IanR

It's not really as simple as that. At current pricing electricity is around 3.5 or 4 times the kWh cost of Gas. Gas boilers are up to 90% efficient, so if you are going to use (renewable) electricity to heat your home, you need an electric heater that is 350% to 450% efficient (averaged throughout the year), for it to have the same day-to-day running costs. With a heat pump, it is possible to achieve and exceed this. If you don't have access to gas, then the comparison to electricity is much more favourable, as you have to spend much more on every kWh of energy you purchase in the form of oil or LPG A heat pump is more efficient with a low flow temp, so larger heat emitters (UFH and large rads) and a large water cylinder, allow flow temperatures to be reduced. The lower SAP score suggests a higher energy loss due lower levels of insulation and/or poorer air-tightness. This means that proportionally larger heat emitters would be required to achieve the same low flow temperature. For UFH that would mean closer spacing of the loops, or for radiators, even larger ones. Undoubtedly a heating system can be more easily designed for low flow temperatures with a house that has a better EPC score, but that doesn't mean they can't work in a house that doesn't. The capital cost is a different matter. If you are not already planning a renovation then the cost of changing heat emitters to UFH and/or large radiators to accommodate a heat pump has to be considered. And if you are planning a renovation, insulation and air-tightness should be high on your list, so however you are heating your home you need to buy less kWh of the energy required.

Yes, if you put an "@" in front of their name they'll get a notification that they've been mentioned. ie @Selfbuildsarah Assuming the the TF/SIPs Supplier worked in 3D CAD, ask them for the Exterior/outline models.

Hi and Welcome, Sketchup is the obvious option, as there is a free version. https://www.sketchup.com/plans-and-pricing#for-personal OnShape also has a free online version, but it's not quite so aligned to an Architectural work-flow (at least it wasn't the last time I used it 3 or 4 years ago), but good for Mechanical Design. https://www.onshape.com/en/products/free It will take 10's of hours (perhaps a 100) to get it modelled from scratch if you've no experience of any 3D modelling system. You could also contract someone to do it relatively cheaply at somewhere like People per hour: https://www.peopleperhour.com/services/architectural+rendering?ref=search How has your "Final Design" been created? is there a 3D (CAD) model available? It could save a lot of time if you have access to it.

If you are going the RHI route then I'm happy to recommend who I used, who are Eco East Anglia https://ecoeastanglia.co.uk/ If you are not going RHI route there may be cheaper options, but still worth checking with them on price.

RHI definitely puts a premium on the prices. Some of it is justified due to the MSC process requiring additional steps from the installers, some of it not. I can only see the grant going one way, so assume what replaces RHI will not be as "generous". The government will tackle new builds first and can do that mostly with stick (legislation) rather than carrot. For the existing housing stock - rentals and social housing will be first and again they can do this mostly with legislation. It's only when they get to owner-occupied that the encouragement of grants will be required and by then perhaps prices will have dropped a little for heat pumps and increased a little for fossil fuels, so the gap is much reduced that the grant needs to cover.

They must offer different prices across the county. Here's my current deal with PFP, it is variable, and they're offering a 12 month fixed for a few tenths more. I'm thinking it's probably wise to take the fixed deal.

There is the start of a plan, with the high level investment identified https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/945899/201216_BEIS_EWP_Command_Paper_Accessible.pdf And give them their dues, they're already delivering on the actions stated as required for 2021.

You'd be better off going by how much LPG the previous owner purchased per year, or paying for someone to do some detailed heat loss calcs. My experience of the EPC's created for house sales are they are a tick box exercise with lots of assumptions, so *could* be wildly out. You should be able to get far cheaper. That gets you to a level where the losses won't be too high on the UFH, and if you've already "booked" this cost, I feel the pendulum has swung in favour of going with an ASHP. The job now is to reduce heat losses to permit a smaller ASHP and reduce the install cost further, and that looks like it is already in your plans. Edited to add: You need your new ASHP heating system commissioned by 31.03.2022 as RHI is finishing. It does sound like there will be something to replace it, but no details yet.

I've just moved from Symbio to PFP Energy, both are charging 12.5p / kWh. Symbio are terrible though, hence my move. Have you got a link? the devil's in the detail. Currently announced was that new builds would be net-zero-carbon from 2025. There hadn't been an announcement (to my knowledge) on how they were going to encourage existing housing stock to more away from fossil fuels, only that EPC requirements were going to be ramped-up from 2028 - 2035.

EPC's aren't necessarily all that accurate, is that 34,500 kWh space heating demand confirmed by how much LPG you purchase in a year? LPG boilers are up to 90% efficient, so that would be around 38,500 kWh worth of LPG annually, plus what ever your DHW demand is. Unless you also have alternative heat sources, such as log burners, and then it will be difficult to calculate. Where did you get this figure from? and what does it include? Unvented cylinder, buffer, larger radiators and/or wet UFH? Hopefully that figure includes everything you need. Is that the cap now? Even with low flow temp (35°C) heating emitters? What ever heating system you go with, insulate as well as possible and make the property as airtight as possible. Ideally you'd plan for a low flow temp heating system, so if you don't go for an ASHP now, you won't be ripping it all out if you need to in 10 - 15 years. Low flow temp heating systems require ideally UFH with "good" insulation underneath and/or larger radiators plus a hot water cylinder. This I don't necessarily agree with this. I've never had LPG, but it looks like it's around 6.5p per kWh (45p/litre and 7kWh per litre). At 90% efficiency, that costing 7.2p/kWh With electricity at 12.5p/kWh, you've only got to get a COP of 2 and an ASHP is cheaper to run. You'll be far better than a COP of 2, you could probably get to a COP of between 3.5 to 4 for an average throughout the year. The lower you can get the flow temp, the more efficient the ASHP will be. Large heat emitters and large hot water cylinder means lower flow temp. How much insulation can you get under your floor? Are you considering wet UFH? Are you planning any significant renovation, or are you trying to improve insulation with minimum disruption?

Are you bring the cable up in a trench, or over-head? Ours was in 125mm ducting, in a trench, dug by us, so I got them to create a non-serviceable, underground joint to the domestic supply cable. The joint is underground with nothing that marks its position. I couldn't convince them to bring the "public" supply cable all the way to my kiosk.

The DNO would only bring their cable to a point 25m from the meter position on the property, joining to a domestic supply cable at a position that was in a field, so we made that connection underground and brought that to a self-built kiosk on the edge of the curtilage. The kiosk serves multiple roles, with the mains water stop-cock and splitter to house and out-buildings there and also a relay point to get the PoE and data cabling to the Entrance within 100m.

The cooling has no effect on the efficiency of the ASHP. Cooling wasn't initially allowed with RHI, but is now. It changed in 2017 I believe. Ref. https://www.ofgem.gov.uk/environmental-and-social-schemes/domestic-renewable-heat-incentive-domestic-rhi/applicants/eligible-heating-systems Yes, cooling is effective, but since mine is via the slab, is slow to react, ie. it will take 2-3 hours to lower the slab temp before the cooling effect is felt. I also have cooling available via MVHR, from the same buffer that supplies the UFH, but as I don't cool the buffer below 12°C, it's not that effective via MVHR. No effect on RHI - COP on ASHP and low flow temp is unchanged, so max RHI allowed on the Nibe I have (F2040-12)

Looks expensive to me. I paid £11K excl. in 2017 for a 12kW Nibe + Cooling module, with a 500l Nibe UVC, 200l buffer, Modbus module and controller, installed. Nibe seemed more expensive than most, but offered the cooling module, which few others did at the time.

In planning terms, Amenity land is an area of land that has a residential use, ie. can be used for the enjoyment of the attached dwelling, but can't be considered Residential Curtilage, so you can't have permanent domestic structures on it such as sheds, bike store, bin store, washing line etc. and doesn't count towards PD for outbuildings where you can cover 50% of the original curtilage. To the best of my knowledge it requires no boundary separating it from the residential curtilage , so does not require fencing off. I certainly know of a few that are just extensions to the garden. I see it often used in rural areas where the planners have allowed a change of use, but wish to keep the residential paraphernalia close to the building and not spread out into what was previously agricultural land. Start off small, and see if anyone complains.

Today we don't, but there are the green shoots of a plan. Carbon capture still requires development to scale up, but is in the plan to allow continued use of Gas for flexibility in electricity generation. There's also a plan for long term electricity storage, to help with peaks and reduce the amount of Gas power stations required. Ref. https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/945899/201216_BEIS_EWP_Command_Paper_Accessible.pdf The above linked document is a long read, but a good overview of the Governments thinking with future predictions.

I don't believe that is the argument, one size clearly does not fit all, so there will continue to be a mix of technologies that provide heat to our homes and in a wider context to industrial and commercial buildings and powering transport etc. But, that mix is going to change. The only technology available today that could be up-scaled to provide the majority of net-zero-carbon heat for homes at anything like a similar price to that currently paid is electricity. The plans currently in place are therefore to generate more renewable electricity as a proportion of the total electricity produced, generate more electricity in total to allow a shift away from fossil fuels, and prepare the housing stock to be heated by non-fossil fuel sources. There will be a proportion of homes and buildings that for one reason or another can not viably be heated by electricity, and the other options you mention will fulfil that need. Since this is a long term shift, new technologies may be developed that can be up-scaled sufficiently to be included in the mix. Green hydrogen is an obvious example, and has the benefit of being able to be supplied within most of the the existing domestic natural gas infrastructure (although not the gas grid side, which would require upgrading) - it's just that currently it's a very inefficient user of electricity and a step change is required in the electrolysis process to make it scalable for heating homes. It doesn't take a heat pump evangelist to then appreciate that they offer a relatively efficient method for using electricity to provide the heat in our homes, so cannot be dismissed as a "niche", "failed" or "snake oil" technology.

The 2025 date is for new builds, and requires them to have a zero carbon heating system. For the existing housing stock the only plan currently announced is 2028: EPC C or above for all rental, social and houses sold; 2035: EPC C or above for all housing. There's been no suggestion yet on how the transition to non-fossil fuel heating systems will be encouraged, or forced for existing housing, but it is the stated aim.

No.

Welcome Martin. Garden rooms seem to be a hot topic currently, no doubt spurred on by lots of people needing work-from-home space. I also work in automotive engineering, what part of the country are you from?

Yes, if you don't plan a significant renovation, then your situation is different to the OP, so you would need to include replacement heat emitters and additional plumbing into the ASHP costs, which probably means Gas is the more cost effective solution today. Although I'd still run the figures through RHI, just in case it closed the gap. As an average COP, across the whole year, that would not be a a good assumption. If you were renovating, and designing for a low temp heating system, exceeding 4 would be achievable.

The OP isn't building flats...

RHI paid out considerably more for me, but even at £3,290 would cover the difference on a new build. Cost of Electricity v. Gas is in parity today, but Gas will soon be loaded with the green tax that will be coming off of Electricity, and then I expect additional carbon taxes to be added to Gas to make it less competitive. There is no compelling reason to install a Gas boiler in a new build, let alone Oil or LPG

Apart from future proofing your home at no additional cost (with the help of RHI), rather than using a technology with a shelf-life.

We need a "disagree" emoji to save time replying to such rubbish. Which would be less than a third of the kWh of Gas/Oil required to heat the same property. Same price as Gas, cheaper than Oil or LPG.