Green Building Forum - Passive House with no tapes/membranes, no ducts, no back up heating system. Mon, 20 May 2013 21:29:53 +0100 http://www.greenbuildingforum.co.uk/newforum/ Lussumo Vanilla 1.0.3 Passive House with no tapes/membranes, no ducts, no back up heating system. http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=6890&Focus=113752#Comment_113752 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=6890&Focus=113752#Comment_113752 Wed, 27 Jul 2011 01:17:02 +0100 sinnerboy
http://www.vtt.fi/inf/pdf/workingpapers/2005/W22.pdf]]> Passive House with no tapes/membranes, no ducts, no back up heating system. http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=6890&Focus=114503#Comment_114503 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=6890&Focus=114503#Comment_114503 Mon, 08 Aug 2011 19:41:35 +0100 spoonandfork
Posted By: fostertom(and inner plasterboard too) carried on the flatstrap noggings


does that mean you have to put more flatstrap on the underneath of the rafters when you come to line the inside?]]> Passive House with no tapes/membranes, no ducts, no back up heating system. http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=6890&Focus=114512#Comment_114512 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=6890&Focus=114512#Comment_114512 Tue, 09 Aug 2011 09:49:18 +0100 fostertom Passive House with no tapes/membranes, no ducts, no back up heating system. http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=6890&Focus=114546#Comment_114546 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=6890&Focus=114546#Comment_114546 Tue, 09 Aug 2011 20:46:16 +0100 spoonandfork Passive House with no tapes/membranes, no ducts, no back up heating system. http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=6890&Focus=114557#Comment_114557 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=6890&Focus=114557#Comment_114557 Tue, 09 Aug 2011 22:22:00 +0100 fostertom
Note that this as breathing construction only works if about same again insulation (e.g. EWI-like EPS) lies outboard of the OSB - but that's a rule of thumb you should check to your satisfaction.]]> Passive House with no tapes/membranes, no ducts, no back up heating system. http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=6890&Focus=114589#Comment_114589 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=6890&Focus=114589#Comment_114589 Wed, 10 Aug 2011 13:08:02 +0100 djh Posted By: fostertompuncture the pbd for electrics etc as much as you like.
I thought that the rule of thumb for breathing construction was that the inner barrier should be five times less permeable than the outer barrier?

I think that what you mean is that it's a 'warm' construction, or at least 'semi-warm'.]]> Passive House with no tapes/membranes, no ducts, no back up heating system. http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=6890&Focus=114613#Comment_114613 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=6890&Focus=114613#Comment_114613 Wed, 10 Aug 2011 20:06:32 +0100 spoonandfork Passive House with no tapes/membranes, no ducts, no back up heating system. http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=6890&Focus=114619#Comment_114619 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=6890&Focus=114619#Comment_114619 Wed, 10 Aug 2011 21:42:47 +0100 spoonandfork
internal floor with UFH pipes buried at the lowest part
100mm polystyrene
Solar slab with a dpm in the middle and heating pipes running through the lowest part
300mm polystyrene
foundations
heat exchanger below ground (to dump excess heat and to raise temperature of earth to reduce loss from solar slab). Is this backfilled with earth?]]> Passive House with no tapes/membranes, no ducts, no back up heating system. http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=6890&Focus=114625#Comment_114625 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=6890&Focus=114625#Comment_114625 Wed, 10 Aug 2011 23:46:45 +0100 fostertom Posted By: djhI thought that the rule of thumb for breathing construction was that the inner barrier should be five times less permeable than the outer barrier?That's right, but according to my 'what-ifs' with a Euler diagram program, that 'lnner' can in fact be up to half way thro the insulation sandwich i.e. the OSB outboard of the studs/rafters can be the airtight barrier plus modest vapour resister; everything inboard of it can be part of the interior as it were, and the more or less unbroken EPS going on outboard of the OSB is about 5x less resistant than the OSB. However, everyone check that prescription to own satisfaction.]]> Passive House with no tapes/membranes, no ducts, no back up heating system. http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=6890&Focus=114626#Comment_114626 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=6890&Focus=114626#Comment_114626 Wed, 10 Aug 2011 23:49:02 +0100 fostertom Posted By: spoonandforkwhat happens where the OSB and EWI (EPS?) meets the ground Tom?Many ways of detailing that. Current project uses an internal loadbearing frame and the walls are effectively suspended from first floor, so don't need support at ground level, so don't really touch wet or cold ground and can unite with the slab insulation.]]> Passive House with no tapes/membranes, no ducts, no back up heating system. http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=6890&Focus=114643#Comment_114643 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=6890&Focus=114643#Comment_114643 Thu, 11 Aug 2011 13:29:59 +0100 Viking House Posted By: spoonandforkViking, the first drawing you posted - just to make sure I understand - comprises from top to bottom:

internal floor with UFH pipes buried at the lowest part
100mm polystyrene
Solar slab with a dpm in the middle and heating pipes running through the lowest part
300mm polystyrene
foundations
heat exchanger below ground (to dump excess heat and to raise temperature of earth to reduce loss from solar slab). Is this backfilled with earth?That's correct, but since we found a cheaper source of collector absorbers we're reducing the size of the Solar Slabs and increasing the Solar Collectors area to make it more responsive. The Solar Slab is used as a buffer! The heat exchanger in the ground is back-filled with earth!]]> Passive House with no tapes/membranes, no ducts, no back up heating system. http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=6890&Focus=114667#Comment_114667 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=6890&Focus=114667#Comment_114667 Thu, 11 Aug 2011 19:47:15 +0100 spoonandfork Posted By: Viking HouseThe Solar Slab is used as a buffer! The heat exchanger in the ground is back-filled with earth!

I understand the solar slab stores energy (your original design was for it to store enough for 100 days' heating). But can you draw the heat out as required to the UFH in the upper most slab? I mean, can you increase the flow rate in the pipes and this will heat the upper slab and use up the store more quickly? Or is it just passively giving off a constant background heat that can't be altered?

Tom, what heat source is going in your project pictured above?]]> Passive House with no tapes/membranes, no ducts, no back up heating system. http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=6890&Focus=114673#Comment_114673 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=6890&Focus=114673#Comment_114673 Thu, 11 Aug 2011 20:42:08 +0100 spoonandfork Passive House with no tapes/membranes, no ducts, no back up heating system. http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=6890&Focus=114675#Comment_114675 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=6890&Focus=114675#Comment_114675 Thu, 11 Aug 2011 21:19:36 +0100 Viking House Passive House with no tapes/membranes, no ducts, no back up heating system. http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=6890&Focus=114676#Comment_114676 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=6890&Focus=114676#Comment_114676 Thu, 11 Aug 2011 21:39:59 +0100 Viking House Posted By: spoonandfork Do you have any info on using the walls of a building as an equivalent to the solar slab described above? Using wall pipes behind 100mm external insulation to deliver low grade heat at temperatures between 14-18 degrees; 14 degree water makes the wall act like it had 200mm of insulation and 18 degree water makes the wall act like it had 400mm of insulation.]]> Passive House with no tapes/membranes, no ducts, no back up heating system. http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=6890&Focus=114686#Comment_114686 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=6890&Focus=114686#Comment_114686 Fri, 12 Aug 2011 02:04:48 +0100 fostertom
If the idea is to pump quite a lot of 'free' heat into that interface as a substitute for adequate EWI thickness, well what happens in Dec/Jan when the free heat is extremely scarce? Your backup fuel burner will be working flat out!]]> Passive House with no tapes/membranes, no ducts, no back up heating system. http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=6890&Focus=114691#Comment_114691 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=6890&Focus=114691#Comment_114691 Fri, 12 Aug 2011 08:26:52 +0100 Viking House The 16-18 degree water pumped through the pipes on non sunny winter days will come from the heat store beneath the house, where excess summer heat is dumped all summer long.]]> Passive House with no tapes/membranes, no ducts, no back up heating system. http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=6890&Focus=114712#Comment_114712 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=6890&Focus=114712#Comment_114712 Fri, 12 Aug 2011 12:43:01 +0100 fostertom
But applied to the extg wall/EWI interface, if the input temp is any less than desired internal temp, that nearly-interior part of the sandwich is being maintained at lower temp than it wd be without that cooling input there. That does mean less outward loss from the interface, but also means the interior is cooled below desired temp, so extra internal input from rads etc has to be applied and you're back to square one.

Best thing is to input heat at the extg wall/EWI interface, 1K or so higher than desired internal temp - say 19C flow, 17C return =18C mean, for 17C internal temp.]]> Passive House with no tapes/membranes, no ducts, no back up heating system. http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=6890&Focus=114737#Comment_114737 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=6890&Focus=114737#Comment_114737 Fri, 12 Aug 2011 21:07:39 +0100 spoonandfork Posted By: Viking HouseThe 16-18 degree water pumped through the pipes on non sunny winter days will come from the heat store beneath the house, where excess summer heat is dumped all summer long

so you're able to pull warm water from underneath the ground when you like, so it's not passive like the solar slab?

*

Posted By: fostertomBest thing is to input heat at the extg wall/EWI interface


(i assume extg = external)

why's that better than lower temperatures closer to the exterior in the wall?]]> Passive House with no tapes/membranes, no ducts, no back up heating system. http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=6890&Focus=114780#Comment_114780 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=6890&Focus=114780#Comment_114780 Sat, 13 Aug 2011 11:55:34 +0100 Viking House Posted By: spoonandfork So you're able to pull warm water from underneath the ground when you like, so it's not passive like the solar slab? I call this the "Heatloss Barrier" construction method, with just 100mm of insulation in the external walls and roof and wrapping an average house with 1km of Under Floor heating pipe costing €500, you can build or renovate a house to performs like a Passive House for a fraction of the cost.
Because airtightness levels, window U-values and cold bridging details are less critical it seems to be an excellent solution for renovation projects.

So the "Heatloss Barrier" method is not "Passive" like a Passive House with a Solar Slab wrapped in 300mm of insulation, but with just 100mm of insulation in the walls/floor/roof along with water pipes in the walls and roof, it exploits Low Grade heat storage and usage methods to potentially reach similar energy usage levels, but it is more active in the use of pumps and controls etc.]]> Passive House with no tapes/membranes, no ducts, no back up heating system. http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=6890&Focus=114859#Comment_114859 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=6890&Focus=114859#Comment_114859 Mon, 15 Aug 2011 16:02:21 +0100 djh Posted By: spoonandfork
Posted By: fostertomBest thing is to input heat at the extg wall/EWI interface


(i assume extg = external)

why's that better than lower temperatures closer to the exterior in the wall?
I was curious, so I wrote a simplistic spreadsheet, which I hope is attached.

It has, outside-to-inside, insulation, pipes, insulation, blocks. By varying the thicknesses and conductivities you can simulate heated pipes on the inside of EWI and heated pipes on the outside of EWI as well as heated pipes in the middle of the EWI.


"You are not allowed to upload (heat-loss.ods) the requested file type: application/vnd.oasis.opendocument.spreadsheet"]]> Passive House with no tapes/membranes, no ducts, no back up heating system. http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=6890&Focus=114882#Comment_114882 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=6890&Focus=114882#Comment_114882 Mon, 15 Aug 2011 23:01:44 +0100 spoonandfork Passive House with no tapes/membranes, no ducts, no back up heating system. http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=6890&Focus=114907#Comment_114907 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=6890&Focus=114907#Comment_114907 Tue, 16 Aug 2011 13:21:05 +0100 djh Posted By: spoonandforkgood stuff, can you process it via google docs and try again?
Sorry, that would require me to create an account, login etc. I don't understand why .ods is blocked - does it get used a lot for pr0n files? :shamed:]]> Passive House with no tapes/membranes, no ducts, no back up heating system. http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=6890&Focus=114908#Comment_114908 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=6890&Focus=114908#Comment_114908 Tue, 16 Aug 2011 13:27:36 +0100 SteamyTea Passive House with no tapes/membranes, no ducts, no back up heating system. http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=6890&Focus=114960#Comment_114960 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=6890&Focus=114960#Comment_114960 Wed, 17 Aug 2011 15:19:24 +0100 fostertom Posted By: spoonandforki assume extg = externalextg = existing - sorry for 'trade' abbreviation! So I'm saying heat input at external face of existing wall, with EWI applied outboard of that.
Posted By: spoonandforkwhy's that better than lower temperatures closer to the exterior in the wall?
To answer that, determine the temp gradient thro the wall thickness, from interior, thro the existing wall, thro the EWI, to exterior.

Wherever in that sandwich you place your heat input layer, if the heat is input hotter than that point wd naturally be (on the gradient you've just determined), then it will have the effect of warming the interior (as well as warming the external world as a substitute for adequate insulation outboard of the heat input layer).

If the heat is input colder than that point wd naturally be , then it will have the effect of cooling the interior (as well as still warming the external world as a substitute for adequate insulation outboard of the heat input layer).

So if the heat is input hotter than that point wd naturally be, then the wall can act as a significant (or the sole) source of heating to the interior. Whereas if the heat is input colder than that point wd naturally be, then it's actually adding to the heat load that will have to be provided to the interior by other means.

NB when we say 'hotter than', it need be only about 1K hotter, in a superinsulated airtighted building.]]> Passive House with no tapes/membranes, no ducts, no back up heating system. http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=6890&Focus=114965#Comment_114965 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=6890&Focus=114965#Comment_114965 Wed, 17 Aug 2011 15:48:44 +0100 MarkBennett
Specifically, if the heat input layer is put at the interface of the super-structure and external insulation then it will effectively be at the same temperature as the internal air temperature (assuming constant internal temperature). In this case, the heat needs to be applied at, or slightly above, internal room temperature. Anything lower will make it worse than having no heat input.]]> Passive House with no tapes/membranes, no ducts, no back up heating system. http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=6890&Focus=114967#Comment_114967 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=6890&Focus=114967#Comment_114967 Wed, 17 Aug 2011 15:56:56 +0100 SteamyTea
Steady state is equal to:
T=T(x,y,z)

Dynamic state is equal to:
ΔT=δT/δx,δT/δy,δT/δz

Or think of it as the more it has to spread out the cooler it gets as governed by:
PV/T=C but in this case P and V become the wall thickness and area (the x,y,z)

Use thermal conductivity to establish the temperature gradient of your wall.
λ = − Q/(∂T/∂n)

and has the units W m−1 K−1

Purely out of interest (and I think Mike George may be interested too), has anyone does a condensation analysis on this idea?]]> Passive House with no tapes/membranes, no ducts, no back up heating system. http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=6890&Focus=114969#Comment_114969 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=6890&Focus=114969#Comment_114969 Wed, 17 Aug 2011 16:03:54 +0100 fostertom Posted By: MarkBennettif the heat input layer is put at the interface of the super-structure and external insulation then it will effectively be at the same temperature as the internal air temperatureNot quite - about a 1K drop thro a 500 stone wall, assuming 200 of EPS outboard (with 16K drop), thus 17K inside to outside difference.

So for 17C inside air temp, inside wall face needs to be 18C, mean temp at heat input layer 19C, so 20C flow/18C return temp to your solar collector. Or figures of that order.

Note, that's an incredibly low temp to be running your solar collector, which brings unheard-of solar collection/conversion efficiency and also goes a long way to minimising the simultaneous heat loss from solar collector back to external scenery, which usually knocks cold-weather (Dec/Jan) collection on the head.]]> Passive House with no tapes/membranes, no ducts, no back up heating system. http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=6890&Focus=114978#Comment_114978 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=6890&Focus=114978#Comment_114978 Wed, 17 Aug 2011 17:01:40 +0100 MarkBennett
Connect the cavities of the panels together so that any air leakage can easily be pumped back out again. Sounds an expensive but interesting idea, which is not too dissimilar from what is being proposed here.

Found a paper during a quick search: http://www.ibpsa.org/proceedings/BS2009/BS09_0805_810.pdf]]> Passive House with no tapes/membranes, no ducts, no back up heating system. http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=6890&Focus=114986#Comment_114986 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=6890&Focus=114986#Comment_114986 Wed, 17 Aug 2011 20:02:13 +0100 fostertom
Remains to be seen which approach - vacuum (incl tubes) and/or multiple glass - is better on balance for collection at ultra-low flow/return temp in mid winter - but for sure vacuum is much more expensive, whereas built-in-situ methods such as Viking illustrated plus patent glazing in front can be cheap, maximised-area, and can be part-financed from the roof-covering budget.]]>