JohnMo

Not sure BCO will give a monkeys. If the SAP report says you pass go, you are good to go. It's what the SAP assessor wants really. Mine wanted manufacturers calculations for U value for the whole window.

The kit was pretty easy overall, the additional insulation added a bit of complexity but it's very solid, pretty much keeps noise out, so quite overall. Only downside is overall airtightness. Better sliding doors would help. But at the end of the day with the dMEV fan ticking over, it's humidity stays nice and low. Heating - doing it again I would do a through wall Aircon unit for heat and cool, instead of tying into the house. The experimenter in me, would do a Larson strut if doing it again.

That was my thoughts also, one of the key selling points is you don't need steel, other than rebar. Other thought was why do you need an 8.4m wide opening. Other was this, for an 8.4m opening?

Not really you should have a 3 point actuator, so it will have power to move one direction and power to move another, plus it will need to read flow temperature

The word should is what makes people nervous, "should" and "is" are very different. Plus all the talk about fires starting from the MC4, it's more likely a "should" than "is", for safety. I prefer to be on the safe side and know when I come to pull the inverter, it can be completed without live high voltage DC kicking about.

To get a notification sent to someone type "@" and continue with no spaces to type the person's name. You will get a drop down list, choose the person - done. Comes up like this in the message @Nickfromwales

Couple of things to watch for. UFH works well with plenty of insulation and with zero insulation, but works very differently in both systems. Different flow temps are needed and different running regime. So don't let loops cross the two different floor build-ups, have dedicated loops in each section. You may want to to run two different manifolds and mixers for each section. They may need very different running temps. The zero insulation build up will require a very low and slow running regime, if you switch it off you will have reheat the whole sub floor each time, which will use loads of energy. The way to operate is to switch on at start of heating season and off at the end of the season. If you really don't want to do that install radiators.

Sorry have never bought in to that. The inverter DC isolator is fine for working on the PV array. But not fine to allow replacement of the inverter. You really need to be able to positively isolate the array, and AC sides to safely remove the inverter. I have 3 arrays and each has a dedicated DC isolator for the array as well as a DC isolator in the Inverter.

Limited head room already, I really would explore the big room feeling of a vaulted ceiling, will make your life so much easier, the additional headroom will make room feels way less cramped. Make a central flat section for running MVHR ducts.

By far the easiest is to put the insulation on top of the rafters, is that possible?

Looking at the drawing, not sure how you will be able to assemble without loads of joints. The material between the rafters will be fine, just a pain cutting. The under drawn sheets you will never get them in big sheets in place there isn't the space. Needs a bit of a constructability review

Depth for depth, done perfectly PIR on paper out performs mineral or natural wools and cellulose. But getting PIR to fit perfectly isn't the easiest job. So realistically natural or mineral wool may out perform PIR by a country mile. Plus there is decrement delay - how quickly the insulation allows heat to penetrate in to the room. The denser the better PIR is pretty rubbish.

Good luck cutting that straight and square. I would fill with cellulose or mineral wool. A drawings may assist visualisation. Why not make it vaulted?

Think you have missed my point. In Scotland you are not allowed to install smoke alarms in kitchens - you have to install heat alarms. They are not the same thing.

That's why you don't install smokes in kitchens, you do heat detectors so they detect real fires, not a cooking smoke. Been using heat detectors in kitchens (various houses) and smokes elsewhere - never had a nuisance trip.