1er Heat Accumulation floor house in summer - solutions?

Heating, insulation, ventilation, VMC, cooling ... short thermal comfort. Insulation, wood energy, heat pumps but also electricity, gas or oil, VMC ... Help in choosing and implementation, problem solving, optimization, tips and tricks ...
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Re: Heat build up 1er floor house in summer - solutions?




by ojal » 28/04/16, 00:28

izentrop wrote:
ojal wrote:Thank you for your answers :)

izentrop wrote:Hello,
Exterior blinds for windows in the south to prevent solar heat gain.
By closing the shutters, the problem is the same :(
If the shutters are very hot and at the same time the windows are open, the heat comes in anyway.

I was talking about outdoor venetian blinds for example, which let in the light but not the heat.

I confirm that shutters closed and window closed, the problem persists :( So the idea of ​​putting on awnings does not at the moment provide any solution ... :)
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Re: Heat build up 1er floor house in summer - solutions?




by Obamot » 28/04/16, 00:52

ojal wrote:
Obamot wrote:- you do not give the thickness or the types of insulation in under-roofing, nor do we know how they were laid (photos would help, especially the areas of jointing between insulation and against the structure.)
The attic is not insulated, the insulation is projected on the plasterboard ceilings of the floor and this insulation is without breaking over the entire surface of the house in the inner periphery of the marrow ...

I do not understand, you say in introduction:
ojal wrote:We had reinforcement of the attic insulation 3 years ago, but we did not feel any difference in summer comfort ...

Now you tell US that they would "not be isolated"!

ojal wrote:The interior insulation of the walls comes below the ceiling insulation and therefore at this level there is no thermal bridge ...

I do not know what definition you give to thermal bridges. But precisely there is always with the ITI vs ITE (an ITI in your case is to prohibit) the thermal bridge in ITI is permanent since it is against all the inertia of the walls of facade that must fight, I do not see why you would say there would not be any? : Shock:

ojal wrote:The facades accumulate heat, it feels very well in the late evening or outside we feel very well the radiation emitted especially on the south and west faces ...

That's what I'm telling you, and the phenomenon is magnified by the absence of ITE on the front walls of the attic (or ITI it does not matter)

ojal wrote:In the winter, I can measure colder zones and thus thermal bridges with a thermal bridge, but in summer, all the walls are at the same temperature and I can not visualize any thermal bridges. .. In summer, temperature differences are not as important as in winter ...

that's because you imagine that the cold enters a building. Outside a thermal bridge it is not that (in winter it is not the cold that enters but the heat that leaves ...) Error of conventional reasoning.
In summer thermal bridges are often manifested by a stack effect (heat accumulation) and an unfavorable phase shift because too limited: which is your case.

ojal wrote:I can not for the moment consider an insulation by the outside, nor to modify the insulation of the walls ...

The tracks that I have to ventilate the attic to lower the temperature since it must go up very high, but is it useful ???

What do you want ... the laws of physics do not have the virtue of adapting to people's wishes, you have to live with them! It is the ITE the only serious solution to this problem (or else you must try to condemn the attic by dispersing 30cm of cellulose wadding on the ground and condemn / isolate the access itou, but that will not prevent the effect. stack of the walls, because the heat also penetrates there in the lower floors since you must have only a weak thermal resistance R <2, which is very insufficient). Otherwise you could be satisfied with an ITE (panel of Compressed LDV) covering the walls of the attic and descending one meter below the attic floor, and a good 30 cm of LDV under the roof, I only see that. But in the absence of a proper ETI, it will remain a thermal strainer, alas.

And what would it be worth to spend in insulation that would not be positioned wisely? It would be wasteful
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Re: Heat build up 1er floor house in summer - solutions?




by ojal » 28/04/16, 18:54

Obamot wrote:
ojal wrote:
Obamot wrote:- you do not give the thickness or the types of insulation in under-roofing, nor do we know how they were laid (photos would help, especially the areas of jointing between insulation and against the structure.)
The attic is not insulated, the insulation is projected on the plasterboard ceilings of the floor and this insulation is without breaking over the entire surface of the house in the inner periphery of the marrow ...

I do not understand, you say in introduction:
ojal wrote:We had reinforcement of the attic insulation 3 years ago, but we did not feel any difference in summer comfort ...

Now you tell US that they would "not be isolated"!
I did not express myself correctly :)
The attic is said lost, it is industrial farmhouse and insulation is projected on the ceiling plates.
On the basic rockwool insulation which was packed, about fifteen cm, we added 32cm of .KnaufSupafil Loft 045 which alone has a resistance of R: 7,1 m2.K / W.

One of the questions I ask myself is whether the insulation of the ceiling of the floor can contain the heat that accumulates in the attic and if it is by that happens overheating of the floor. Between the attic and the upper floor, we can consider that there are no thermal bridges.
I wish to analyze this because if the overheating comes from there, I will be able to implement a ventilation system which should be able to easily lower the temperature of the attic which must go up VERY high in summer ...

Who would know how to calculate this situation? I'm just talking about whether the insulation of the ceiling of the floor is sufficient?

Thank you :)
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Re: Heat build up 1er floor house in summer - solutions?




by Obamot » 28/04/16, 19:32

Hello,

1) As you have not answered the questions, that we have no picture of the construction details as requested above, it is hardly possible to answer new questions, as we do not know what are we talking about? Type of skeleton of the roof, etc ...

2) I've never seen that we could project LDV (mineral wool) under-roof without confining it, how does it fit the ceiling? If it is not confined (and despite what industry say) is a dangerous product (as dangerous as asbestos told me our chemist, so be very careful!)

3) If, on the other hand, you talk about the ceiling of the last floor before the attic (suspended ceiling under slab / attic floor), this insulation is useless in this case (you found it yourself: because all this slab provides a stack effect against which it is difficult to fight) and I strongly advise you to live in these rooms, you could breathe tiny particles of the old wool (and later the new) and it is strongly to avoid! If you can not do without living there, I urge you to put a vapor barrier to separate you from the insulation - it should be a top priority - and its installation must be completely sealed, under penalty of serious possible health problems in the long run (asthma etc). After its installation, I also advise you to decontaminate everything to remove all the glass wool dust (protective suit of rigor, respirator, glasses and boots and to do very carefully, to marry the walls too.) If you protect before work with a plastic film, it may be better, but it will not remove the residual contamination before work.

4) Once again you suppose that there would be no thermal bridge, but nothing allows you to affirm it, and the mere fact that you have heat, partially proves that there is one ( you simply forget the heat that passes through an insufficient ITI facades ...). Do not forget that in summer, the heat is also spread by the ambient air, so we like it or not, we do not start from a situation at 20 ° C, but rather that of the seasonal curves of observed temperatures, to which is added the furnace of your attic which is transmitted to the structure of the construction (failing ITE) adding still that which you produce by your computer equipment (etc) and adds the heat that produces every human being present in the premises (about 60W of an incandescent lamp per person, ie 120W to two).
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Re: Heat build up 1er floor house in summer - solutions?




by ojal » 28/04/16, 21:25

Here is a small diagram of my situation :)
img227.jpg

Big inertia on the slab which is in passing a gigantic thermal bridge ... But I do not think that it is by that the overheating happens in summer ... This thermal bridge makes me just lose calories in winter when the differences between Indoor and outdoor temperatures are important ... In summer, on the contrary, it should even be used as inertia for braking the temperature rise of the floor ...
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Re: Heat build up 1er floor house in summer - solutions?




by Obamot » 29/04/16, 06:04

img227 thermal bridges.jpg


The heat is trapped in 4 different ways:
- recess in the attic where it must be the furnace;
- the relatively mediocre ITI in the walls (R <2) does not prevent heat from entering (see corrected sketch) it is on the other hand very effective in keeping the accumulated heat locked up, up to a height of R = 7 where it accumulates but ... inside and on the ceiling !!!
- the thermal bridges (slabs and uninsulated walls) fed directly by the rays of the Sun, ask no better than to reach a point of equilibrium, so they spread their heat as and when in the slabs, which Once heated upward, the convection principle creates an endless cycle and only increases the temperature throughout the day, since it can only accumulate under the insulation on the ceiling. .
- the transit of heat in the slabs is accelerated because of the Δº between hot façade in the south VS north facade colder ... So, instead of reaching a point of equilibrium (in principle on 1m), there is there is a permanent circuit that self-feeds as a kind of continuous pumping (since concrete and cinder blocks are good thermal conductors).
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Re: Heat build up 1er floor house in summer - solutions?




by ojal » 29/04/16, 08:58

thank you for your reply :)
So you think that lowering the temperature in the attic would be totally ineffective? It is possible, nevertheless would there be a member able to make a calculation of the insulation of the ceiling please? We should make a temperature assumption in the attic and see how the temperature drops in the insulation to ensure that this insulation is sufficient ...
I remain fixed on this problem of insulation of the ceiling, or on the lowering of temperature inside the eaves, because it is in the short term the only axis on which it can intervene ... :)
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Re: Heat build up 1er floor house in summer - solutions?




by Obamot » 29/04/16, 13:38

- It is not us who decide, we must remain humble, it is the context of the problem, which relates to this or that choice.

- It is not in the insulation that the temperature must drop (but on the cause of the thermal bridges which are at least 3 in number, since in addition to the slabs, we must not forget the walls perpendicular to the facades and not shown in your sketch), not in the insulation that the temperature must drop, since precisely being made of light material, the insulation offers resistance to heat, so there is no chance that this will happen. Where it is necessary to intervene it is at the level of heavy materials, of high density => to avoid penetrating calories (solar radiation) either slabs, facade walls and perpendicular walls or even metal profiles if the he framework of your roof consists of it ...

- The calculation is already done R = 7 but that works against you since it traps the heat! It is not a calculation that would be necessary (we have nothing to do with it as long as we know where to intervene, how and why) it is a thermography perhaps to convince you (?) What I'm not trying to do anything else, I just describe the technical approach ...! the measurements would give you nothing more than what I described to you. Take an infrared laser thermometer and take your measurements yourself, you don't have to look for noon to XNUMX p.m.! Because of your ceiling insulation (instead of insulation under the roof) you cannot benefit from what the "technical void" that your lost attic constitutes would bring you SINCE YOU ARE CUT FROM IT AND THAT IS WHY IT IS IS A PART OF YOUR PROBLEM which would not be the case with under-roof insulation or the air present in the attic could work in your favor (subject to having been checked on site) ...

- The solution is simple and in two steps, you have to tackle the causes (an ITI does not):
a) put an under-roof insulation of 300mm, since this is where you say you want to intervene, it will cut the effect of the penetrant from the top.
b) it looks like you have not understood the red arrows that lead the facade heat (?) you need to make an ITE to circumscribe the fat penetrating through the facade ((sorry that your ceiling insulation is useless for far).

And this, even if it will not guarantee to reach your goal, since it would be absolutely necessary to do these two stages simultaneously. As plan "B", you only do the ITE, and observe how it behaves without under-roof insulation (and this to try to recover the placing of your insulation in the ceiling) that's what I would do since this is where we should start (even if I know that you said that you could not do ITE, I do not take it into account, I just tell you what technically corresponds to the solution that it takes this problem, there is no other and in my humble opinion of technician in civil engineering, reinforced concrete.)
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Re: Heat build up 1er floor house in summer - solutions?




by ojal » 29/04/16, 15:09

I have noted your answer and your analysis certainly relevant. Thank you :)
Since I'm not going to go into a big insulation project from the outside in the short term, I still want to validate that the furnace I have above my head - in the attic - is not the source partly at least of the warming up of the floor ...
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Re: Heat build up 1er floor house in summer - solutions?




by Obamot » 29/04/16, 19:26

Yes, but that's the problem forums when the pros answer, it's because the people who come are often there to validate their own hypotheses, when they should leave them in the locker room before entering. Because the result is a selection bias of the answers given so that they match expectations (which is rarely the case). Some even come to ask for advice "with a view to undertaking work ", they tell us (as we then see from the questions, that the work is already under way.)

The answer has already been given partially, see my sketch among others, and it was given given the elements that you have brought yourself. Partially because we still do not know what are the structure of the roof, support of tiles, beams, wall / s support / possible separation / s, or the slab of the attic under which is your insulation in the ceiling ( not for nothing we ask for photos).
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