LnP

Face shields, masks, sun screen, tidy site, barriers around holes ... I have the feeling this thread has drifted back to CDM roles again. Like the OP, I'm struggling to understand the new Building Regs PD and PC roles. I've done some Googling to try and understand what's involved, but mostly what I've found is from RIBA and architects, who might not be interested in helping self builders find their own way. Is there any helpful guidance for self builders out there?

I think you're talking about this Scottish Enterprise Plan. As a UK tax payer, I sincerely hope this doesn't happen. It's got as far as it has because of successful lobbying by vested fossil interests who promote hydrogen as an energy vector because they hope it will be their saviour. It will only happen with tax payer subsidies and it's a waste of electricity. The solution to the curtailment problem is not to downgrade the excess electricity to hydrogen, but as the excellent article by Justin Rowlatt points out, eliminate it by balancing the grid. The notion that burning green hydrogen makes any sense at all is missing the point that decarbonisation of energy requirements is most efficiently done by electrification - heat pumps, BEVs etc. The priority for large scale green hydrogen production should not be to waste it by burning it, but to use it for applications where there is no alternative like manufacturing ammonia or methanol. Now there's an idea I could get behind, a Scottish chemical industry with well paid jobs making fertiliser and chemicals from green hydrogen from Scottish off shore wind. It will still need subsidies but I'd rather put my tax payer money into that.

My planning consultant shared a BNG assessment report from an ecologist for a small garden plot, just 0.015 ha. The baseline area-based habitat score was 0.41 units and the proposed development eliminated all but 0.01 of those units. To replace the lost 0.40 and achieve the 10% net gain, they had to achieve a score of 0.45 units. There was a deficit of 0.43 units. Of these 0.12 units must be of other neutral grassland of medium distinctiveness and 0.29 must be of individual trees of medium distinctiveness. The deficit can be compensated on other off-site land owned by the client, or a financial contribution to off-site ecological enhancements. There are different places to go to buy credits, but if f you buy statutory credits, there is a "spatial risk multiplier" which doubles the number of units you need to buy. In this case it meant they would have had to buy 0.87 credits which would cost £36,540. There is the option to buy credits in the local market through a registered provider .... and to help you with your project, some ecologists are setting themselves up as registered providers with banks of credits .... which looks like a conflict of interest.

Most economists would agree with you, that a carbon tax would be the most efficient way to incentivise decarbonisation. But we would need strong leadership and political consensus for it to be accepted. Canada had one but there were lots of exemptions. It was unpopular. One of the first things Mark Carney did when he became prime minister in March was to abolish it. We do have an emissions trading scheme though, which requires industrial carbon emitters to surrender carbon credits. It's a carbon tax on natural gas and coal electricity generation ... but ironically, since we have a marginal cost pricing system for electricity, this increases the price we pay for all our electricity, including renewables ... which disincentivises heat pumps! Domestic gas boilers are outside the emissions trading scheme.

@Daniel H I'm a bit confused by your post. Addressing BNG is just another one of the topics you need to address when you make your planning application. If you don't this, your application isn't complete. Your options are: claim the self build exemption, but be prepared to sign a unilateral undertaking not to sell your house for 3 years after completion, and pay the LA ~£1000 in legal fees; claim the de minimis exemption, if you meet the criteria, i.e. < 25 m2 area habitat and < 5 m linear habitat will be impacted; get an ecologist to do the assessment, but since you can't take credit for points added in a private garden, be prepared to buy the offsets you'll need to replace the points lost from your plot by your development plus the 10% you need to add - budget £30,000 - £50,000 for this.

Good questions. Have you asked MBC what their advice is? They’ve probably seen more self builders than any of the other people you’re dealing with.

This is a working paper .... prior to a consultation. Don't hold your breath.

Given that hydrogen as an energy carrier is a non starter for the economic and safety reasons mentioned above, there are other ways to deal with curtailment. Interconnectors can solve not only curtailment but also Dunkelflauten. Time of use tariffs will help. Also, the Royal Society recently published a report recommending hydrogen as a means of storing energy to deal with the ups and downs of renewables - electricity via electrolysers to hydrogen then via fuel cells back to electricity for distribution to consumers - it's expensive though. It's also worth pointing out that, despite the marketing blurb from the gas companies, even green hydrogen has a climate impact. It's very leaky stuff and when released into the atmosphere, has a significant global warming potential. Grey hydrogen (produced by reforming natural gas) even with carbon capture and storage (CCS) is also no climate angel. Natural gas extraction and distribution leaks methane (a global warmer), the reforming process creates CO2 , the CCS process has a parasitic energy requirement, is expensive and doesn't capture all the CO2 . It will be a sad day for the climate, for our bank accounts and for our safety if we start burning hydrogen to heat our homes.

It's telling that the clip @nod shared on the switch to hydrogen is from British Gas. The fossil industries, gas network operators and boiler manufacturers are lobbying hard on this.... naturally, because without it, they're sunk. Consider this, to heat your house by burning green hydrogen will require 5.5 times as much renewable electricity as heating it with a heat pump or twice as much if you heat your house with resistive electrical heating. That's 5.5 times as many wind farms. And as @Mike says, as more people make the switch to electrical heating, the fixed costs of operating the gas network will have to be shared among fewer consumers. For these reasons, hydrogen will be prohibitively expensive. Additionally, the safety issues of having hydrogen in your home are problematic. It has a wider flammable range, is easier to ignite, generates higher overpressures when it explodes and is harder to keep equipment leak tight. Additionally, hydrogen gas hobs release more NOx that natural gas. NOx has been implicated in respiratory diseases. There have been three trials proposed for domestic hydrogen in the UK, Whitby (near Ellesmere Port), Redcar and Fife - notably all disadvantaged areas where consumers might be more attracted by inducements from the vested interests sponsoring the proposed trials - Cadent, Northern Gas Networks, Scottish Gas Networks. Whitby and Redcar have been abandoned largely due to independent academics and engineers stepping in to shine a light on the safety issues and misinformation being provided to the residents. Cadent engaged the engineering company Arup to do the risk assessment for Whitby, to estimate the expected frequency of leaks and explosions. Introducing hydrogen with no additional engineering mitigation measures gave unacceptably high risks, higher than gas. They proposed measures to get the risk down to the same level as gas. They considered this level of risk to be tolerable which is in itself flawed, since legislation here requires risks to be managed to be as low as reasonably practicable - heat pumps are a practicable way to heat your home with less risk of fire and explosion. Some experts challenged other conclusions of the Arup risk assessment. There will be challenges to decarbonising by renewable electrification - grid capacity, curtailment, Dunkelflauten. But solutions are available. There are uses for hydrogen for which, unlike heating, there is no alternative - e.g. making ammonia or methanol and desulphurising fuels in refineries. That's the first priority for green hydrogen. But if science and economics are allowed to prevail over politics and lobbying, we won't be heating our homes with hydrogen. @Wadrian, I don't think you need a gas connection!

I was in hotel accommodation recently which had bathroom wall finishes which we liked. Wherever there might otherwise have been tiles, so shower surrounds, backsplashes etc., they'd used approx 5 mm thick sheets of what I imagine was stone filled resin. It had the look and feel of stone and was better than some of the formica laminate sheet type material I've seen. I'm attaching some photographs. Does anybody know what this material is and where I can get it? Thanks Thanks

This demand calculator might help https://www.ssen.co.uk/our-services/tools-and-maps/demand-calculator/

How will you heat your DHW in winter? If it's with the heat pump, what recovery time will you get with 3.5 kW?

Generators already have to buy, trade and surrender carbon credits through the UK Emissions Trading Scheme. At the consumer level, you're talking about a carbon tax and you're right, a lot of economists think it's the right way to incentivise reducing carbon emissions. Unfortunately it's politically difficult. Canada used to have one and it was very unpopular. The first thing Mark Carney did when he became prime minister was to ditch it. Pity.

Perhaps because the regulator sets it up to work this way, since the context to the proposal is to help the UK achieve its net zero target. They want to incentivise renewable generation close to the demand to reduce the required changes to the grid. Beefing up the grid to get electricity from far away places is expensive and the pylons are politically difficult.

I'm still learning. Thanks for the clarification, yes designed and commissioned, but not installed. And I noted your earlier comment "When I shared my detailed calcs with them they stopped talking to me!" So they won't guarantee your 6.5 kW requirement. They say they take care of: System Design & Diagrams Installation Support & Installer Training On Site System Check & Commission The Latest Cool Energy InverTech Heat Pump With Remote Support Over Wifi High-Quality INOX Stainless Steel Unvented Pre-Wired Cylinder Full Handover Pack & Insurance Backed Guarantee They also "take care of the paperwork" to claim the £7,500 grant.... does that mean they keep all of the grant money? Otherwise, how would they make their money? £7,500 might seem a lot for what they're delivering, but for the customer, it's still a free heat pump, cylinder etc, so could be attractive. But the question would be, is there an umbrella scheme operator out there who will work with the client on the design? Or do they all insist on over-designing by a factor of two? Or is the over-design inherent in the MCS heat loss calculation methodology?

Sorry, no I meant hybrid in the sense of the way we work. It'll be just an ASHP.

Definitely a good solution and hats off to you for sorting that out. I'm not planning to DIY but am thinking about a hybrid arrangement with a guy who's a qualified plumber and electrician - Gas Safe, NICEIC etc. He's done work for me before and we get on well together. I'm more involved in the work than a typical customer and he's happy with that. We'll discuss what we need and he's happy for me to buy the kit and for him to install it. I value and respect his experience and occasionally I bring a different perspective. He's not MCS certified as he thinks it's a rip-off for something he's already qualified to do. For our self build, we've discussed him installing the heat pump under an umbrella scheme, but we haven't finalised that yet, hence my interest. This would be his first heat pump installation but he's up for that and interested in the project. Maybe I can buy the kit cheaply, as you have done, have him install it and I still get the grant. We can work this out so he and I both benefit. He's also interested in installing the PV, but that's another story!

Coolenergy are not the only people offering an MCS umbrella scheme. If you do an internet search there are several others including for example this one from Vaillant. Does anybody have any thoughts about or experience with those?

Great blog and nicely written. Regarding goggles misting up, the mist is tiny droplets of water condensing onto the lens. If you put something on the lens which breaks the surface tension of the water droplets, they all merge into a continuous layer, which you can see through. Dilute detergent or soapy water works. Dilute baby shampoo won't sting if it gets in your eyes. Licking the lens can also work .... depending whether you like the taste of dusty goggles!

I think I posted Warrington's UU elsewhere, but here it is again. I'm not a lawyer, but a couple of differences I noticed: Warrington provide for the possibility that the self builder could be released from their obligations if their circumstances change. Unless I missed it, Dorset does not. The Warrington UU says: "PROVIDED THAT the requirements in paragraphs 4 and 5 shall not apply in the event of a change of circumstances acknowledged by the Council in writing acting reasonably which prevents the Original Owner from Occupying and/or not Disposing of the relevant Dwelling within such three (3) year period." I'd be thinking about ways in which my circumstances might change, for example my place of employment changes, I lose my job and have to move house, I need to move closer to aged parents, I get sick and need to move into care, etc. It looks like the Dorset UU would prevent me from doing that. In the Dorset agreement, your self build has to continue to be your "sole or principal residence" for three years. Does this prevent you from owning a second or holiday home? None of this is legally required by the Act or Regulations. The self build exemption is provided in The Biodiversity Gain Requirements (Exemptions) Regulations 2024. They very simply exempt self builders. And self builders are simply defined in the Self-build and Custom Housebuilding Act 2015, Local authorities are over-reaching their legal mandate. I continue to believe that the way they're implementing the self build exemption is outrageous. Warrington Self Build - draft UU26.9.24 - FORMATTED 16.10.2024 CLEAN (1).docx

You can't beat the second law. Once you've converted the electricity (work energy) into heat energy, any device you design to get back to work energy can never get you back all the energy as work. Some energy will always be rejected as heat. The best you can theoretically do is a Carnot heat engine which has an efficiency of (Th - Tc )/Th - hot and cold temperatures in Kelvin. And there's no actual such thing as a Carnot engine. Yes, great if you can find a use for the rejected heat. I've got a fantastic energy project I think you might be interested in investing in ....

At the moment, curtailment is usually because the grid doesn't have sufficient capacity. We should spend the money on increasing the capacity of the the grid so it can handle all the wind and solar, rather than expensive energy storage just because the grid can't handle it. Eventually though we will need storage to balance supply and demand. How to manage intermittency and curtailment was studied by the Royal Society and reported here, and indeed they found a potential use for hydrogen, i.e. renewable electricity via an electrolyser to hydrogen, stored in a salt cavern and back to electricity by a fuel cell or ICE and generator. It's expensive both in terms of capital cost and the round trip efficiency of 41%, i.e. you only get 41 kWh of electricity back for every 100 kWh of renewable electricity you put in. Back to my original point though, advocates of hydrogen who don't understand the thermodynamics will assume that we can improve on the 41% as we get better with electrolyser and fuel cell technology. I'm afraid lobbyists and parties with vested interests looking for subsidies, exploit this and persuade politicians that the economics will improve. We can't and they won't. These are second law losses and you can't beat the thermodynamics. Some people correctly argue that interconnectors, which were not included in the RS study, could be a better solution - you connect to renewable sources where the wind and sun blow and shine at different times. Interconnectors avoid second law losses. It all about the difference between the two types of energy, heat and work!

Power is to work as speed is to distance 🙂. One is the rate of the other.

I don't understand your point about enthalpy. Did you mean entropy? Either way, there are different ways to state the second law. I tried to make it simple and deliberately didn't bring entropy into it. I just saw something which was incorrect, is a common misconception and incorrect in a way which sometimes leads to poor energy policy making. So I hoped to straighten that out. A political example ... if our politicians understood this science better, they wouldn't be wasting tax payers' money on subsidising projects which use hydrogen as an energy vector, for example this one in Aberdeen, especially given that in Montpellier they already learned the hard way. Compare: Renewable electricity -> hydrogen (heat energy) via an electrolyser -> electricity via a fuel cell -> work energy via an electric motor .... or -> work energy via hydrogen internal combustion engine. Versus: Renewable electricity -> work energy via an electric motor in a BEV. Apologies if this has hijacked the thread!

No. Heat and work are the two different types of energy, measured in Joules. Power is the rate of doing work measured in Joules per second. A J/s is a Watt. The first law (conservation of energy) is easy. The second law is tricky. Politicians don’t understand it which is one reason why we get incoherent energy policies.