[Tom Foster]

Pleeese don't fill your valuable empty cavity. True, for now the 100 inner skin is as much massiveness as an ordinary heated house with accidental solar gain can make use of.

But in future, when it gets really serious, you'll be wanting to capture masses of solar heat and feed it into the back face – or middle i.e. cavity – of the biggest thermal mass you can lay hands on – that is, your cavity wall with cavity filled with e.g. weak concrete, or clean shingle if using the cavity to pass sun-warmed air through to charge up the combined mass of 2 leafs plus shingle fill – all inboard of an unbroken 'tea cosy' of thick EWI.

[Tom Foster]

Maxwell's Demon!

If you think that, I can see the flaw in it – can you?

[Tom Foster]

Yes, as noted in my post of 21 Jan above, interseasonal I-ZF would store into the uninsulated ground nearby or beneath (with 'wing' insulation) but that project's presently mothballed.

So am meanwhile interested in 'extended short-cycle' storing into above-ground building fabric, especially as massive as is typically found in older buildings. Trombe with air movement is one of the several ways envisaged, to collect solar heat. Conservatory is a variant on Trombe, with a moving-air collecting cavity battened off the face of the house wall on which the radiation falls, rather than collecting air from the conservatory space itself. The trick is to maximise temp of take-off air, harvesting the temp peaks and rejecting the troughs, as cloud comes and goes, across the sun. That way, the considerable momentary power of the sun can be harvested while it's out, rather than averaging it down to daily-mediocre.

How would your conservatory have contributed to a near-PH insulated/airtighted/MHVR'd house? Would that extend the benefit deeper into the winter season?

[Tom Foster]

Hope the OP is still around – wd like to get an answer to that last Q, and continue the discussion. Perhaps we should “Send this member a personal message.”

Prob not externally lath and plaster, as he's not willing to change external appearance with EWI, so prob timb frame exposed. Should be no problem insulating quite well between the frame members; it's the major thermal bridges created by the timb members themselves, and how much insulation can be applied across their face internally. A case for aerogel applied to the members' face, in strips a little wider than the member. That cd be quite effective.

Or dare I suggest multifoil?

[Tom Foster]

whooof

[Tom Foster]

That's v informative, thanks Mark.

I understand that much moisture has been stored into the mass during summer, when often internal RH and certainly absolute air water content is higher.
I understand that that summer equilibrium gets adjusted down to lower moisture content in the mass, when the heating season comes and internal RH often and certainly absolute air water content is lower.
I understand that there could be a heat demand in effecting that transition, going into the heating season (but presumably that means there would be a heat contribution towards the end of the heating season?)

First point – it seems to me that that heat demand would be a one-off, albeit maybe a prolonged one, of gradual re-equilibriation during the beginning of the heating season. I don't see that humidity fluctuations during the heating season would then continue to be a nett heat demand, exacerbated by larger mass creating larger quantities of stored moisture to be shifted.

Second point – you say that the beginning-of-heating-season re-equilbriation would be by evaporation. Are we saying the summer moisture has been stored into the mass by condensation to liquid? Or is it held in there as vapour, which wouldn't then have to be 'evaporated' but would merely move out driven by partial vapour pressure, which I think would create no external heat demand?

[Tom Foster]

AFAIK what I mentioned before 'in no uncertain terms', was about Interseasonal/continuous storage of masses of summer heat, which will allow future relaxation of the loss-reduction imperative, and will reintroduce the possibility of more indented-envelope, glassier, lightweight, simpler-built buildings – Buckminster Fuller again, perhaps – because the necessary massiveness will be remote (or just underneath) the above-ground building.

That's a future project – I-ZF – Interseasonal Zero-Fuel; for now I've imported much of the ways-and-means thinking that's gone into that, into achieving surprisingly much of the aims of I-ZF, but by short-cycle capture of heating-season (not summer) solar heat and storage of same within above-ground PH-style fabric (not remotely/beneath), and by prolonging the storage duration there, from 1.5 to 2 days, to nearer 10 days.

As it's shaping up, collection should be by natural-convection means, transport at variable volume proportional to current solar intensity, by PV-powered fan or pump (depending on chosen thermofluid). Extra-cost apparatus looks to be minor – mainly a matter of re-arranging fabric elements you'd mostly be having anyway.

The ultimate prize would be complete elimination of backup heating system, for what that's worth. Or at least minimised call on same, if the backup were just an electric element in the MHRV. Or maybe keep that woodburner anyway, for the January black-hole!

[Tom Foster]

That answer is greatly appreciated Nick, and so was Mark's most recent one.

Lots to follow up there; already engaged in some of your suggestions; in addition seeking informal engagement (including engaged disagreement – yes please!) here, on GBF etc.

Just to say, now, that I'm as 'passionate' as you to 'plug the leaks' in all the ways that PH has so effectively prioritised. No way I want to supersede or replace that, and there'd be none better than the Institute to take on some of the ideas I'm proposing, as an evolution of PH.

True I'd like to be able to 'spend' some of my increased/manageable/stored solar heat on slightly relaxing the stringencies of PH-required workmanship and in-use discipline – but that's optional/red herring – wish I hadn't mentioned it!

If you say 'it's been tried and failed before' maybe 'before' was without the benefit of recent development of PH or (near-PH) 'leak-plugging', which I agree is indispensable, to reduce heat requirement to within range of UK-weather solar heat availability during the heating season.

[Tom Foster]

Is this what you're thinking? http://www.artistsdomain.com/dev/eere/web/1940.html

My god! – not remotely!

the building gets lost beneath the panels – where is the joy of living and the quality of life?

It's specifically done without dedicated panels, to get away from 'bolt on technology'. The architectural art of it is to find ways to make the solar building look (near) normal but with a hint of 'something interesting happening here'. Luckily the client wants the building to look like I've designed it anyway – whether it works fully or partly solar-wise will be interesting to us – will it be to you?

Suppose it's too much to wish that someone would say ' tell us more, Tom'. Even tho a faithful AECB member, I feel like an unwelcome intruder, rocking the boat.

[Tom Foster]

OK Nick, maybe I'll read it.

Maybe we need a new word for 'doing more and more with less and less material and resources'.

That's what me and Buckminster Fuller are interested in, so I promise to let you keep 'Growth' for 'doing more and more using either more and more resources or less and less resources, makes no difference, it's still growth to me'.

[Tom Foster]

Is this what you're thinking? http://www.artistsdomain.com/dev/eere/web/1940.html

My god! – not remotely!

the building gets lost beneath the panels – where is the joy of living and the quality of life?

It's specifically done without dedicated panels, to get away from 'bolt on technology'. The architectural art of it is to find ways to make the solar building look (near) normal but with a hint of 'something interesting happening here'.

Suppose it's too much to wish that someone would say ' tell us more, Tom'. Even tho a faithful AECB member, I feel like an unwelcome intruder, rocking the boat.

[Tom Foster]

I'd really appreciate it if you'd say briefly what things happened c1980 that you're retroviewing now, so I can check whether this now is really the same – because I don't feel I've given you much to go on so far.

[Tom Foster]

I wonder what 'This' was tried? I wonder if it was really the same as my 'This' – would it be interesting to
a) check further into my 'This'
b) illuminate rather than dismiss?
So far, I'm none the wiser from your words.

[Tom Foster]

Tom,
I must confess that I don't understand your premis of “beyond PassivHaus.” Once you've tackled the fabric and ventilation (as far as PH) then you're are left to concentrate upon DHW and electrical efficeincy – these are the most cost effective next step.

As I say, PH is brilliant at what it does, but it's not the end of the road – there's always a 'beyond'! So I hope our PH experts, or even AECB with its sponsorship of Gold Standard etc, don't get left behind.

There is definitely more to concentrate on, than DHW and electrical efficiency, once you've tackled fabric and ventilation – especially as DHW and electrical efficiency, by reducing one kind of useful heat input (rightly, because uncontrolled and often electric) merely increase the requirement for fuelled backup heating.

What PH doesn't majorly address, is maximised solar capture as an alternative to
a) fuelled backup and
b) minimised heat loss.

PH is above all about minimised heat loss, as the key to everything, but that's a hard master to follow to the necessary limit (some say too hard for sloppy/cost-minimising British builders and bolshy British end-users) – and PH doesn't recognise that there's a more relaxed alternative. That is, to have more/maximised stored solar heat available, so that both
a) less or no fuelled backup is needed and
b) heat loss needn't be so rigorously minimised.

Solar, I'm guessing, came into evolving PH, first as an overheating problem to be screened out or safely absorbed. Then, I'm guessing, its limited usefulness as a heat source was recognised and that careful balance between overheating and usefulness became well developed. However the danger of overheating puts a low limit on the amount of solar heat that it's prudent to allow in. There's far more out there waiting to be harvested!

That's because PH can hardly conceive of any kind solar capture (leaving aside PVs and wet DHW panels) other than through window glass, incl sunspaces. And once inside the glassline, PH can hardly conceive of any way of receiving the solar heat, other than onto heavy surfaces. That form of receiving has severe limitations
a) as to quantity (intensity x glass area x duration) of solar heat receivable
b) as to ability to remain cool and so resist overheating, and
c) as to duration of storage of that heat.

The fundamental problem is that solar heat is received onto/into the massive heat-storage media on the same face as it later usefully comes back out. In that situation, it's roughly true that only the inboard 100mm of the massive element plays an active role, however deep and dense the element extends backward from its active in/out surface. That thickness of any mass can only offer 1.5 to 2 days max storage of heat, however deep and dense it is. That's the fundamental limitation of PH – solar heat storage duration insufficient to bridge over the length of typical sunless spells, during the heating season. No amount of heat loss reduction can compensate for that – after 1.5 to 2 days there will be nothing to supply the inevitable nett loss, however small that is, but fuelled backup heating.

How about if the building fabric were able to
a) receive and store far more (intensity x glass area x duration)solar heat
b) take it away (largely passively) to storage, from the receiving surface, as it arrives, so the surface remains cool and so does not overheat the interior, and
c) the duration of the massive storage is more like 10 days than 1.5 to 2 days?

Hint – the key to the above is storing the received solar heat into the back (remote) face of the massive storage medium, so that heat travels from there unidirectionally to emerge usefully from the front (room) face. That way, full benefit is obtained from all the density and full thickness/depth of the storage medium, rather than just from the inboard 100mm of it, as happens when the stored heat flow is bidirectional, in/out from the same inboard face.

Would that be a useful step beyond PH?

I look forward to hearing the flaws in this vision, to which I have a client willing to put his money where my mouth is and finance thermal simulation, to get the numbers/sizes on the principle, in this particular location. That's why I'm asking Tas, IES or Hot3000 – which is best?

Wish me luck!

[Tom Foster]

Oi! what about the safety of emanations from induction hobs? Has all human knowledge on the subject been covered in just the first two posts above, leaving the field free to talk about something else?

[Author]

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