IanR

There's just the BUS (Boiler Upgrade Scheme) starting in April to replace RHI for Heat Pumps, that provides the £5K grant for Air Source and £6K for Ground Source.

Green Hydrogen, certainly has a place in the future net zero world, my comments relate only to heating homes. There are 70 millions tons of annual, legacy, hydrogen production that need to be replaced, eventually, by green hydrogen. However, due to the costs of green hydrogen and the unwillingness of the hydrogen production industry to start the transition without government incentives, almost no progress has been made on that transition. While some of the legacy hydrogen uses should slowly reduce, if we ever reduce the amount of oil we refine, there are plenty of additional, hard to electrify, industrial and heavy transport sectors whose only option will be to move to green hydrogen and will further increase the the need for green hydrogen. There is no getting away from the fact that as it takes 1.5kWh of renewable energy to produce 1kW of green hydrogen (before any compression, transport or Electrolyser, costs are considered) it can never be more "efficient" or lower cost to use green hydrogen than it is to use the renewable electricity directly. There's little agreement currently about the costs of getting green hydrogen in to the home, but the range is somewhere between 3kWh and 6kWh of energy for every 1kWh of hydrogen. That is a really inefficient use of renewable energy. If the hydrogen that has got to the home is then burnt, that 3kWh - 6kWh of original renewable energy will generate 0.9kWh of heat, with roughly the same NOx emissions as burning natural gas. The alternative is to transmit the renewable energy directly to the house, as electricity and use a direct electric heater with a total loss of 5%, or feed it in to a heat pump and achieve an ultimate gain of 300%. With the heating of buildings having a clear alternative to green hydrogen, that is cheaper and cleaner (no NOx emissions), I see the current trials of up to 20% hydrogen blended into the natural gas supply as a pointless exercise that releases more CO2 than just burning 100% gas would have. My understanding is that at the point of the trial there is no blue hydrogen being used, with first availability being 2025, and the trial happening now. The "low carbon" branding of CCUS Gas, used for blue hydrogen production is currently under dispute. The Gas industry have not enjoyed having their homework checked, and have reacted very badly to reports suggesting their theoretical analysis of the CO2 reduction CCUS can achieve seriously under estimates the fugitive methane released in reality. Methane having 9 times the climate change effect of CO2. Absolutely agree that hydrogen use will substantially increase as we move towards net zero, but not for heating homes. Yes the electricity grid needs continual updating as we move to more electrification. To use 100% hydrogen in the home would require an even bigger upgrade of the Natural Gas network. Due to much higher pressures required and the hydrogen embrittlement of steel, the entire replacement of all pumping assets, joints and valves is needed as well as putting in to question the current steel pipeline network that supports the domestic supply. The gas industry like to point to the fact that the plastic pipes entering home are already capable of carrying hydrogen, but this is a very small part of the story. The domestic gas supply industry is facing an existential crisis, and is trying its hardest to stay in the game. They don't really care if hydrogen is the expensive option for heating homes, they need to protect the asset they have in the form of the gas grid network.

I hadn't followed the link, so this is the one with the mini steam methane reforming unit in front of the fuel cell that's about £20K. The efficiency figures are opaque,. The SMR process releases the same CO2 from Methane that burning natural gas does (as long all the carbon monoxide produced gets converted back to CO2). It must be giving itself some efficiency credits back for the electricity it produces, the production of which may or may not be at a time when you use it.

I'm not sure how you are obtaining the green hydrogen for the FC boiler, if you are comparing a gas boiler to a green hydrogen fed FC boiler. I personally do not believe green hydrogen (or any colour hydrogen) will ever be piped in to UK homes via a public network.

End-to-End it's really not. And what if your hot water requirement and electricity need are not in the balance that the FC boiler delivers them. Using hydrogen today releases more CO2 than natural gas as we do not yet have Green Hydrogen facilities for the volume production of green hydrogen, for the simple reason it is not economic to produce.

I wasn't aware they required notifying, but they insisted I upgrade the local transformer for any new connection anyway. If that really could stop you going ASHP, then how about a Gas system boiler with UVC and emitters designed for low flow temp, so it's an easy swap to ASHP later, if when it does break down Gas replacement boilers are banned. Hydrogen for heating houses may possibly be used for properties that don't have the space for heat pumps and it's not feasible to join them to a district heating solution, but as direct electric heaters will be cheaper to run, I can't really see much use of hydrogen in homes. You have to question why the 20% hydrogen blend is even being tested as a stepping stone. It only delivers a 6% CO2 saving, and that's if Green hydrogen is used, which doesn't yet exist in the UK at volume, so currently Hydrogen is made from Natural gas, releasing more CO2 in the process than the saving it provides by displacing 6% of the Natural gas that would otherwise have been burnt in the home. It takes significantly more renewable energy to produce hydrogen, pressurise it (at far higher pressure than natural gas) and pump it to a home than the net kWh of hydrogen you get to burn in the home, it is far more efficient to only loose about 5% of the renewable energy transmitting it to the home across the grid and using an ASHP to at least triple it's energy value to heat a house. Not sure of the logic in a fuel cell boiler... Once you get the inefficient hydrogen into the house you then convert it back to electricity in a far less efficient process than just burning it directly.

I'm not sure you can pluck figures out of the sky for pricing. I didn't get just TF prices within 15% of each other, from different suppliers for identical performance, so I'm not sure how it could be said that TF is/was 10-15% more expensive than masonry. In fact I had a 40% spread on just my TF quotes (Beattie Passive were a significant outlier). And, is the difference in cost the same for all performance levels. Is it really more expensive to achieve PassivHaus targets, for instance, in timber than it is in masonry. And does the cost difference include the efficiencies that can be made on the foundation/slab, for having a light weight structure, or does it just assume standard strip foundations for each?

As I declared, I was making assumptions, and had assumed that the "Efficiency of main space heating system" value #206 in Work Sheet 9a of the SAP Calcs, where for an ASHP should be several hundred (%) gets rolled in to the algorithm to push up the EPC score, but perhaps it's only used for estimating heating costs... Either way, whether it is an ASHP of FF Boiler the annual heat demand for the property should be unaffected.

Renewables has nothing to do with PassivHaus, and SIPs is a poor way to deliver a structure that meets PassivHaus targets due to cold-bridging, air tightness and decrement delay, which will all require counter-measures to mitigate the inherent issues with a SIPs structure.

Hmmm.... not sure how familiar you are with PassivHaus.

While an ASHP v. fossil fuel boiler improves the EPC score due to the better efficiency of the heat source, I'd assume it doesn't effect the annual heat requirement for the house, so I would think it is OK to use an EPC from prior the ASHP installation, as long as no work has been done after the EPC that effects the heat loss calcs. ...but I am making a few assumptions there, so if this is specific to an application you will soon be making, you are best getting Ofgem's view.

Yes, the Heat Pump is sized to the MCS calcs by the Installers, but Ofgem check that the system installed is capable of delivering the heat requirement of the grant being paid out. If the system is undersized for the EPC energy requirement, the application is put on hold while more questions are asked and evidence requested. The grant is then rejected if the compliance team at Ofgem are not satisfied. I've witnessed this exact scenario. One of the RHI rules is that the EPC "accurately reflect information about your home at the time you apply", as well as being under two years old and with no loft of cavity wall insulation recommendations, so it would not be legitimate to provide an EPC from before works were done to improve a home, if the application was made after. I agree, this would be against the rules. My previous point is that there is no requirement to have an air tightness test, so an EPC may legitimately overstate the energy requirement if the actual air tightness is below the defaults used in the EPC calcs. For a new build I believe the default is 5m³/h.m² and 10m³/h.m² for a conversion, not sure for an older house.

Your example shows exactly what I was highlighting, assuming your actual energy use is closer to the MCS calcs rather than the EPC calcs. Part of the RHI check though is that the installed system is capable of delivering the EPC energy requirement, so the installed system will be oversized for the need.

There is plenty of funding available to disprove climate change. Those 100 companies mentioned here would love it to be proven untrue, as I'm sure few will survive the movement away from fossil fuels, not to mention nation states using their cyber warfare capabilities to discredit the scientists and organisations that made the case for humans causing climate change.

Pricing is closer than that, but you have to get in to the detail. I priced both up for mine and there was £3K to £4K difference. You can't have a combi-type boiler with ASHP, so you can't save the money on not having a Hot Water Cylinder. To be fair then on ASHP you need to compare pricing with an Oil system boiler install. Then all the cylinders, valves, buffers, expansion tanks etc. are the same for each install, and the only difference is the "boiler", and in Oil and LPG's case, the storage tank for the fuel. Oil and LPG System Boilers when I looked where around £1,500, off the shelf and an branded ASHP was around £5K. But then it was at least £1K + Install for the Oil or LPG storage tank. So the difference is a lot closer. Yes, you can do an Oil combi install a bit cheaper, but it's now not worth it as Oil and LPG boilers are banned from replacement from 2026, at which point you'd then need to install the hot water cylinder anyway.

It's a bit of a balance, and the paperwork has to stack up. Since 2017, RHI has been capped at a max annual heat requirement of 30,000 kWh. While your RHI will be higher, the closer you get to that figure, if your actual use is that high then you are saddled with paying for that energy requirement year after year. Low temp flow rate and high SCOP of the ASHP also push up the RHI payment. If your annual heat requirement is too high, you may struggle to have sufficient emitter area to get the flow temp down to the 35°C, which provides the highest RHI payment. Basing the RHI on the annual energy use defined on the EPC has opened up the RHI grant to being "gamed". EPC's can be quite inaccurate, as they can be completed with lots of default values, ie. for air tightness, if the property hasn't had an air tightness test, and for cold bridging, to avoid the assessor having to do the detail calcs for a particular property. In theory, if a property owner was so minded, and knew their property was better than the default air tightness value, and better than the default cold bridging Psi values they could allow the EPC to be completed with the default values to take the higher RHI payment, when their actual usage will be lower. With the system costs to the owner being not just about the initial investment, but also the day-to-day running costs, I would have thought the best balance would be achieving as low heat loss as possible, to keep the long-term bills down, making sure you have a 35°C flow rate and a high SCOP on the ASHP, and then leave it to the assessor to work out the EPC, without being too helpful... The installed system output does need to be roughly matched to the EPC heating requirement.

You can get them much cheaper, it was around £7.5K with all ducts, terminals, distribution boxes, heat/cool wet heat exchanger, plumbing valves, controls + + + Airflow will do your design free of charge and then give you the Bill of Materials to take around to their distributors for the best price. The volume the distributors sell determines the terms they have with Airflow. TP gave me the best price, but they didn't have a clue what they were selling me, just ordered what was on the Bill of Materials and delivered it. The likes of BPC couldn't get close to the price either for the DV1100, or an equivalent system with 2 domestic units.

I've got a single Airflow DV1100, which can deliver 1100m³/h. It's classed as a commercial unit, but PH certified. I'm at 1650m³ and on boost only need to run it at 65%, so generally runs very quietly.

I used Self Build Insurance T/A Trade Direct Insurance Services Ltd. (Godalming) I never had to claim, so difficult to recommend, but it was underwritten by Zurich, so assume OK. They do need a rebuild value for the original structure, as well as a contract value for the conversion. There's nothing to say you would get planning permission for a new build if you "lost" the original structure. A barn conversion local to me had around a third of the structure fall in during a gale, mid-conversion, and the LPA immediately put a stop notice on them. They weren't allowed to continue until the original structure was reinstated and they proved via an SE report they were still achieving 65% (I think) original timber present in the conversion. This happened just as I was starting mine, so prompted me to have all my insurances in place.

Did you really just say that? I'm not sure you've thought this through, or perhaps I've missed your sarcasm again.

You'll need to start using emojis to make it clear which statements you make are meant to be taken seriously. I really can't see the point. This argument was put to bed in the naughties.

Whatever.

Why would our burning fossil fuels effect the Universe? Pretty sure the effects will be limited to our own planet. And why would the temp rise stop at 3° if we choose to do nothing? Not that "just" a 3 degree rise wouldn't be catastrophic for many.

Most of the western world has bought in to net zero because no one has yet come up with a sensible alternative.

So, 35% - 40% is not renewables. Where as the authors' quote was "almost entirely wind, solar and storage". But his fantasy piece starts with "most of the “Western” world", which isn't restricted to NY. The author's an activist that is pushing a political agenda, not providing a fact based opinion piece.