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Yeah but outside the heating season you don't want all that heat anywhere, as heat – wd be gd to turn it into electricity. Even if it could be turned into dhw, a catering kitchen wastes far more cooking heat than it'll ever need as dhw. A client of mine supplies the hotela and boarding houses of Torbay with linen; he has 2 rotating drum drier/ironers that will each process 2 tablecloths in 10secs. Each is 46kw gas fired and it all goes straight out the roof. His dhw water need is a tiny fraction of that, and who else around (on industrial estate) could take his energy, which is readily capturable, being hi-grade. Wd be ideal if it cd be captured and turned into electricity to power a fleet of electric vans – he has lots of em, all doing short urban trips.
Very interesting – but like the argument for energy saving lightbulbs, lagging cylinders and hw pipes etc., energy-saving cooking and other kitchen appliances result in whole-house energy savings only outside the heating season. During the heating season, less heat given off to the house's interior by appliances, lightbulbs, hw system etc.simply necessitates same amount of heat to be supplied from elsewhere i.e. the central heating.
However, if the appliances' etc heat input is electrical, with 22% power-station- to user efficiency, then for the sake of global CO2 it's worth using less of that and substituting e.g. central heating gas at 90% efficiency.
As to efficient cooking, what about induction hobs, which are cool to the touch but heat a suitable (iron, is it?) pan directly by creating eddy currents in it. That would presumably work through an insulated coating or twin-wall arrangement to the pan, including to the underside?
I'm interested in such things as applied to catering kitchens, which exhaust prodigious amounts of heat that's high-grade enough to be fairly easily captured. If only a hot-ish airstream could be directly converted to electricity e.g. by the (presently inefficient) thermocouple or piezo-heatpipe systems that are under development.
Bloody ell, is this a turf war or what? Mike George has massive energy and intelligence – why not help him as an ally, rather than try to run rings round him as if he's some kind of threat?
If you really want to try and develop this debate you need to define what constitutes a “large building” furthermore the geometry would need to be described dimensionally.
Maybe I'll postulate some figures so that they can be proved silly – that could run and run. Or I could propose a mind-experiment in which it's accepted that the building is 'sufficiently large and suitably shaped'.
The Pentagon maybe, covering vast area with untold subterranean levels full of electrical load – would anyone deny that towards its centre, subsoil will have long since stabilised (stabilized) at the annualised 'sol-air' temp at the nearby 'surface', i.e. room temp? In that extreme case, the principle seems established – yes?
Would this building have perimeter insulation to avoid flanking losses?
Probably – it's a trivially easy way to make the building as 'large' as it needs to be.
If these ambiguities are not addressed the whole thing will constitute pure conjecture.
I dunno – it would be very interesting and useful to debate not how big the building is, but how small could get, and which of the numerous other variables would be key. That's a fascinating mind-experiment that's already happening, regardless of preconditions set by the unfascinated. It's also a thermal simulation experiment that's already happening. All we need is some megabucks so it can be a physical lab and site experiment too. Members of this forum are invited to jump on the bus and not have to catch it up later.
The earth in the southern UK fairly deep below ground like 5 m is at a constant temperature of 10 degC.
That 10oC presumably being the annualised air temp or maybe sol-air temp at the surface, above the piece of ground in question? That is, the average between the extremes of winter at say -5oC, and summer at say 25oC? Some say this stable temp sets in only 2-3m below surface, but anyway, temp at that depth is bound to the annualised surface temp – agreed?
So what happens when you arrange for the annualised surface temp to be maintained higher than 10oC, for a year or three? For example by sitting the uninsulated floor slab of a large building maintained at 18-22oC all year round, on the piece of ground in question? It'll take a while, but won't the ground below gradually come up to that average 20oC, at least under the centre of the building? If not, then what's keeping it cold, contrary to its behaviour when it's exposed to and links its temperature to the natural annualised surface temp?
Omitting the insulation leads to a situation of permanent heat loss from the building to the ground.
I'd question that “permanent”.
Any more thoughts on this? I'll be needing answers soon, on general up-spec'ing of HRV systems – like aiming to provoke condensation in the system in order to recover latent heat, instead of dumping it outside asap to avoid risk of wetness in cheap machinery and ductwork.
That was an important statement by David Olivier, which Mark Siddall questioned. Needs an answer!
Yes I saw your link to those on the main window thread – very impressive. Do they do any really cool finishes, or does it inevitably look like shiny coloured plastic? Used to be possible to make grp look like metal, e.g. powdered brass mixed in, and even chrome plate that!
3″ of hemcrete sprayed internally then
What about the old helical rigid galv ducts?
Are we expecting cooking to require less fuel in future?
Lizzie Lines, can you tell us the results of your window quotes invitation? See http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=527&page=1#Item_8
PaulinMontreal recommends Hot2000 http://www.greenbuildingforum.co.uk/forum/index2.php?DATEIN=tpc_reyahkhcw_1144599747
I don't know if it's up what's required here.Hi Paul, from whom I gratefully learned my main ways and means about airtight detailing, in Taunton I guess 2yrs ago!:
I realise I haven't actually done this to an existing building yet; intended to but it didn't happen. In newbuild I've for years full-filled the cavity below DPC down to founds (a good reason to not trenchfill), whatever width that was. Where it's a retaining wall I've put 100-150 of EPS or Cellotex externally but haven't yet had a solid block found wall to similarly insulate externally. As to optimum thicknesses, depth below, possible reduction/elimination of under-slab insulation etc, I'm still looking for definitive answers too. Excavation method I'd leave to the contractor's discretion – plenty of other such digging on any refurb runs same risk from underground services etc.I always do this whenever possible, since I first saw it (in UK), for both newbuild and (usually less easy) for refurb. In refurb, works well with a french drain – there's another added-value. By so insulating the perimeter, those dubious area:perimeter factors no longer apply; the whole slab can then be insulated equally, tho' to lesser standard (or not at all?)
However I just carry the insulation vertically down, which is easily done – so I wonder what the advantage of the horizontal 'umbrella' is – seems to create risk of displacement and general complication.
And I wonder what the optimum ratio of thickness is, between the perimeter and the remaining under-slab insulation. Thicker or thinner? In fact how to decide upon the perimeter insulation's thickness, especially with none under-slab.- AuthorPosts
