scottishjohn

you have basically confirmed my thoughts --fit ufh in good insulated slab anyway , our climate here is very similar to cornwall --continuos spring interspersed with a bit of cold and heat # over heating --wife will soon sort that that -she is a window opening freak . so sounds like smallest ashp you can get --3kw will kill the job . Or i might go for solar thermal as ihave had until recentely 2x20 thewrmoax evac tubes onroof of present house 20years ago idi a retro fit underfloor system in this house by routing all chip board floors ,then coveringwith 6mm ply it has workeed well and solar actually contribute to space heating as well as the hot water# downside was storage tnak not large enough at 300litres so in summer it sometimes looked like a steam engine . kit i got then was crap --not the tubes ,but all other bits ,like plastic air separator unit --yes it melted and so did the panel sensor rersult so much heat that the plastic insulation melted off the copper pipes --so thats 170c + for sure . maybe will do what I always wanted and use to .solar thermal and large tank if heating load is as low as you say . the day I finished the installation was in february --i turned off lpg boiler and on a good sunny day it would run UFH att 25c + lifting tank to 50c so maybe my nutty professor idea of a 5000 or10000litre concrete tank insulated to death on outside could be a winner will wait to see final heat clacs when house is fully designed to make decisons --evactube panels are half price of what they were so i could have twice the are for same price

maybe i,m being a bit cavailer --but me, I would start with insulation below it and make it twice the thickness you think-you can always dig down to your exsisting found and see how thick that is --then make yours thicker --bit more concrete is cheap enough at this stage --you get alot of concrete for 8K- -scotland rule is founds are twice as wide as wall on normal ground ,wider if its soggy ,you can always drill and "rebar " it to exsisting found as well at that stage , brick tie brackets or full length angle plate on exsisting walls to secure your sips to them as well -job done, just my thoughts

If you check out integraspec ICF they do end sections for window +door holes so you get complete insulating wrap,no wood -- sono cold bridge anywhere --so maybe use something like that +dpc and then coping stone ?

doing some reading it would appear ,if you believe the hype, that a passiv house can do without UFH I find this hard to believe and would welcome all views on this subject my thoughts at this early stage are to fit UFH pipes to slab anyway -at least . I have even read that next year there will be a graphene heater element that will work with tessla power wall and solar Pv -- that too sounds a little star trekish

durisol is maybe front runner for my projects ,but may go SIPS. on paper durisol if roughly cement rendered both sides to seal them give best "u" value of anything ,as far as i can find ,presuming you beleive what they all say and add a layer of PIR on outside and you got passiv house although they say no bracing is needed they also say only 4ft per pour. my thoughts ,and correct me if you disagree ,why not just use a little low expansion foam or "no nails" as you lay the blocks --that should help with keeping them in place

Hi, i,m a 67 year old finally getting round to building my own house and along with brother and one for him as well 2 x 1 acre plots bought in s/w scotland overlooking the river cree estuary on the solway with outline planning already --now the problems start .LOL now its trying to sort out the best way to proceed --been hunting internet for a few months now already so expect lots of questions been in the motor trade for 40 years , so plenty of hands on engineering experience , in performance tuning conversions and racing , last thing we built was our garage about 30 years ago 30m x 24m portal frame unit and then total rebuild on a petrol station .but never a house ,so far OH and built a couple of PFA aircraft as well, a kit fox and a europa ,fingers getting itchy for a different challenge