stubiff

Yes, have seen the Willis/UFH threads. If I go down the UFH route then looks like an option, rather than ASHP. Other thing with UFH is not sure it's that suitable with carpets, which is our main preference. There could be a hall, lounge and bedroom on the GF. Edit: carpet is ok as long as underlay and carpet tog is low. So more faff of getting something that's suitable.

They heat objects, not just people, so should work with the fabric of the building. You both mention efficiency, which I'm less concerned about. Guessing a 'conventional' ASHP and UFH setup can have a higher setup cost.

Am thinking about heating and HW for a self build. Current thoughts are: HW - electric boiler, e.g. Stiebel Eltron DHE Heat - infrared radiators, e.g. Herschel Anyone have experience of, or thoughts on, please. Context: No gas supply. 3 showers a day, 1 bath a week. Airtight, well insulated build so hopefully low-ish heat demand. Long term/retirement home so needs to be low maintenance and easily repairable/replaced. Not sure on UFH as it's hidden. Issues in current house, and generally I'd guess, seem to revolve around water - noise, leaks, unwanted heat in summer. Not had a problem with the electrics! Would rather spend £1/2k per sqm on usable space rather than a plant room. MVHR. Probably/possibly PV to offset some usage. Energy efficiency is not the top priority; simple, user-friendly system is. Thinking of all/some wood fibre insulation so may help with retaining/holding infrared heat. Thanks.

@jack Yes, I did read up a bit. It interested me as a DHW solution (the electric version) but then read about not being able to control it very well. Was only recording what other people had commented on.

Additions in bold. Yes: UFH (inc upstairs bathroom), ASHP, hot water tap, insulation, airtight, mvhr, triple glazing, Posi joists, external blinds/shading, active cooling, horizontal wiring, accessible services/utilities, timber frame, Sunamp. Preference/Debatable: Bi-folds/sliders, upstairs heating (non-bathroom), external render, balconies, bath in ensuite, multiple ensuites.

Not that you need/want more, but to provide it in a different way (even if it's not as efficient, it may be simpler or preferred). The link from @pdf27 is very useful, thanks. "As only limited heat can be transferred by air, the heat load of the house has to be very low, if air heating is the only space heating system." Am not necessarily wanting to have all the heating provided by the MVHR, but to get a picture of what 'main' heating is required to make things work. As, if the MVHR is 'required' in an airtight house then it makes sense to at least look at what can be done with it, on top of ventilation. One may choose (just) to have a woodburner, say, to be the source of a 'lot of heat', and let the MVHR + heater do the rest. I know a lot of people have ASHP + UFH (as the main source of heat), but there are other options (preferred or otherwise, which I am looking at).

Assuming an MVHR and fairly airtight, and appreciate that everybody's setup/situation is different. Just wanted to get a picture for heat input, say on an average winters day (no sun!). Do you have the heating on in the morning and it lasts for a few hours (with MVHR on), or right through to early evening, or right through the night. If the house requires an MVHR does it makes sense to incorporate extra heating supply via that, thus using less of the 'main' heat source. Thanks.

Thanks for the replies so far. To summarise where there is some consensus. Yes: UFH (inc upstairs bathroom), ASHP, hot water tap, insulation, airtight, mvhr, triple glazing, Posi joists, external blinds/shading, active cooling, horizontal wiring, accessible services/utilities. Preference/Debatable: Bi-folds/sliders, upstairs heating (non-bathroom), external render, balconies, bath in ensuite, multiple ensuites.

We use the bi-folds a lot (open wide). The problem is they let a lot of heat in! Can't win.

Wondered if people would like to share what they think is the best thing in their build (could be anything, design, service, object, visible/not). If you were doing it again what is the first thing you'd include. If you were doing it again what is the first thing you would include that you didn't or had to retro-fit. What is a waste of space. TIA.

@jack Yes, was thinking the more 'continuous' route rather than expecting it to cool in 30 mins.

For those with, instructions of, or experience of, MVHR with some form of cooling (and extra heating for that matter), am wanting to understand the scenarios where it has benefits. I appreciate it is not really a replacement for AC or similar (as mentioned elsewhere). What is the temperature the cooling part outputs at, is this controllable. How is it controlled, e.g. set a temp that it kicks in at. What range can this be in. Can it reduce the temp by 2/3/4/X degrees. E.g. could it reduce from 25 to 23/22. Assume it would struggle to reduce once above Y degrees. Appreciate different models may do different things. I.e. if some overheating can be reduced by other methods, say fabric/external, then the cooling could have the correct comfort effect? Thanks.

Anyone else with experience of wood fibre, cellulose or equivalent, for decrement delay. Thanks.

@Dan F thanks for the link, and for all the other replies. Before I’d read the link then my summary was going to be, ideally: Have some decrement delay. Have some but not a massive amount of solar gain windows and externally shade them. Active cooling of some sort. Reduce/eliminate internal heat generation, e.g. HW tank. i.e. There is no easy/one solution VC and it sounds like it is quite difficult or costly without active cooling. Speaking to my other half again, then cooling or at least more comfortable summer temps is the highest priority. Will probably start a new thread to talk about cooling. Thanks.

Some insulation is not as good at keeping heat out though. And the difference is, heat coming in affects the house/household, heat going out is just lost energy.

Thanks for the reply. Do you have any other cooling/ventilation (apart from opening the windows!). Assume going for wood fibre instead of the Frametherm would make the delay even longer.

Apologies if this is the wrong forum. Am looking at a timber frame (probably) build in the future. Although one requirement will be retaining heat, another one, possibly as important, will be not overheating in the summer. From what I've read then decrement delay can help with this so maybe looking at something like wood fibre insulation or similar. Has anyone experience of this, or designing for it. Alternatively, would you recommend other methods, e.g. MVHR with summer bypass, MVHR with cooling, UFH with cooling, AirCon, solar shades, anything else. Thanks.