gravelld

It's generally the contrast between cold and hot that causes chilblains. The cold makes blood vessels contract, the warm makes them open up too quickly bursting vessels (that's why they feel warm, look red and swollen). Given your house's designed performance I really don't think this will be a problem for you in the future. UNLESS you do a lot of outside work or you have some condition e.g. Reynaulds. Even then can't see it happening. I'd be tempted to go for plug in heaters but you have to consider re-sale... no-one will believe you that they are sufficient.

@Moira Niedzwiecka Will PM...

@Moira Niedzwiecka Interesting, was your BC Melton? Might be useful to trade some advice in the future!

Is that ironstone @Moira Niedzwiecka ? Are you in Leicestershire?

Seems to be putting a fairly high price on installation, or am I wrong?

Is this higher figure because of the smaller amount of glazing required?

This technology continues to advance. Use the plug in ones. For a new build wire up properly with Ethernet, obviously.

On the gas grid?

It's odd they think that DHW will be more efficient than the lower temps required for UFH?

What's to the left of the picture? Could you build around it, having it encased in another house? My old Uni did that in one of the student bars, quite an interesting effect. On the other hand, you end up with a pretty large dwelling which might not be what you want.

Yeah but there's a maximum of 20,000kWh you can claim for I think... we're over that. After that it looks like it's just the SPF that can alter the payout, which apparently is calculated by the installer. Sounds like no opportunities to game the system whatsoever.

Apparently according to https://renewable-heat-calculator.service.gov.uk we can claim £8,400 over seven years on the installation of an ASHP (not including inflation). My guess this round figure is because we're at some sort of maximum. What's the premium on an MCS install of an ASHP? Edit: looks like I can increase the amount if we get an ASHP with a better SPF.

My understanding was that, even with a high performance fabric first design, it was really difficult to achieve "A" without renewables (which is a weakness of SAP imo). How did you manage it - do you have a heating system which ticks certain boxes? Or installed a bike rack? (only joking, I realise we're past CFSH craziness).

Right, but that's because the burn is more efficient for a number of reasons, I get that. I'm just sceptical that the result of the burn doesn't just go up the chimney. I'm probably discounting the effect of radiated heat and conduction through the metal, but it would be good to understand the science a bit. And do all stoves have the heat exchanger mentioned for the Springvale? Mine doesn't - I take the top fire bricks up and there's just the flue. And yet it claims 75% efficiency!

Are the efficiency ratings realistic? Gut feel is that a LOT more than 10-15ish % of the energy goes up the flue.

When I looked at this, the largest estates were Skoda's Superb (Octavia also large for the class) a Mercedes (can't remember the model) and an Audi (ditto).

But what is a "pass" in SAP?

Sorry... what? What overall standard? Does the Welsh system have some overarching standard to achieve, rather than the individual items?

Maybe I missed something, but in no way is this "just meet the minimum standards". It's going to make a massive difference to a developer box built to 10 m3/(h.m2) (and probably not achieving it).

I think you need to decide on the best insulant for the loft and go from there. I don't understand what you mean by "inconvenience" - all I know is that loose EPS bead will be very messy and probably leave you picking them out of your garden for the next decade or so. What are the target U values for the loft? Blown cellulose? Mineral wool would probably give best value in most cases, but it depends on your overall design.

I think I would trust the airtight paint more than S+C for long term air tightness. Unless your work is the only S+C coat in history that doesn't crack.

With 300mm cellulose it's likely you need to pay attention to air tightness and bridging as Peter suggested. I bring bridging up, because the way you described the build up I'm not sure how the timber frame is encased.

When you get down to U=0.1 I think it's much, much more important you work out the detailing right. I'm thinking particularly how the continuation of insulation and airtightness works at eaves level, but also how well the insulation is installed. It's easy to come up with an authoritative U - work out the R for the rafter section, allowing for a %age reduction for the timber, then add that to the underside insulation, then get the U. Goes without saying and I guess you can't do it, but "proper" warm roof over the top would be better. Would 75mm rafters be beefy enough?

Sounds like you're doing a good job James. The things to consider with cellulose are: - Inherently better air tightness of the insulation itself, which leads to... - Less wind-washing - Higher decrement delay Assuming it's being pumped in and it's a ventilated roof, how do you deal with maintaining the ventilation gaps?

I might be taking you too literally - but I disagree. There will NOT be a "re-think". Societal development does not happen by "thinking" or grand design, it happens by collective action, or more specifically a series of action. That might be action by disruptive (yuk!) startups, volte face by populist governments, fashions, trends, world events... anything. No-one at any point will "think" this through beyond short termist positions, of which I would count things like governmental market control, new product development and so on. Examples like "where will the charging points go" are very myopic. A solution will be found, of some sort. If there's no solution, it probably won't happen in the first place, or people in tower blocks simply won't have cars... sometimes bad shit happens. No technical development in the history of mankind has happened with zero disadvantages. Even the wheel flattened people's toes now and then. As such it's almost pointless discussing what might be, because no-one knows, and anyone that does know is (a) lying, (b) deluded or (c) trying to sell you something. We'll learn and have to live with it either way.