JohnMo

May also depend where you live city or county, we have to have a lay-by arrangement at the entry so postman van can park of the road and the first 10m of drive from road edge tarred to road spec. The rest has to SUDS compliant, so self draining. We are on a slope so are having crushed stone with lime through it; so it sets into position, while being water permeable.

Expanding on Gone West comments The maths for downward heat loss in simple terms is Equation. U value, multiplied by area, multiplied (flow temp of water - ground temp below floor). For a given flow temperature. Poor u value, lost heat downwards is higher than upward heat transfer to room. To compensate the flow temperature is increased. Good u value downward heat loss is low more heat to room. To compensate flow temp is decreased. Troubles come with poor u value, as your downward becomes large, so to get a suitable heat supply to the room you have to flow at a higher temperature, (as too much heat energy is going down) which further increases your loss downwards. (flow temp of water - ground temp below floor) this part of the equation becomes larger. In simple terms that means a u value of 0.1 or better, flow temp mid 20s, 0.2 u value, flow temp could be in the 40s for same conditions outside the floor area.

And they are?

As you have a nice well insulated extension to the old building, the whole building is now a sum of new and old parts, not just the old parts. So as far as energy usage is really s new building it not all new and it's not all old. If the EPC only covers the old, it is out of date and needs to include the new part also. As you say easy done and is issued as a new EPC. We had to do same when we renovated and converted parts of the building that hadn't been used for a hundred years.

Run round the show houses in your area check out the bathroom fans, we checked our local ones prior to building, dMEV was very difficult to hear. Non dMEV made a racket. Your choice your money

Or they need to turndown the thermostats and/or the flow temperature at the manifold. We have UFH, it gives a very even spread across the whole house all the time. Basically don't operate like a radiator system, lots of on off cycles as you are wasting energy. Two modes of operation, chunk heating, a few hours to charge the floor, then leave the heat to slowly release or very low temperature for a long time. We tried the later first, but with well insulated houses the normal manifold mixers don't turn down low enough. We tried min setting at 28 degC and overheated somewhat. So went to chunk heating 6 hours at 30 degC which worked fine. Have made mods for next heating season, so I can reliably get to any temp I want, maybe somewhere close to 24/25 flow temp.

It will also alter the way you are allowed to ventilate the property. Better than 3 drives you are driven to MVHR, 15 a simple extractor in wet rooms and kitchen or even passive stack ventilation. Different airtightness and ventilation affects your sap EPC score. So if you predict 5 and get a 2.5 in Scotland, you would have to retrofit MVHR or a similar balanced system. Also if you choose 15 you will have to make sure you meet or exceed the trial house within the sap EPC report, with extra insulation and renewables etc.... otherwise you could fail the EPC criteria. It all fun and one said it was easy, the more you ask the bigger the learning curve. You architect should be steering and helping on this.

Two stages. Before build, done to your drawings and your airtightness prediction. If above 15 (I think) no airtight test required. You build the house, have an airtight test complete, if required Any changes to spec are advised to EPC person, you or the builder sign a form that the details are accurate, send back to EPC person. They issue as built EPC.

I would have a good read in the heat insulation section, will be examples in there

How deep are your rafters and how much room below do you have?

Isn't the 4000W just for overcooking. So the inverter is rated at 3.6kW, but you can add more panels (in your case an extra 600W), so in low sunshine periods you get better performance up to 3.6kW. The inverter has Max AC Power: 3.680 W Max DC Power: 4.200 W

No-one likes to hear criticism, but you need to set ground rules for your guests and enforce them. Sounds like your a pain live next door too; if their complaint is to be believed, I would just keep calling the police to complain.

Just been on the site and the simulation tools. To get a u value of 0.1 you need HCONTROL HYBRID 45mm HYBRIS 210mm thickness BOOST'R HYBRID 35mm So even without any air gaps you are at 290mm, without the air gaps you get no where near 0.1 So even their simulation says it's not possible.

But does that include all the air spaces you have add between each layer? Most of these systems when you take into account full build up depth, do not give any improvement on a basic glass wool. I think we would all like to get great levels of u value without thickness, but it's not realistic.

When we were getting quotes for turnkey the builders were saying they had their own insurance and because of the liability they would not allow us on site, unless invited at key stage inspections. So really depends on what way you are doing things. We ended up doing most the build ourselves and were self insured. Only real issue is liability if someone injuries themselves, so you may want to cover yourself with third party liability insurance. Didn't see much benefit to in theft insurance as the excess nearly covered the replacement cost of anything left on site. We ended having a wheel barrow stolen, that was it, and someone writing on a project plan on the wall. Other thing to consider is rebuilding cost if a storm rips through the place at the worst time.

Difficult to hear the when on. Low energy motors so don't cost any more to run than high output normal extractor. Plenty can go in ceiling. Quick search https://www.extractorfanworld.co.uk/envirovent-eco-dmev-ht17v-zone-1-selv-continuous-ventilation-unit--humidistat--timer-4123-p.asp

No surprise you have mould issues, if it not windy your ventilation rates will be next to zero. If you put a CO2 meter in your bedrooms you would also most likely have a unhealthy level of CO2 during the night. If you don't have vents above the windows, I would crack open the window, there should a way to open very slightly and close the latch/ handle. But in the medium term look at what you could retrofit. Here is good write up, their fans can be picked up a very good prices if you shop about, look for the model number as they are sold under different vendor name in the UK. https://www.zehnder.co.uk/blogarticles/evolution-dmev-technology

dMEV. Almost silent in normal mode, quiet in boost mode. Low and slow continuous ventilation. You need a window vents be open in dry room (bedrooms etc) to be effective as they use cross ventilation to sweep out CO2 in bedrooms and damp air in wet rooms. But more expensive than a normal extractor. Normal fan, makes a racket only on for a short time, not really sure how effective they are if you have a damp issue. Cheaper than dMEV. What ever you choose, don't position near a window or doorway, as it will not be effective.

Some systems allow you use both. Generally I believe load compensation is a active in one room and applies a shift in temperature to the whole house. So if you use the load compensation in your living room and it hotter than your setting, it will cool the CH flow temp to all rooms. Weather compensation is a low and slow, long boiler run times at very load loads. So possibly suits people that are home slot of the time. Load compensation is run it hot and for short periods with some modulation. Possibly suit people out most the time.

Think others on here are using UVC as buffers, Joe90 I believe is, I am using a vented thermal store as my buffer, just converted it to use a 2 pipe layout.

So the boiler is slightly oversized for the coldest day, so anything warmer outside will make the boiler feel more oversized. You will probably need a buffer. If you look at my other posts under heat pumps, there is the calculations for buffer sizing. If you are implementing weather compensation, whole system would be run 24/7 on a variable temp based on outside temp. The heat geek website tells you how the set up weather compensation and how to balance the system. The room thermostats will only be there to limit room temp, so the sun is out and warming the room, the thermostat/trv in that room will turn off the heating in that room only. For this type of system a simple dumb mechanical thermostat/trv is all you need one per radiator.

I really wouldn't bother installing. Manage the room temperature by air temp. Manage water flow temp with a decent mixer at the manifold.

I would run the whole downstairs, upstairs dressing room and upstairs wet rooms as a single zone from one thermostat, get a wireless thermostat and don't commit to its location until you start using the house, them find the best place for it. It is unlikely the bedroom UFH will be on if you are well insulated. Simple 0.25 deg (or better) hysteresis thermostat in each bedroom. It would be worth balancing flows so the bedrooms don't get enough heat to get the thermostat to operate. Turn loop flows down or spread the loops to 200mm spacing. I would delete the utility, hall and landing loops, and just spread out the other pipes routed through those areas across the floor. Based on loop spacing it is unlikely you will need a buffer, as long as you operate a large volume system. The last thing you want is just a bedroom calling for heat as that will lead to the heat pump short cycling. You will need a manifold that can accurately manage flow temps at or below 25 deg. Or use something like an ESBE CUA100 instead of manifold mixer.

Do you have the option of weather compensation? Are you on a heat pump, gas boiler or something else? What sort of house are looking to fit the system too, such as insulation standard, one bedroom flat, 20 bedroom mansion etc as it makes a difference.

Reference condition based dMEV you referred to. I am not in agreement with the comments made with respect MVHR. I have MVHR as our airtightness is less than 3, so had no option. But dMEV, operating based in air quality is a great way to go as ventilation is only done when needed and on a room by room basis, MVHR is all or nothing. I have attached a report on such a system which make interesting reading.Atamate_SDAR+Paper+2019+(1).pdf