u value for 215mm inner leaf concrete block

baguio

I am trying to work out the overall u value for a masonry wall. However, not sure what value to put in for 215mm inner leaf concrete block. How do I determine this? Where is this info available?

I have the BRE u value calculator which has a listing of most materials but not this.

ardara1

baguio wrote:

I am trying to work out the overall u value for a masonry wall. However, not sure what value to put in for 215mm inner leaf concrete block. How do I determine this? Where is this info available?

I have the BRE u value calculator which has a listing of most materials but not this.

The lambda value of Heavy concrete block in Ireland is 1.15 - so 0.215 divided by 1.15 will give you the R-value - add this to all other components R's (including int & external resistance) then divide into 1.
Contact Hytherm and they give out a U-value calculation program for free - I got it about 2 weeks ago head about it on BOARDS - it's good for Irish constructions.

Mellor

not sure how the BRE calculator works, but the resistance is the same for 100 and 215 blocks, they increase proportionally with thickness, can you select a 100mm block and alter thickness?

baguio

@ardara: Thanks for the tip re. hytherm. Will give them a call.

@mellor: Yes, thats what i was doing. See the bre calculator output here

How is it coming out with such a high u-value (see left hand corner) when building regs is 0.27??

Is there a glowing mistake there somewhere?

ardara1

baguio wrote:

@ardara: Thanks for the tip re. hytherm. Will give them a call.

@mellor: Yes, thats what i was doing. See the bre calculator output here

How is it coming out with such a high u-value (see left hand corner) when building regs is 0.27??

Is there a glowing mistake there somewhere?

YOur cavity resistance of 0.18 is for a plain high resistivity cavity - Kingspan has foil to one side creating a LOW emissivity cavity with a default value of 0.44 - but it can go as high as 0.65 if it has been measured by a certification body.

baguio

ardara1 wrote:

YOur cavity resistance of 0.18 is for a plain high resistivity cavity - Kingspan has foil to one side creating a LOW emissivity cavity with a default value of 0.44 - but it can go as high as 0.65 if it has been measured by a certification body.

Double clicked on 'cavity resistance' and found the 'low emissivity' setting. Adjusted, but thats still leaving me with an overall u-value of 0.32? There must be something else wrong with it i think.

ardara1

baguio wrote:

Double clicked on 'cavity resistance' and found the 'low emissivity' setting. Adjusted, but thats still leaving me with an overall u-value of 0.32? There must be something else wrong with it i think.

You've included a Delta (Gaps between boards) AND you've put in V BIG wall ties (Like Strap ties with a large cross setional area) - typical SS Wire ties are so small as not to be a factor even up to 5/m2 -
Take both out and see what happens.

baguio

ardara1 wrote:

You've included a Delta (Gaps between boards) AND you've put in V BIG wall ties (Like Strap ties with a large cross setional area) - typical SS Wire ties are so small as not to be a factor even up to 5/m2 -
Take both out and see what happens.

u = 0.29 - beginning to get closer to the expected. I will run it off on the hytherm calculator when i get it.

Mellor

trying using a lightweight block for the outer leaf. it should help.
the insulation could also be increased
ill stick a few values into the Hytherm/xtratherm calculator. and see what comes up. I've been usng it for about 2 years now.

With the same build up I got 0.29
changing to medium weight blocks and adding an external layer resulted in 0.28
upgrading to 70 insulation, got it to 0.25

galwaytt

doesn't all this just go to show that conc block building is simply not sufficient to meet the 0.27 value you're chasing, easily, and that other forms or construction would be better?

Mellor

not really, the only change required was and extra 10mm insulation, the rest were mistakes in the OPs calculations. TF would need more than 70mm to reach minimum also.

ardara1

galwaytt wrote:

doesn't all this just go to show that conc block building is simply not sufficient to meet the 0.27 value you're chasing, easily, and that other forms or construction would be better?

Kingspan have certified cavity resistance of 0.65 - the cross setional area of a wire tie is 13 (not 80)

answer is 0.26

ardara1

galwaytt wrote:

doesn't all this just go to show that conc block building is simply not sufficient to meet the 0.27 value you're chasing, easily, and that other forms or construction would be better?

What would you recommend?

muffler

ardara1 wrote:

What would you recommend?

I could nearly answer that

Anyway lads dont go off down the "block vs timber" road. Keep her between the hedges as they say (or topic if you prefer)

Mellor

Anyway lads dont go off down the "block vs timber" road. Keep her between the hedges as they say (or topic if you prefer)

Its be done to death as they say, I blame the propaganda type adverts they stick in the paper

Concrete built is better built,
Performs better in fire
Better sound insulation
Thermally effective

Timber frame houses are built to last
Fire proof
Sound proofed
thermal efficiancy

they all say the same but spin it different

baguio

@Ardara1/Mellor: Thanks for the help. Finding the Hytherm calculator much better.

Viking House

Does the U-value calculator take "Thermal Looping" into account which makes the U-values worse by an average of 30% because of the air flow between the insulation and the inside block?
What about the cold bridges where the window cills sit on the inside wall?
And where the inside 4 inch block sits directly on the rising wall making a direct connection to the outside through the foundations?
And the cold bridge at the roof where the walls meet the roof insulation , are these calculated automatically by the U-value calculator?

Kingspan and Xtratherm have U-values of 0.015 W/m2k when they come out of the production plant, after 28 days when they go to the building site the U-value is 0.025W/m2k. What happens for the next 28 days or 28 years to the U-values of these products? Do the U-values get gradually worse as the insulating gas migrates out of the insulation boards?

galwaytt

muffler wrote:

I could nearly answer that

Ha ! I ain't bitin'...........;)

Viking - the cill isn't supposed to sit on the inside wall, so that shouldn't be an issue - if it's on the inside leaf.........it's in the wrong place, for both insulation and - arguably even more importantly - damp issues.......

Mellor

Viking House wrote:

Does the U-value calculator take "Thermal Looping" into account which makes the U-values worse by an average of 30% because of the air flow between the insulation and the inside block?
What about the cold bridges where the window cills sit on the inside wall?
And where the inside 4 inch block sits directly on the rising wall making a direct connection to the outside through the foundations?
And the cold bridge at the roof where the walls meet the roof insulation , are these calculated automatically by the U-value calculator?

Kingspan and Xtratherm have U-values of 0.015 W/m2k when they come out of the production plant, after 28 days when they go to the building site the U-value is 0.025W/m2k. What happens for the next 28 days or 28 years to the U-values of these products? Do the U-values get gradually worse as the insulating gas migrates out of the insulation boards?

I imagine it doesn't take this into account, as if done right it is avoidable. Some boards are design to to aviod it too.
The same could be said about particle and quilt insiltion in timber frames. When they slump due to gravity they suffer two problems, the insulation is compacted therefore reducing its effectiveness, and the area at the top is uninsulated. I agree about the foundation its a problem area,
But the wall and roof junction shouldn't be a problem, the roof insulation is supposed to be carried over into the soffit, joined with the wall insulation, of course keeping an air gap. If the cavity close it installed right it should have a very small impact.

surely the boards are tested to find the long therm value, the migrating gas is most likely the agent used to blow the polymer, when this leaves this is replaced with air, and trapped air is still quite a good insulator.

wornout

just a quickie here,anybody here care to declare their qualifications to answer this man's question.there are a lot of people out there trying to build eco friendly homes and protect the environment for themselves and their children and they are looking for answers on the internet.be very careful

smashey

From what I can see, all the replies to this type of thread are generally taken from some literature/regulations somewhere and should be easily found by a quick search. Posters on here do not have to declare their qualifications. This has to do with their right to anonymity. Any post that is way wide of the mark will soon be pointed out as there is a pretty knowledgable bunch of contributors here. Also, we are just giving general advice and specific advice should be sought from the op's architect/engineer/technician.

muffler

wornout wrote:

just a quickie here,anybody here care to declare their qualifications to answer this man's question.there are a lot of people out there trying to build eco friendly homes and protect the environment for themselves and their children and they are looking for answers on the internet.be very careful

I know what you are getting at here and lets say its along the lines of axe grinding. First of all anyone offering advice here should know what they are talking about - if they dont then they have no errand here and as smashey said if their posts are out of order they will soon be told by others.

Nobody has to declare their qualifications and any advice given is purely of a personal nature - see my post here on another topic.

Now Im not one for posting up on a public forum what has been discussed in private but all I will say is that we have had private discussions about this before and I advised you of both my and boards.ie position.

Im giving you a yellow card this time but please dont give me reason to make it a red one

baguio

In fairness, Mellor and Ardara1 know their onions.

Any post that is way wide of the mark will soon be pointed out as there is a pretty knowledgable bunch of contributors here.

That right there is the power of message boards such as this one.

Mellor

wornout wrote:

just a quickie here,anybody here care to declare their qualifications to answer this man's question.there are a lot of people out there trying to build eco friendly homes and protect the environment for themselves and their children and they are looking for answers on the internet.be very careful

The OPs question was quite straight forward, he seams happy with the help he got,
Ocasionally advise is posted here that is wrong or maybe just misunderstood, by rest assured because it doesn't take long to be pointed out.
The thread relates to the U-Value of concrete blocks, afaik all info is correct,
But I understand your point, the topic of eco building is very sensitive. And all info should be taken with a pinch of salt because as important as u-values and construction, lifestyle and building conditions make such a larger impact.

ardara1

wornout wrote:

just a quickie here,anybody here care to declare their qualifications to answer this man's question.there are a lot of people out there trying to build eco friendly homes and protect the environment for themselves and their children and they are looking for answers on the internet.be very careful

HI WORNOUT -

Are yu talking about the original question about the 215 block - and getting the U-value right? - If so then what qualification do you want? There are a set of guidelines laid down in recognized EN standards that we must work to to work out a U-value/Lambda Value/resistance/thermal bridge value/energy assessment - all you have to do is follow the standards - or you could ask a bloke in Sweden I suppose! - all the rules/standards are written into part l - whether you're an architect/engineer/bloke from Sweden - you have to stick to the conventions laid down.

But then that'd be boring!

smashey

ardara1 wrote:

HI WORNOUT -

Are yu talking about the original question about the 215 block - and getting the U-value right? - If so then what qualification do you want? There are a set of guidelines laid down in recognized EN standards that we must work to to work out a U-value/Lambda Value/resistance/thermal bridge value/energy assessment - all you have to do is follow the standards - or you could ask a bloke in Sweden I suppose! - all the rules/standards are written into part l - whether you're an architect/engineer/bloke from Sweden - you have to stick to the conventions laid down.

But then that'd be boring!

Nice one ardara1.

Off topic, but are you from Ardara?

ardara1

smashey wrote:

Nice one ardara1.

Off topic, but are you from Ardara?

Come on Smashy a policeman wouldn't ask you that!

smashey

Ello, ello ello.

The more Donegal men here, the better.

muffler

Guess which one he is?