Dreadnaught

I did wonder. I suspect yours is even more colourful! ?

@Nickfromwales, wow, thank you for your comprehensive reply. That was very helpful indeed. I am learning fast. Quite a lot of that was known to me but not all. As its in a conservation zone, effectively yes (or at least the slap a TPO on the moment you reach for the saw as your required to give advance notice). Thank you. Two people have now shot down the idea of electric UFH. You plus one on private message too. So I am moving on from that idea. The next idea is to use a MVHR post heater for space heating. And, with a unit like the Zehnder ComfoCool, for cooling too. Airflow rates with MVHR is relatively low so heating (or cooling) capacity is also low In mid winter, if more heating is required then the air flow of the MVHR would also need to be increased, with possible problems of noise (whistling) and low humidity (possible to be remedied with a enthalpy heat-exchanger) I think that using the ducting for heating and cooling will require for all the supply ducts to be insulated Duct heating can also lead to a burnt-dust smell Any thoughts? Ever seen such a solution used, Nick?

@JSHarris, yes. Thank you. I have learnt this from you. Decrement delay: I have rejected EPS beads for this reason and am only targeting frame systems that use blown-cellulose insulation. My design has a very poor form factor, 4.9. Its a bungalow with a flat roof. As I am following a fabric-first approach and passive house, this probably means 450 mm of blown cellulose all around, possibly even in the floor. A benefit of this will hopefully be a desirable decrement delay. Is is in this context that electric mat UFH is appealing to me for space heating.

True. Terry uses off-peak electricity to store heat in his slab at night, via wet UFH. That heat is then released into his house gradually over the subsequent hours. But with a passive house, I am not sure the slab heat-buffer is needed. A passive house needs so little heating that even direct heating at night using electric mat UFH of a few kW might be sufficient to maintain a constant temperature throughout the day/night cycle even in the depths of winter. Of course I would need to do the calculations but this is my hunch.

Thanks @JSHarris & @Construction Channel. That's clear then! It goes in the draw labelled Silly Ideas.

@Nickfromwales, thinking some more, and taking note of what you said about emitters and the wish to maintain a constant ambient temperature across the day/night cycle in the winter, I tried to imagine the simplest solution possible. Assuming a passive house, this is what I came up with: E7 electricity electric mat underfloor heating throughout, which is on at night with E7 Willis heater and Sunamp* for DHW, again charged at night from E7 cooling: install a cheap (sub £1k) air conditioner (otherwise known as an air-to-air heat pump), if needed Strikes me that this hits all the marks. It would not give the SPFH2 gains from a heat pump, nor take advantage of the cheapness of gas. But, my word, it would be relatively cheap to buy and install and low maintenance! Nick, what do you think? * I believe the Willis heater can now be built in to the SunAmp

Thanks @Nickfromwales. Very interesting and good advice. I only wish I could have a slab! The problem is a tricky site with protected tree roots and a risk of clay heave. The solution looks like screw piling with a void beneath the floor. I am still in the design phase and am hoping things might change by talking to the right SE. Listening to you, I am keen that they will. (Oh and I wont have PV either. I have a whopping (if somewhat sick) chestnut tree slap bang due south and inches from the edge of my plot. I am in a conservation zone. Trust me, I shall be having a close look at this tree). Very good point. I raised the question of decrement delay with Beattie recently but did not receive an answer. I even asked if they would substitute blown cellulose insulation for EPS beads but they said they would not.

UFH pipes go under the floor but, when linked by a ASHP, they can be used for cooling as well as heating, @JSHarris-style. But… air convection works against the cooling effect at the floor. So wouldn't it make sense to put the UFH cooling pipes in the ceiling not under the floor? Or… is the best compromise for both cooling and heating is not put them in the floor or ceiling but in the walls instead? Is this a silly idea? (I thought of this because, in my build, I may not have a concrete slab and have an insulated timber-frame floor instead. It strikes me that it could be just as easy to put the pipes in some of the internal walls as it is it put them on the floor.)

@JSHarris is yours a monoblock?

@jack, wow, spectacular!

Oh interesting. What was your motivation? Did that one bedroom not have much external light?

Oh that's a clever idea, and most encouraging.

What do people think about internal windows in a design? I have large plate glass floor-to-ceiling window on one side of a corridor which could throw light into a bedroom on the other side of the corridor if I put an internal window. That internal window could perhaps be high up (I have 3m ceilings in that area). Its also worth mentioning that that bedroom has no other windows other than roof lights. I am slightly concerned about sound ingress with internal windows. And whether they can be made to look any good. Anybody have any internal windows in their design? What do you think of them?

Its perhaps worth considering that that those USB-A sockets may well be obsolete in a few years time. I personally wouldn't install them now. USB-C is on the way (for all my bits and bobs at least).

@Lots2learn, lets organise that. PM inbound.

Why would you want to pre-warm the air through the ground? @JSHarris points are well made. An alternative if you can really justify the expense might be a brine loop system? But as you are going for a near passive house levels of insulation, your heat demand will be very low so I suspect you wont be able to justify the expense.

@Lots2learn, oh I am interested in how Bartram will make a frame for a PH. Looking cursorily at their website they give the impression that most of their frames are not for PHs. On my list is MBC, PYC and Touchwood but I am far from making a final decision and am interested to learn from your example. While not going for certification, are you going to model your house in PHPP? I have a first model for my design and I found the process revelatory. Recommended.

@Christine Walker, I will be following in your footsteps, quite some considerable distance behind. I have read all your posts with careful interest. I too will not doubt have times when its hard to see the end. I am rooting for you!

@Lots2learn yes I do have PP but I am going to go back to vary it, so I wont be breaking ground until the next spring at the earliest. Bartram is new to me. Looking now. Nearby I see. How low-energy do you plan your build to be on the spectrum between building regs at one end and passive house at the other (I plan to be at the passive house end, myself).

@Lots2learn, nearby indeed. I will be following your build with interest. You're ahead of me. Do start a blog, if you can find the time! Which timber frame company have you chosen?

Welcome, @Lots2learn. Your forum name could equally apply to me! In what part of Cambridgeshire are you building? My plot might be nearby.

An article in this week's Economist (might be behind a pay wall), entitled: Smoke and mirrors. Wood-burning stoves, the picturesque polluters. The government wages a careful battle against a middle-class favourite. https://www.economist.com/britain/2018/08/25/wood-burning-stoves-the-picturesque-polluters?frsc=dg|e

Welcome. For new builds, there is an optional standard for energy efficient homes called the Passive House standard. I wonder if you are familiar with it. There is also a related standard specifically for renovations called EnerPhit. Either route has the potential to provide a supremely comfortable home with very low annual energy builds.

That's great to hear, Moira. And for everyone else, having had the privilege of seeing those windows in person at an earlier stage of Moira's build, I can confirm that those windows really are rather wonderful.

Good point. What might be the monthly rent for a 20m x 20m for a site hut plus container? How might I go about guess-timating that? Any ideas anyone?