JohnMo

Ours is just about the same, we have tiles and poured self levelling compound to level with the tiles.

No spreadsheet sorry, but info that may help, we run on just normal E7 (13p and 30p per kWh), and my total annual bill divided by kWh consumption for the whole electric (including a standing charge for gas) works out at 16p. Last year's heating season was a mix of trying to batch heat in E7 period and straight WC. This year doing straight WC. Dull, wet, cold day (no solar, clothes washing and drying) we end up running out of battery early evening. We are generally paying £40 less per month average with battery compared to without. 7 to 8 Deg daily CoP should be around 4 to 4.2, above that CoP drops slightly and it's more dominated by DHW and below that it's colder and higher flow temperature so drops again.

Good marketing trick, seems most have no clue how to operate a heat pump, and want to run like a gas boiler, should appeal to the majority. Make their running costs cheaper, but not sure they caught the idea with battery, multiple charge periods every day, run your heat pump on WC for peanuts.

Not sure it would be that good for that either, as @JamesPa says really a battery assisted tariff

That's why I moved from them, monthly bill kept going up even when usage kept coming down.

Couple of things to look at Heat DHW in a set window or two only. I found leaving to sort it self out used bucket loads of electricity. Target temperature anything above about 50 degs target temperature the heat pump doesn't always hit target temp, so the immersion is switched on. The heat pump learns this then does it every time. Depending on house DHW usage one 1.5hr heating slot is ok, or if not enough a 1.5 and 1.0 hrs slots. Do a risk assessment do you need legionella cycles? If not needed, switch the immersion control off in the Daikin controller.

There is a heat geek video out there on settings for the Daikin heat pump. https://www.google.com/url?sa=t&source=web&rct=j&opi=89978449&url=https://m.youtube.com/watch%3Fv%3D-EUeqDSv5ag&ved=2ahUKEwiLtMPJuZKJAxVoxQIHHd4GOQMQwqsBegQICxAG&usg=AOvVaw0Ry-3OeQATO-3oa7i2d-ei You can adjust dT on yours I cannot do it direct on mine. Adjusting the dT adjusts how the ASHP operates, but also adjustable when the heat pump stops and starts.

I say embrace the cycling, rapid on off as not good, but cycling on a controlled manner is generally good. There is a lot of miss information out there, that heat should not cycle, they do and will when heat demand is below min output, and even if the condition doesn't suit the refrigeration side they will manage by cycling. Mine rarely gets down to 4kW output on a 6kW ASHP. I am back to WC mode but in essence doing exactly the same as you comment you referred to but just leave to do it's own thing over a longer period. Couple of givens, at temp where you just start to heat the house almost every heat pump is way over sized, they cycle to manage heat delivered. The lower the flow temp the more difficult the heat pump finds it to control and run for extended periods. I fiddled with the compressor start stop hysterisis to get a 10 to 15 min run in mild conditions. That was a figure I found some useful heat was being added to the house, any less than that the house temp slowly dropped. Some will implement a control strategy where at higher OAT they use the controller thermostat combined with WC. I would drop your flow temp a couple of degrees and monitor. For reference this is mine at 9.5 Deg OAT. About 12 to 15 mins on and 30 mins off. Max flow temp was 29, min power output 5kW.

The major parts are £1500 for battery, about £600 for a decent hybrid inverter, £900 for the PV panels, plus mounts and a few bits and bob, so about 50/50 parts and installation on your lower price quote.

Trouble with A2A is it really depends on the spec you are looking at. It varies hugely by manufacturers and price paid. As does efficiency, humidity control and noise and drafts. Good one are not cheap, but can be very efficient and nice to live with. You get them so they add and remove humidity based on what they are set too, plus some will introduce fresh outside air, so act as ventilation also, in both heating and cooling modes.

Get online, then ring your local merchants. Mine came straight from Celotex via an online seller all the way up to NE Scotland for free.

They also yield the same U value at the same thickness. I used Celotex as it was cheaper at the time. Be careful using anything these AI bits say, they can randomly make stuff up, verify yourself. Also floor U value changes with perimeter area ratio.

Only really when using high temp radiators. With UFH the floor surface temp will only be 1 to 4 degrees warmer than the room depending on outside temp.

Long term 150 to 200mm PIR insulation with UFH pipes at 150 to 200mm centres stapled to insulation and then screed. Ventilation two strategies both will lead to similar heating costs MVHR, no trickle vents Or demand MEV or dMEV. You have trickle vents, but they only open based on humidity rise, these are in all dry rooms. dMEV or central MEV unit for wet rooms. Again theses need to respond automatically to humidity levels. Roof insulation 400mm Wall open to discussion aim for 1.4 or better. Need to look at how windows and doors are installed for cold bridging. Detail airtight details.

Are you in Scotland or England, your profile says both. Traditional in Scotland is sarking boards not OSB. The traditional boards shrink and leave small ventilation gaps, then I would add a breathable membrane, and no need for counter batten, you just slate direct to sarking boards. This then gives the correct wind loadings for Scotland. Why not full vaulted? Then posi rafter and glulam ridge beam.

£90k for DG windows. Aluminium are also rubbish U value. £22k for your plumbing and heating. You need a better ventilation strategy. Only 50% of light fittings are low energy. Looks like a bear minimum building regs build, I would consider upgrading insulation, ventilation, this would make the heat pump half the size. Possibly the best way to get poor insulation, sounds great on paper, but if not done really well performance is poor. If you are building to sell on quickly, ok. But if you intend to live in it, I would look upgrade quite a lot.

If a new build zero vat for one. Other than that stupid expensive

A traditional roof is designed to be fully vented, so insulation above the ceiling only. Adding insulation to the underside of the roof will achieve nothing at best or worst lead to your rafters rotting as they will have no ventilation to drive of any accumulation of moisture. Your money would have been better spent adding more floor insulation to the loft

Just found the reference document average for all domestic is 7.3kW, driven up by the older housing stock https://tools.bregroup.com/heatpumpefficiency/dwelling-heat-loss

@Beelbeebub out of interest do you have a heat pump in your house? Is the house well insulated etc? Do you have any green tech also?

Maybe not

So 1600 years of me heating my house and producing all the DHW I can use. So 1600 boilers a year.

But they aren't expensive. Think the statistic is a 6kW heat loss covers over 80% of all properties. So just over £2k to £3k for just about any heat pump.

Bringing things back to reality, urgent for us but spaceX just relanded a booster rocket, all methane powered, how many thousand boilers would that power a year. But space is sexy so it's ok. Urgent probably, but no one seems to care.

Its just an amendment, the original plan was accepted and initiated, so that doesn't change with an amendment. If you did new planning application, everything starts a new countdown. We changed our planning drawings before getting a warrant and the previous owner had initiated so that still stood.