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I am thinking of ASHP and MVHR... so NO smoke pipes 😀

If the UK government tried to organise that, it would be a disaster. How would you know how many miles a car that is taken off the road had done. And can you imagine trying to collect the payment when someone moves, or just does not have the cash. Much easier to just have a fixed fee, payable monthly, 6 monthly or annually, we are used to that, and we have the systems already in place. What it really comes down to is what the charge should be, trying to make 'fair' for everyone just means we all loose out. We really should treat personal transport as a privilege, not a right. I hate public transport, really hate it. Why I pay the price to have private transport. Running my car cost me more than running my house.

I agree the level of waste can be horrific on some sites - but you can build traditionally and not generate anywhere near the normal level of waste - by ordering carefully, sorting waste out (wood, cardboard, food containers - builders seem to go through no end of plastic bottles), free cycle (people will take very small amounts of insulation etc if it is free), and broken blocks, tiles etc can be used for hardcore for your patio base - I think very little waste will be generated by your choice of build route. And once your builders know that you are on the case on waste, they will be more careful and having of cuts sorted and laid out, they will be more likely to use them.

I've done it as well, but we weren't living in the house and we could get a micro digger in for bits. We also hire a little motorised dumper. We kept all the waste and crushed it down to hardcore. I also forced my family to help:

Doable. I've done it. We were lucky that we could get a micro-digger and dumper into the house to make our lives easier. I certainly wouldn't consider it in a house that was being lived in though, it made a right mess. If I was to do it again though, I wouldn't use screed, I'd use the conc as the finished floor, tying UFH to rebar in it, which should also save some depth.

I'm being deliberately provocative here to stimulate out of the box thinking, please bear with the explanation and numbers, but then feel free to critique. In summary I am proposing that, for retrofits (at least in the South of England, where many of the UK houses are), we should abandon the insistence on achieving low flow temperatures in favour of accelerating roll out, which is necessary to mitigate climate change. So here goes: I think we all know that ASHPs are the way to go for low carbon heating, and that low carbon heating is an essential part of combating climate change that the way to make ASHPs work efficiently is to minimise the flow temperature that the current model, whereby ASHPs are subsidised by government yet still cost up to 3 times as much as a gas boiler to install, is not working, in the sense that it is not gaining the traction hoped, let alone the traction required to meet climate change goals that large ongoing government subsidies are likely to be unsustainable politically, however strong the environmental arguments that most ASHP installations 'require' replacement of at least some radiators, almost all 'require' the replacement of the DHW tank and other sundries, and that this contributes massively to the cost and disruption that, because we 'need' different flow conditions ‘specialist’ design is required that local plumbers, who are surely the mainstay of the retrofit market for gas boilers (which is the retrofit market), are not engaged in the process because its too complex, onerous and expensive and because of point 6. Now if we could fix #5 and #6 then #7 is fixed more or less automatically, #3 no longer need applies and we can achieve actually #1, which is the real goal So what is getting in the way - answer: a) regulation and b) #2. Regulation is ultimately fixable, but #2 is a function of the physics. Several manufacturers now do high temperature heat pumps which run at 65 or even 70C. These are much dismissed on this forum because they are less efficient, and the received wisdom (which, until recently, I, physicist by training, bought into) is to design for the lowest possible flow temperature, which is what triggers most of the other challenges. From a physics point of view designing for low flow temperature is undoubtedly the right answer, but engineering, particularly system engineering, is about trade offs between practicality, performance, cost and other factors. So what if we designed for a flow temperature of say 65 (and a delta T of 5)? The average radiator temperature would be about the same as the common 70/50 combination, so we almost certainly don’t need to change out radiators. At a flow temp of 65 you can easily heat the DHW, with a standard coil, to 50( provided that the HP has a decent modulation ratio) so we don’t need to change out the DHW tank. In many, perhaps most, domestic environments the primaries split near the boiler into 2x22mm (upstairs and downstairs), which is sufficient for 6kW, 7-9kW at a push, on each leg, sufficient for most households, so we don’t need to swap out the primaries. And we don’t need to upgrade the ‘standard’ 22mm feeds to the DHW tank because they are already good for 6kW at a delta T of 5C, which is sufficient and twice what an immersion heater delivers. We will have to swap out the existing diverter valve (a few 10s of £) and we will need to connect up the controls differently (maybe half a day for the electrician), but that’s about it. No need for MCS, extensive replacement of functioning hardware, extensive lifting of floorboards (or solid flooring), replacement DHW tanks etc; a regular plumber and his electrician friend can just do it in a day or two. But, you say, the efficiency will be terrible! Well sure it won’t be as good as it could be, but there is almost always a trade off between capital investment and long term cost and that trade off is not ‘one size fits all’. I would suggest that, while a SCOP of 4 or more is desirable, it is sufficient, in the real world, if the SCOP is such that the running cost are about the same as whatever the current system is. In the case of gas, the predominant heating in the UK, this means an SCOP of about 3 currently (because electricity is 3 times the price of gas), a figure likely anyway to reduce as the Government (hopefully) reduces the wholly artificial weighting in favour of gas that exists at present. Some weeks ago I posted a model of weather compensation (which I attach to this post) and this can be used to estimate the effect of increasing flow temperature. I have taken, as an example, the LG figures for their 12kW model. This shows, for conditions in the South of England (where a large proportion of the UKs houses are situated) an modelled SCOP of 4.4 (with weather compensation) and a ‘design’ flow temperature of 45, frequently the target for retrofits where radiators as are present. If we increase the flow temperature to 65, the SCOP reduces to about 3.5. That’s a big reduction, but arguably a sacrifice worth making in return for the advantages in terms of up-front cost and disruption. Most importantly, even allowing for poorer-than-model performance, its good enough by the definition above. It is dependent on a reasonable (but by no means perfect) setting up WC, but if installers weren't spending so much time on replacing perfectly functional equipment, they could perhaps do this and pop back a couple of times in the ensuing heating season to adjust. Of course radiator and DHW upgrades can, and should, still be offered, but as an option not as a requirement, which is how they are currently positioned. This decouples the part which is transition to low carbon heating, and the part which is system improvement and, vitally, gives consumers choice. The upshot is, I think, that we could for a good proportion of households, eliminate much of the ‘compulsory overhead’ associated with retrofit of a heat pump. Yes it means compromise, but the rewards in terms of climate emissions are enormous. The MCS brigade probably wont like this, but that’s just tough. The ASHP market cannot possibly continue as a niche sector if it is to achieve our climate goals, and the constraints imposed by MCS confine it to just that place. This has to change! Discuss! (but in doing so please bear in mind that the objective is to find practical solutions to achieving mass retrofit with existing, or near-existing, technology, not to achieve perfection). WC Simulation.xls

Unless your house is, or will be, extremely well insulated, I would be wary about expectations from ASHP. I have one and I am happy with it, but I wouldn’t put one in anything other that an extremely well insulated modern house. And certainly not one without oversized radiators, underfloor heating etc.

Say the 100mm insulation has a U-value of 0.2 W/m2, then with the UFH flow at 35oC and the ground beneath at 5oC, then the loss in Watts will be 0.2 * 72 * 30 = 432W. Nearly 0.5kWh constantly leaking away to the Earth. Do the same for the roof with 150mm of insulation when 5oC outside and 20oC inside: 0.133 * 72 * 15 = 144W. To get anywhere near the same low loss through the floor you'd need a minimum of 250mm giving U-value of 0.08 * 72 * 30 = 173W.

It’s funny as when I saw the price of £2.25 I thought, f**k that’s expensive. But when I wrote the total of £13.50 I did think “am I just being a real tight arse here?” 😂. I guess the answer is yes then.

MBC high performance TF with double glazing Reynars windows and doors

Was going to but SWMBO has packed it away to make space for something else.

I knew it'll add extra cost but didn't realise it would be this much. Can you let me know if there is an objective way to calculate the costs. I am working on 2000-2400/m2 as over all build costs. Thinking of MBC high performance timber frame as the first option.

I think I'm with you on this one. I've had a look around and found one done with a plastered return and it looks good.

It will know if Nigella is on your telly and you are watching Whack Off.

They are all hard enough for us not to notice.

Hello, and welcome. I can't answer any of your questions but, we do have some very smart people on here, who i'm sure will be along soon.

PW spec says 5kw sustained 7kw short bursts so may be worth checking they dont mean collective export is 8.6kw when SE is at max?? There wasnt a note at the bottom saying you got what you want but warranty is now void

And your designers. I would have to rummage a long way back, but i recall that the big contractors had targets of something like 10 skips per 1,000m2.* (Ours was 2.) That involved everyone through technical design, ordering, and use as well as site manager ordering reuse of ends etc. But on top of this came simply using less in the first place. Efficient use of all structural elements, no overdesign, no overdig, natural drainage...all sorts. We reckoned 25% less material used, let alone waste. So my view was that hemp etc were easy ways to seem green, while not addressing the less blingy aspects of waste.....use less. It also saves stacks of your money. What i don't understand is that straw is not used in the same way as osb. Or in blocks. There is so much as a waste product. I think sawdust is still added to concrete blocks as a filler. * that became zero to landfill, so a good thing. They way they managed that with mixed rubbish was to classify it as non recycable. Less to recycling would be even better.

A house is like a boat and a passive house is like a boat with no holes in it. I can never underestimate why people argue that a boat would be better with holes in the hull. You can still fit whatever engine you like.

Remove the sticker ( POWER OFF AT ALL TIMES!! ) and turn the immersion down from 5 to 4. Test after 24 hrs to see where it settles. Re-adjust as necessary each 24hrs until you're happy.

@LSB Yes they're awesome aren't they! There is an Extensions book under development and I hope she'll do a Retrofit book in the future to help when looking at structures that don't mee the current building regs.

My EV charger is a dumb as a box of rocks, activated each night at 12:30to 04:30 to benefit from the cheaper electricity tariff just the way I like it

I don't like the sound of that. Although I don't have an EV I feel I need to buy a dumb, simple unmetered EV charge point ready for when I might need one, ready to fit when I need it without having a smart meter. I hear talk of EV chargers needing to "communicate" with someone or something. Not at this house they won't

Inverter sorts that out. AFAIK theres a comms link between the inverter and the batteries with each battery pack having a charge controller. Black magic takes place and you're batteries get charged. If its an SE3680H inverter youve got even with 30kwh storage youll still be limited to 3.6kw from the inverter

I did my install piecemeal, which I would definitely not do again. Plan it upfront, get the G99 upfront if your plan requires it, then get it all done in one go, including battery if you want one. All I can say in my defence is that I was rushing to get something installed before winter 😅. If you're going MCS, a tariff like Octopus Flux will mean it's better to export to the grid at peak, then import electricity off-peak. You don't pay VAT on exported power, of course.

Our architect suggested it but there are some pretty nasty chemicals added to make it fire proof resistant. On top of that is all the taping of joints to make it air tight and what happens to the tapes when the adhesion dries out and gaps appear, if moisture then gets in I dread to think of the mess that would be created. It's just my opinion but a lot of modern building construction seems to be short term 'in the moment' options and only time will tell if these system work.

We have a B&B first floor and MVHR. Love it. The MVHR ducts run horizontally in the loft and down vertically into rooms so no horizontal ducts in the B&B floor. I think all the vertical sections are boxed in built in wardrobes upstairs. Never noticed a noise issue due to penetrations through the floor. The B&B company provided clips to fix battens to the underside of the beams to which the plasterboard is fixed. You just need to plan ahead so you don't have issues with the clearance for shower waste pipes. All of ours run in the insulation and screed above the B&B. Don't run vertical ducts too close to walls, the room vents are sometimes a bit larger diameter than the duct so the duct needs to be a few inches away from walls.

I think I was being kind with office My took one look and said car showroom Seriously it like one of those where the Architect has be given free license and told don’t worry about the budget There isn’t one BUT If funds arnt an issue and you like it Build it

I really like it. I love the Huf Haus look. My wife’s uncle built a Huf Haus 10 years ago and it looks as new and fresh now as it did when it was built. He is a very accomplished architect (retired) so could have designed his own house but didn’t.

During a kitchen / diner knock-through refurb, the customer asked me, "What do you think of the tiles Nick?". I said "If you like them, what the feck has it got to do with me?". It's your house, and your design, done the way you like it, and you're the one paying for it. Pointless asking what people 'think', I'd just say to ask 'the massive' here for constructive criticism; so you get feedback to hopefully illuminate any non-obvious faux-pas. Good choice with the Nudura, how far are you going with the upgrade to the rest of the original build fabric though?

1HRFR ( 1 hour fire rated y'all! ). Would indeed need to be made up of non-combustibles, but B-Regs will dictate / mandate this when you apply, and at that point you will know your possible choices for materials / finishes etc. 8' sounds a perfect size to shoe-horn this in, crack on!

Well, interesting thread, fir my part I designed a house which was well insulated firstly, only double glazing in wooden frames as the coatings used are not far short of triple glazing figures, I did no calculations whatsoever, purely guesswork, small ASHP off EBay (which could be switched out fir a bigger one if required in the future), bifolds. MVHR, UFH. The house only needs heating for a couple of months of the year, the rest of the time it’s completely stable, woodburner for upping the lounge temp if required (and a nice feeling when looking at the cold outside ) No heating upstairs (apart from electric towel rads and electric UFH for warm toes after bath/shower). IF a bedroom needs heating (old people or illness) a simple plug In heater raises the temp very quickly and it lasts (not had to do this yet). I would never consider a certificate fir being passive but I can simply show anyone the very low electricity bills throughout the year, what’s not to like 🤷‍♂️

How is this?

You can go as close as legally possible if your wall is 1HRFR. Wood cladding not acceptable unless there’s a solid block wall behind it. Foundations don’t differ between non-sleeping and sleeping accommodation.

Open Applehill Topo edit.pdf

Wow, it looks amazing. A lot of glass was my first thought. What is the orientation of the elevation with a lot of big windows?

Personally I think you’ve lost some of the character of the old house. I’m also not convinced with the flat roof parapet. It looks a bit unwieldy and out of place.

Very doable, but watch for: - what is your current floor construction? Make a test dig in a place you can easily fill in if you decide not to progress. I made 20x20cm hole under fireplace hearth and got good idea of the scale of a challenge - BC: agree what floor buildup is acceptable so you know exactly how deep you have to dig. I ended up with 150mm hardcore+50mm lean concrete blinding (what BC reqested and pi$$ed me off)+150mm PIR+100mm slab with rebar and UFH: total of 450mm meaning digging 350mm below existing slab. Don't think about reducing insulation thickness to save digging: it is not a passivhouse, your floor temperature will be at least 30°C and the last thing you want to do is to send too much heat into the ground. - test hole should also give you idea about soil condition: some are easier to excavate, some (clay...) are proper pain. - it can be done by hand, great exercise for back muscles - plan timing: do it after the extension is done and the area leading to entrance should be the last and done like F1 pitstop, otherwise life is challenging for few days

I used that to bridge over old floor boards before tiling. I stapled it down which is what i would do again. Then tiled. The problem I had was that the floor was bouncy, very old and probably under-designed joists, so the STS, being flexible, did not help in stiffening the floor. I think it all settled down, but a few tiles came loose when i walked on the floor perhaps too soon. (Not my house, now sold, so no latest report available). Of course normally people don't jump on a toilet floor. If your floor is robust then yes I would say STS is fine, and easy to use. plus helps a little in insulation. If bouncy then I would use a cement board which would probably kill the bounce.

Too busy mate. Just FINISHED a box section arch for the pub and a reversible sign. Paid in pints and crisps! 👍

Install 3x more than you think you need, may waste some energy in summer or looking another way give your local community some free green energy. But will have some to use in the winter. Lots of solar and ASHP, maybe an electric vehicle it not convinced yet.

Got it, thanks https://www.sciencedirect.com/science/article/abs/pii/S0921344912001620#:~:text=Further carbon sequestration by lime,the storage of greenhouse gases.

Welcome to the forum. 72mSq is a big Kitchen (9x8m) depending on the slab buildup and the insulation / air tightness of the overall build, you will want to be heating a lot of concrete and lots of insulation, it might be worth looking at the Willis heater option. These are small, a few Kw, water heaters that you can run over night on the cheap rate to warm the slab and let it cool during the day. @TerryE has done this successfully and done the sums, for his house, to show the cost / value outcomes against ASHP anyway.

Spectrum are a really good company and know what they are doing. I’d recommend them.

Believe you need to be G3 certified to sign off an unvented cylinder install. You can do most the work yourself, as long as you can suitably certified plumber to sign it off. So no idea why you would want building control involvement.

Put some polythene over the top, as concrete reacts with the aluminium

Too right! Hi Alan. Hope this helps... there is a lot of prep work you can do.. seems like you have already started raking out a borehole log so well done. We call this a desktop study, often folk slag this off but what they don't know is that it forms part of the BS design codes to site investigation and good practice. Try and find out as much info as you can online, look at the BGS viewer to see what kind of bedrock you have and superficial deposits. Speak to the neighbours (very good to do as we weave this local knowledge into a site investigation report), well I do as it carries weight.. believe it or not. Ask say about flooding, were there any landfill sites, was it in a bad corner of a field that the farmer filled in? .. think of the things that might be relevant to your site, be friendly and get them talking. Sometimes they produce old historic photos and give you pointers, history of the site and real nuggets of info that can literally save thousands later on. Other stuff.. have a look at the services, if rural... then where are they, what services will you need.. drainage is a biggy. If in the town.. where do you think they might be and how deep to the sewer in the street, if rural have you available space for say a soakaway or easy access to a water course that does not dry up in the summer.. Next thing to do is to have several walk overs of the site and wander round about. Try and understand how the topography has been formed and importantly what has been changed over time. Are there culverts, how does the land drain, where are the water courses, are there big trees, if so which way are they leaning.. If you see the power company / water folk digging up the street stop and ask them about the ground! many of them are keen to tell folk what they know!.. sleep on stuff for a while.. be curious.. think of everything you can and try and work out why the things you observe are the way they are.. and write it down. The objective of the above is to try and encourage you to look outwith the site and understand what is going on round about. Do your best here and put all the info you have into a document with some photos. Now you have the makings of a desktop study and off the back of that you then plan the intrusive site investigation. Your SE and investigation company will meet you with open arms if you turn up well prepared and won't make a fool of your efforts.. if they do then find another SE GI company pronto. If you come to me and say Gus.. I want to build this house.. I'll say.. to do it right and do our best to avoid things coming back to bite us we need to start with the above. This way we take all reasonable steps to mitigate the risk to you and we can then focus our effort on the different designs knowing we have started out doing things the right way.. done the leg work. The above is the starting point of planning an intrusive investigation that reduces the risk of wasting money while at the same time providing useful design information that can unlock options for the building / basement.

If you have MEV, dMEV or MVHR extract in the kitchen then you are already covered. Hob extract isn't required. If you don't have a either of the above, then you will need the extract working.

Simple. The stat in the immersion reaches the set point, and bingo, no more input goes to the immersion and export kicks back in at full wallop. Shut off the power to the immersion, whip the lid off, and post a pic of the settings on the stat head please.

That low a temp is only feasible if you have a large / over-sized hot water cylinder, of course. Possibly set to 50oC at the outset and see how you manage with that temp / capacity.