Nick Laslett

This is the thread I was thinking of with an excellent post from @HerbJ breaking down the MVHR numbers for another member.

BR requirement for supply is based on no. bedrooms. That is what you see in the first line of the Paul quote. BR uses a different criteria for extract. There is possibly an “and/or” requirement in BR to satisfy the criteria. MVHR are not designed to satisfy UK building regs, but to give you a pleasant house environment (forgive gross oversimplification). But if you install the right MVHR unit it will comply with both Building Regs. The MVHR thread here does explain it, and the spreadsheet notes cover the calculations in detail. Just like the heat loss topic, you can do your own calculations. I will find the link. First post has the MVHR_sizing spreadsheet, and ventilation building regs document. This is what I posted in 2020 to help myself to understand the building regs requirements circa 2020. This was from the Vent Asia website at the time.

This is a complicated topic. My memory from the research I did here back in 2019/20, was that for building regs the MVHRs were turned up quite high, but once the dwellings were being lived in, the MVHR was turned down. This was stated by at least three members here. This is what they imply with the statement commissioned on Level 3 for ventilation requirements. The supply requirements are less stringent, which is why you see the two ventilation numbers, one for BR using the number of bedrooms, the other is a Passive House standard.

MVHR, A/C and ComfoPost all need condensate drains, The planning and installation of all this stuff is where the professionals can really add their value. Many different ways to route all this stuff, but really helps if you design it in from the beginning. Same with the external blinds. Just look at villas in Provence or Tuscany, they all have thick stone walls, small south facing windows with external timber shutters. If you can design in motorised external shutters, this would solve this problem. Won’t suit all house styles. Good video on this topic.

This is the Fancoil thread I have bookmarked. Panasonic have Fancoils and ASHPs.

My vote: Timber covered/capped with Aluminium. My neighbour has Cedral. Impossible to love. Hard redline for wife & I. Tricoya is amazing. James Latham will sell you Tricoya by the pallet, massive decrease in price per board, but far too much material. Do not do what we did. I baulked at the price and work fittings timber covered aluminium like the Marley Alutec system. Basically with Alutec you fit the timber, then you fit the aluminium, so in my ignorance I decided that meant you were doing the work twice. In my defence, the Thermohouse roof boards are so thick, that you need fascia boards taller than the off the peg PVC/Aluminium boards, 460mm. As with most of my build decisions, I decided to go off-piste and make up my own system. We used Medite Exterior MDF, supplied by Latham’s for the fascia boards. We used 12mm cement board for the soffits. All painted using the Dulux Weathershield system. It took us 6 months to cut, paint and install all these boards. Medite’s technicals on Exterior MDF require 7 coatings on both sides of the MDF. 1. Seal all edges with MDF sealer - 2 coats 2. Dulux Trade Weathershield Preservative Primer + (BP) - 2 coats 3. Dulux Trade Weathershield Exterior Flexible Undercoat - 2 coats 4. Dulux Trade Weathershield Exterior High Gloss - 1 coat (but in reality 2nd coat once fitted. ) Each board took 7 days to turn around.

Good thread about the ComfoPost

Fancoils, A/C or A2A heat pump. My build isn’t finished, so MVHR not commissioned. But I did install the ComfoPost fed from UFH circuit to provide 2°C to 3°C degrees of cooling. Can’t wait to get it working. This is probably the worst way to address this issue. All the supply ducts need 13mm insulation, and the plenums, manifold etc. The MVHR moves so little air, that this cooling will not be noticeable. But if I hadn’t done this, I would be kicking myself later on. It would not be going to far to suggest that few on BuildHub would endorse this approach, you are just throwing away money. In any case, right now with just the UFH the house is still at 21.5°C, with it being 32°C outside today. My strategy for cooling our house. 1. ASHP for UFH cooling 2. Insulated foundation with UFH 3. Insulated poured concrete 1st floor with UFH. (part of ICF build) 4. Solar control glass on south facing windows 5. 50cm Roof Over hangs on upstairs south facing windows. (Not nearly enough overhang, possibly pointless?) 6. Comfopost for MVHR Other things to consider: 1. Properly designed window shading 2. External Shutters 3. Fancoils 4. Smart glass

I did not get on with Electric Hot knife at all. For conduit runs and back boxes I just used the multi-tool. Plunge cut little cubes and pop out with painters tool or other flat edge. If I was in a hurry for a long conduit run, I used the Bosch mini grinder to do the tram lines and then plunge cut with multitool to make the cubes. My electrician just used his chaser tool, with dust extraction. Very neat and quick. Just a reminder that EPS will degrade the PVC jacket on standard electric cabling. LSZH or use conduits.

My resident design guru, concurs that these are good places to have wallpaper. The panelling/wallpaper combo is a winner.

I use VMware Fusion, but there are free alternatives like VirtualBox. M1 Macs are ARM based, so you can’t have an x86 partition like you could on Intel based Macs. You can run Windows on an M based Mac, it is just more of a challenge. One advantage of running LoopCAD in a virtual machine, is that you can reset the 30 day counter.

Hamiltons in Norwich https://www.doorsandfloors.co.uk//parador-akustik-protect-500-underlay-6m²-roll.html This was their recommendation, we visited the showroom with one flooring product in mind and totally changed our choice after looking at a lot of products.

Just a point about the grinder. I have the dust attachment, which greatly increases its stability. There are brushes and a spring, so the disc does not touch the concrete until you apply some pressure.

🤣, I wish it was so! My wife always says it is our perfect, imperfect house. At least most of the bodges are of my own making. I find after a day or two of scrutinising a cockup, the pain fades, or you have to do the work again.

@MortarThePoint, seems like a tricky topic. It was never on my radar as being an area that needed special consideration, oh well. I bought the concrete grinding/polishing discs for my grinder and smoothed all the bumps. I used Ardex Feather Finish Rapid Drying Patching And Smoothing Compound to address the dips. (I took it so seriously, I bought a 4m aluminium straight level) Good disc selection and advice here. https://rightlines.co.uk/?syclid=110c7de9-f13f-409c-803f-0bdfabe44a46 We used Parador Akustik 500 underlay, with Quickstep 14mm Engineered wood flooring. the Parador is 2.6mm thick with a thermal resistance of 0.01 m²K/W. Google is telling me that 1 TOG is equal to 0.1 m²K/W, so Parador has very low thermal resistance on the Tog scale, unless I’m confused, which does often happen. The Quickstep engineered wood has a thermal resistance of 0.14 m²K/W. https://parador.de/en/accessories-underlay-akustik-protect-500-1744869?srsltid=AfmBOooaFaFrjJSMVF_Wc4ClyHZbqSLTl4WEjgl9t-tVqKvkH6494yvB The heat transfer from the UFH seems fine. I think off the top of my head that the weather compensation curve has a max water temp of 32°c at -2°c outside, but I will have to check. We have 300mm EPS under the concrete. It is an MBC insulated foundation. We still have cheap foam underlay and protecto mats on top of the wood flooring, so hard to really get a read on the heat transfer. Still have bare concrete upstairs. Even though we have had the ASHP in cooling mode, I might grab the thermal imaging tool and get a reading. We had glued down oak flooring in a previous property, wanted to go with floating at this one. Will be interested to see how I feel about the difference once we are actually living there.

@HughF, I’ve said this many times before, but when I first found BuildHub in 2019, my first takeaway was this overheating issue. All these well insulated houses, with high air tightness overheating in the summer. At that time it was unclear if RHI allowed you to run an ASHP in reverse. I was working in the Middle East and was thoroughly sick of air conditioning 24/7. I thought it must be possible to add enough cooling to a UK house just to take the edge off the summer heatwave, without resorting to aircon. I’m glad that fan coil units are part of the regular discussion now on BuildHub. I know this issue doesn’t affect everybody in the UK, dues to the vagaries of the UK weather. Good luck with your search to find a good solution. I’m sure members with more familiarity with the topic will be along soon.

It was good to hear at the 1h 16 minutes mark that the slab is insulated, not clear what approach they used.

Some notes as I watched. The house has its own mini power plant, generating electricity from gas. Timber frame construction. 21 days to construct the timber frame shell, using 4 men. Save 60% from fuel bills. House can be disconnected from National Grid due to the power generator. Valerie comments on the speed of construction using timber frame, but in 1981 these guys only have hammers, no nail guns. 4 bed house without land would cost £35,000. 14 minutes in and Potton Timber frame factory pops up. They are the suppliers of the house. 18 minutes, It looks like 120mm timber frame, with glass wool insulation and a vapour barrier, then plasterboard. 21 minutes, the much heralded computer makes an appearance. It looks like a Tandy TRS 80. The conservatory has some solar panels, but not many, I bet the efficiency in 1981 tech was probably less than 10%. 23 minutes, they are using Pilkington glass in double glazed unit with reflective layer to help keep the heat in. The conservatory still seems to be using only single glazed glass. 24 minutes, Design theory - “Passive solar space heating” Add a green house to the side of house to capture heat, then somehow transfer it to the rest of the property. Ah more details later in the show, they have a fan that transfers the heat. This actually seems like a good idea. 25 minutes, Argon gas for DGU. “Enables a window to become a radiator!” Maybe a touch hyperbolic. 28 minutes, they appear to have fitted one room of the house with a coal fired heater! TOTEM - Total Energy Module. Will run on methane, diesel or anything in between. Uses a Fiat 500 engine. It produces 15kW of electricity from a generator. Off grid is the future! 42 minutes, the Milton Keynes plot cost £13000. Stopping here for now.

BBC Archive upload of 1981 Money Programme special about Future Home 2000. The program follows the construction of a new build home for the future incorporating ideas for the future of homes. The house was build in Milton Keynes, and is still there today. I’ve only watched first 5 minutes, and the programme has made me smile and chuckle a few time already. It looks like a great program! I thought BuildHub members might find it interesting. Address: 8 Downley Avenue Milton Keynes Google Maps link: https://maps.app.goo.gl/WXyp3NbkvbpM3ZZ98 The house is visible on Streetview. Unfortunate for current owner that this has be uploaded by BBC.

Secon Renewables an ASHP supplier to installers does a very long insulated flexible pipe that is from their Solar Thermal installs. They talk about it being used for ASHP installations and now list it in the ASHP ancillary section of the website. https://www.seconrenewables.com/flexipipe-coils-8463-p.asp

Spec of the Intatec ashp flex hose you can buy from BES. https://www.intatec.co.uk/product/heat-pump-hoses/ I think the MCS MIS 3005 requirements might dictate the specification of the flexible hoses, but I could be mistaken. Here is a thread with discussion on this topic, with links to other threads. People seemed pretty relaxed about the exact flexi pipe requirements. I think the main part of the spec to worry about is suitability for high temperatures. There is a minimum bore to match the amount of heat you want to put into the system. This thread has some good details about a DIY insulated ASHP pipework including flexi hose joined to other pipework.

Just re-reading your first post, and this quoted section jumped out at me. My experience is with one new build. Your project will need to take into account the existing foundation and the new foundations and their relationship.

@yellowbert, thank you for using tags in your topic. 👍 There are always a lot of site and structure specific requirements that need the structural engineer’s sign-off. There are many different solutions to foundations, UFH, etc, no one right way. When I was first on BuildHub researching my build, I came across many posts advocating insulated raft foundations. *Raft/Slab these terms do appear to mean different things to a structural engineer, lets just park that for this post. What I liked about this approach was how simple it was. As a layman it was easy for me to understand how it worked and how it was constructed. I felt that an insulated raft foundation with embedded UFH gave you a finished floor in a lot of quick steps. It removed the need for a separate insulation step and screed step. It reduced the moisture going into the build, which a screed step introduces. The larger the mass containing the UFH, the more gradual the heating curve, whereas a thin screed layer will heat and cool quickly. An ASHP is more efficient giving a low heat for long periods, which suite UFH in a larger mass. Removing the screed and second insulation layer should give you more room height. One advantage of the screed layer is that it can put right any issues in the level of the raft. Here is a useful thread discussing insulated raft foundations, with contributions from lots of members that have an insulated raft. Just to confuse things even more, insulated rafts are also called passive slabs.

This is my first year, where I have been interested in the slab cooling at my place. We are still fermacell boarding at the moment. I don’t have the weather compensation dialled in for cooling, but currently running with a flow temp of 11°C, with room temp of 20°C. There is a thread here somewhere, with lots of useful info about dew point and automating the ASHP temp to track above the dew point. I have just lagged all my pipes, and at the moment 11°C flow temp seems to be working to keep the house cool. The only visible dew is on the manifold, but it is not dripping. We have UFH pipes in our concrete first floor, which does increase the area we have for cooling.

Wow, it is always a surprise to find another building reg, that you haven't observed. My inspector didn’t seem to care about front door spy hole, nor the security chain. Is this actually a building reg? My door supplier never mentioned it. The answer is YES. It gets worse, apparently the DDA Compliance (Disabled Discrimination Act) dictates the height of the spy hole. Sometimes you will need to fit two to comply, eek! Here is the passage from Approved document Q: @Berkshire_selfbuild, you will be alright with a Ring doorbell.