prior having the heat pump installed. Total CO2 emissions for heating + DHW before ASHP = 1520kgCO2e, with ASHP = 540kgCOe. Also assuming the electricity grid continues to decarbonise (more renewables) then this figure with the ASHP will continue to decrease year on year.
Thanks for this Dom. Very interesting. Your low bills and emissions are terrific and most enviable from the perspective of a leaky 1950s as-yet-not-retrofitted house. In your third line, ‘House’ means ‘Non-heating use by household equipment’ I presume (all contributing 100% to heat in the house no doubt, albeit often in warm weather when none is needed). Was there a reason for not correcting your 777 kWh of ‘before ASHP’ resistive electrical heat?
Hi @Paul_Hadfield.
Yes, “House” here means general household appliances (including electric oven, TV, computers etc) and yes, the majority of the waste heat from these devices will be indirectly heating the house, ie providing passive thermal gains.
A lot of the “resistive heat” is for heating hot water so has been excluded from the degree.day correction. Either way (correcting it or not correcting) it would not make much difference to the results.
