JohnMo

Give these an email or call. They supplied mine cut to specific size, quick turnaround. http://www.enviroform-insulation.com/

There is a heat loss spreadsheet on here, think it's in the boffin corner. Unless the ground floor is insulated I would not fit UFH, as so much heat will go downwards to heat the earth below the building, your heating bills will huge. You will have oversized rads so you would run them the same as UFH at low temp for long periods. Our last property was circa 1830, the downstairs walls were battened out and rock wool insulation used then plasterboard. But you will remove around 100 to 115mm from each wall floor space. The other two floors had no additional insulation in the walls, the heating bills weren't that bad really. Look to minimise drafts and air leakage. When you install the log burner have the chimney sealed around the flue pipe, I think they vermiculite fill it afterwards. If you make a good job of draft proofing you may may need to consider ventilation afterwards, dMEV fans install in the same holes as normal intermittent fans, but provide slow and quiet controlled ventilation continuously.

My suggestion would be - Go to B&Q (or other similar outlet) and pick up loft legs. Less thermal bridging than metal, less time, sometimes life is just too short.

I have tigo optimiser and Growatt inverter. But mines 10 panels in a row as a single string. All seems to work ok. With panels on different elevations you would ideally do two strings. But I think I would just go down the route of micro inverter, no optimisers required keeps it all simple.

Or is that 1/10 the cost

Why not use 15mm PIR. Aerogel is super expensive. Same insulation value about 1/3 the cost

Would you need to add a zone valve or manual valves also and effectively circulate through a loop that does not involve the boiler. You need your underfloor heating pump to start, but you also need a loop forming that is upstream of the UFH tcv. This will allow the discharge side the the UFH manifold to flow somewhere and give an inlet flow through the tcv and pump. Without this your system will not move water about the circuits.

I'm just using wireless timer thermostat. We like the house temp around 19 degrees. I know if there is any sun out we will get solar gain also in the winter. So I set the thermostat at 19.5 at 01.30 and at 18 at 07.00 this will switch off the heating, if it's not at 18.1 the heating will remain on for a while. Have found the temperature continues to climb slowly until about 09.00 where it is at about 19 for the rest of the day. Our living room is 20 at the moment (sun out), zero degrees last night, and 6 degrees outside now. We are not quite passivhaus.

Difference in price between day and night is 4x. So you could have cost saving with immersion on coldest days for DHW?

Think I went through every possible solution for our roof including multi foil. I ended up spray foam, reflective airtight vapour control and 50mm service void. If I had a clean sheet of paper I would consider just having external insulation, no cold bringing to think about, easy enough to install. All you wood is within the heated environment, so no condensation risk.

I found through experiment that the lowest input (kWh) to the house for heating is batch charging the floor. Basically the UFH goes on at 1.30am and is run until 7am with a flow temp of 30 deg. Tried running the flow temp for the UFH as low as I could, continuously but the kWh input was huge (nearly double) in comparison. For more or less the same temperature in the house. This depends where you live, ours went of, for a couple weeks and now had sub zero nights, little or no solar gain in the day and day time temps not much above 5 degs. So heating is back on.

If you don't want concrete, why use a screed, which is concrete. Use the proportion of concrete you were going to use in the screed and do strip foundation and insulated suspended wooden floor. Or passive slab. Was told not to use screw piles on a building as you make it worthless, screw piles may have a 50 year life, but a normal building should be there for 100s. How do you replace a corroded screw pile?

If you are going fixed price, make sure you include everything you want in the price. Changes after quote will be expensive. Go over what lights, what sockets/switches etc you need, wall finished/ materials. Make sure you know spec of windows and materials, same for internal and outside doors and handles etc. Know what heating system you want. If you are going airtight, get an air test prior to plasterboard and at completion. Make sure there is a requirement to fix air leaks to meet agreed airtightness after first test. Sounds like lots of decisions need to made, but make them once and stick with them. Upgrades and downgrades always cost after an agreement is signed. If you are not sure agree a per M2 cost to added to fixed price, then if you decide on a floor tile more or less expensive you both know where you stand.

But the air in the cavity will not be at 20 deg unless you have a huge depth of insulation on the outside wall. The cavity assuming no other insulation will be midway between inside and outside temp. So 20 deg inside and -2 outside, it would be at 11 degs, a lot less if a ventilated cavity. On a cold winter day do you choose an insulated coat or a thin single skin rain coat. The single skin will trap air, but you will be very cold. The trapped air the installation keeps you warm.

You will need to look at your contract. But you have paid for a service to be completed, the drawings etc were completed at your request using a paid for service, so they should belong to you. Ask him/her for the the drawings in the native formats.

Not sure if you have soak aways - these can be dug out etc. As there is nothing stopping you as the land owner digging holes. You can bring services on to site, water, electric etc. Rebuilding a walk is a maintenance task, not covered by planning regs.

True, based on 0.4 P/A. 100mm is 0.14 150mm is 0.1

If you are going for UFH make sure the floor is well insulated. Aim for a U value of 0.15 or better. Circa 200mm PIR will give around 0.1 or 150mm around 0.15. Screed on top of the insulation and UFH pipes to bring the floors level with existing.

It will rise, but whether you need heating will depend on your insulation values.

In theory the same thickness wool will loose about 50% more heat than the PIR. However at 50mm the insulation value is not very good. Are you sure you comply with building regs? Even on the external walls? What size studs are you using? As simple sketch may help.

Another thread

Really depends on how you are building, how many storey etc, there was a recent thread on this.

Not sure where the sizing for worst ever case weather comes from. It is only likely for a few hours a year and maybe only once every few years. So pretty meaningless. MCS Standard MIS 3005, requires the unit to achieve 100% of the duty at an external temperature condition exceeded for 99.6% of the year. So you basically ignore those few hours where it could be - lots of degrees. MCS also states supplementary heat is not permitted from direct electric at external temperatures above the design external temperature (“bi‐valent point” or “balance point”), but other alternative auxiliary sources of heat are permitted where this is not reasonable practicable in which case the system becomes a ‘hybrid’ system. Although additional supplementary heat may be required when the external temperature drops below the bi‐valent/balance point, this will occur for very short periods of the year and therefore does not significantly affect overall seasonal efficiency even when direct electric heat is utilised. Heat pump sizing standard rating condition for ASHPs used to be air at 7oC and water flow at 35oC. However, in practice they may be required to produce water at approximately 55oC with design ambient temperatures of circa -2oC. At these latter conditions the output of many heat pumps could be as little as 60% of the output at ‘standard’ (nominal) rating. For example a 13kW ASHP may provide 13kW of heat at 7oC and 35oC flow temperature but it is unlikely to do this at an air temperature of -2oC and water flow at 55oC. The actual output could be as little as 7-9kW and hence, if relied upon for the design of the system, it will be vastly under-sized incurring the cost of expensive supplementary heating and/or lead to issues of poor comfort.

nominal mix, ratio of C25 concrete grade is 1:1:2, in which one part is Portland cement mixed with 1 part of fine aggregate/ sand and 2 part of coarse aggregate with required quantity of water

https://www.heatgeek.com/how-to-size-my-heat-pump-or-boiler-heat-loss-cheat-sheet/ May be worth running through this also