JohnMo

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.

The most space-saving method is to buy a variant of the Zehnder Comfoair that has one internally. In warmer parts of the UK it's often omitted - the unit will then regulate the airflow (or even cut it off) if necessary, which can be OK for short periods. We never bothered and we get -9 for days on end. Not sure preheat is really needed in the UK. The units just slow down the incoming air, which isn't a big deal, when its that cold your house air humidity drops like a stone. Fitting seals to the cupboard door will probably enough for airborne noise, if the door is fairly solid. Vibration could be another problem, depending on what you're fitting it to (floor / wall / material, etc). We have a unit in our hall between two bedroom, mounted on wooden stud walls that are lined with two layers of 18mm ply. Hear when you open the cupboard doors but only then. No worries the MVHR filter deal with this. Not really understanding your sketches? Need some more detail

First before you do anything else analyse what actually happening with the heat pump. Are you getting long run time consistently (more than about 15 mins) or are you getting some rapid on off cycles. or something different? I would look to rationalise the number and size of zones to just a couple. The issue you will have are Heat pumps need flow rate Any heat source needs somewhere to dump the heat generated. Think the current setup is good for neither. You currently have so many zones, that when only one or two are calling heat they are all quite small capacity. If you are happy with current bills and house comfort just repair what you have. If you would like to reduce bills also, I would look to engineer the LLH out of the system, by getting rid of most the thermostats, running a more open system (ideally one zone, maybe 2)

Why, if you building a lean to against the house, yes, but a water proof garage no. Our timber frame rests directly on the garage floors, if it sloped so would every wall etc. nothing would be square. Had lots of garages and never had one sloping. In fact build severe vehicles on garage floors, if they sloped that would be a nightmare.

I would decide what you are doing exactly, then update the current plans and resubmit as an amendment. Then get your building warrant after that is approved. Get your architect sorted, you will also need a structural engineer for structural certificate, if you are changing the structural design and as designed SAP report for the new warranty. Take the opportunity to add an ASHP to the plans, and insulate to death and sort your airtightness details.

Had a look to see what I bought, it didn't say assume non bacterial. Air being supplied is being filtered, so not sure is much of an issue. Extract normally isn't, but we use terminal filters to catch the rubbish being sucked out the room, so don't see where the issue would be there either. Not sure how long an anti bacterial coating would last before it was depleted.