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My initial plans were to have rainwater harvesting, build hub taught me no.. so with that scrapped I needed an alternative, soakaways are difficult due to bed rock levels. In addition to this we have lots of run off on the croft, and the track to the house floods. We have already installed a pond for the ducks and this has a large berm to the back and sides so that the runoff is held back and slowly soaks away, but this winter has proved it overflows regularly, that's around 3000L extra. So the plan was to install an overflow pipe from this pond to a new larger pond. The larger pond also acting as rainwater run off capture. The larger pond will have 2 levels, a pond and then an extra layer to act as a overflow that can evaporate and or be pumped to the rubble drain in drier times. I got a big carried away with the backhoe and ended up with around 10M x 8M and over a meter deep. The overflow capacity will be around 30k - 35k L. We had to peck out some of the rock to get depth, and at the front used "as dug" rock from the quarry to form a rough and rugged stone wall, quite in keeping in Caithness. Time will heal the scars and soften the edges with planting. Due to the two levels we came up with the idea of hiding the liner under some camo net, that we intend to plant up in time. Not sure how this will stand the test of time. From the house the rainwater enters a rock filter, an idea loosely based on a post from @ToughButterCup- thanks. From the rock filter we have created a little stream that the rainwater will flow down and into the pond. In addition to this we have a pump that will take the water via a home made skimmer from the pond and filter the water from the pond through the rock filter and stream constantly. This also has a diverter to pump the water past the house and into the field to reduce the overflow capacity in drier times. This is the rock filter, and some of the pipework yet to be buried. Getting to this stage ticked a box for building control as we now handle our run off. We got our completion certificate on the house this week, yeah. There are some things to finish, the second bedroom needs decorating and trim work. And a few small jobs here and there, but in general the house is decorated, and fully functioning. We started the build in earnest around May 23 I think, so quite pleased with the effort and timescale we achieved. It's was built by me and Mandy with the odd person helping with concrete pours. 3 months in summer were busy with the cabin rentals that saw Mandy spend 3-4 hrs a day turning them around for the endless NC500 travellers.😁 We're embarking on the VAT reclaim soon. To summarise the build: 89sqm True bungalow Floor 0.094U (300mm EPs 120mm concrete) Walls 0.139U ICF with 50mm EWI and 25mm PIR IWI Cold roof 0.1U 25MM PIR 400MM mineral wool. UPVC triple glazed windows and composite doors MVHR, 4kW PV in roof, 5kW ASHP, UFH. EPC A103, Airtightness 0.83 ACH.

I see a few mentions of the expense of MVHR. I self installed a simple system complete for less then £1500 in a 260m2 house. It has no sensors just manual boost which we use occasionally, otherwise it stays on trickle rate 24/7, even when some doors and windows are open. Really happy with the air quality (which I monitor with sensors), best value for money in the whole project and a no brainer in a new house IMO.

All the reading of posts on here at the design stage and the hard work implementing the experience of others on your own self build can be summed up / justified with just 1 image. Even when building on a very tight budget. This is my energy usage @ The Windy Roost since we got here. Upto January 24 we were in the static, we were never really warm used Air to Air heatpump for heating, hot water and cooking was LPG. We also had around 4 summer months of our cabins being used, again electricity for heating and cooking, DHW is LPG. The blue line makes me feel warm and fuzzy inside. That's our electricity for the self build, a whole house fully electric and blissfully warm with ample DHW. (With some limited cabin usage). To all self builders going through this, it's worth the effort👍.

I thought these photos might interest you ..... the first one taken a few minutes ago The slider in the kitchen has been open all morning - right hand side of the image is to the North, and thus the Winter Garden is in wind shadow (wind NW) , but in full sun (it was raining when I took the photo) There is a 2.5 meter overhang for a 'veranda' shown here earlier in the build. We call it a Winter Garden - yet to have anything in it , but won't be long now. SWMBO intends to fill it with - knowing her - a jungle or as close to that as she can get. There's one episode of Grand Designs where Kevin WotHisFace showed a similar design, but he calls the area a Breeze Corridor. The look of triumph on Debbie's face was a picture. First time she'd ever been 'on trend' she remarked.

We leave the window in our bedroom for much of the summer. I support we could turn the MVHR off but it's so cheap to run and as it guarantees fresh air regardless we don't bother. Despite my statz-esque approach to kids leaving the entrance door open I try to remember a house is there entirely for our benefit and and enjoyment and not as a science project.

I don't mean to be harsh, but don't you think you kinda brought this second mess on yourself? You actively chose to get back a tradesperson who you already know made a potentially life-threatening mistake and he wasn't even able to fix it when told about it originally! What made you think his second-fix plumbing in your bathroom would be any better? If he didn't provide a quote, what did he agree to? What do you have in writing? Did you take detailed photographic evidence of his mistakes before you fixed them? If you've got pics, ask him for an itemised bill, and then you can prove that he didn't actually fulfill those things properly and therefore you're not paying. But to be brutally honest, I think you partially brought this on yourself and might need to chalk it up as not-too-expensive life lesson.

Sorry but I can't see ANYTHING in that kitchen that will make it £55K. Howdens could replicate that, or any other kitchen supplier for that matter. Choose the best of their range, and fit yourself, Get good stone worktops and splashbacks, and buy the same top end ovens and hobs and other appliances as the German supplier is proposing. (yes this is an answer from a man)

You must get to the bottom of this before parting with your cash. I see this a lot.. the vendor claims no knowledge.. but I know they know that they are not offering a clean sale. Ask this.. are you the first punter that has pitched up or have there been others who have clocked that the vendor is not playing the game? I have seen this over the last 40 years.. If you can't get a rural plot soakaway or similar to work etc then the plot is often only worth the agricultural value.. it's a fact folks and there is usually no magic bullet. It may be that the plot is worthless.. you don't want to be the idiot that buys it. It may be that you can do a deal where they give up more of their land and you share the soakaway say, now the plot has value. It's time to say to them.. look we need to sort this out or we are off. If you are not firm now you could lose your shirt. Forget CCTV survey for now and get the big stuff sorted. Who owns what and what rights of servitude exist. Understand that first.

Ventilation, ventilation, ventilation, stick a living, breathing, cooking person inside a box wrapped with plastic and you are going to get damp and mould.

I didn't put in any central heating in our passive house. None. These are the reasons. 1. Believed the evangelical true believers that seems to think energy is like magic. 2. Stubbornness driven by a desire to outsmart everyone else. 3. Complete confusion with the range of options. 4. The outrageous prices charges for ASHPs by plumbers who can't count their own fingers. 5. Option to fit an A2A was always there. We use a single resistance heater now . It works fine the rooms are all comfortable but it's dear to run. About €700/year I think. I put extra infrared heaters in the bathroom for comfort. I had expected it to be cheaper but we can't bank enough heat overnight on a TOU tariff. Also electricity is after triplling in price since 2019. Time over again I would ..... Fit UFH with a willis heater and the option of an ASHP like @TerryE with electric UFH in bathrooms too. Or install an A2A from the start with electric UFH in the bathrooms.

You can calculate and design it pretty easily. 75mm rigid ducting is ok for 2.5m/s flow speed so 28m3/HR. Assuming normal ceiling heights and a desired ACH of 0.3 then each pair of 75mm ducts will supply 37m2 floor area. So if you have a floor area of say 35m2 that'll be ok with one 75mm supply and one extract. If you have a floor area of 300m2. Then you'll need 8.1 pairs of supply's and extracts. Manifolds only come in 8 or 10. I would be happy with 8 in this instance as it's pretty close. Then sketch out on your plans one duct to each supply and extract room. Double up extracts for the kitchen and then for the dampest/furthest room until all the ducts are used up. Similar process on the supply side. Easy. Keep sketching until you can draw it without any ducts over lapping. That'll make it easy to install. As for materials, It's all much the same stuff. I would buy the cheapest. About £113/50m roll at a quick Google. Leave space for two of these between the mvhr unit and the manifolds. Install your supply plenums opposite the room door, usually over a window. Install the extracts close but not directly over the source of steam. Say 1-2m away and again opposite a door if possible. These ones are cheap and work fine. For the larger ducting to outside I like the rigid insulated stuff. Nice and tidy and doesn't leak as much heat as the metal. Finally site the MVHR unit inside the heated envelope, with short runs to outside for the inlet and exhaust, where it won't cause noise or vibration issues and can be serviced easily . I wouldn't skimp in the unit or buy something too obscure as you'll need parts in future. Aim to have one with a headline M3/HR of about your house volume. That way at normal rates the fans run at about 30-40%. Bargains can be had. This one is ok for about 120m² floor area. If you post your plans I'm sure we could collectively design it for you in about 15 mins.

I worked on a PH project last year (south of England) where the clients decided against any heating and it's been on an ongoing effort to retrofit it ever since. They also based the decision on talking to other people that live in Passivhauses and claim they only turn on the heating twice a year. Be very wary of those sort of claims: the people making them are often highly invested (financially and emotionally) to push the performance of their building. Also just because one PH building does not need active heating it means nothing for the next. ASHP is a bit of a red herring. The question is, do you need heating, and if so where and how much, and then ASHP is one possible solution to that. What is the max heating load and annual heating demand in your PHPP model? This is key. The project I mentioned before had a heating load of 3kW. This can be provided by a plugin 3kW heater - but then they baulked at having 3kW heater on 24/7 through the cold parts of winter (£25 per day). Mains gas or a heat pump are the options to reduce that cost.

This week the roof was cut in. Can see the spaces for the Velux rooflights and get a different picture of the inside - the vaulted ceilings in the rear living area in particular. The builder recommended a ceiling in the upstairs bedrooms at around the 3 meter / 9 foot mark which is high enough even if you're bouncing on the bed! Still leave a bit of space for storage so may leave a small hatch and floor this area after setting it up. It's a warm roof so this is all conditioned space. Next week they'll add OSB and Solitex WA, then baton and counter baton and that's them finished! The roofer is due in after Easter to install the tiles and the Velux will go in sometime then also. There is also an AEV for venting the soil pipe to install. There's a ventilated ridge, and other details that will be interesting to see installed. Should stop ice dams forming! Big decision point is around the rear picture window - it's to be metal clad. There is the option of adding additional insulation on the outside and then stud work for the ventilation behind the steel cladding or just insulate internally only. Also the roof of this feature needs to be worked out. Some drain to the back of the house but that needs a gutter. Most drain towards the house which I didn't realise and the water channels to either side. This junction has to be perfect or it ensures rain ingress. There's a good local team recommended by the builder so I've left word and hope they'll get in touch next week so they can build out the 7 degree backward slope needed for the roof of this area. There is a lot of metal posts in the house which worry me but I had a few hours onsite today to take my time and see if it's something to worry about or not. The contact area with the foundation or wall are very small so there may be cold spots but I feel for a first attempt, the detailing is sufficient. I just didn't realize how decisions about moving walls etc impacted structural changes until I saw them onsite. Decisions made years ago haunting me a bit, but I can live it! It's still a wonderful house. The next two will be better!! The air tightness will be a challenge but I got some samples of Tapes, Gutex and Phonotherm I plan to use by driving to the company I'm buying them off and seeing their warehouse up front. I hope to entice one of their technical guys onsite for an hour to get their advice on a few things. I expect a detailed post at a future date to address this. Lots to think about. I plan on using Moy Metac in the timber frame wall - 220mm worth. The frames are mostly at 600mm centers. I'd calculated I'd need 43 rolls off the plans but now looking like 53 when I did a quic calc onsite. They do a roll that is exactly 220mm deep and 1200mm wide so plan to cut in 1/2 and it should press fit in the space nicely. I could do this before the windows and doors arrive, just need to find a good price! And hope it isn't swiped! Windows to be measured either next week or 2 weeks later due to builders holidays. Delivery 9-10 weeks after that. Bricklayer, still chasing quotes! Hope to get that done Late April / Early May. Waiting on council to approve brick style as the plain red in the estate isn't to my taste, I've gone for a blend of brown, red and beige. As a project there's a LOT to think about, decisions to be made and money to be managed! Spending is SO easy, tracking it and keeping in budget not so much!!

But an ASHP will do DHW as well with a COP of 3 - 4.

Where they are not installed correctly for a passive house. Bollocks. Because people here have proved they work if designed properly 🤷‍♂️(I know mine did).

Many thanks to those who’ve contributed to this thread. I’ve just replaced the bearings in my Vent Axia Kinetic MHVR following the directions above. Unit is 6 years old and had become more noisy with some louder squeaking which sounded like a bearing being tortured. I encountered two issues: when disconnecting the motor cover the circuit board was left on the motor - there are a number of pins connecting it to the motor holding it in place, though was fairly easy to lift off and carefully put to one side. The second was that the bearings were a different size than those above! I’ve shown the motor number and bearing measurements from my unit, so a bit of a setback though quick enough to come from Bearing King - I ordered some high efficiency SKF bearings, more expensive though still only £24 for four. Enclosed are some photos of the process - including one of the poor old bearing that had clearly failed (one of the motors was much less free spinning than the other). While I had the unit off the wall, we took the opportunity to clean the vent pipes using a pull tape and home made microfibre “sweep” - photo included for those interested.

I think it has dramatically improved productivity. EG getting the same job done with less time and less people. Take an average DIY project. We get inspiration from something like Pinterest or Instagram Vs trekking to a library to borrow a specific book. Then we research how it's done on youtube and Buildhub. Avoiding many of the pitfalls of doing it the wrong way and wasting loads of time through trial and error or asking our 1 mate who has tried it before. The I draw it up on my laptop in SketchUp, make a Google sheets doc for the quantities. Try calculating by hand the amount of OSB to sheath an awkward roof VS just clicking on the surfaces in 3d model and you'll soon see how much time it saves. We order materials from Screwfix and the merchants on our phones, pay with cards and they magically appear the follow day. No need to take time off out day job. Before we'd have needed to drive into town, go to the bank, withdraw cash, visit the BM, load it all into a trailer and haul it home. Then look at all the amazing things that weren't available to my grandfather at an affordable price that massively speed up building and often enable a job to be done safely by one person. Here's a few I use that springs to mind. 1. Cordless electric tools. Take on a 9*3 a few times with a hand saw and then tell me technology hasn't improved things. 2. Cable ties 3. My mobile phone. I use it for everything. From all the above bits up to "walkie talkie"ing my wife to flick a remote switch or valve while I investigate the other end. 4. Laser levels. 5. Modern adhesives, tapes and expanding foams. 6. Cheap safety equipment like gloves, disposable overalls, dust masks, goggles and hearing protection keep guys out of the sick bed and in work every day of the week. 7. Cherry pickers Vs ladders 8. Cement mixers. 9. Volumetric concrete lorrys. 10. Conputer designed roof trusses. 11. Cranes, including those wonderful truck mounted remote control ones. 12. eBay gumtree etc allow me to afford stuff like ASHPs at a cheap price. 13. Led Headtorches

Having now lived several years in a near passive house with it's low heating bills and constant comfortable internal temperature, my view of old houses like this has changed considerably. To properly upgrade it will cost a LOT of money. You either upgrade it, or pour lots of money into it every year in heating. I firmly believe that the market value of old inefficient properties like this should be much lower than a well performing house, to reflect either the high heating bills or the work needed to upgrade it. I am not saying don't buy it, but buy it with your eyes open, and I hope you are not the one owning it when the market finally wakes up and people realise poor performing houses really are worth less.

Kitchen and utility room finished. I need to fit the overflow for the utility room as it wasn’t in the pack and fit some black laminate tape to the top and bottom of the cookers as the light grey carcass stands out like a sore thumb. The sink drawer unit has been a pia but I managed to get the kitchen manufacturer to make me two short drawers and I cut out the back of the top drawer to get it to go past the sink. Feels a bit bodgy but it works and looks fine. I’ve made a bit of an arse of the Quooker plumbing insofar that the flex bit doesn’t really work as the weight is fouling the other hoses. I’m not entirely sure I can fix it to be much better. A job for another day. Main thing is we have hot and cold water in the house now.

Go to band p eps, they are a manufacturer not a re seller, save a fortune they will cut what thickness you want so you could go 100mm eps 90eps 80mm traditional sand and cement screed. good thickness to keep the ufh pipes well covered and a good lump to use as a big radiator.

We finally have a flushing loo that isn’t a fly ridden blue plastic box. I claimed the right of jus primae. Shower next so we’ll have one working bathroom. Doors will be finished this week too so we can move in at the end of the month.

For completeness it extracts to a duct that attaches to the back of the hob and runs down behind and underneath the cabinet. This was a fiddly thing to put together. A bit like the scene from Apollo 13 where they have to make a CO2 filter out of bits that don’t quite fit. The duct doesn’t come with the hob though so you need to buy that separately and they do different types to suit different installations.

Ultra / Mapei / Bal etc are all fine and usually on the shelf in most decent outlets. Been installing bathrooms for over 30 years with all of them, never missed a beat . My 2 cents, do not use silicone for fundamental sealing, just use it as a cosmetic seal; I don't EVER use silicone to seal trays before tiling, instead use CT1 as it is a completely different product without the short service life that silicone(s) tend to have.

We're not passive, but pretty well insulated and achieved 1.6 on the air test. We have had our MVHR running 24/7/365 for over 6 years now (except when changing filters). We have one program for winter, and one for summer, and we occasionally put the boost on (to clear cooking smells a little faster). We never open windows. Doors are for going through and closed immediately. Excellent air quality was the primary goal, and that's exactly what we have. What's more, not only have we never had a musty smell, never mind any mould, but the house stays virtually dust (and allergen) free. Best of all, and despite a degenerative lung condition, my wife is still enjoying better health than she did prior to living here. We wouldn't, and she probably couldn't, live in a home without MVHR ever again.

You could make the same point about the central heating. Is that as valid? We fitted our MVHR ourselves. It cost us less than £3K, IIRC. When I did the heating calcs the air recirc losses on the top 2 floors meant that we would have definitely needed some form of central heating solution for these upper floors without it. This would have cost us a lot more than the install cost of the MVHR. We just leave ours running 24 × 365. The running cost is in the noise compared to the heat recovery energy savings during net heating days. And as @dpmiller points out: fresh air and no damp year-round. And yes, in the summer we open windows as and when desired or needed. The MVHR still keeps the wet rooms and unused bedrooms fresh.

@saveasteading the two removable grease filters are in this caddy. The four replaceable carbon filters are in the second picture with two either side. The third picture shows the grease filter caddy/holder in place. Excuse the dust.

I installed 1 row of tiles at the eaves, and used fake lead flashing under the tray to the top of this row, it looked a better option than the panels into the gutter. I mentioned some of it in This blog, but I'll look later if I have any pictures of this flashing detail.

I disagree. I think it's a knowingly unpopular move led by clear science on particulate emissions. But let's just agree to disagree on this.

I think you are into a case "ask 100 engineers and you get 100 right answers". What you need to do, initially, is break it down into important parts i.e. structural forces, thermal properties, looks, easy of construction, price etc. Then analysis each part and how they go together. Some construction methods have developed over millennia and it is only in the last 250 years that post rationalisation has happened. An example of this is one of my favourite discussions about lime versus Portland Cements. They are both interesting and do their jobs well, but many think that the traditional lime mixes are better 'because the Romans used them' (even though the Egyptians beat them to it by a 1000 years at least). Another example is, as you have found out, is to do with cavities. These are a relatively late development and were originally just a rain screen over a solid structural wall. Trial and error, plus improvements in materials and manufacturing processes, the simple wall has changed to a two walls, tied together, with some being single load bearing, other both load bearing, and sometimes filled with insulation. The designs are used differently for different purposes, sometimes it is just decorative, other times it is structurally important. Another area you will soon find out about is the thermal performance, again, there are many different opinions. Some say that you need the insulation on the inside, other say on the outside, this is because while mathematically the U-Value of a wall is the same in both directions, the energy inputs may not be i.e. a heated house may be putting 5W.m-2 though a wall at night, but when hit by bright sunlight it may go to 100 W.m-2. Totally different regimes for the same structure. Then there is air and water tightness. Traditional masonry walls are inherently 'leaky', so putting insulation in a cavity may cause thermal bypass problems or the insulation type may absorb water. This is why internal insulation (on the room side of both cavities) can give a better performance than the same amount of insulation value within the cavity. The same may be true for external insulation, but could be harder to fit because of roof overhangs and window reveals, but is often easier to install because there are no joists or wires to move (this is more about retro fitting than new builds) So basically, it is hard say if there is a best system, it is a case of 'it depends'. All systems can work well if designed right, just as all systems can fail if executed badly (by twat builders). The main things to keep in mind are: Will it be strong enough Will it keep the weather out Will it look right Will it last Is it affordable (the space station is strong, thermally brilliant and air tight) Can it be repaired and modified That is enough to be going on with I think.

If you don't use a prepared for- or installed- MVHR how do you deal with humidity and "odours" in the wetrooms?

The other "trust the theory" thing, is from the experience of others, I believed my house would be well insulated enough not to need any heating upstairs. So I didn't for any in the bedrooms. Instead I fitted an electric point on the wall of each bedroom for a panel heater if they proved to be too cold. I have never needed to fit those panel heaters and the points for them remain unused.

Another point, I stayed in a passive house many years ago before I knew much about them. And like you, thought it was stuffy. The house was empty and we were offered it as workers accommodation for a few days. It was well into the stay that we realised the mvhr unit was turned off, probably because the house was empty before we were given the keys.

Thanks to the relatively mild weather this winter i decided to start chipping away at the bathroom project, which is being extended into part of the extension which was finished over a year ago. This gave me the opportunity to install the bath, sink and toilet in the new bit, at which time I’d totally disconnected the old bathroom allowing me to strip it out and that’s worked really well for my as I struggle to do more than 4hours in a single day so I could keep doing a bit and stopping when I’d had enough. didn’t fancy tackling the ceiling for plastering in the new bit so got a pro in to do this bit for me, all done in a couple of hours which was nice. and made the most of the space and got the painting done after putting a layer of 10mm marmox board down ready to accept the underfloor heating mat Next job was to start making a frame to hold the toilet frame and the sink and cabinet Decided on making my own cabinet rather than paying silly money for an MFC one, got pine furniture boards, a pocket hole jig and a new router and came out with this which I’m pretty happy with that all got painted and the sink installed, wall mounted tap and the wet room panels that I’m using both for this and for the walk in shower area all installed. got to work cutting the OSB backing and wet room panel for the toilet in prep for the final big push to disconnect the old and commission the new, that was a hard days work! And then bath and toilet all installed once the shower area is complete the bath will be disconnected again to lay the underfloor heating, self leveller and the flooring before being put back in place, and eventually building the wall and plastering it. Made a start on stripping the old bathroom out Next job is to patch up the loft insulation where the old spotlights were, new wiring in place for a single light fitting this time, airtight membrane adhered to the walls and then battens before reboarding it ready for plastering. Floor is coming up also to be replaced with 22mm chipboard to match new bit.

Hello. I am an MVHR Designer and I thought I would weigh in on some of the posts made, as I think they are a bit misleading. This is incorrect. Where i-joists are used, rigid ducting is the norm. The major advantage being the ease of cutting holes in i-joists, and the amount of holes that can be made (following guidelines on the data sheets). People often think of semi-rigid (flexi) ducting as space saving, but clearly with this type of joist you would require far more holes because there are far more ducts. A good designer will ensure the guidelines for holes are not breached. It is straightforward to cut duct with a hand-held grinder, even with a 1mm cutting blade. See my post above, rigid ducting is the norm where i-joists are used for the floor structure. 28m3/hr down a 75mm duct is fairly standard for a lot of companies, however, an optimal design will use two ducts for this flow rate (or higher). Bearing in mind that lower air velocity = lower pressure = lower sound. Most people would rather spend a bit more, have more ducting etc to have an inaudible system, over saving a few quid but having a system they can constantly hear. This is generally true. Rigid steel ducting tends to be lower pressure/sound. Semi-rigid does get unnecessarily harshly judged in my opinion. I have designed perfectly good systems for Passivhauses. In my experience it is due to many early systems being in semi-rigid, and were poorly designed and/or poorly installed. Even though it is straightforward to make connections airtight, I see more often semi-rigid systems with leaks due to improperly connected ducts to manifolds, plenums, etc. With rigid steel duct you just push it together once and it is airtight. And lastly the high volume of air many companies design for each duct. When I design I aim to put less than 26m3/hr down a 75mm (ID) duct, and less than 18m3/hr down a 63mm (ID) duct. To the OP, it looks like a nice system.

Thank you for that, I might have a word and see if they can offer something for us.

This is a copy of Andrew Jones's on stage presentation at The Home Building & Renovating Show in March 2024 at the NEC (Suggest you watch on youtube) -

My justification was, I am earning, if I don't spend on this, it will go on rubbish elsewhere. The spend now, while I can afford it, is a reduced utility bill when I can least afford it - retirement. It's a better return than a same money in a pension pot.

Yes, an extractor to the outside. It's through a gravity flap which has a rubber seal on and is pretty airtight, certainly not entertaining any backflow. It will very rarely (depending on wind direction) flap open briefly on very heavy gusts and so I've considered going to a motorised damper, but it's just not bad enough to really worry about...

When I signed the contract for our timber kit I hadn’t fully appreciated the financial exposure we’d let ourselves in for. It wasn’t clear in the contract that for several months the timber kit company would have 80% of the total kit price. I tried to get them to put some kind of financial protection in place in case they went bust and despite them saying they would look into it they never did. Fortunately it turned out fine and the kit turned up etc. However during that period three companies went bust with clients losing significant sums of money (some documented on here) so my fears about it were real enough. There are a few kit companies that put your money in Escrow so you have protection and I’d only do it that way in future or stick build on-site as I’d at least own the materials regardless.

Recirculating cooker hood with carbon filters and MVHR extract vent nearby but not directly coupled. Boost the MVHR rate while cooking if you want to.

I would never mount a CU on plasterboard fixings. Mark out the exact size of the CU on the wall, cut that shape out of the plasterboard, and extend the cut out sideways to reach the centre of the adjacent studs. Fill your hole now with a sheet of at least 12mm plywood, securely fixed to the adjacent studs. Fix CU to plywood. I would probably even attach a batten to the inside of the plywood in line with the mounting holes so the screws can go through the plywood into the batten. Fill joints and paint plywood.

To make sure the roof leaks in future I imagine. 😮‍💨

WHAT temperature does she need to be comfortable? In a well insulated house, forget the concept of fast heat. A properly well insulated house will keep it's heat for a very long time, so forget the old concept of turn the heating on in the morning (when you might well want it to heat quickly) and turn it off at bed time and let the house cool down overnight. A well insulated house simply does not work like that. It heats up and stays warm. So just choose what temperature she wants and set it. It does not matter if on first heat up it takes a while to get there. It barely cools down any overnight so takes little time in the morning to heat up again. Or just leave the ASHP running 24/7 just controlled by a thermostat.

See Also I guess Granny is not going out much so will need heat 24/7 so I think most ASHP and UFH works on the principle of constant temps not neat up and cool down. Therefore a well designed ASHP system will work with additional Granny’s instant heating.

All plumbing done. You can just about see our tundish behind the new OSO UVC. The small extension to the consumer unit contains the 240VAC power relays to switch the Immersions and the slab Willis and pump. Everything neat and tidy. Jan is a happy lady. We've also had a couple of deep baths to celebrate. Still got to tidy the last power lead. The shelf above is my "network rack" 🤣

Yup. Cheaper than shoplifting. ASHP is a no brainer if you can, otherwise (as it’s an attic essentially) then A2A air con for heat and cool. Average CoP north of 3. Air conditioning in an office in a loft in the summer will be heavenly, and I doubt it would be otherwise survivable. Windows wide open / drafts / noise etc isn’t always practical in an office, unless it’s in the middle of nowhere and deadly quiet? I’d sack the UFH off and go A2A.

I have always held the view an electric boiler is a solution looking for something to solve. If you are going to heat the house with electric resistance heating, just fit individual panel heaters, controlable room by room. An electric boiler just adds complications and cost to achieve the same aim (if you are lucky) of heating the house by direct electric resistance heating.

Depends where you are and your climate (you price in € as the only clue to your location) Under floor heating from an Air Source Heat Pump will be the cheapest "electric" heating. Roughly 1/3 the cost of direct electric heating. And it can heat your hot water as well.

It's the "system" built up around the BUS grant that forces a cartel to charge as they please. Perhaps the journalists would do better if they looked at an installation in detail, costed the equipment supplied, noted how many people and how long it took then ask "so how can you be charging £4K for 2 man days work"? (for example)