I've not been here for a while ... sorry, got a number of ideas, sorry for long diatribe that follows
I do not believe a solid house made from stone,concrete etc needs AC. The thermal mass makes a good job of stabalising temps.
We have Passive House extension,and all internal walls dense-block, so very little temperature fluctuation day-to-day and high thermal mass.
In the 2018 heat wave (went on for weeks) the temperature climbed to 25C (extternal was well over 30C day after day for a couple of weeks), that's quite uncomfortable to "just sit still" in. We used night-venting to cool, but in order to achieve that you have to be there, to open windows / security, so if we went away for a couple of days there would be no night-cooling. and we would gain a degree or two, which we then couldn't lose the following night. Lets the flies in too.
Personally, if I was putting UFH heating in, I would have reversible heat pump and cool in summer (when PV would be plentiful)
Including a complete new septic tank
We put anew digester thingie in when we were having major work done, on the grounds that the septic tank was old and might well fail in near future. We were able to re-pipe all downpipes, which just went to soakaways nearby (too nearby maybe??) to the old septic tank, and now use that as rainwater harvesting
re-wire
did that too in the old part of the house. 4 x CAT5 to each room, and HA for the light switches. Seemed like a huge expensive luxury, but having now lived with it for a number of years very pleased to have done it. The main benefit was to reprogram the switches after we moved in and only then realised what we would actually want each switch to do. And we have added some "master switches" for things like all lights off when going to bed; and also all upstairs lights off at 10AM - I have no idea why visiting kids turn on a light in the morning, and leave it on, rather than open the curtains ... also "pathway" switches to light all the way to kitchen (from upstairs; from the patio when coming in with an arm full of dishes after day turning to night on a balmy summer's evening, and so on. Alarm brings on all the lights in the house; "vacation mode" makes it look like we aren't away (ironically ..). Basically it just gives us flexibility over what the switches do. We haven't actually changed any circuits since a month or two after we moved in, but we changed lots in that period. We have at least half a dozen lighting circuits in the kitchen, individual dimmers for those would be an a nightmare to set each time, we just have 3 switches for 3 different "scenes" - Cooking (full blast!), Chill (subdues) and then Gentle (a coupe of steps down from Full Blast)
We also put in a whole house, plumbed-in, vacuum cleaner. We like that. "Bag" is in the garage, empty less than once a quarter, and all the "recirculated dust" that makes it through the filter of a conventional Hoover is confided to the "bag location"
Another suggestion: put a single isolating switch, with "neon light", for all the white goods in the utility room. These days they all use some parasitic power when "off", which annoys me even if 1W, but so many stories of fires, recalls, and even recalls-after-fixed ... I'm more comfortable with everything physically off when not in use / when we are away.
Alarm, including Fire Alarm (rather than a battery one that you might not hear ... our Fire Alarm sets off the Burglar Alarm sounder, no way of sleeping through them!)
CCTV? Seems excessive, to me, but I would prefer that either the blighters do over someone else or, if they come in here, I have some nice piccies to give to Boys in Blue. We have both overt and Covert cameras, and in the sheds, and where yobs might come over the fence at the back and muck about smashing stuff.
ceilings are simple no complicated architrave
We put in pukka plaster architraves in all the rooms after rewire/redecorate. Made a lovely improvement, and was one of the least-cost, best-feel-good, things we did
Next we move on to PV. ... export, hopefully of 7,000 x 5p, £350, giving £800 pa
Battery and self-use, rather than export?
They almost certainly will be moving to BEV(s) in the future, so additional benefits possible.
BEV has to be at home during the day to benefit ... Our primary BEV goes to work each day; we have debated having 2nd BEV and toggling them each day, so that "the other one" is at home charging from PV, and doing that instead of Battery (or instead of 2nd battery). Shifts £7,500 from battery-budget to 2nd-car budget
Now for heating. ... ASHP could be good
My staring point for ASHP (or GSHP) is UFH, and thus hard floors throughout and no carpets. Also very high levels of air tightness and insulation, so that the low temperature heating easily copes and the house is toasty warm for piddly-little amounts of energy. Having, personally, gone for "zero energy" I now advise "Go for max comfort, but still tiny amounts of energy" instead.
one or two wood burners anyway, but which are not planned for heating the house, just top up
We use, solely, the Wood Burner Stove at the shoulder Autumn/Spring ends, instead of boiler. House well insulated, MVHR moves the heat around, and the "fire" is a very cheering sight.
Our Wood Burning Stove is Passive House certified - it has its own external air supply, so as not to compromise the air tightness layer (by Building Regs requiring a wide open air-brick in the room!)
some rads are doubles, but closer look needed ...
With Heat Pump if you don't go UFH then likely to need much bigger RADs (for lower temperature CH water). If you insulate much better then original sized RADs may well turn out to be right-sized
So where am I going wrong? What am I missing?
As others have said, I too would aim for "no heat" rather than "not much heat". I would still install heating, in order to be comfortable. But well insulated, air tight, the heating requirement is tiny (Passive House has design requirement for peak heating to not exceed 10W / sq.m., so a one-bar-fire would be sufficient for an average 3 bedroom house
)
she would like a WT
I've considered that, each time I raise it on this forum the general advice has been that amateur sized ones are relatively high commitment, and I don't really want that sort of solution. PV, by comparison, is install-and-forget (but the wind blows during the dark of course ...). Solar Thermal IME is high-maintenance, but subjectively from posts here I would say that for 50% of people it is zero maintenance, and the other 50% is more maintenance than makes economic sense. I would NOT bother with Solar Thermal again, I would install extra PV and convert that into hot water only when I wanted it, and use the extra PV juice for something else the rest of the time.
Personally, I thought EWI would be a good idea, but it's an awful lot of surface area, so costs might be too high
I'm in the EWI camp too. The real gains come when you have good insulation, air tight, and zero cold bridging.
If your external brickwork is beautiful its a difficult decision. If not then cheapest is bang the insulation onto the outside of the walls and render over that. The insulation join at the top, "under" the roof eaves and joined to the loft insulation, is the tricky bit - kinda "jack up the roof, put the insulation in, and lower the roof back again"!
Cold bridging becomes exponentially more problematical as the rest of the building is improved. If it gets to the point where it starts rotting things its very expensive to sort out.
If it causes convection draughts it wrecks the whole "comfort" benefit (Passive House wants window inside surface to be no more than 4C colder than air, in order NOT to get falling air / convection / draught / turn up thermostat / exacerbate!)
hence the IWI compromise
Get a Passive House consultant in and see what they say. I reckon the money, spent on the advice, will rule out (or in) some choices, and focus your mind on things that have a more certain outcome.
IWI steals all your, internal, thermal mass, so you can't "store" solar energy from the sun when it is helping in Autumn, Winter and Spring, and you are back to "lumpy" temperature swings.
many, and large south facing windows
You need to keep the sun off them in Summer, but encourage it in during Winter - eg. with overhang.
Helpful to also keep the sun off the West facing windows too - deciduous trees some distance away are ideal. East side too, but sun / air temperature cooler in mornings, so of the three I think that least important to protect.
the smaller number (and size) of north windows might benefit from triple glazing
Triple glaze the lot. Price differential DG / TG unlikely to be significant Pay attention to the frames and avoid and cold bridging etc. and make sure installation integrates with the insulation layer so that is "continuous". You need to be aiming for the inner surface to not get cold and induce convection, and therefore draughts; I doubt you can do that with DG.
We bricked up 50% of our North windows. They weren't really needed, and were hugely disproportionately cold. Those rooms , which were Arctic in Winter
, are now snug. Of course if that is the only window in that room its not a good choice!
One of the biggest difference makers I found and it was late in the process was the search for air gaps.
We had air tightness test of the main house, before we ever thought about building a Passive House extension or major insulation initiatives. Also had Ivan round one freezing cold Winter evening, with his Thermal Camera, having had the heating on full blast all day. That was helpful to see heat-leakage (pleased to say we didn't have much).
We blocked up all the air leakage - amazing some of the places that blower-pressurisation smoke test found gaps to escape through ...
Have you considered an entire rebuild? IE knock it down and start again to modern specs. We are planning something similar and TBH refurbing the existing is soo bloomin expensive and nowhere near as good in the long run
This is excellent advice. Wish we had new-built, rather than improving. And our outcome was that even with a relatively easy building to convert (1960, mostly "poured concrete") it was still far too difficult, so we built Passive House extension to hibernate in during Winter.
Knock down and Rebuild, to Passive House standards, will create a fantastically comfortable building, with the associated known additional health benefits, and capable of being heated on diddly squat of energy.
