Sun, 26 Jul 2026 22:34:38 +0100 https://www.greenbuildingforum.co.uk/newforum/ Lussumo Vanilla 1.0.3 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=4146&Focus=55897#Comment_55897 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=4146&Focus=55897#Comment_55897 Fri, 12 Jun 2009 22:13:51 +0100 beelbeebub
I'm just about to submit a planning app on bungalow with room in roof (so 1+1/2 story?).

I have a layout (see below) that has been created after consultation with the architect and a planner.

The light blue sections are windows
Dark blue are entry/exit points like front door or patio doors(i.e. openings down to floor level)
The green rectangle shows the upstairs area

It is currently back with with the planner for comment. If he gives the nod we'll work up the full application an go for it (fingers crossed).

Assuming the planner say go:

The building is ~9.5m by ~13m, aligned with the long axis (13m one) North/South.

The overall height is 5.5m from floor level. The floor level will be just above local ground level (we will have to dig down but will dig down so that the new ground level is lower than the building floor level.

My budget is ~150k all in with me acting as the prime contractor.

As I am in a conservation area and an area of outstanding natural beauty the external look of the place will have to be "traditional" e.g clay tile roof (this has been specifically highlighted by the conservation officer) and render or brick exterior (i'd like to avoid brick on cost and personal taste grounds but am not dead against it if there is a compelling reason). That's not to say other external finishes like wood or metal are off limits, just we'd need a good reason for specifying them.

My question to the forum is:

WHAT SORT OF CONSTRUCTION SHOULD I GO FOR? I'm talking about foundation, wall and roof construction.

I have my theory on the best construction, but I won't post it yet as I'm interested in other people's ideas, this is really a brainstorm session so I can get lots of view points to help me make a decision.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=4146&Focus=55898#Comment_55898 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=4146&Focus=55898#Comment_55898 Fri, 12 Jun 2009 22:14:52 +0100 beelbeebub https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=4146&Focus=55899#Comment_55899 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=4146&Focus=55899#Comment_55899 Fri, 12 Jun 2009 22:15:37 +0100 beelbeebub
http://www.navitron.org.uk/forum/index.php/topic,7774.0.html]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=4146&Focus=55902#Comment_55902 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=4146&Focus=55902#Comment_55902 Fri, 12 Jun 2009 23:30:23 +0100 tony

Foundations as shallow as they will let you, walls brick with lime mortar and block lots of insulation 300mm glass or mineral wool in cavity then at least as much in the roof. Air sealed construction.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=4146&Focus=55903#Comment_55903 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=4146&Focus=55903#Comment_55903 Fri, 12 Jun 2009 23:33:35 +0100 djh
Hopefully there'll be some more comments along in a minute! (for anybody else, anything I write that's cryptic is probably to suggestions on the navitron forum)

Foundations: It all depends on the ground conditions, so you'll need to give more info. Even then you're probably best to rely on somebody who's familiar with the site. But be aware car tyres are very labour intensive!

Walls & Roof: When you say you will be prime contractor, do you mean you will be managing or labouring? If you're labouring, then pick a technique you feel comfortable with. I like straw but it will take more space than you've allowed for. Render seems the obvious choice for the external surface.

Design: without seeing the surrounding properties etc it's difficult to make any useful comments. I'd assumed from the high windows on both E and W that you were close to other properties on those sides, but I guess not if the road is N/S. Equally, the roof seems to be gable at the N and hip at the S, which is a bit odd and it's not clear why you didn't maximise the floor area and windows on the S?]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=4146&Focus=55908#Comment_55908 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=4146&Focus=55908#Comment_55908 Sat, 13 Jun 2009 09:37:07 +0100 beelbeebub
Could you elaborate on the air leakage thing?

@djh:

The ground is a stiff clay mixing to limestone rocks before hitting limestone bedrock. It's virgin ground so should be pretty settled.

By prime contractor I mean I will be project managing the build, organising the various sub contract trades etc. I may also be doing some labouring. A bit depends on the build technique. As you say it's best to be comfortable with the build technique.

The high windows are partly for privacy from the road on the east side (as we're likely to be dug in passing people and cars will have a great view in) On the west side doesn't really have a view other than a hedge and the back of a school sports hall.

The roof is a gable at both ends. The sunspace and entrance porch are "cut out" from the roof. This was to help with planning as the planners were unhappy with a monolithic roof so the architect suggested that we cut sections of the roof out to help satisfy them. This leaves the gable on the south end as a stepped wall.

The window area on the south side is pretty maximised within the restraints of the planning. They weren't too keen on a continuous band of glass running across the south side so we had to break it up.

We tried to maximise the south advantage by putting all the living areas in the south side, the cooler bedrooms are on the north side, but the site is a bit constrained in width and orientation.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=4146&Focus=55916#Comment_55916 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=4146&Focus=55916#Comment_55916 Sat, 13 Jun 2009 12:24:35 +0100 tony
http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=931&Focus=10164#Comment_10164

try your own search for chalet bungalows and air tightness too.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=4146&Focus=55919#Comment_55919 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=4146&Focus=55919#Comment_55919 Sat, 13 Jun 2009 14:10:49 +0100 beelbeebub
Aha! I think I see what you are getting at. The roof/ceiling joists meet the roof rafters at the top of the wall. Inadequate sealing at this point allows outside air into the void between the ceiling and upper floor?

My guess is that this is a problem caused partly by the complication of having 3 elements meeting at the same point (wall top, rafters and joists). I can see that this would be a right pain in the behind to detail and construct.

Fortunately the design I (currently) have doesn't suffer from this 3 element joint. The floor of the room in the roof area doesn't extend to the wall/rafter junction (see diagram). The green is the 1/2 story and the blue the ground. The red circle is the potential leakage point.

This still leaves me with the question of sealing the sloping roof to the wall tops but should be an easier problem to solve.

The design was actually the architects idea, primarily to give a more spacious feel. The 1/2 story only extends over the north portion of the house, over the living area we are hoping to extend the room up to the ridge.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=4146&Focus=55924#Comment_55924 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=4146&Focus=55924#Comment_55924 Sat, 13 Jun 2009 18:53:39 +0100 sinnerboy
http://www.planningportal.gov.uk/england/professionals/en/1115314255826.html]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=4146&Focus=55983#Comment_55983 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=4146&Focus=55983#Comment_55983 Mon, 15 Jun 2009 13:27:36 +0100 djh http://www.energysavingtrust.org.uk/business/Business/Building-Professionals/Helpful-Tools/Enhanced-Construction-Details
"these details improve on the performance delivered by the standard Accredited Construction Details"

Or better yet, use the passivhaus details http://www.amazon.co.uk/Passivhaus-bauteilkatalog-Okologisch-Bewertete-Konstruktionen-Constructions/dp/3211297634/ref=sr_1_1?ie=UTF8&s=books&qid=1245068591&sr=8-1
or google for "passivhaus details" for various online versions of some details]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=4146&Focus=55984#Comment_55984 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=4146&Focus=55984#Comment_55984 Mon, 15 Jun 2009 13:43:02 +0100 tony https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=4146&Focus=55987#Comment_55987 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=4146&Focus=55987#Comment_55987 Mon, 15 Jun 2009 14:15:06 +0100 Paul in Montreal Posted By: tonywhy not go better than passivhaus?Why would you need to? If your house doesn't require heating, then going "better" than that is a waste of money and resources. Good engineering is about doing the least amount possible to meet the requirements - if the requirement is no heating, then achieving that is enough. You can't save any extra if your heating bill is already zero. Except, the cynic would say, passivhaus is not really passive house at all as they all have heating systems!

Paul in Montreal.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=4146&Focus=55991#Comment_55991 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=4146&Focus=55991#Comment_55991 Mon, 15 Jun 2009 16:08:51 +0100 tony https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=4146&Focus=55999#Comment_55999 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=4146&Focus=55999#Comment_55999 Mon, 15 Jun 2009 19:00:11 +0100 beelbeebub
I'm planning a compromise with a small heating system based around a heatstore combining feeds from a small (12kw) condensing boiler, a wood stove and possibly solar panels. If all goes well it will mainly be used to heat the domestic hot water, but there will be a an underfloor heating system available if things get a bit chilly.

I think that I'm leaning towards a masonry inner leaf (for the thermal mass) then 125 -200mm of PU/PIR foam bats. The external rain screen will be a render. I'm wondering about including a small cavity (12.5-25mm) between the external face of the insulation and the render for damp proofing. It is effectively a single skin wall from a structural point of view. I'm trying to keep the wall thickness down so as not to eat away at the internal floor area. The main alternative to this system would be a SIP wall, significantly thinner, even if I had to add thermal mass internally (the whole thermal mass thing is a bit unresolved in my mind).

For the roof I'm thinking of a SIP system (currently undecided) mainly to get the clear roof space but also because of the U values. 150mm panels seem to give just under 0.2 so hopefully a bit of insulated plasterboard on the underside should push this down to 0.16

My target U values are less than 0.2 for the walls, ~0.15 for the roof and at least 1.6 for the glazing. if I can get (afford) better glazing I will.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=4146&Focus=56000#Comment_56000 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=4146&Focus=56000#Comment_56000 Mon, 15 Jun 2009 19:08:24 +0100 tony
Hope all goes well.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=4146&Focus=56001#Comment_56001 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=4146&Focus=56001#Comment_56001 Mon, 15 Jun 2009 19:16:14 +0100 sipman
Build the whole house with142/150mm SIps Panels no complicated junctions, the whole house from Slab upwards would be built in two weeks. Once water tight you could manage the project working inside and outside at the same time.

a "u" value of 0.2 will be ok, as if you have stated you are going to install a heating system, but bear in mind you will need minimal space heating. The house will be airtight to approx 2 m3/hr/m2 at 50pa provided the plumbers seal any penetrations they have made to the external sips walls.

Not convinced that you should any additional thermal mass, an insulated airtight house will peform well enough.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=4146&Focus=56005#Comment_56005 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=4146&Focus=56005#Comment_56005 Mon, 15 Jun 2009 22:00:31 +0100 beelbeebub
The thermal mass question is still unresolved. My gut says a bit of mass is good, esp if my roof structure is v.low thermal mass.

Some of the arguments about modern usage patterns (i.e. out all day, so low mass for quick response on return) are compelling. My main thought is that a lightweight system requires some good control to prevent over and undershoots. A massy system has an easier job, a bit like the difference between driving a lorry and a sports car. Get it slightly wrong in the sports car and you're doing 100mph before you know it.

I'm also slightly iffy about the life of SIPS, it's not a hugely rational thing and I'm open to be convinced. I'm kind of aiming for a long life structure. Most of the buildings nearby are heading past 150years and still going strong. Sure they've had windows hacked through walls, been converted to flats, bedrooms have become kitchens, toilets, central heating, wiring, phones have all been added but the basic structure is still solid and should be good for another 150 by which time they'll have had the teleporter wired in, a fusion station in the basement and the roof will have been replaced by a force bubble or something.

I know SIPS have been used for 50 odd years but will they last another 100? esp with all the hacking/extending/converting that inevitably goes on as buildings encounter changing architectural and social fashions.

I'm not saying that SIPS won't last just that we don't know for sure that they will.

There are plenty of timber buildings lasting several hundred years but they all use discrete load paths, if a load bearing post or beam is in the way or damaged it's relatively easy to replace it or route the loads around it with more beams/posts. As the loads are transferred through the skin I can imagine that replacement or rework are difficult.

Carbon fibre structures use as similar strategy of stresses skin supported by lightweight monolithic foam. They are notorious for being dodgy when it comes to damage and the difficulty of repair and reworking.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=4146&Focus=56007#Comment_56007 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=4146&Focus=56007#Comment_56007 Mon, 15 Jun 2009 22:37:19 +0100 beelbeebub
THe wall would go something like :

Blockwork (hopefully 150mm otherwise 200mm) DARK GREY

A vapour barrier would be between the blockwork and the insulation e.g blue poly. BLUE

Then the foam insulation.The first two layers would be fitted so that the vertical joints don't line up, the final layer would be aligned so the vertical joints match with the first layer but the horizontal joints don't line up. This should make a labyrinth path for the air. In addition the joints would be taped. Finally a layer of vapour permeable paper will wrap the lot up to prevent wind penetration into the insulation. YELLOW

A vapour barrier would be between the blockwork and the insulation. (Tyvek?) PURPLE

Then the gap for water drainage

Then a rainscreen. LIGHT GREY

Comments?]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=4146&Focus=56008#Comment_56008 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=4146&Focus=56008#Comment_56008 Mon, 15 Jun 2009 23:15:56 +0100 tony https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=4146&Focus=56014#Comment_56014 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=4146&Focus=56014#Comment_56014 Tue, 16 Jun 2009 07:38:26 +0100 beelbeebub https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=4146&Focus=56018#Comment_56018 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=4146&Focus=56018#Comment_56018 Tue, 16 Jun 2009 08:52:42 +0100 Mike (Up North) They do do it at monster sizes but its less freely available.
This is similar to our local method except they dont do the external insulation so it is (ive missed out vapor layers etc).
This is what i have found ie struggled with (learnt) so may help somebody with thier own variant- its never as easy as it appears:
Block (laid flat = 225mm)
batten horizontal (plank)top/bottom/middle
insulation board
studding 50mm ( 2 x 2)
plasterboard
Ive done this with 100mm insulation and the problem are as follows
1) fixing thropugh 100mm of board is hard. There are screws (i used 6 x 130) to pick up on the solid wall you would need to use hex head rafter screws (eg from S/fix at 150mm+ length - these get pricey as are in packs of 20 not 200)
2) You have to be exact in marking where the batten is otherwise the the insulation mounting screws miss, hence using plank size wood to ensure a hit.
3) although the internal studding is fixed top and bottom at 50mm its still quite bendy(or is bent) so occaisionally you need a big fixing to go all the way through to support and get it back in line.
4) Kingspan/celotex is not flat - longways/cross ways = bowed bananas (need EU regulated straight bananas)and at 100 mm its is surprisingly strong and resistant to straightening. A screw head will pull through very easily. So you need to make ply washers ie 6mm ply about 2"x2" to clamp it onto the batten. If its too bowed then the stud frame is well off of the wall, this can be shimmed square of course.
5) you could lay further planks horizontally and clamp through the insulation into either the batten or the wall, but agin the max hammer fixing is about 130mm with only 30 penetration into the wall, and you have the framing that would be on top. This framing void is for services - I can do pipework with the 50mm gap.

The advantage of this method is that the insulation board runs top to bottom continuously. I have rebated and sealed it to the upstand of the floor slab perimeter insulation. The perimeter insulation is 50mm board, so i cut a 25 x 25 rebate along the top edge, then brought the wall insulation standing 25mm off of the solid wall down to sit atop the perimter upstand. Thats my home-made robust detail.
Likewise at the rafter level going cross-ways i cut strips of 6mm ply into 120 mm widths and fixed this to the underside of the joist up against the wall head sole plate, thus the insulation can then be sealed tight upagaintst the underside of the joist. Then from above i filled downwards between the joist to meet this ply. It was too difficult to cut and fix up the wall and threough the joist as a continuous run.

Hope this gives you food for thaught. I had to work this out myself as I went along. thats not too much of a problem, what got my goat was the derisory commnest form the builders - whats the point, thats not how we do it, its good enought way we do it etc etc.

Cheers

Mike up North]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=4146&Focus=56021#Comment_56021 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=4146&Focus=56021#Comment_56021 Tue, 16 Jun 2009 09:22:42 +0100 beelbeebub
I'll have to price up v.carefully the extra cost of 3x 65mm using cheap screws and easy fixing vs 1 x 200mm using expensive screws and more of a bugger to fix.

I was wondering about screwing the first layer direct to the masonry. The following layers will be screwed into the first layer. The actual weight of the board will be taken by them standing on a base (the bottom of the cavity) so the screws only have to take the side loadings.

I know that this will pierce the vapour barrier but to overall hole area will be pretty small. The boards will act as a vapour barrier themselves and the idea is that the outside membrane is much more breathable than the inside membrane so the small amount of water that does get through can escape quicker than it can enter, a bit like trying to fill a bucket with a small tap and a big hole in the bottom.

I'm toying with the idea of ditching the barriers all together and using the PU as the vapour barrier. This would be most effective in a multi layer skin so none of the joints line up. I'd have to be very careful to tape all the joints too.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=4146&Focus=56025#Comment_56025 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=4146&Focus=56025#Comment_56025 Tue, 16 Jun 2009 11:20:53 +0100 tony https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=4146&Focus=56028#Comment_56028 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=4146&Focus=56028#Comment_56028 Tue, 16 Jun 2009 14:11:51 +0100 beelbeebub
Humm, why is that? Is it because the screw fixings will pull out? Will it sag?

Having worked with PU foams in a different context I remember that they were rather like a soft wood (say balsa) to work with. Not particularly strong but not meringue.

I'm planning that the weight of the bats is taken vertically i.e. they stand up on their own. The screw fixings are functioning rather like wall ties in a cavity wall, just to prevent the buckling.

I was thinking the rain screen would function as an independent leaf. It would stand up on the foundations (via a dwarf wall brought up just above ground level) and be attached at the to to the SIP rood overhang. The top attachment is only to prevent the rain screen falling over sideways. Effectively it would be separate from the inner leaf and insulation.

I've attached a picture. For speed I've shown the roof as a flat SIP, actually it would be a pitched SIP.

Note that the rainscreen (structure pink, render muddy grey) is self supporting and doesn't touch the insulation.

What do you think?]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=4146&Focus=56465#Comment_56465 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=4146&Focus=56465#Comment_56465 Wed, 24 Jun 2009 13:50:07 +0100 harrylime https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=4146&Focus=56493#Comment_56493 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=4146&Focus=56493#Comment_56493 Wed, 24 Jun 2009 18:03:39 +0100 breatheconstruction https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=4146&Focus=56610#Comment_56610 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=4146&Focus=56610#Comment_56610 Thu, 25 Jun 2009 19:18:33 +0100 beelbeebub
I looked at ICF but was turned away by the lack of internal thermal mass. They are a great Idea but the problem is that the thermal mass is locked up inside the insulation.

Given that the Durisol material is some type of mineralised wood (hence I suppose the insulation value from the porous nature) I wonder if they could vary the mix throughout the block so that there was dense concrete in the inner face changing to insulating for the outer face. That would be a very interesting product.

I'm a little confused by HarryLime, is he saying the vapour permeability of the PU sheets could be a problem? I have to admit that I have slight worries on that score. I would rather only have a single thin vapour barrier, but if I put a polythene sheet between the blockwork and the PU I could risk trapping moisture in the PU. Not there is a school of thought that says this is not a problem as PU is inert. If possible I would like not to trap water in my structure.

That brings me onto simply using taped PU bats as the vapour barrier, any ideas?]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=4146&Focus=56613#Comment_56613 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=4146&Focus=56613#Comment_56613 Thu, 25 Jun 2009 20:12:44 +0100 breatheconstruction https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=4146&Focus=56630#Comment_56630 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=4146&Focus=56630#Comment_56630 Thu, 25 Jun 2009 22:41:12 +0100 beelbeebub
But the porous wood cement bit must be low thermal conductivity as it goes from external face to internal face. If it had hight thermal conductivity it would act as a thermal bridge.

If it is a low thermal conductivity material then the internal face of it must act as a low thermal mass solid?

Thermal mass the specific heat capacity (SHC) i.e.the energy required to change the temperature of 1kg of by a given amount (usually 1K). But if that material has a low thermal conductivity then it doesn't matter what the specific heat capacity of the material is as it won't reach the surface very easily.

Conversely a material with high conductivity but low SHC would heat up and cool down too quickly.

If I had a house with 1m thick granite walls that were nicely heated to 20c then I opened the door and a cold 0c wind blew through, the granite surface would quickly cool down even though an inch below the surface the granite was still warm. In this case the thermal mass wsa unable to moderate the air temperature.

To act efficiently thermal mass must also be coupled with the correct thermal conductivity. Now I'm not sure quite what that balance is, maybe it is Durisol. But intuitively it seems that anything that is conductive enough to be a good thermal mass must be too conductive to be an insulator.

Does anyone have any explanations?

Have I got the wrong end of the stick?

]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=4146&Focus=56652#Comment_56652 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=4146&Focus=56652#Comment_56652 Fri, 26 Jun 2009 11:15:19 +0100 tony
If you did that you'd be nuts! The granite would not cool that fast -- it would take 12 to 24 hours to cool the top surface and a month to cool the whole wall.

the heat stored in the granite is huge compared to the ammount taken away to heat air. Presumably we only open the door for as short a time as possible.]]>