jack

1. Yes. 2. Possibly feasible, but from my point of view is mostly a set of drawbacks. I actually had a leak in our UFH shortly after we moved in. It appears that an electrician who was asked to do something at the last minute before the polished concrete floor was laid accidentally drove a screw into an UFH pipe. I dug out the concrete around it and fitted in a loop of UFH pipe using joints. It's been over 6 years since then and no problems. That said, this leak was relatively easy to find, because it was right near a recess for a socket (which is why the electrician was involved). If you had a leak buried in concrete you'd have more of an issue finding it, but the real question would be what would cause such a leak? There are no joins if you do it properly. There's very little thermal stress given you're running low temperatures. I can't really see what would be likely to cause a failure.

A few years back I went to a friend's house who'd just finished a full-on gut and renovate. They'd put in UFH on the ground floor, and basic building regs insulation with little attention to airtightness. I found their house to be uncomfortably warm, at least partly due to the blood in my feet boiling from being in contact with the hot floor. If you have decent insulation, you only need to run your UFH at a relatively low temperature. In my case, I've turned down our ASHP to the lowest temperature it can do (25 deg C), and that works just fine in all but the very coldest weather. The polished concrete floors are extremely comfortable in winter, and pleasantly cool during those periods of summer when the ASHP is run in cooling mode. As someone else said, the stuffiness could also be a lack of ventilation. MVHR will help with that.

*better than

Yes, but my house was 98% complete when we moved in!

Half-hour minimum. Often, if I have a project to do over the weekend, I spend Saturday looking for all the tools and materials. It's usually dinnertime by the time I've found everything I need, so I finish up for the day. Sunday morning I go to start again, then realise I'm missing something essential. Quick trip to Screwfix or Toolstation (me not being able to start a job without such a trip has genuinely become a standing joke in our house), back home, half an hour finding all my gear again, then if I have any time left, I make a start. Rinse and repeat. Now you know why it took nearly 5 years from moving in until sign-off.

Every time I start a job, it takes me half an hour to find all the tools and materials I need (even if I was working on the same job yesterday). Half an hour a week would leave progress at a permanent standstill.

They stopped selling direct to the public a few years back, but they recently (less than a month ago, I think) changed their policy.

If you want an ICF house, build an ICF house. You obviously have it all figured out.

We have a Resitrix membrane. The product itself is excellent quality - tough as boots and feels like it should wear a long time. We had some installer issues though, as described in tedious detail on BuildHub a few years back.

We've got a 5.5m triple glazed lift and slide, and a regular glass door. I think it'd be very annoying having to open the sliding door every time you wanted to go out into the garden. In fact, if I were doing this room again, I'd ditch the sliding door altogether and put in some large opening windows instead (maybe with a pair of French doors in the middle). The way it's laid out at the moment, there's really nowhere to put furniture without having it back onto glass of some sort.

Exactly the same experience for me. We had a couple of receipts in the name of people working on site accepted (the trade price that they passed on to us was way cheaper than we could get it even taking into account VAT reclaim). I even had one receipt in some random person's name accepted. It was from a builder's merchant. Ours was a cash purchase. We assume that they accidentally used the previous customer's details when putting our order through the system, and we didn't notice until years later when we went to claim. All was accepted first time without question. I do think that being meticulous with your notes helps. We used the covering letter to explain every slight inconsistency or oddity, and that seemed to work. I suspect it might depend who you get. I definitely get the impression that HMRC's behaviour in this area can be quite variable.

Where are you getting these temperatures from? Models? Real world data? Bear in mind that to achieve the same U-values as the sorts of foam insulation typically used with concrete, you'll have a significant thickness of cellulose, and cellulose is an insulator (i.e., it resists movement of heat). You therefore can't just assume that the same internal heat gains will result in cellulose reaching 30° while concrete will only increase to 23°. On a warm/sunny day, you'll also have heat traversing the insulation from the outside. Assuming the use of low heat capacity foam insulation with the concrete, heat will traverse the insulation much faster than a high capacity insulation like cellulose. That's because the energy added to the outside of the insulation needs to raise the insulation temperature to cause the energy to move through the insulation, and you need more energy to raise the temperature of a given volume of cellulose than the same volume of foam insulation. Also, because the cellulose is thicker (necessary to achieve the same U-value), heat will take even longer to traverse it than the foam. Why do you believe that concrete returns heat to a room overnight, but the cellulose somehow immediately drops from 30° to less than room temperature such that the house needs additional heating? For what it's worth, I live in a cellulose-insulated house and it doesn't behave anything like how you describe. It's generally pretty resistant to temperature change, much like how high "thermal mass" buildings are said to perform. It tends to take a long time to get warm, for example, but once it does, it retains the heat for a long time. This can actually be a bit of a disadvantage, because after a string of hot days, even aggressive night-time purging doesn't always cool the building fabric enough to overcome daytime gains. Dense-pack cellulose tends to resist air movement. We achieved under 0.6 ACH (i.e., the Passivhaus requirement) with no special attention to airtightness other than a good basic design and paying some attention during construction. Why do you think cellulose houses aren't soundproof? Our house is as soundproof as any other house I've been in, and others on here have remarked on how quiet cellulose-insulated houses can be. Solid feel is something I agree with. I would prefer that concrete or masonry solidity, but it isn't a big deal. I should add that if I were building again, I would certainly consider some sort of ICF construction. My main point is that you seem to be making a lot of assumptions that don't bear out my experience.

Yes, you do. It certainly doesn't hurt, but I can't say I've found ours to be hugely effective. The main issue is that unless you run the MVHR on boost overnight (which is when it will generally be triggered), you don't actually exchange all that much of the cooler outside air for the warm air inside. You also use a lot more power on boost compared to the standard setting. As long as you don't have issues with noise or insects (or you have insect screens), opening windows is much more effective. If I were doing this again, I'd include concealed roll-down insect screens on all bedroom windows, and on at least a couple of downstairs windows that can be locked open a crack at the rear of the house, to take advantage of stack ventilation without being eaten alive by insects.

Welcome to Buildhub. Many of the objections are irrelevant. The question is whether the application meets planning requirements, not whether there's a "better" (according to your neighbour!) way of doing it. Things like drainage and insulation are covered by building regulations, which happen after planning is approved. In general, it's extremely unusual for a single neighbour objection to have any impact on a planning application. Objections can only be taken into account if they raise valid planning objections, and the planners should already be taking those into account. They can have an impact if the neighbour is able to see an issue that isn't apparent from the planning application (eg, a breach of the 45 degree guideline). I don't know whether any of the objections here would fall under that heading.

Yup. This is overly simplistic imo. You need to look at the interaction between heat transfer properties (ie, U-value), heat capacity, thickness, and how they interact between different layers of building materials. Do you know for a fact that a concrete building with external low-heat-capacity insulation will perform better than a blown cellulose or wood fibre construction having the same overall U-value?

@FM2015 works in the industry, but has done a pretty good job of staying on the right side of the forum's rules against commercial advertising.

I can't recommend anyone, but given the amount of money involved, I'd be looking at getting at least a handful of quotes to compare. One problem you'll likely face if do go the low-energy route (and if you're building a house of almost 600m2 and are concerned about energy costs, you certainly should!) is that lots of suppliers don't have experience with low-energy houses. They make bad assumptions about insulation U-values when modelling heating requirements, for example, but also don't have any gut feel for how such houses work in practice. Our plumber, for example, insisted that anything less than a 12kW ASHP was going to take so long to heat the hot water that the house would cool down and we'd get cold. But our house only drops a degree or so in 24 hours, so not having the heating on for an hour or two while the tank recharges makes no perceptible difference to the house temperature. As a minimum, you might also want to think about what sort of U-values for walls, ceiling, and floors you want to aim for, as this will inform the heating design parameters.

Size isn't everything. Our house is almost exactly half the size of yours with very high ceilings (so large volume), and we comfortably get by with a 5kW ASHP given our insulation and airtightness levels. I have no idea who's done your calculations, but even a 590 m2 house should comfortably be heatable with a single ASHP assuming you go for reasonable insulation and airtightness (the latter being increasingly important to energy consumption as the volume of the building increases).

I had a couple of friends from New Zealand many years who were all over that. Asked an Australian friend of mine if he'd gone to a Catholic school because he said "haitch". Oddly enough, he had done exactly that.

Good point. My electrician didn't charge VAT because he was below the threshold. We bought stuff ourselves for him to install (under his guidance), and then claimed it back at the end.

We have cabling to all TV points in the house. We did use wireless before I got everything terminated, and suffered the usual occasional loss of connection (need to reconnect by putting in password, etc). Solid as a rock since we moved to wired. Same with my kids' Xbox. The worst offenders are printers. I've always had problems with the connection reliability of wireless printers. Hard wiring them makes the experience a lot more pleasant.

If someone just supplies materials, you have pay the VAT and claim it back once the house is complete and signed off. Supply and fit, and most types of labour-only, must be zero rated at the time of supply. You can't claim back VAT on labour, so it's important you get it zero rated by the supplier when it's invoiced. You can reclaim delivery charges for materials when you claim for the materials at the end. You can't get VAT back on services (eg, surveys, architects) or hire (eg, scaffolding). It can get a bit complicated: hire a digger, you pay the VAT on the hire and you can't reclaim. Hire a digger with operator on the same invoice, they should zero rate both the hire and operator. Hire a digger and pay someone separate on a day rate to drive it? Zero rate the operator, pay VAT on the hire and can't reclaim. I've heard it expressed as taking the lowest VAT rate of any component on the invoice, and applying that rate to everything else on the invoice, which is why it makes a difference whether the operator and digger are invoiced together. I'm sure someone will be along to correct me!

I suppose it's possible Loxone will one day start demanding ongoing fees for the software (app, miniserver updates), although I've had it for over 6 years and there's been nothing to suggest they're planning to go this way. Their disengagement with the DIY community is more to do with the fact that they no longer directly sell or support the product themselves. You can still buy it through resellers, and there's plenty of support around on the Loxone Google Groups forum (and probably others). Personally, I think their miniserver and programming environment is a great combo. You can avoid the rest of their expensive proprietary hardware by sticking to DMX for outputs (dimming and relays). There are other options for inputs, although I don't recall what they are.

Welcome. I didn't know Theben did that sort of thing - interesting. I have an 8-channel Theben dimmer as part of my Loxone installation and it's been solid. KNX is supposed to a mature set of protocols with excellent interoperability between brands. Do you have any idea what went wrong?

I wasn't referring to your measurements, I was just giving a hypothetical example of why there's more to stair design than stair angle. The 260mm I referred to is just the floor-to-floor height (2.6m) divided by the number of rises (10), in my example.