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Using an air source heat pump (ASHP) to reduce your carbon footprint - guide

Using an air source heat pump (ASHP) to reduce your carbon footprint - guide

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No gardens, high-density, overshadowed properties, no room to put the required kit. And probably the biggest problem. most of the housing stock will be nowhere near the required minimum efficiency level.

Has anyone ever tried putting a heat pump system into a 2-up-2-down terrace house?

I call out the North as that is where I live but the Midlands and some areas in the South have the same issues. But the North also has the issue that temperatures and weather can be noticeably harsher. I assume that an air-sourced heat pump would be less efficient the colder the ambient temperature gets?

From the BBC GCSE revision guide:

 

Userlevel 7

A really important point raised about the suitability of using an air-source heat pump in some house types, @knight 

 

It’s certainly not a simple path to zero carbon heating - not sure if you’ve seen it already but there’s been an interesting discussion going on here about the implications of using hydrogen heating systems over here -

 

 

Userlevel 7
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I would suggest that the answers for the North of England are likely to be found in the Trial and Demonstration Projects already being undertaken elsewhere by Community Energy Groups.

Two energy strategies are worthwhile further investigation.

 

1: The first is Borehole Thermal Energy Storage, which is being Trialed by the Owen Square Community team in Easton (Bristol). This captures solar energy which is then stored below ground using a technique pioneered by ICAX.

Owen Square is a series of roads with terraced houses and little ground space. So its tactics are a fair analogue of the northern housing which @knight refers to.

 

2: The second is to use borehole-inserted Ground Source Heat Pumps (GSHP). These use heat collector tubes inserted vertically into the ground rather than spread horizontally.

GSHP technology has a higher efficiency than air-sourced, but suffers from the problem of pipes freezing if too much heat is extracted during a cold winter. The trick to this is to find locations where underground water-flows continuously past the collector-pipes, thereby replenishing the body of heat available to be harvested.

I don’t yet know if anyone has tried sinking a borehole GSHP system into abandoned and flooded mine workings. But if not, there’s probably grant-money available to try it @knight !

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Erm @knight - were you involved with the Festival of Debate, organised in May’21 by Community Energy England based in Sheffield?

As a couple of months has passed since that event, it would be worthwhile contacting the coordinator, Emma Bridge, because she’s on your doorstep! She will know if the event has triggered further community-based projects to undertake actual energy initiatives rather than discussions.

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Erm @knight - were you involved with the Festival of Debate, organised in May’21 by Community Energy England based in Sheffield?

As a couple of months has passed since that event, it would be worthwhile contacting the coordinator, Emma Bridge, because she’s on your doorstep! She will know if the event has triggered further community-based projects to undertake actual energy initiatives rather than discussions.

I wasn’t and I didn’t know about it. Thanks for the heads-up though. I may look to see if anything has happened. It would be great if it did.

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Our CEO, Adrian Letts, shares his thoughts on the Government’s plans to shift green surcharges from electricity bills onto gas bills:

 

I was pleased to see that the Government is planning to shift green surcharges from electricity bills onto gas bills in the FT this morning. 

Removing levies from low carbon electricity is necessary to help households make the switch from gas boilers to climate friendly electric heat pumps. We need to make clean heat the cheaper choice and show consumers that a zero carbon home is ultimately a more valuable home. 

The focus now must be on ensuring we effect this transition while protecting vulnerable consumers. 

You can find out more by reading Options to Reform Energy Bills - research we commissioned with Public First earlier this year. 

 

 

Is this a win for anyone who’s making / has already made the move to heat pumps @juliamc @nealmurphy @Bev @Heatherd …..? 

 

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Agreed - wasn’t there a slogan a while ago that ‘the polluter pays’ ?

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@Tim_OVO Thanks Tim, interesting. Lucky old us if this turns out to be the case, but I fear for the millions of households who cannot afford to change their technology. What on earth will happen to them? :( 

Userlevel 7
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@Tim_OVO Thanks for the info from the CEO.

Definitely a positive step forward.

There needs to be a clear rationale to explain to the public the reason for the change. And there needs to be support for low/middle income households (grants / low cost loans etc.)

If the policy is successful in moving people from gas to electricity and the policy costs stay the same then there will be a revenue gap in the future. It’s how this shortfall is addressed:

  • Could increase unit charge of gas further (won't be popular for those unable to transfer and will leave those last to make the switch paying very high prices)
  • Could switch costs back to electricity later (won't be popular unless this rationale is explained)
  • Could move costs to general taxation

There’s an analogy with shifting fuel duty when the switch from petrol/diesel to EVs happens. It’s all about the framing and the deemed fairness of the policy decisions.

Userlevel 7
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Adrian Letts wrote:

Removing levies from low carbon electricity is necessary to help households make the switch from gas boilers to climate friendly electric heat pumps.

We discussed this issue in the session with Simon Maine in August. See the bit about the carbon tax here for which I supplied this diagram:

 

Just a couple of months ago we were believing that the ‘Environmental and Social Obligation’ element would become a new Carbon Tax. Instead it seems the Government proposes shifting it onto gas.

Since then we’ve seen Insulate Britain emerge as an offshoot from XR and begin taking disruptive protest action.

Regardless of the nature of their protest, I have sympathy with their underlying grievance. Today’s news doesn’t alter this at all. If the mechanism of an ‘Environmental and Social Obligation’ didn’t resolve the poor insulation in our housing stock when it was levied on electricity, it will make no difference when moved to gas.

The vast majority of our housing is still not in a state where it could replace gas boilers with (electric-only) Heat pumps.

And we will still be building those houses for another 8 years anyway because they’ve been pre-registered to avoid the current Building Regulations requirements. :rage:

 

Userlevel 6
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Adrian Letts wrote:

Removing levies from low carbon electricity is necessary to help households make the switch from gas boilers to climate friendly electric heat pumps.

We discussed this issue in the session with Simon Maine in August. See the bit about the carbon tax here for which I supplied this diagram:

 

 

Has the diagram changed much with the increase in gas costs etc both for domestic gas usage and the impact of gas prices on electricity generation?

I wonder what the diagrams will look like this time next year. 

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Well I think we can assume that the yellow segments are a greater proportion of each ring!

VAT will rise proportionally of course because it’s a percentage.

The other three colours will have shrunk. Green & purple are ‘fixed’ in contracts with Ofgem.

I wonder how OVO views its Operating Costs in blue. I suspect they’ll want to retain their profit margin to a large extent in order to give them a substantial buffer against market fluctuations.

I think we also ought to consider where the extra money is going to. Unlike the USA we’ve become heavily reliant on purchasing energy from countries who aren’t friendly towards us. So we tend to suffer more when compared against global averages.

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Just wanted to pop back here to highlight this recent guide from our content team on Heat Pump costs and benefits.

 

Considering a Heat Pump in future? - We’d love to hear your thoughts on this introductory guide (which is a great compliment to @Transparent’s more detailed guide above!) :smiley:

Userlevel 6
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Just wanted to pop back here to highlight this recent guide from our content team on Heat Pump costs and benefits.

 

Considering a Heat Pump in future? - We’d love to hear your thoughts on this introductory guide (which is a great compliment to @Transparent’s more detailed guide above!) :smiley:

Looks useful

Would it be possible to include something on annual service costs in the ovo guide. I am sure all heat pumps will need an annual service to comply with the warranty? Is this more expensive than a gas boiler? 

Also would it be possible to include some examples of repair bill ranges for heat pumps, e.g. compressor failure, leaks, electrical controller failure etc. 

Just to give an idea of running costs. I have seen some eye watering examples but these may not be typical. 

Userlevel 7

Some great feedback this, @Jeffus - I’m gonna make sure we pass it on to the team as I agree, maintenance costs will be another important factor to consider.

 

Where have you seen these eye-watering running cost examples then?

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We've only had our Heat-Pump since April and so far so good. It's great not having to rely on fossil fuels to power our heating, although we can never be 100% sure our energy is coming from renewable energy. Recently we had solar panels fitted and we are now looking into having battery storage which seem very expensive, perhaps we should wait a while?

Userlevel 6
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I would question the assertion that only a house with an EPC rating of B or A should consider a heat pump. Our house is rated D (although I question some of the figures and reckon we're actually a C) and our heat pump is working fine.

 

The problem is that the EPC rating doesn't actually tell you how well insulated your house is, which is what matters when considering a heat pump. I could improve our EPC by installing solar PV, which would have no impact on how well a heat pump works. Ironically, I could also improve it by removing a gas boiler and installing a heat pump!

Userlevel 7
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The information I gave about a house requiring an EPC above 80 in order for it to be acceptable for a Heat pump has come during a 5-way conversation with engineers who designed and monitored the trials in Wales 4 years ago.

Unlike the BEIS/OVO Trial, the Welsh Government and the Housing Associations left the functional aspects of the Trial in the hands of some very senior engineers from the DNO and the GDN.

Not only did they constantly monitor and optimise the installed systems, but they created loads of very valuable data. This has been made available to be used as a starting point for future trials, but unfortunately not the one you’re on!

 

Remembering back to that part of our conversation about EPC, the point being made by the engineers referred only to the insulation part of the usual SAP survey/calculations.

In other words they used the accepted SAP scoring mechanism to assess the insulation properties of the houses, rather than just did a standard EPC, such as might be required when you sell a house.

So there would be no thoughts of bending the score by installing PV  Panels because that has no effect on r-values and thermal retention.

Userlevel 6
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While it's clearly correct to only assess insulation scores when deciding a property's suitability for a heat pump, EPCs as they exist now don't do that. I've always thought that they aren't fit for purpose because they are using a single score to measure multiple things.

Userlevel 7

Some interesting comments here about the effectiveness of the EPC ratings, particularly relevant as more people consider the energy efficiency of their homes prior to getting an Air Source Heat pump, @Transparent and @M.isterW.

 

Would love to hear your thought on all things EPC over here too :wink: :

 

 

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We’re switched to HVO biofuel from kerosene to run alongside our air source heat pump for our winter heating as a bivalent system. The ASHP works when it’s over 8C outside and the HVO takes over when the heat pump is at its least efficient: https://myhomefarm.co.uk/ho-ho-ho-for-hvo-will-it-be-a-warm-christmas

Userlevel 7
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An interesting plug for My Home Farm, @mrmhf ! :sunglasses:

So long as it’s for a non-commercial venture, I guess the Moderators will let it pass.

I’m unsurprised that you’ve effectively moved to a mixed-fuel system… especially in the old farmhouse you’re living in. What we still lack is a hybrid Heat pump where the secondary fuel doesn’t add CO2 to the atmosphere.

Two quick observations:

1: 8°C is quite a high temperature, below which you deem your ASHP too inefficient.

2: Whyever use an ASHP when you have sufficient land (and water) in which to lay Ground Source Heat Pump collector-coils? You’d achieve 25-30% greater heat output for the same amount of mains-power fed in.

Userlevel 6
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 @mrmhf , is the problem with your heat pump that it isn't able to generate enough heat in colder weather? Or does the efficiency drop to a point at which it makes economic sense to use an oil boiler?

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An interesting plug for My Home Farm, @mrmhf ! :sunglasses:

So long as it’s for a non-commercial venture, I guess the Moderators will let it pass.

I’m unsurprised that you’ve effectively moved to a mixed-fuel system… especially in the old farmhouse you’re living in. What we still lack is a hybrid Heat pump where the secondary fuel doesn’t add CO2 to the atmosphere.

Two quick observations:

1: 8°C is quite a high temperature, below which you deem your ASHP too inefficient.

2: Whyever use an ASHP when you have sufficient land (and water) in which to lay Ground Source Heat Pump collector-coils? You’d achieve 25-30% greater heat output for the same amount of mains-power fed in.

Good point about hybrid heat pumps. 20% of heat pumps in the Catapult trial that OVO are part of are hybrid heat pumps. I assume these are gas. 

It may be in the future that in some areas of the country green hydrogen could be used in hybrid heat pumps? 

I see some of the major house builders are running trials heavily insulated houses with infra red panels instead of heat pumps in new build houses. 

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 @mrmhf , is the problem with your heat pump that it isn't able to generate enough heat in colder weather? Or does the efficiency drop to a point at which it makes economic sense to use an oil boiler?

It's the efficiency drop coupled with the high electricity tariffs. Last year, with electricity at 11p/kWh it was fine. At 22p/kWh it’s become ridiculously expensive to run when compared to fuels like oil, for example.

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