Ed Davies

I'd very much like to do the same sort of thing as I think @PeterW wants to do but in a rented house it's not really sensible to fiddle with the mains wiring so I'll probably just put some temperature sensors on the flow and return pipes. It's an oil boiler with fairly conventional S-plan wiring. I'm currently logging various room temperatures and humidities, etc, and have a 1-wire sensor stuffed up the radiator in the room I use as my study. All feed into an MQTT server running on a Raspberry Pi which puts all the data in a Sqlite database. To get a finer-grained view of the what the heating is doing I'd add two mains-powered relays in parallel with the motors for the CH and DHW valves and look at the output with something. Something could be an Arduino (I have a few of various sorts) but actually I'd likely use an ESP32 (haven't played with these yet but read a bit about them) or say sod it and just use a Pi Zero-W. Whatever - something with Wi-Fi which can talk directly to my MQTT server would be least hassle. “Filtering” would consist of only sampling the relay outputs every few seconds, sending an MQTT report if they've changed or once every minute or two if not.

How about a couple of small mains powered relays in a separate small box adjacent to the wiring centre? Run 5 (or 3.3) V or even 1-wire or the like through those. E.g., https://www.amazon.co.uk/Socket-AC220V-Voltage-Electromagnetic-Relay/dp/B00K82ZDR0

I very much like your approach @pdf27 . The equivalent to your £1/bolt metric I use is £30/watt - a rough estimate of the cost of provision of energy off-grid in winter. E.g., for calculation of how high grade windows and doors are worthwhile. There should be an equivalent metric for on-grid. Not just the p/kWh but for the marginal cost of generation capacity: how much does an extra watt of wind turbine cost or an extra watt of gas power (including the well in Qatar, the LNG plants, the ships, etc). I got rather mocked and dismissed by some Passivhaus worthies on Twitter for mentioning this approach. While Passivhaus has a lot to recommend it (it's probably the best standard currently available for, say, a design/build contract) I don't like the way it allows solar gain via windows but not by PV [¹]. Similarly some on GBF have argued for a “fabric first” approach which encourages bigger windows but doesn't allow for “eco-bling” (PV panels) which might actually bring in more net watts per pound. [¹] Yes, I know that more recent iterations of the standard do take on-site generation into account but I think it's still rather indirect. Much better, IMHO, to include expected generation (and variation of generation) directly in the modelling of the house's performance.

One can be sceptical about how much insulation 4mm of anything, however clever, will give but, yes, something vapour closed like that would be what's needed.

Probably is a crap idea: it'll make the concrete under the Rockwool colder likely resulting in condensation building up there. This sort of thing needs a very good vapour control layer to be safe.

And the shallower the light hits the surface the more it's reflected. Straight on it's only about 10%, by the time it's 80° to the normal (10° to the surface) it's something like 60%.

Hire of the materials requires full rate VAT and you cannot reclaim it. Labour to erect and dismantle the scaffolding should be zero rated. VAT Notice 708 mentions scaffolding as a particular example of this in section 3.4.2 https://www.gov.uk/government/publications/vat-notice-708-buildings-and-construction/vat-notice-708-buildings-and-construction So it's helpful if the scaffolder puts as much of the price on the erection/dismantling and as little on the hire as they feel is reasonable. ?

Cute. I rented a very similar house in Tongue (north coast of Sutherland). Had the kitchen extension on the end rather than the back but otherwise looks alike. Same dormer pattern. What's the ground floor? I considered buying the one in Tongue when the owners put it up for sale but various things put me off. The biggest was that the ground floor was solid concrete so adding insulation there would have been hard work. Without foundations and with the water table at ground level most of the year I'd have been very nervous about digging it out to any depth to replace with insulation. They're not all like that, though; another house up the road which I think was originally the same but had a fire many years ago and had been rebuilt a bit larger had a suspended wood ground floor.

Where you have a box of electronics for each panel to do at least part of the job of the inverter so you get a separate maximum-power-point tracker for each panel. Very useful if the panels are likely to get different amounts of sunshine, e.g, because the array is spread over bits of roof with different orientations or slopes or if there's shading that moves across the array during the day. Sometimes the box has a complete inverter and the output is mains AC. Usually then there's a separate box which co-ordinates them all (e.g., doing the anti-islanding stuff and data display). Or each box can just produce an intermediate output voltage with a separate box doing the conversion to mains voltage.

Me, too.

One question though, if you build the garage before getting planning permission for the main house would you get the zero-VAT/reclaim on any of it? Probably not a deal breaker either way but worth considering.

Ah, being somewhat obsessed with airtightness I hadn't considered that possibility.

Yeah, if you try to store all the heating you'll need in the winter during the summer (e.g., http://www.earth.org.uk/milk-tanker-thermal-store.html ) then the numbers won't work. But there're long periods in the shoulder seasons (spring and autumn) when currently harvested energy just about balances your energy use averaged over a small number of weeks and even in the worst bits of the winter there's some energy to be harvested. My rather big bet is that a large thermal store will cover the gap from, say, early December to early February when there's a net energy loss from the house.

Isn't there something seriously wrong if an overflow lets air in? Should it tee in before the trap otherwise it'll let sewer gasses out into the room?

I should have built a shed/garage on my site during the year I was getting planning permission and a building warrant. I now think it would have been fairly straightforward agricultural permitted development as it'd be on a decrofted patch within croft land. Would have been good practice. The 20' container I have is great but something a little wider would have made storage a bit less chaotic and a little longer would have meant there'd have been a lot more weather when I could have been making up the posts and rafters, etc.

Was going to suggest a cat but then I saw this: https://imgur.com/gallery/oMSGxJP

Courageous. And oil has roughly half the specific heat capacity and half the latent heat of fusion of water. And it's less dense so its volumetric versions of those figures will be worse still.

Yes, fixing the price of contracts would be very helpful for some but I'm not really expecting to have many contracts. Talked to a local chap about him doing my drains. Thinking about it, might well ask him to help with the windows as well. Have a recommendation of another local chap to do the steel roof. Will need an electrician at some point (bit far north for you, @ProDave?) …

3.14.11, bottom of this page: https://www.gov.scot/resource/buildingstandards/2013Domestic/chunks/ch04s15.html It's 3.14.12 in the 2017 version but doesn't look much different at a quick glance.

My windows will all be Velux. For simplicity, even the one vertical one will be.

Why's this not like having a house with a couple of outside sockets? Just a rather small house.

Yep, at most they're likely to say “if you want to do that then we have a Euro account you could use”. Looking online they don't seem to be pushing anything of the sort, though.

Absolutely. My only aim, really, is to avoid losing out too badly if the currencies diverge wildly. The problem is storage. I bought all the timber for the floor then changed my mind and decided to do the roof first with the result that about half that timber got sufficiently weathered that it'd require so much sanding that it was better to buy fresh. I suppose I could order and pay for, say, the windows now with delivery at some point in the future but that has its own risks, of course. Thanks chaps, those online accounts look interesting, particularly the Transferwise with a debit card. I'm going to run this past brother in law who flings around considerably more money than I have.

Indeed, always a gamble. OTOH, the price of timber seems to have risen about 10% in the mean time which I suspect is largely a result of £/€ rates so it'd only be like buying some timber futures at the wrong time. Can't really see it getting “worse” (if one has €) than it was pre-referendum but can easily see the possibility of it going a lot further the other way.

I'm currently with NatWest so RBS would be the obvious one to talk to but the RBS in Lybster closed a year ago and the one in Wick's gone or going very soon (not sure). There's one in Thurso, at least for now so could talk to them or maybe BoS or whatever in Wick. AFAIK nearest NatWest is in Aberdeen.