What is the Benifit of Cavity Insulation

arghh

I have installed Kingspans boards (60mm) in the cavity of my new build at a cost of €2000. While there is no doubt that they are of some beneficial value would it be better to put the insulation on the inside of the house instead of in the cavity.I am just a lay person and have no figures to back up my argument but it does not make no common sense. In my case I went with the flow, in case I got it wrong but when I look at the practical side I just do not see the benefits being of any significent value. What are your thoughts on this?

BadCharlie

Well kingspan is one of the better types of insulation which you picked to use which is good.

Firstly insulation on the inside of the house is normaly used on timber framed dwellings. Its a lot easyer to put insulation on the inside of a timber framed house then your typical block house.
I would think that having the insulation in the cavity block build is easy for the builders to do, as you have your wall ties to keep your insulation in place.

Also i be more worried about your ceiling/roof insulation then wall as that is where most of your heat will get out.

Firewalkwithme

One very simple reason that springs to mind is that since the cavity is there you might as well use it instead of losing some interior area. Also, if you want to hang anything heavy from your wall, it's a lot easier to fix it to blockwork. If you put the insulation on the inside face of the wall you will need to provide something to fix plasterboard onto thus adding to your costs.

Also, the insulation may have a vapour barrier to prevent dampness in the inner leaf. If it's not in that cavity then you could find any walls butting up to you external wall getting cold too.

Viking House

One of the biggest problems with partial fill cavity walling is "Thermal Looping" where the U-value is reduced by an average of 35% because of the air gap between the inside block and the insulation.
Roadstone admit the problem in this link http://www.roadstone.ie/products/Blocks/SafeWarm.htm
and here is an article from Construct Ireland about the problem http://www.century.ie/cent/PartialFillCavity.pdf

The second problem is "Cold Bridging" where a lot of heat is lost.
This occurs between the wall and the floor, around the windows and doors and where the roof meets the walls. Most Irish houses that we checked with the Thermal Imaging camera showed major heat loss in these areas.

Sorry to be the bearer of bad news!!

When you dryline you only insulate 90% of the wall because you are not insulating the parts where the middle walls and floors meet the outside. Drylining with polyeurethene backed plasterboard causes fungus and mould growth.

Reyman

arghh wrote:

I have installed Kingspans boards (60mm) in the cavity of my new build at a cost of €2000. While there is no doubt that they are of some beneficial value would it be better to put the insulation on the inside of the house instead of in the cavity.I am just a lay person and have no figures to back up my argument but it does not make no common sense. In my case I went with the flow, in case I got it wrong but when I look at the practical side I just do not see the benefits being of any significent value. What are your thoughts on this?

There is one considerable advantage in having the insulation in the wall cavity. It provides greater thermal capacity in the inner walls of the house.
i.e. Because the inner concrete wall is inside the insulation it retains the heat well and you will not get rapid changes in the temperature of the house

bcoffey

has anyone used those SafeWarm blocks from Roadstone referred
to by VikingHouse?

http://www.roadstone.ie/products/Blocks/SafeWarm.htm

What are the cons?

Ewan

Vikinghouse,
would you recommend any particular insulated plasterboard slab for the inner leaf of a house ??? are the insulated plasterboard slabs prone to cause mould/fungus growth as you mentioned of the polyurethane plasterboard??

Mellor

Ewan wrote:

Vikinghouse,
would you recommend any particular insulated plasterboard slab for the inner leaf of a house ??? are the insulated plasterboard slabs prone to cause mould/fungus growth as you mentioned of the polyurethane plasterboard??

polyurethane plasterboard that Viking mention IS the insulated plasterboard.
Alot of insulated plasterboards are polyurethane based, or the similar polyisocyanurate. But not all of them.
Phenolic resin based insulations are very breathable. This should eliminate the problem. They also achieve one of lowest U-Values in building products. They cost more, but it is money well spend. And to get the same level of insulation you need less, so that balances it a bit.
Newer insulated plasterboard products are available with Phenolic insulation

Viking House

If I was drylining I would use Softboard because it is very hydroscopic helping the building to breathe, regulating the water vapour levels inside the building naturally.
It also is very heavy and holds onto heat 10 times longer than Polyeurethene because of its density.

Go to page 4 of this document to see the breathability of Polyeurethene and Polyiso boards, they are between 200-800 times less breathable than Softboard Woodfibre boards.
http://www.natural-building.co.uk/pdfs/Breathability_in_buildings.pdf

Go to page 26 to see what happens when you dryline with non-breathable petrochemical insulation materials.

Inside air laden with water vapour will get into your walls because of high pressure inside the house and lower pressure outside, also because of the need for heat to go towards cold. You need to let the moisture out by letting the wall breathe not trap it in the wall to grow fungus.
The UK has now become the leader in the world with the incidence of Asthma and Whales is the UK's hotspot.
There are many places in the world with much higher humidity levels than here and they don't have these problems. The Irish climate is used as an excuse for bad building practise. If we are going to copy sombodies building systems why not copy Germany or Scandinavia instead of the UK?

Mellor

Viking House wrote:

If I was drylining I would use Softboard because it is very hydroscopic helping the building to breathe, regulating the water vapour levels inside the building naturally.
It also is very heavy and holds onto heat 10 times longer than Polyeurethene because of its density.

Phenolic resin based insulations also allow walls to breath. And have better resistances than mineral wool, polyiso, or polyurethane.

What kind of thermal resistance do standard softboards have? As for holding on to heat, Im not really sure what you mean by that. Could you explain it in a little bit of detail, as im sure there is more to it than I am aware of.. Density and mass help to hold on to heat, but its hardly the only criteria, resistance to heat transfer is obviously more important. Not all material that are dense hold on to heat well, (eg metals). And materials like concrete hold on to heat very well, far better than wood, as it has a high specific heat capacity. But concrete won't make a good insulator.



If I was to build my own house tomorrow, i'd go for a breathable high performance insulation, and use dense construction. I also wouldn't dryline and I am yet to see it done right/fully. But I wouldn't go for standard cavity construction, I'd need to resolve the issues with sloppy mortar work resulting in thermal looping. But I haven't had time to run through details yet.

Viking House

Hi Mellor how are you?

Polyiso boards have a vapour resistance of 40,000-50,000 MNs/gm
Woodfibre has a vapour resistance of 25 MNs/gm.
So polyiso is not breathable, the only way moisture can escape is through the joints causing condensation on the wall, Sorry!
Woodfibre is about 0.45W/m2k so you need more to get the same U-value as Polyeurethene but because it is 10 times heavier it looses heat 10 times slower.
U-value is not a good enough measurement of heat loss, it is only part of the equation.

Heavier insulation materials let heat pass through a lot slower.
50mm of softboard on top of a roof insulated with lets say 200mm fibreglass gives the effect of an extra 200mm of insulation because it slows down the rate of heat loss by 6 hours.

Here BASF are using technology to address the issue of Decrement Delay.
http://www.functionalpolymers.basf.com/portal/streamer?fid=290929

http://www.viking-house.net/decrement-delay
Check out the two graphs with the blue borders and see what happens when you increase the density of the insulation from 20kg/m2 to 70kg/m2, the phase delay is increased by 6 hours and instead of a temperature fluctuation of 13 degrees you get a temperature fluctuation of 3 degrees and a house that needs no heating or cooling..

http://www.natural-building.co.uk/pdfs/Roof_PAVAROOF_PITCHED.pdf
On page 2 you can see the improvement in Decrement delay when you increase the thickness of Softboard.

Ewan

Lads,
i think theres a shampoo add that goes "now for the science bit"...!:eek:
great document vikinghouse on breathability......must sit down and read it in detail....
a few more questions.....can the breathable boards be bought from builders suppliers..or are they through specialist companies??
can they be mechanically fixed to inner leaf blockwork..and skimmed

I intend on having a room in the attic space....the foiled back insulation i see between rafters on lots of new builds is obviously non-breathable and creates problems over time with decay and rotting of timbers:mad: ......any recommendations on breathable insulation that wont break the bank....

Mellor

Viking House wrote:

Hi Mellor how are you?
I'm good, hows work going? still busy as ever. I imagine you're more and more in demand with the BER and DEAP now in use.

Polyiso boards have a vapour resistance of 40,000-50,000 MNs/gm
Woodfibre has a vapour resistance of 25 MNs/gm.
So polyiso is not breathable, the only way moisture can escape is through the joints causing condensation on the wall, Sorry!
I'm well aware polyisocyanurate isn't breathable, I never have and never will claimed it. Its the same as polyurethane, only better thermal resistance.
I claimed that Phenolic resin is breathable, I dont have the vapour resistance figures as the link you gave yesterday didn't mention it. they also spelled polyisocyanurate wrong, which is a little unprofessional for a scientific document.

Woodfibre is about 0.45W/m2k so you need more to get the same U-value as Polyeurethene but because it is 10 times heavier it looses heat 10 times slower.
Copper is much denser than woodfibre, but it loses heat quicker, far quicker. The only way that density would cause reduced heat loss would be where two material had the same specific heat capacity and the more dense one obviously has a holds more heat as it is related to mass.

But the claim that more density equals longer heat retention is false. Only when SPC are very close or equal (or the denser one is higher). And this is not always the case. it is material dependant. Infact, polyurethane has a higher specific heat capacity than wood fibre. But the weight of wood overtakes this.


U-value is not a good enough measurement of heat loss, it is only part of the equation.
Heavier insulation materials let heat pass through a lot slower.
50mm of softboard on top of a roof insulated with lets say 200mm fibreglass gives the effect of an extra 200mm of insulation because it slows down the rate of heat loss by 6 hours.
If a material lets heat pass through it slower than another one, then it has a lower U-Value. If two materials have the same U-Value, then they MUST let heat pass through at the same speed, as this is what U-Values measure, the rate of heat passes through each m2 in area for every degree kelvin difference on either side.
When this area is discussed heat and temperature are often confused, the wood fibre lets the same heat through, but resulting temp is different

the increase in mass in dense insulation, is nothing compared to building with heavyweight structure. Which will increase a building mass by tons rather than kilos. All reports on the topic will refer to this. having concrete wall will help in this area too.


Here BASF are using technology to address the issue of Decrement Delay.
http://www.functionalpolymers.basf.com/portal/streamer?fid=290929
That article also refers to the mass of the whole building, like concrete walls as opposed to timber or lightweight block. I read that article and its actually mainly on phase change materials, which wax particles in finishes that melt and absorb heat while doing so at around 26 degrees. I've heard of their use in large buiding, but on a domestic scale, how often are we above the 26 degrees required to benefit in this country? Still very interesting stuff.


http://www.viking-house.net/decrement-delay
Check out the two graphs with the blue borders and see what happens when you increase the density of the insulation from 20kg/m2 to 70kg/m2, the phase delay is increased by 6 hours and instead of a temperature fluctuation of 13 degrees you get a temperature fluctuation of 3 degrees and a house that needs no heating or cooling..

I knew the increased mass would have an effect, I didnt think it was that large.
Do you have the same study done for walls? If thats true, then tradition concrete walls should perform better than timber frame and lightweight block systems. As long as the U-Values are the same like in the example.

Even though wood had a higher heat capacity than concrete, the mass of the concrete is greater, and the heat capacity of a concrete wall is greater.

http://www.natural-building.co.uk/pdfs/Roof_PAVAROOF_PITCHED.pdf
On page 2 you can see the improvement in Decrement delay when you increase the thickness of Softboard.

Didn't mean to go on so long there. Only trying to highlight the fact that you misunderstood me regarding Phenolic resin insulation and breathability.
I agree that mass plays a big role in the thermal dyamics of a building, but applying this to insulation only is wrong, and I was trying to highlight that for some readers. I agree with all of your principals in the context you take them. But sometimes some of them could be taking up wrong by a layperson.

The main confusion in all this comes down to the difference in heat and temperature. Two walls with the same U-Value let exactly the same amount of heat through (heat is a form of energy), the temperature in the room will increase to different levels because of the materials in the walls roof and room itself. Dense materials with high heat capicites cause lower temps, but not just insulation, all material that the heat passes through.

I recently did a temperature analysis for a cross section though a wall. Finding the temperature changes through the wall, at points of material change for a set difference in internal and external air temp.
It might be interesting to take a look at heat capacities of different materials next time........



sorry if theres any mistake, or parts that dont make sense, it late and that took a while.

Mellor

I was gettin tired last night and forgot to mention the inverse of dense materials. They take longer to heat up in the winter, but hold on to it longer. So a slower responce time from heating, but gentler changes and less fluctuations.

Viking House

Apologies Mellor

I misread your earlier post, but I am happy to have evoked your informed response. I did a search for Phenolic resin but found nothing, can you send me your info?

I am not convinced about the thermal mass benefit of concrete as it looses most of its heat in 3 hours

Take two same size rooms with the same size windows, one room has concrete block walls and the other has Poroton block walls. The sun is shining through both windows, the Poroton block room is 3 degrees cooler because Poroton soaks up more heat that is released slowly for the next 12 hours but it is not as dense as concrete. I know this because I have first hand experience from builders in countries that use these systems as standard.

My understanding is that you need to use a combination of U-value and density in your insulation material, this is why Paroc is the market leader in Scandinavia and not Polyeurethene.

Aeneas

Hi Viking House
Is softboard suitable for flooring an attic. I have a single storey extension to my home and I need to use the attic space for storage. It has 6in of fibreglass, as compared with 18in in the main body of the house. I want to avoid the whole business of raising the joists and I was wondering if I floored it with softboard would that 1) provide my floor and 2) double the insulation.

Mellor

its hard to find out info about Phenolic resin, and even harder to compare anything you find,
kingspan and other companys that sell it describe it a lowest u-value 0.022 andlower in some products, and low vapour permenace suitable for application.
what I take from that is that the materials lets vapour through, just not as much/fast as say mineral wool. but vapour can pass through unlike polyiso and friends.
I have vapour values, but im unsure how good they are as i couldn't find any relevance on the units
www.barnvale.co.uk the second one is Phenolic resin, its different shape, but properties should be the same.
from looking at vapour check site, its around the same as a vapour control layer for domestic use, comercial one such as pools obviously need to get vapour our quicker. but in houses if vapour escapes too quickly interstitual condensation can occur.

ardara1

In the over all scheme of things guys -

Taking a reasonable well insulated/performing building fabric, with good condensing boiler and best practice controls, and a good permeability of say 4

Lets say a 'B' house

Oh yea - the achieved U-value is the same in walls floors & roofs -

Will the density of the insulation improve the rating - yes or no?
If yes - but how much? (Say in Kwhrs)

As for the material being breathable (We trying to achieve agood air permeability by puttin plastic to the inside of the build or taping up or using mastic etc) - will it mater?

If you say yes - can you give an example (locally) where the problem has been so bad it has been recorded - or better still the building has had to be rebuit/demolished?

SOme times I think we're debating angel on pin heads type of questions.

Mellor

the B house comment reminded me of a thread i was going to start,
the rating system is a joke, ill start a new thread on the system now

ardara1

Mellor wrote:

the B house comment reminded me of a thread i was going to start,
the rating system is a joke, ill start a new system now

See you there

galwaytt

Viking House wrote:

Go to page 26 to see what happens when you dryline with non-breathable petrochemical insulation materials.

sorry, but that diagram is not the cavity construction in use in this country, so is misleading. That diagram is a cavity formed between a dry trade and solid masonry, with vented cavity between, and with opes for services into that cavity. That system is neither in use nor would be approved, I imagine, by the DoE.........This is based on my experience of working with DoE on this and related subjects.......

Mellor

ardara1 wrote:

Will the density of the insulation improve the rating - yes or no?
If yes - but how much? (Say in Kwhrs)

From my understanding of the topic, it won't affect the rating.
As from the graphs VH posted, the dense insulation improves the comfort of the building, reduces temp fluctuations. The heat energy coming in is taken in my building materials. This happens when the external temp is higher than internal. So heating isn't affected. When the internal temp is higher, it shouldn't make a difference. as heat is leaving the structure/room

Sparky78

Would I be right in saying that if your house has a high decrement delay then it would take longer to heat up and take longer to cool down.This would mean it would be more benifical to someone who is in the house all day.
And a house with a lower decrement delay would be more benifical to someone who was out most of the day and needs the house to heat more quickly and for less time.

ardara1

Are we talking thermal mass here?

If so the other 3 walls in the room along with the floor will have a greater effect than the density of the insulation in the out side wall?

Again - does it matter that much?????

And can VH give evidence (actual) for the moisture/dampness/mould problems?

Mellor

no its not thermal mass, thermal mass works to absorb heat from the room as it is heating,
but it doesn't work well in domestic situations,
its better suited to large building were the slab can be cool during the night, allowing for a heat offset in the morning, WIT is an excellant irish example

the idea mention on this thread is that a dense outer wal aborbs heat as it enters the building, rducing fluctuations, this only applies to conditions when the outside temp is higher than the inside one

ardara1

Mellor wrote:

no its not thermal mass, thermal mass works to absorb heat from the room as it is heating,

the idea mention on this thread is that a dense outer wal aborbs heat as it enters the building, rducing fluctuations, this only applies to conditions when the outside temp is higher than the inside one

Did the first post not ask if it'd be better to dryline or use cavity? - or am I not making it complicated enough?

muffler

ardara1 wrote:

Did the first post not ask if it'd be better to dryline or use cavity? - or am I not making it complicated enough?

That could have been mentioned in the first post but the thread is titled "What is the Benifit of Cavity Insulation" so I dont see a problem with previous posts

Viking House

galwaytt wrote:

sorry, but that diagram is not the cavity construction in use in this country, so is misleading. That diagram is a cavity formed between a dry trade and solid masonry, with vented cavity between, and with opes for services into that cavity. That system is neither in use nor would be approved, I imagine, by the DoE.........This is based on my experience of working with DoE on this and related subjects.......

I still get plenty of projects for pricing on my desk from Architects using 9 inch cavity blocks drylined with Kingspan/Xtratherm. They rarely specify a ventilated cavity behind the insulation. When you put a ventilated cavity behind Kingspan/Xtratherm drylining, while drylining a partial filled cavity wall, you mess up the U-values you are suppose to achieve, but you reduce the risk of mould. If you don't ventilate a cavity behind the dryling you get better U-values but also greater risk of fungus growth. So whichever way you go you lose.

Viking House

Sparky78 wrote:

Would I be right in saying that if your house has a high decrement delay then it would take longer to heat up and take longer to cool down.This would mean it would be more benifical to someone who is in the house all day.
And a house with a lower decrement delay would be more benifical to someone who was out most of the day and needs the house to heat more quickly and for less time.

An insulation material with a 12 hour decrement delay, loses half as much heat as an insulation material with a 6 hour decrement delay, everything else being equal, so it's twice as good at keeping your house warm.

200mm of fibreglass in your roof has a decrement delay of 5 hours, so the outside 5 degree cold makes its way through the roof in 5 hours, the cold heats up as it comes through the insulation and comes in at about 10 degrees. If you put 60mm of Softboard on top of the fibreglass insulated roof, the decrement delay is increased by 6 hours and the cold now takes 11 hours to come through the roof and comes in at 15 degrees. The 60mm of Softboard has, in this situation, the effect of an extra 200mm of fibreglass in the roof.

Softboard also stops the wind blowing the heated trapped air out of the insulation underneath.
In Scandinavia they normally put a layer of paper on top and between between layers of insulation in the attic to reduce air movement within the insulation, so a layer of building paper on top of the insulation in your attic improves the effect of your insulation by 30%.

We built a house with high decrement delay material in Wicklow and the temperature is fluctuating between 16-22 degrees without heating.
Houses built with these materials require much less heating and retain heat longer than houses insulated with plastic insulations. We hope to improve on this and bring future projects into a 4 degree unheated fluctuation.
A standard log cabin with 30cm walls retains heat and stays cosy all night when the heat is turned off, the U-value of the walls is quite low at about U 0.65 but it holds onto its heat for much, much longer than say a caravan insulated to U 0.30 with Polyeurethene.

Viking House

Again - does it matter that much????? The specific heat capacity and density of insulation is as important as U- value, so it matters a lot.

And can VH give evidence (actual) for the moisture/dampness/mould problems?

The UK is now officially the leader in the world when it comes to Symptoms of Asthma, and South Whales is the hotspot. Ireland using the same non breathable building systems is not that far behind. A Polish Engineer mentioned to me last week that "The Irish are very busy building houses (for mushrooms)"
Every second Irish house I go into has fungus on the bathroom cieling/wall, don't tell me you haven't noticed. The black spots you see are only 5% of the problem, the Tip of the Iceberg!! I will post a link to the UK Asthma document during the week when I refind it!!

Mellor

Viking House wrote:

200mm of fibreglass in your roof has a decrement delay of 5 hours, so the outside 5 degree cold makes its way through the roof in 5 hours, the cold heats up as it comes through the insulation and comes in at about 10 degrees. If you put 60mm of Softboard on top of the fibreglass insulated roof, the decrement delay is increased by 6 hours and the cold now takes 11 hours to come through the roof and comes in at 15 degrees. The 60mm of Softboard has, in this situation, the effect of an extra 200mm of fibreglass in the roof.

sorry Viking but that is completely wrong, cold never moves through any building structure, it nevers moves anywere. Cold is a adjective, nothing physical. HEAT is a adjective, but it is also physical energy.
Heat leaves the building, if the walls have the same U-Value then the amount of heat lost is the same. Heat moves, cold doesn't.

I have agreed that decryment delay can reduces fluctuations in temp, but only when the external temp is higher than the internal temp, as heat moves from the outside through the wall, and more is absorbed by the building structure. Similar to cooled slabs in large buildings.

how often in this country is the external temp air temp higher than the internal temp. On the hottest days, the internal air heats up quite quickly, that is why we open windows to have a high number of air changes.

ardara1

Viking House wrote:

Again - does it matter that much????? The specific heat capacity and density of insulation is as important as U- value, so it matters a lot.

And can VH give evidence (actual) for the moisture/dampness/mould problems?

The UK is now officially the leader in the world when it comes to Symptoms of Asthma, and South Whales is the hotspot. Ireland using the same non breathable building systems is not that far behind. A Polish Engineer mentioned to me last week that "The Irish are very busy building houses (for mushrooms)"
Every second Irish house I go into has fungus on the bathroom cieling/wall, don't tell me you haven't noticed. The black spots you see are only 5% of the problem, the Tip of the Iceberg!! I will post a link to the UK Asthma document during the week when I refind it!!

Sounds like sale air VH - need to look at your ventilation, fresh air should be brought into passive houses as well

I've asthma - I'd asthma when I lived in an 1880 red brick uninsulated draughty house with an outside bathroom and ice forming on the inside of windows in the winter. I now live in a early 20th cent house insulated conventionally - drylined and in certain parts pumped - sealed to b'jasus, double glazed - my kids don't suffer.

To blame Asthma on the type of insulation you buy - or sell - is taking it a bit far! - perhaps it's the shower gel we use?

Viking House

Mellor wrote:

sorry Viking but that is completely wrong, cold never moves through any building structure, it nevers moves anywere. Cold is a adjective, nothing physical. HEAT is a adjective, but it is also physical energy.
Heat leaves the building, if the walls have the same U-Value then the amount of heat lost is the same. Heat moves, cold doesn't.
I have agreed that decryment delay can reduces fluctuations in temp, but only when the external temp is higher than the internal temp, as heat moves from the outside through the wall, and more is absorbed by the building structure. Similar to cooled slabs in large buildings.
how often in this country is the external temp air temp higher than the internal temp. On the hottest days, the internal air heats up quite quickly, that is why we open windows to have a high number of air changes.

Hi Mellor

We have to agree to differ here. I have discussed this with too many educated people from Scandinavia, Germany and Holland to think otherwise.

Our Polish builders know from experience that there is a big difference in heating costs between putting Paroc or Polysterene on the outside of Poroton blocks in Poland. Both have a similar U-value, but when you use Paroc they say the heatloss is halved.

Karl a Sweedish Architect colleague checked this out with some of his friends who are Science lecturers in Stockholm and Jonkoping Universities, both aggree that U-value alone is not enough when calculating heatloss and denser insulations dramatically slow down heat loss just like a heavier coat or blanket.

A friend with a building company in Helsinki who studied the science of building materials in Helsinki University for 4 years also states that denser/heavier insulation materials loose internal heat more slowly.

Niall Crossan who works as an engineer for Ecological Building Systems agrees that denser insulations dramatically slows down heatloss and it doesn't matter if it is cold of warm outside.

Pat Daly who lectures on Envoirnmental design had an article in Construct Ireland on Hemp Lime construction, he mentioned that the Hemp Lime house far exceeded its U-value calculation.

A caravan well insulated with Polyeurethene gets overheated after an hour in the sun.
Most dishwashers insulated with dense Paroc are still hot in the morning 10 hours after you turn it on.

Log cabins with 300mm walls are actually quite good at holding onto heat even though the U-value of the walls is only about 0.7, even when the fire goes out they are still quite cosy in the morning.

Many desert houses with 14 inch clay walls have an internal temperature fluctuation of 5-6 degrees while the external temperature can fluctuate by 40 degrees, the midday heat comes into the house at midnight and the midnight cold comes in at midday. What's the U-value of a clay wall?

Our first 300m2 Passive Timber Frame house built with dense insulation is costing less than 50cents/week to heat as we speak so I have personal experience of this.

Viking House

Aeneas wrote:

Hi Viking House
Is softboard suitable for flooring an attic. I have a single storey extension to my home and I need to use the attic space for storage. It has 6in of fibreglass, as compared with 18in in the main body of the house. I want to avoid the whole business of raising the joists and I was wondering if I floored it with softboard would that 1) provide my floor and 2) double the insulation.

Yes to both questions Aeneas, it would also stop the wind in your ventilated attic blowing heated air out of your insulation.

Mellor

Viking House wrote:

Hi Mellor

We have to agree to differ here. I have discussed this with too many educated people from Scandinavia, Germany and Holland to think otherwise.

If you read my previous post you see that I talk about heat movement and temperature fluctuations. Not heatloss.

You are telling me that somebody on that list told you that cold moves through the wall. I find that hard to believe, as anybody claiming to be educated in that area should be well aware that heat moves not cold. That is the area I claimed to be wrong. By the way thats the only section of the post I was calling wrong, incase its not clear. I am pretty sure you misunderstood my last post.

When it is warmer outside than inside heat enters through building fabric. This causes a rise in internal temp. I have already agreed that denser building materials reduce the fluctuations (with the same U-Value). Be they denser insulation like softboard, or structure like the log cabin, clay walls or concrete walls. If they have the same U-Value, they let the same heat through, that is the definition of a U-Value, but the same heat produces a lower temperature due to the heat capacity/thermal mass. More heat is store in the fabric which reduces the fluctuations. Same heat, different temperature.

Mellor wrote:

I have agreed that decryment delay can reduces fluctuations in temp, but only when the external temp is higher than the internal temp,

By this I mean that when it is colder outside than inside, heat leaves the building (except for solar gains), so there are no fluctuations as heat is passing out. Denser materials do not reduce the fluctuations in this situation as there is no heat source to create them. Denser materials can have a different advantage here in that heat stored during the time when it was hotter outside is now released to colder areas(both outside and inside). I never denied this advantage, I just pointed out that it wouldn't reduce fluctuations.


I agree with most of what you say, and most of the ideas. I agree that dense material can have a number of benefits. But sometimes the way the concepts are put across is misleading. For example, the advantage of dense materials applys to all materials, not only insulators. Structural materials are very much affect also. For example the caravan verses log cabin reference. The log cabin works well because timber has a high heat capicity. But I would imagine the U-Value is closer to .4

I know it can look like I target your posts, but its not that.
I agree with the list of people, comments and facts on the matter. Infact I have spoke with a person on that list on the topic and related ones. I dont think I've said anything to disagree with the density concept, I agree with it and I also agree that U-Values aren't the only thing that affect performance of a building. But they are a mesure of heat loss, BUT heat loss doesn't always equal temperature drop.
I also think that the density concept can also be applied to concrete block walls.
Bedington Zero Energy Developments (BedZED), a very famous low energy development in the UK used used very high mass concrete internal walls, mineralwool insulation and local brick or timber (embodied energy) facing. The dense structure works the same way as the comcepts you have listed above. They cavity wall elements are much thicker than traditional cavity walls as the BedZED was designed to achieve a U-Value of .10
They used a number of low energy solutions in almost every area of buildings from water, electricity, heating, working and transport. These are not only passive houses, but passive communities.

Aeneas

Viking House wrote:

Yes to both questions Aeneas, it would also stop the wind in your ventilated attic blowing heated air out of your insulation.

Many thanks Viking. This may solve a problem I have been thinking about for some time. Is softboard widely available? And what is its cost roughly?

arghh

Should SEI or some independent agency have information on this matter as it raises serious issues.There seems to be more questions than answers

ardara1

arghh wrote:

Should SEI or some independent agency have information on this matter as it raises serious issues.There seems to be more questions than answers

Not the SEI but Irish agrement board or British Board of Agrement or CE methods test all materials used in constructon and they prove whether or not a a construction method is suitable for Irish construction practices. As an architect under Part D I must ensure that all materials specified is fit for purpose - In this Part,
“proper materials” means materials which are fit for the use for which
they are intended and for the conditions in which they are to be used,
and includes materials which:
(a) bear a CE Marking in accordance with the provisions of the
Construction Products Directive; or
(b) comply with an appropriate harmonized standard, European
technical approval or national technical specification as defined
in article 4(2) of the Construction Products Directive; or
(c) comply with an appropriate Irish Standard or Irish Agrément
Board Certificate or with an alternative national technical
specification of any State which is a contracting party to the
Agreement on the European Economic Area, which provides in
use an equivalent level of safety and suitability.

Or could speak to some bloke in Scandinavia.

I think that by posting such damning conclusions about certain construction methods - Evidence of failure should be shouwn to back up the theories - 1000's of houses have been spec'd using these mthods of many years - if they don't work WE NEED TO KNOW

arghh

ardara1 wrote:

I think that by posting such damning conclusions about certain construction methods - Evidence of failure should be shouwn to back up the theories - 1000's of houses have been spec'd using these mthods of many years - if they don't work WE NEED TO KNOW

I would not have no issue with the insulating properties of the insulation that goes in to the cavity and that it does some good.But say as in my case I spent €2000 and the delay it caused the blocklayers I am not sure that its the best way. I am a lay person so I would not have figures to back up my argument but if insulalation is not sealed tight and good to me it loses alot of its benefits. The way it is installed now it is impossible to do it correctly. I blame whoever sets standards here there must be a better way to build a block house and to insulate it better easier and more cheaply. I read a post here or on some other forum and the poster said that the design and insulation came first then the heat source came second.So instead of SEI giving grants away on boilers etc they should give it to people who insulate well and give practical new ideas on how tow to do it right.There are like you man Duncan Stewart you are as dumb as ever after watching his show,both of them (Duncan shows and SEI website) have no bite

Mellor

arghh wrote:

The way it is installed now it is impossible to do it correctly.

Not exactly, if a blocklayer is careful if works perfectly, thats a big IF
the other option is to us rigid insulation that very slightly corrugated. This means the insulation slab can bend around obstructions such as mortar blobs. Only a few companys use this at the moment, but I imagine that if the likes of century homes keep passing out propaganda on of the evils of concrete construction, then most companys will change the design they use. The sooner the better.

ollie30

hi mellor,are there any manufacturers/stockists of the mentioned insulation in Ireland,sounds like a good improvement as long as its not over priced.better maybe to pay a bit extra for it now than regret not having it when its standard practice in 4-5 yrs time