Ed Davies

Exactly. A post on my blog on the subject where I try to work it out from first principles: https://edavies.me.uk/2014/08/radiators/ TLDR, I think a heated floor emits heat about 50/50 split between thermal IR and convection/conduction. For a “radiator”, on the other hand, it's more like 1/6th by radiation and 5/6ths by convection/conduction. Multi-leaf radiators maybe even more by convection/conduction.

Re his last tweet, worth noting though that the upfront emissions for PV are presumably because of the amount of coal generation feeding the Chinese grid. AFAIK, there's no intrinsic reason why PV emissions shouldn't be zero, i.e., there's no part of the production process which requires fossil carbon.

I'm a bit surprised there are any cut edges, exposed or otherwise. I'd assumed you order them in the appropriate lengths so cutting isn't necessary. Is that unrealistic? I have to admit, looking at @Cpd's roof, I'm wavering towards wriggly tin rather than box profile.

Yes, that's right. It won't be calibrated so there's little you can say about the actual air change rate but it'll show up leaks and, depending on how you use it, may give you an idea of relative changes in leakage. Here's a thread on the subject from the other place. Sadly, the pictures seem to have disappeared: http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=7396

Maybe now's the time to be starting to play with the home made blower. People obsess on the air change rate/leakage when the house is finished but that only measures the overall airtightness achieved at the inner surface. What you actually want is have the airtight layer further out in the construction so that air leakage doesn't bypass any insulation you've added, so you're not effectively living in a plasterboard tent. So if you put a parge coat on the kitchen brickwork to make it airtight it would be worth checking that for leaks before adding insulated plasterboard or whatever. OTOH, some care is needed with vapour control as well. From a purely energy-efficiency point of view it'd be ideal to have a hermetic seal round the outside of the house with all the insulation inside that. Unfortunately, that'd result in a cold surface accessible to the inside air where there'd be condensation and mould.

They're documentation is not explicit on the subject but I'd assume it's the pressure difference the fan is blowing against. That'll be made up of the any pressure differences between the indoor and outdoor air and the resistances to the flow of the ducts and terminals. If the system's at all properly set up then the duct and terminal resistances should dominate but it could go badly wrong if, say, the inlet and exhaust ducts went to opposite sides of the house on a windy day. What's not clear to me is whether that graph is for both the supply and extract paths together or for just one path. Of course, the pressure caused by resistance in the ducts and terminals depends on the flow rate: the higher the flow the greater the pressure difference.

@PeterW is suggesting making your own “mains”. That's what the inverter is for. (But I'm a bit doubtful about a cheap modified-square-wave inverter feeding a reactive load like a transformer.)

Isn't this table mixing up air change rates needed for normal background operation (around 0.4 ac/h) and the boost conditions needed in the “wet” rooms which will also only need around 0.4 ac/h most of the time? Depending on whether the system goes to boost if somebody gets up in the night the sound levels when on boost are much less important than for normal operation.

If you hire a crane or digger or whatever with driver to operate it then the whole lot is zero rated, not just the driver's labour.

Yep, later came across another page (from a maker of clips designed for fire protection) which basically said it was OK to mix metal and plastic clips to meet the different requirements. https://tidi-cable.com/uk/18th-edition-wiring-regulations-bs7671-changes/ So, I'd think that a cable clipped to, say, the side of a joist would need clips at 250mm spacing but only every third one, or something like that, would need to be metal????

This is 17th Edition, still up-to-date on the spacing? Applicable to firefighter safety as well as just cable support? https://www.electriciansforums.net/threads/clips-maximum-spacing-distance.4153/ osg table 4a < 9 250 horizontal 400 vertical

Doesn't this depend on what they mean by “enlarged part”? I'd assume that if you have a 10 metre wide house then you can add a 3 metre extension on one side then extend that by another 2 metres but not add a 5 metre extension then later another 5 metre extension beyond that so it must mean at least the total amount of extension on one side of the house. But is it the total amount of extension on both sides? From the way it's worded I'd assume not (so you could add 5 metre extensions on both sides if it was detached) but the interpretation section doesn't help make that clear.

Just thought of this: normal mains LEDs (e.g, MR16s with GU10 connectors) have somewhat crude switch mode power supplies in them so presumably produce continuous output. AIUI, filament LEDs, on the other hand, have a lot of individual LEDs in series and work at full mains voltage so I assume they flicker at 50 or 100 Hz (depending on whether there's a bridge rectifier upstream of them). Does that make them unsuitable for use in workshops with rotating machinery (strobe effects making running tools look stopped, etc)?

My thinking would be that you need to do the arithmetic on your heat loss, DHW use, PV generation throughout the year, cost of mains electricity at different times of day (E7 or E10, etc) and so on. Give us some numbers, it'd make for a more grounded discussion.

Let's hope not. Is “non-corrosive” another auto-correct? Whatever, what does it mean?

Assuming the buffer and UFH pipework between them are over 15 litres, wouldn't such an unvented system need inspection? If not, what's the difference?

If you're carrying an oxygen cylinder while fighting a fire a bit of cat 5 is probably the least of your worries.

In general, yes, but a lot of installations can be allowed by permitted development. What's allowed by permitted development and the exact conditions vary a lot between countries. England and Wales are pretty similar to each other, Scotland is significantly different. Not sure about Northern Ireland. If you're in England then this is probably where to start: https://www.planningportal.co.uk/info/200130/common_projects/27/heat_pumps

Also, you can't reclaim on labour but you should be able to get it zero rated so if you hire scaffolding and have the company erect and dismantle it you can usefully get them to split the invoice out into labour (zero rate) and hire (full VAT).

AFAICS, there are some pros and some cons to pre-apps: Pros: If you're doing something unusual it's a cheap way to see if it's worth the time and expense of a full application. Their feedback can be helpful in getting together a full application which goes through more easily. Cons: It takes time and, maybe, money. The planners can let their own prejudices influence the response without review yet if you ignore what they say it might be harder to appeal a later refusal on the full application. Maybe it depends, in part, on the relative cost of preapps and full applications. In Highland preapps are free. I was going for something a bit unusual and had no idea if the planners would like it or hate it (they liked it), their response was fairly rapid (about 7 or 8 weeks IIRC) and the few tweaks suggested in the response were useful so I was overall very happy that I put one in.

Me too. Can't help thinking it's back to front, though. You want the workshop before starting on the house. One of many things I'd do differently knowing what I know now.

For threaded rod, stainless is about twice the price but 1/3rd the thermal conductivity. 14.4 W/m·K for stainless 304 vs 40 or 50 ish for carbon steel. The heat loss difference probably isn't significant but condensation round the ends might be noticeably better. https://www.engineeringtoolbox.com/thermal-conductivity-metals-d_858.html

Mobile phone? IIRC, you don't have a smart phone so probably not one with the bright LED on the back but even so the screen of a feature phone can give useful amounts of illumination if you're even a bit dark adapted. Excellent. This is a good read on the subject: https://www.darksky.org/our-work/lighting/lighting-for-citizens/lighting-basics/ Something that's not widely understood is that it's light going out sideways which causes the most light pollution. Light going vertically upwards is proportionally less harmful (though less than ideal, of course). The key phrase is “full cutoff” of “fully shielded” - the lights only illuminate a puddle below them and don't leak extra light out sideways.

There have been quite a few houses built like that in the Netherlands. Not that big a deal other than the need for the service connections to be flexible. Obviously, there are a lot of houseboats there plus fairly ordinary-style houses which float but also some which are normally ordinary land-based houses but are designed to float when flooding happens.

In the rental house I'm in now there are quite a few bird strikes on one window downstairs, but not on an otherwise similar one just round the corner. I'd speculate that the difference is that the one with the strikes is next to a bush and the birds see the reflection of that and try to fly into it.