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Post by hal on Jul 27, 2022 10:07:17 GMT 1
Here is one someone might be able to answer definitively, so far I have only had head scratching when asking the question...
A solid French farmhouse, built 1880. Cold as ice in the winter, with an upside that in summer it is cooler than any house I know that has aircon - certainly cooler than mine.
Owner considering extensively modernise the house as the chore of cutting wood for the winter is getting too much.
The fundamental part of modernisation will be lining all the walls and ceilings with placo board over a layer of insulation.
The insulation will allow heat retention during winter, BUT - and here is the question - will it also counter-act the natural cooling effect during summer...?
I say it will in theory, but I could not begin to hazard a guess as by how much.
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Post by Polarengineer on Jul 27, 2022 10:18:11 GMT 1
My thoughts are that in theory, the stone reacts the same and will be cool on the inside in summer, but now the placo and inulation will prevent that cool temperature affecting the room and any heat in the room will stay there.
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Post by pcpa on Jul 27, 2022 10:37:44 GMT 1
I can only answer in regards to a solid brick wall building, it retains the thermal mass and the characteristics of the house but slows down the transfer of heat to and from the mass.
What does that mean in practice after insulation? You can return to an empty unheated property in winter and get the room temperature up quickly but it will take a couple of days to feel really warm.
In spring and autumn if you overdo the heating (easy with my storage heaters) then opening doors and windows to allow the colder outside air in has less effect.
I don't think there is such a thing as a "natural cooling effect" of stone but would gladly learn the science if it does, I think its just down to the thermal mass and inertia, if the walls are damp then there would be cooling (latent heat of vaporisation) but throwing up placo without making provision for the dampness is a recipé for disaster.
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Post by hal on Jul 27, 2022 11:47:24 GMT 1
My thoughts are that in theory, the stone reacts the same and will be cool on the inside in summer, but now the placo and inulation will prevent that cool temperature affecting the room and any heat in the room will stay there. My thoughts too, but how to calculate it? Something tells me that losing the natural cooling effect will be dramatic... |
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Post by hal on Jul 27, 2022 11:51:24 GMT 1
I don't think there is such a thing as a "natural cooling effect" of stone but would gladly learn the science if it does, I think its just down to the thermal mass and inertia, if the walls are damp then there would be cooling (latent heat of vaporisation) but throwing up placo without making provision for the dampness is a recipé for disaster. I think you know what I mean - I just resisted using flowery words! Nothing about damp, House is dry as a bone. |
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Post by rabbit on Jul 27, 2022 12:23:09 GMT 1
We used to have an old French farmhouse. 1m thick walls. It had been double glazed and placing board over insulation on inside as you describe. It was always cool inside in height of summer
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Post by hal on Jul 27, 2022 13:58:08 GMT 1
Ah, now, that is interesting. Thanks! A pity you do not still have the house - you could have earned yourself a bottle or two of fine malt...  This house has maybe 500mm walls, and it is very cool. Yours must have been a proverbial fridge! I have suggested a half way house by lining with plasterboard with a decent gap but no insulation... after all, if stone is a such good natural insulator, it should in theory do the work of man-made insulation except as said it will take a couple of days to really feel it in winter. My thought is that it is a small price to pay for the benefits in summer. I do not know the insulation factor of placo, but cannot imagine that it is that great. But, what do I know |
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Post by Polarengineer on Jul 27, 2022 16:37:00 GMT 1
the calculation is not difficult using Fouriers law, but you need to know the thermal conductivity of each material, the thickness of each layer including air gaps, the area to be considered and the start temperature on the high temp side to find the temperature on the low side. convection and radiation are not considered here but can have some influence. see www.engineeringtoolbox.com/conductive-heat-transfer-d_428.html |
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exile
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Massif Central
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Post by exile on Jul 27, 2022 17:24:04 GMT 1
halStone is generally a very poor insulator. It does however have high thermal capacity. If you need proof, this evening at sunset stand in front of a South or west facing wall. You should be bathed in heat. Now repeat tomorrow morning - no heat.
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Post by landmannnn on Jul 27, 2022 21:44:04 GMT 1
It's all about the glass...
My 1550's stone house has no windows pointing west, the others are pretty small. So it doesn't get much heat from the sun. Checking online, my UK house with lots of glass is now at 25° at 10pm. With no heating in either house, butter is liquid in the UK but about right in my old farmhouse.
So if you want a stone house to be warm in winter, placo the walls with loads of insulation.
If you want the house to be cool in the summer, close any shutters putting to the sun, the amount of insulation won't make the make the house warm.
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Post by pcpa on Jul 28, 2022 0:06:20 GMT 1
My new house has only one tiny window on the South elevation as ventilation for the toilet, during the refurb a VMC will take care of the ventilation and I am going to brick up the window but leave a false (backlit during daylight hours) frosted glass non opening window on the inside.
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Post by cernunnos on Jul 28, 2022 7:12:42 GMT 1
It's all about the glass... My 1550's stone house has no windows pointing west, the others are pretty small. So it doesn't get much heat from the sun. Checking online, my UK house with lots of glass is now at 25° at 10pm. With no heating in either house, butter is liquid in the UK but about right in my old farmhouse. So if you want a stone house to be warm in winter, placo the walls with loads of insulation. If you want the house to be cool in the summer, close any shutters putting to the sun, the amount of insulation won't make the make the house warm. We have no placo on our outside walls , just pointed with chaux , double glazed windows and floor/ceiling insulation all round .The house is warm in the Winter and stays nice and cool in the Summer , built around 1600. |
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Post by annabellespapa on Jul 28, 2022 8:18:20 GMT 1
Hi Hal, we have a stone longere here in Brittany, very thick walls, stone, infill and stone again, so in all about 850mm thick but not solid, house was insulated about 20 years ago, so all loft spaces 30cm thick insulation, plaster board walls with 50mm insulation with a void of 50mm to the internal stone wall.
When we arrive in the winter it takes about 24-36 hours to get the house heated to a reasonable temperature (log burner and central heating) but it then holds the heat, so the log burner tops up the heat, with no central heating required (5 bed house), in the summer our lounge 6m x 7.5 actually gets cold in an evening
especially when we have stayed out late in the garden, I have ducting installed (just two bathroom style extractors) to take the heat from upstairs and force it at ground level in the lounge to take the chill off the room.
My suggestion would be to fully insulate one room and see what is best.
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Post by rabbit on Jul 28, 2022 14:12:13 GMT 1
halI would go for the insulation. Be careful to insulate any pipes in the void. One winter it got to -5 and there was a lot of coldl air flow in the void, enough to freeze some pipes
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Deleted
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Post by Deleted on Jul 28, 2022 16:51:18 GMT 1
I read about this conundrum nearly twenty years ago when I bought my stone house. Basically it's swings and roundabouts. I don't think there is a definitive answer. I favour insulation. I've just finished insulating and dry lining a wall today. I will say, the room was like a bloomin oven while I was working.
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This house has maybe 500mm walls, and it is very cool. Yours must have been a proverbial fridge!