Pros and Cons of PH

[joth]

43 minutes ago, oldkettle said:

 

The paper seems to be about the US. I don't buy claims about trillions in negative externalities, the rest of "subsidies" seems to have trivial value if you look at the size of the industry.

 

More importantly, here the consumption of energy is heavily taxed so cannot see the relevance of your link. 

 

Everything government does makes things more expensive, if not immediately then in the

long run. 

 

Governments of big countries (USA, EU, China, OPEC) meddle in pricing and it has global impact. Matters less and less if it's "your" government doing the meddling. What the UK government does with taxes is actually a small influence in comparison

 

 

Edited October 2, 2020 by joth

[oldkettle]

10 minutes ago, joth said:

 

Governments of big countries (USA, EU, China, OPEC) meddle in pricing and it has global impact. Matters less and less if it's "your" government doing the meddling. What the UK government does with taxes is actually a small influence in comparison

 

 

 

Are you claiming OPEC sell below cost for years? EU make producers lower energy prices? Are oil and coal getting special treatment making them cheaper? 

And please don't tell me energy should be more expensive due to global warming. This is irrelevant (and wrong, but it does not matter). 

[Mako]

21 hours ago, Ferdinand said:

 

One issue there is that you need to think about time factors in heating up and cooling down, and balance the amount of heat the house can hold with the rate at which it can get in or out.

 

If you have a lot more thermal storage in the extra concrete inside your superinsulated airtight house, then the larger amount of stored heat will escape very slowly once it has built up - and you could have a high swing that eg stays high for a number of days 'cos your insulation is keeping it in. The total amount of heat moved by air is relatively small.

So things like the "decrement delay" (which is a measure of how long heat takes to soak through your walls) become more important. If it takes (say) 12 or 16 hours, that means that it will be a long hot day before the inside starts heating up, and much of the heat can go back out of the walls outwards overnight, plus you can cross ventilate, stack ventilate or purge ventilate.

 

Mine is *not* superinsulated, and in hots circs it can get uncomfortable by early to mid afternoon, so in a real heatwave (outside temp say 30C or more for several days) I need to have my skylights and a downstairs window or two open overnight, and have it all shut it all up before the sun comes out.

 

One slightly unintuitive thing some here have found is that overheating through windows in highly insulated houses is that overheating can be more of a problem in spring / autumn than in summer. That is because we are used to doing things like brise soleil and similar things now, but even though the slanted sun in the spring / autumn is less intense, it circumvents the measures we think to put in for the summer sun by being lower.

Ferdinand

 

Hi,  not sure I’m following, I been told that concrete stays the same temp all year around, at least that’s the aim.

that needs to be controlled by external blinds to stop overheating. More concrete you have in the house the more heat capacity

the house can deal with. On the hotter days, it will stay cooler for longer. That’s my understanding. The insulation in my head is really important

as it stops the heat getting into the concrete from the outside. If you have no insulation, your house would be like an oven in the summer,

And Cold in the winter, hence it will take too long to heat up in the winter, and impossible to cool down in the summer.

Apparently For the concrete house to work it needs to be balanced right.

im still looking into it, but it starting to make sense more I read about concrete homes

[PeterW]

8 minutes ago, Mako said:

Hi,  not sure I’m following, I been told that concrete stays the same temp all year around, at least that’s the aim.

that needs to be controlled by external blinds to stop overheating. More concrete you have in the house the more heat capacity

the house can deal with. On the hotter days, it will stay cooler for longer. That’s my understanding. The insulation in my head is really important

as it stops the heat getting into the concrete from the outside. If you have no insulation, your house would be like an oven in the summer,

And Cold in the winter, hence it will take too long to heat up in the winter, and impossible to cool down in the summer.

Apparently For the concrete house to work it needs to be balanced right.

im still looking into it, but it starting to make sense more I read about concrete homes

 

Concrete isn’t the best storage media - gypsum plasterboard and plaster are better. 
 

Have a read here ..

 

 

[Mako]

11 hours ago, A_L said:

 

The effect on energy saving of thermal capacity more than 100mm from the internal environment is very small and generally ignored, it takes to long (>24hrs) for the heat to get in/out.

 

 

 

Heating load is dependent on the rate of heat loss, i.e. a combination of fabric loss (U-values) and air infiltration rate (ach). The concrete would have to reduce one of these.

 

 

 

Where walls are dominated by a single layer  the wall temperature and the dew point temperature move in step as we go through the wall. As long as the vapour resistance of the external containing layers are not more than the vapour resistance of the internal layers there should not be a problem.

 

Thanks, you mentioned that energy saving capacity is reduced, but if you have solid concrete on internal side, you are using the 100mm

to your advantage and any more is at reduced performance, happy with that? That means there is a saving energy with concrete.

 

if the concrete provides the air-tightness, and there is solid insulation applied externally? Would that help?

 

surely when we talking about vapour resistance to be greater, that means there won’t be any air-tightness in the house?

If the vapour can escape? That means the wall is air-permeable, how are you going to keep the heat in?

I might be wrong, just thinking out loud

 

[Mako]

5 hours ago, Simplysimon said:

covered above

i'm sheeting mine internally with propassive osb and sealing all joints so no membrane, no failure also a service cavity.

Interesting, would you be able to provide a detail?

[Mako]

7 minutes ago, PeterW said:

 

Concrete isn’t the best storage media - gypsum plasterboard and plaster are better. 
 

Have a read here ..

 

 

I have read it yesterday, I think Jeremy got it slightly wrong.

if anything Gypsum has got insulation property to it, he based is calculations per KG, instead of m3, 

imaging how much volume is 1kg of wood, and how much volume would be 1kg of concrete.

its all about density of products. Simple float test should give you an idea.

water - 100mm cube is 1kg

wood - soft dry wood used in construction 100mm cube - would be less say 0.4kg

concrete - 100mm cube - depends on type say 2kg

now you apply your Jouls per kg and see where you get. Do you get my drif?

 

[Mako]

5 hours ago, Simplysimon said:

build with i beams and not timber, more stable, less weight and less timber, win, win, win.

 

I understand and agree that we all make choices, but even I beam is less stable than concrete?

Less soundproof? And less airtight? And won’t last as long? Will also have negative effect on land fill when it comes to rebuild.

 And probably more expensive as well to start with compared to concrete, my thoughts...

[Mako]

2 hours ago, Dan F said:

 

I'm not an expert, but this is dealt with by the wall make up being vapour permeable.  Typically the external board/membrae is something like:

- https://mdfosb.com/en/medite/products/medite-vent

- https://www.ecologicalbuildingsystems.com/product/solitex-fronta-humida

 

This stops water getting in and let's vapour get out.  A vented cavity is needed externally to allow this.

 

 At the same time, an internal airtight board/membrane stops air/vapour being tramsmitted from house to wall.

- https://mdfosb.com/en/smartply/products/smartply-propassiv

 

I think you are potentially imagining a problem, that is actually already been worked out?

 

 

if the vapour can get out of the cellulose from inside out, there must be reverse as well and the cellulose can get wet.

how does cellulose perform when wet?

 

internal airtight membranes, the only weakness is at the joint, can you find out from any supplier how long do they guarantee 

the membranes to work? they have to guarantee for 10years, what happens after that? membranes coming apart within the wall?

plaster boarded skimmed and decorated? where is the vapour going to go? into the cellulose or PIR insulation, not talking about flammability at this point, but how is PIR insulation performing when moisture get in? Fruit for thought....

 

 

[Mako]

16 hours ago, scottishjohn said:

so from you say  do we take it that really you have too many large windows  and or they really should have a solar radiation blocking coat on them to stop excessive solar gain inside the house?

 not pointed at you @Ferdinand directly ,but it does seem to be a re-occurring theme of houses over heating 

 

I have already been told by SWBO  that no mater what sort of MVHR is fitted she will still be opening the windows when ever she wants fresh air .

which makes me question for fitting it --and if house does store too much heat it can be balanced by windows being opened 

and as air quality will not be a problem  and at best  I probably only have another 20 years or less for independent living --then extra cost and complications of MVHR  is maybe not worth it

  and our intention for design is to have an orangery along the whole front of the house - and a similar thing above it - both will have real roof -- not glass 

 looking out over our view --that,s where we will go to cook in the sun  

 

 

another think i read, you only need Mvhr system if you have very good airtightness, if the airtightness is not great 

you get away with trickle vents, but the whole point of mvhr is to bring fresh air and reuse the existing heat.

i thing i will be putting one in. great in the summer you turn the recuperation off just have the fresh air coming in,

keeps the building cooler. but it needs thermal mass, in houses with internal insulation it won't help, it will still overheat apparently.

[Mako]

13 hours ago, joe90 said:

been there, got the T shirt (I just turn the MVHR off). I turned it back on recently now it’s turned colder and the windows are shut.

how long have you had it off?  you need to watch for the mould growth in the ducts, be careful, better get them cleaned.

[SteamyTea]

6 hours ago, Mako said:

its all about density of products.

No it isn't.  This is where the myth comes from.

See my earlier reply.

 

[PeterW]

8 hours ago, Mako said:

 

if anything Gypsum has got insulation property to it, he based is calculations per KG, instead of m3, 

imaging how much volume is 1kg of wood, and how much volume would be 1kg of concrete.

Did you see this table ..??

 

Gypsum is more dense than concrete. 

 

7 hours ago, Mako said:

plaster boarded skimmed and decorated? where is the vapour going to go? into the cellulose or PIR insulation, not talking about flammability at this point, but how is PIR insulation performing when moisture get in? Fruit for thought....

 

 

Ordinary plasterboard is vapour permeable - it’s why if you want a vapour sealed one it has foil on the back. 
 

And PIR works under water as an insulation as it is closed cell and does not absorb moisture. It also doesn’t burn unless it is under significant prolonged heat exposure above 500c, at which point your whole house is on fire so is probably a moot point ... 

[A_L]

2 hours ago, PeterW said:

Did you see this table ..??

 

Gypsum is more dense than concrete. 

 

Mineral gypsum has a density around 2900kg/m³, gypsum as in plasterboard/plaster has a density around 850-1000kg/m^3.

 

 

11 hours ago, Mako said:

If the vapour can escape? That means the wall is air-permeable, how are you going to keep the heat in?

 

No, air permeability is a bulk process. Water vapour can escape by a process known as diffusion, this is a molecule by molecule process which bulk air cannot do. It is this process that vapour resistance values relate to. It is perfectly possible to have an airtight house which has little vapour resistance. Anything described as a 'breather membrane' should have a low vapour resistance while inhibiting the movement of bulk air.

 

 

10 hours ago, Mako said:

if the vapour can get out of the cellulose from inside out, there must be reverse as well and the cellulose can get wet.

how does cellulose perform when wet?

 

The cellulose does not get wet. The external air heats up as it moves into the wall by absorbing heat from it. This greatly increases its ability to carry water vapour (its relative humidity or RH is decreased). In warmer climates where the external air is warmer than the structure it can be a problem, but not in the UK.

[Ferdinand]

 

12 hours ago, Mako said:

Hi,  not sure I’m following, I been told that concrete stays the same temp all year around, at least that’s the aim.

I don't think that is quite what was meant - concrete stores more energy than a timber frame, and will heat up and cool down more slowly if it currently has more energy stored in it.

 

The issue is surely whether that behaviour is useful for what you want from your house.

 

A highly insulated house to say near passive standard may only fall by 1C in a period of 24 or 48 hours with all the heating turned off anyway, even if Timber Frame, so I am not sure what value or functionality is added by large quantities of concrete in that situation.

 

Quote

More concrete you have in the house the more heat capacity

the house can deal with. On the hotter days, it will stay cooler for longer. That’s my understanding.

Not sure. How long it stays cooler depends more on how long the heat takes to penetrate to the interior ("decrement delay"), not how much is stored in the heatsink.

 

For a concrete heatsink to be keeping it cooler in hot weather it needs to be diverting energy away from the house interior. I am not clear how it does this. 

 

Ferdinand

Edited October 3, 2020 by Ferdinand

[ProDave]

23 minutes ago, Ferdinand said:

A highly insulated house to say near passive standard may only fall by 1C in a period of 24 or 48 hours with all the heating turned off anyway, even if Timber Frame, so I am not sure what value or functionality is added by large quantities of concrete in that situation.

 

Not sure. How long it stays cooler depends more on how long the heat takes to penetrate to the interior ("decrement delay"), not how much is stored in the heatsink.

 

Our house is like that, it takes a long time to react to changes in outside temperature.

 

That works well in hot weather. It keeps the daytime heat out long enough not to heat up the house, and then a night purge with windows open cools the house down.

 

It only becomes a real problem when even the night time temperature is too high in a real heat wave so the house will eventually overheat regardless. That has only happened once up here so far which got me thinking about active cooling.

[Simplysimon]

13 hours ago, Mako said:

surely when we talking about vapour resistance to be greater, that means there won’t be any air-tightness in the house?

If the vapour can escape? That means the wall is air-permeable, how are you going to keep the heat in?

I might be wrong, just thinking out loud

as the vapour resistance is greater, this does not mean the air tightness is reduced. good vapour resistance can be achieved in a number of ways, parge coat on blockwork, polythene sheet on timber kit or as i'm doing https://mdfosb.com/en/smartply/products/smartply-propassiv these prevent the vapour from entering the insulated area of the wall. on the outer skin of the kit i have https://mdfosb.com/en/medite/products/medite-vent which is vapour open, this allows for vapour to leave the kit, effectively allows the wall to breathe. the heat is kept in by the cellulose insulation and as the smartply is vapour resistant and all joints are glued and sealed there are no draughts, as it provides the air tight layer as well and therefore little loss in heat.

 

13 hours ago, Mako said:

I think Jeremy got it slightly wrong.

contoversial!

 

13 hours ago, Mako said:

I understand and agree that we all make choices, but even I beam is less stable than concrete?

Less soundproof? And less airtight? And won’t last as long? Will also have negative effect on land fill when it comes to rebuild.

 And probably more expensive as well to start with compared to concrete, my thoughts...

if the kit is built quickly there should be very little movement in the i beams due to the majority being osb and a 350mm i beam isn't going to flex much, so i wouldn't think very much less stable than concrete. it has been observed that a good deep layer of cellulose is eerily quite inside a house due to being pumped to a compaction of 55kg/m3.

as for negative effect on landfill, you are looking at a natural material apart from the formaldehyde glue which would decompose over time as opposed to concrete which has a very high co2 impact in its manufacture and will not break down though could be recycled if it didn't have another potentially non recycleable product such as polystyrene attached to it. the environmental impact of production and end of life materials are not good as opposed to timber and paper. as to costs, i haven't compared to concrete.

 

12 hours ago, Mako said:

you get away with trickle vents,

partially controlled draughts

 

12 hours ago, Mako said:

in houses with internal insulation it won't help, it will still overheat apparently.

what is internal insulation? and all houses will overheat depending on design. insulation is there to stop the heat entering or leaving the building. in most instances in uk, leaving, though down south it is becoming equally important to stop it entering. if you have a house with sooper dooper levels of insulation which has a high decrement delay, this can all be wasted if you have huge amounts of normal 3g glazing to admire the south and west views as the house would potentially overheat due to solar gain.

 

12 hours ago, Mako said:

nternal airtight membranes, the only weakness is at the joint, can you find out from any supplier how long do they guarantee 

the membranes to work? they have to guarantee for 10years, what happens after that? membranes coming apart within the wall?

plaster boarded skimmed and decorated? where is the vapour going to go? into the cellulose or PIR insulation, not talking about flammability at this point, but how is PIR insulation performing when moisture get in? Fruit for thought....

i'm sorry, you need to do a lot more research before asking questions like that.

 

12 hours ago, Mako said:

how long have you had it off?  you need to watch for the mould growth in the ducts, be careful, better get them cleaned.

and that.....

[SteamyTea]

1 hour ago, Ferdinand said:

How long it stays cooler depends more on how long the heat takes to penetrate to the interior

Yes.

It is all in the units.

Energy (heat in Roman Catholic) is measured in joules, J.

Thermal conductivity is measured watts, W.

Now a watt is a joule per second.

So there is the difference, and is where the time element comes from.

[Mako]

10 hours ago, ProDave said:

Our house is like that, it takes a long time to react to changes in outside temperature.

 

That works well in hot weather. It keeps the daytime heat out long enough not to heat up the house, and then a night purge with windows open cools the house down.

 

It only becomes a real problem when even the night time temperature is too high in a real heat wave so the house will eventually overheat regardless. That has only happened once up here so far which got me thinking about active cooling.

What type of construction have you used? 

[Mako]

9 hours ago, SteamyTea said:

Yes.

It is all in the units.

Energy (heat in Roman Catholic) is measured in joules, J.

Thermal conductivity is measured watts, W.

Now a watt is a joule per second.

So there is the difference, and is where the time element comes from.

I’m learning, thank you for explaining, that makes sense. In your opinion with exposed concrete, hoW long would the heat from solar gain

take to get absorbed by the concrete, and how long would it take to release?

I would think that it would be simultaneous as the solar gains are raising the internal temp, the heat is gradually absorbed into the concrete.

depending on how much Heat capacity the concrete or wall product has will determine how soon it will overheat? Do I understand it correctly?

[Mako]

10 hours ago, Simplysimon said:

as the vapour resistance is greater, this does not mean the air tightness is reduced. good vapour resistance can be achieved in a number of ways, parge coat on blockwork, polythene sheet on timber kit or as i'm doing https://mdfosb.com/en/smartply/products/smartply-propassiv these prevent the vapour from entering the insulated area of the wall. on the outer skin of the kit i have https://mdfosb.com/en/medite/products/medite-vent which is vapour open, this allows for vapour to leave the kit, effectively allows the wall to breathe. the heat is kept in by the cellulose insulation and as the smartply is vapour resistant and all joints are glued and sealed there are no draughts, as it provides the air tight layer as well and therefore little loss in heat.

I understand what you saying, but I still find that if the external outer skin lets vapour out it will let it in as well. for example today we have 93% humidity level here, the humidity will get into the timbers of the i beams, OSB it’s like a wheatabix when wet, cellulose the same, how is that protected?

understand if you use polythene you will stop the vapour going into the wall, but increase the humidity internally relaying purely on ventilation 

to maintain the balance. I think wall should be breathable to a degree but if there is vapour passing through none of the elements should be affected by it. Would you agree?

Quote

 

contoversial!
it is but basing it on KG doesn’t make sense, the M3 approach would work, and was added afterwards, that had some legs.

 

 

if the kit is built quickly there should be very little movement in the i beams due to the majority being osb and a 350mm i beam isn't going to flex much, so i wouldn't think very much less stable than concrete. it has been observed that a good deep layer of cellulose is eerily quite inside a house due to being pumped to a compaction of 55kg/m3.

as for negative effect on landfill, you are looking at a natural material apart from the formaldehyde glue which would decompose over time as opposed to concrete which has a very high co2 impact in its manufacture and will not break down though could be recycled if it didn't have another potentially non recycleable product such as polystyrene attached to it. the environmental impact of production and end of life materials are not good as opposed to timber and paper. as to costs, i haven't compared to concrete.

what is classed as build quickly? Most of the time the timber kits are build within 3-5days and than waiting open for 4-12weeks waiting for Windows.

thats if it doesn’t rain during construction, or transport. I was more referring to the entire structure, Roof, tiles, sanitary, cables, plastic ducts,

plasterboard, membranes, tapes, insulation etc 

more often you need to replace the building the greater impact it has.

take your point on the soundproofing, but not convinced, friend had used wolf joists with metal zig Zac in roof construction, blown up with Celulose,

And you can hear everything outside. Membranes both sides, Slate tile, plaster boarded internally.

 

Quote

 

partially controlled draughts

 

what is internal insulation? and all houses will overheat depending on design. insulation is there to stop the heat entering or leaving the building. in most instances in uk, leaving, though down south it is becoming equally important to stop it entering. if you have a house with sooper dooper levels of insulation which has a high decrement delay, this can all be wasted if you have huge amounts of normal 3g glazing to admire the south and west views as the house would potentially overheat due to solar gain.

 

i'm sorry, you need to do a lot more research before asking questions like that.

 

and that.....

Internal insulation, many people use insulated plasterboard internally, poly ICF systems have internal insulation, Timberframe would be classed as internal insulation, not having the thermal mass present. I think guys with concrete houses are reporting minimal overheating, timberframe

Houses overheated almost every day Last summer we had. There is nowhere for the heat to go, other than open windows, and let the free energy

you gained go to waste. Why can’t we utilise this energy? I’m led to believe that concrete or house build from solid Plaster are the way to go.

 

in terms of the tapes, that is proven, when people do extensions, and open the walls, it’s unbelievable membranes pulled apart,  it’s a fact.

 

in terms of PIR, the same it doesn’t perform when wet. Do a test put a board outside and see how much water it absorbs.

XPS you can class as closed cell insulation, I believe. 
 

PIR also burns - Look at the tower block disaster in london Celotex was used if I’m correct.

 

Im trying to find the holy grail of a building the performs and lowers running costs, without additional problems.

similar to Huff Houses, friend did few repairs on one and found Mouldy areas under the roof.

that just points to me that these types of structures are just not cutout for the humidity levels we have here.

different in Alps, Scandinavia, Russia where they have low humidity, minus 20-50C and all bacteria/mould 

growth is killed every year. In here we just keep breeding the mould, breathing it, no wonder we have health problems

As a nation. Same applies to turning off MVHR, what is going to happen to humid ducts without the airflow?

grow mould as it happens, what happens when you turn it on? The mould is blasted into the house where people live.

not good at all, if you have it keep it running 

 

 

[Mako]

16 hours ago, PeterW said:

Did you see this table ..??

 

Gypsum is more dense than concrete. 

 

Ordinary plasterboard is vapour permeable - it’s why if you want a vapour sealed one it has foil on the back. 
 

And PIR works under water as an insulation as it is closed cell and does not absorb moisture. It also doesn’t burn unless it is under significant prolonged heat exposure above 500c, at which point your whole house is on fire so is probably a moot point ... 

Agree with you Gypsum in the mined form has density like that, but in Plasterboard it has been cut, and added other cheaper fillers,

to make it lighter for transport, and cheaper to produce, you get 500-1000kg/m3 of plasterboard  

getting closure to wood, which is classed as insulant compared to concrete.

 

PIR leave it outside in the rain and see in the morning, also it states on the manufacturers website keep dry.

it burns, we seen the tower block going to flame because of it.

it also emit gasses into the households and nobody minds, crazy stuff if you look into it.

 

[Mako]

13 hours ago, A_L said:

 

Mineral gypsum has a density around 2900kg/m³, gypsum as in plasterboard/plaster has a density around 850-1000kg/m^3.

 

AGREE WITH YOU, that means that plaster board is an insulant compared to concrete, 500-1000kg/m3 compared to wood at 400-700kg/m3

 

13 hours ago, A_L said:

 

 

 

No, air permeability is a bulk process. Water vapour can escape by a process known as diffusion, this is a molecule by molecule process which bulk air cannot do. It is this process that vapour resistance values relate to. It is perfectly possible to have an airtight house which has little vapour resistance. Anything described as a 'breather membrane' should have a low vapour resistance while inhibiting the movement of bulk air.

understand the vapour diffusion process, but how does that work with loose fill celulose?
what system delivers permanently perfect airtight house and have little vapour resistance?

 

 

 

13 hours ago, A_L said:

 

 

 

The cellulose does not get wet. The external air heats up as it moves into the wall by absorbing heat from it. This greatly increases its ability to carry water vapour (its relative humidity or RH is decreased). In warmer climates where the external air is warmer than the structure it can be a problem, but not in the UK.

Ok, if that was the case, me thinking, how can the external air heat up, if cellulose is really good insulating product? There would have to be great heat loss for the air to heat up and diffuse the moisture out before it entered the cellulose.

considering that we are all designing homes to 21C internally, that means the summers we had in the last 5-10 years, with temperatures gradually  increasing while the external humidity is still high, would therefore push the moisture into the dry cellulose and germinate Bacteria, mould and rot of the OSB boards timbers, and we can’t avoid that. Again in Scandinavia with dry air, low humidity and  extreme temperatures it could work,  but I’m not convinced same would apply here. I’m asking for more convincing information, in order to make an educated decision.

 

[PeterW]

15 minutes ago, Mako said:

PIR leave it outside in the rain and see in the morning, also it states on the manufacturers website keep dry.

it burns, we seen the tower block going to flame because of it.

it also emit gasses into the households and nobody minds, crazy stuff if you look into it.

Seriously... PIR does not absorb water - it is what is also used for floatation in boats and canoes. Yes, under the correct conditions it will burn, but as I said it needs to be very hot and at that point and more crucially where it is in the “sandwich” of a house, you have bigger issues ..!!

 

Off gassing of materials is an issue not just with  PIR. MDF and other engineered woods can contain formaldehyde, paints have varying levels of VOCs, and you will struggle to find anything other than straw, sheep’s wool, mud and raw timber that don’t have some sort of chemical emissions. Given where PIR is normally used, it is encased in concrete or blockwork, or inside roof structures where the emissions can escape to the outside air, there is very little issue with this in modern buildings. 

[Mako]

12 hours ago, Ferdinand said:

 

I don't think that is quite what was meant - concrete stores more energy than a timber frame, and will heat up and cool down more slowly if it currently has more energy stored in it.

 

The issue is surely whether that behaviour is useful for what you want from your house.

 

A highly insulated house to say near passive standard may only fall by 1C in a period of 24 or 48 hours with all the heating turned off anyway, even if Timber Frame, so I am not sure what value or functionality is added by large quantities of concrete in that situation.

 

Not sure. How long it stays cooler depends more on how long the heat takes to penetrate to the interior ("decrement delay"), not how much is stored in the heatsink.

 

For a concrete heatsink to be keeping it cooler in hot weather it needs to be diverting energy away from the house interior. I am not clear how it does this. 

 

Ferdinand

Yes, if concrete has got the capacity to store more energy, if will prevent sudden changes in temperatures caused by solar gains.

if we are talking about Passive House with all the limitations of window openings, sizes etc you are probably right. But if you want to enjoy life and views etc, you have to calculate with some solar gains. What is the best product to deal with that, would that be Concrete? Or Timberframe 

House with no thermal mass?

i think my point is, when you get solar gains in Timberframe house your house will overheat and you need to dump the heat otherwise you will

have 30C in the house before you know it. With concrete and the mass charged to say 21C you still have capacity to sink the heat into it,

even if the temperature of the concrete increases by few degrees that’s better than 30C plus.

i understand that there is conection between the amount of concrete in the build and amount of solar gain, but this can be calculated

And designed out. It’s harder to design it out with Timberframe unless you remove windows and stop all solar gains. Am I correct thinking this way?