U-Values for Windows

ammc

Anything I've read about windows always states that the lower the u-value the better. So how is it possible that A-rated windows can have a U-value of 1.5 and and B-rated windows can have a U-value of 1.45. Have I missed something here?

BryanF

Read this http://www.nsai.ie/our-services/certification/agrement-certification/wep-(wind-energy-performance)-scheme.aspx

fatty pang

In general the lower the u-value the better. A u-value is a measure of heat transfer. The less heat transferring through the fabric of a building the better. Therefore a low u-value usually indicates high levels of insulation.

The WEP scheme also takes into account the heat gain a window can also provide under certain conditions. The WEP rating is the result of a (subjectively) weighted index that calculates a ‘heat flow’. The scheme is a virtual copy of the BFRC scheme in the UK. BFRC guidance notes clearly state that the rating is a tool for comparison rather than a measure of absolute energy performance - as a u-value is.

BS EN 14438 is a lot more accurate way of assessing the energy balance through a window - but not something for the average punter (or windowman). There is an online calculator here http://www.glass-ts.com/effective-u-value-calculator that provides data for a few UK areas which you would give you a reasonable indication of whats involved.

I personally wouldn’t bother with a WEP rating as its pretty meaningless as a professional specification tool. For the average consumer it will provide an indication of the ‘energy balance’ (whatever that is). Be aware though, that there is a lot more then energy to be considered when assessing the quality of windows.

sydthebeat

Op, both of those Windows would be considered poor by today's standards.

ammc

sydthebeat wrote: »

Op, both of those Windows would be considered poor by today's standards.

I've my windows 3 years now, and I, like others, I suppose, would just have thought having A-rated windows was enough but obviously not so.

Another question, my windows have BS EN1279/2 stamped on them but if windows are gas filled should they have the BS EN1279/3 reference stamped on them as well?

fatty pang

ammc wrote: »

Another question, my windows have BS EN1279/2 stamped on them but if windows are gas filled should they have the BS EN1279/3 reference stamped on them as well?

EN 1279 does not require marking of the glass (with some very specific exceptions). Any markings would be voluntary. ‘CE Marking’ which is now mandatory (it wasn’t in IRL/UK until last year) for insulated glazing units requires products to be ‘labelled’. This requirement will be met by a removable sticker on the IGU that will also probably have other order specific information.
Anybody supplying gas filled IGU’s has to be compliant with all parts of EN 1279. They should be able to provide the necessary documentation for inspection if requetsed.

ammc

fatty pang wrote: »

EN 1279 does not require marking of the glass (with some very specific exceptions). Any markings would be voluntary. ‘CE Marking’ which is now mandatory (it wasn’t in IRL/UK until last year) for insulated glazing units requires products to be ‘labelled’. This requirement will be met by a removable sticker on the IGU that will also probably have other order specific information.
Anybody supplying gas filled IGU’s has to be compliant with all parts of EN 1279. They should be able to provide the necessary documentation for inspection if requetsed.

I take it the documentation is like a licence, as such, rather than anything specific to my windows or any other specific order. I ask because I took one of my window units for testing and they didn't detect any Argon gas in it. I thought maybe the fact EN1279/2 was on the spacer between the panes and but not EN1279/3 may have signaled that there was no gas inserted to begin with....worsening the u-value further

fatty pang

A licence suggests an issuing authority. Unfortunately EN 1279 compliance is not subject to third-party auditing – it's self-declaration for the most part after the initial type testing. Did you ask the supplier for documentation on the glazing unit ?
Non-invasive testing for the presence of argon requires specialised equipment – who did you go to ?
I would love for Santy to bring me a portable detector for Christmas but at around 9k its unlikely.

fatty pang

Although not pertinent to this particular thread I have received several private mails. I don't respond to private emails looking for opinions or information on windows. If I have any comments to make I'll make them in public so the reply can be scrutinsed for accuracy and bias.

ammc

fatty pang wrote: »

A licence suggests an issuing authority. Unfortunately EN 1279 compliance is not subject to third-party auditing – it's self-declaration for the most part after the initial type testing. Did you ask the supplier for documentation on the glazing unit ?
Non-invasive testing for the presence of argon requires specialised equipment – who did you go to ?
I would love for Santy to bring me a portable detector for Christmas but at around 9k its unlikely.

Originally got a typed letter from installer/supplier stating a U-value of 1.4 .... I finally got a photocopy of Cert with the manufacturers logo on it after 3 years of asking and the U-value is now 1.5 . The cert basically contains the WER (minus 0), my order number and window type(low iron/Gas/soft coat. I've seen a different cert from the same manufacturers for a different customer and they have given a more comprehensive cert with a breakdown of each window and dimension and so forth.

I took the unit to the manufacturer and they tested it there and didn't detect any Argon gas. They said that the absence of Argon gas wouldn't affect the u-value significantly.

fatty pang

The differing u-values could be a simple mistake on the part of the supplier, which if so I would expect them to acknowledge and compensate for. If you were sold one product (u-value 1.4) and intentionally supplied with another (u-value 1.5) then that is a serious matter.
If it’s taken the supplier 3 years to come up with a WER certificate that strikes me as very odd. I would suggest that you take it up with NSAI as they will investigate what may be inappropriate usage of one of their certificates.

Argon makes a significant difference to the u-value of an insulated glazing unit. I’m assuming the IGU you have would have a u-value of 1.2 with argon. Take out the argon and that goes to 1.4 – a significant difference. If the window was sold as having a u-value of 1.4 then it would have to have argon. If it’s leaked out after 3 years then I would maintain it wasn’t of merchantable quality. EN 1279-3 allows for maximum 1% per annum leakage. This is the industry standard and would therefore be a definition of what is merchantable quality. If it was never in the IGU then you were sold counterfeit goods.

ammc

fatty pang wrote: »

The differing u-values could be a simple mistake on the part of the supplier, which if so I would expect them to acknowledge and compensate for. If you were sold one product (u-value 1.4) and intentionally supplied with another (u-value 1.5) then that is a serious matter.
If it’s taken the supplier 3 years to come up with a WER certificate that strikes me as very odd. I would suggest that you take it up with NSAI as they will investigate what may be inappropriate usage of one of their certificates.

Argon makes a significant difference to the u-value of an insulated glazing unit. I’m assuming the IGU you have would have a u-value of 1.2 with argon. Take out the argon and that goes to 1.4 – a significant difference. If the window was sold as having a u-value of 1.4 then it would have to have argon. If it’s leaked out after 3 years then I would maintain it wasn’t of merchantable quality. EN 1279-3 allows for maximum 1% per annum leakage. This is the industry standard and would therefore be a definition of what is merchantable quality. If it was never in the IGU then you were sold counterfeit goods.

1.4 was the U-value I was told at the outset, this was also the u-value on the letter received after 1 year, but a u-value of 1.5 is on the cert received after 3 years.

Would the NSAI be the agency to go to if the supplier was Northern Ireland based? There is no NSAI logo or reference on the certificate. There seems to be a few other discrepancies on the cert which is ringing alarm bells for me which would need clarification

fatty pang

I had understood that you had an NSAI certificate. If the windows come from a UK supplier, their organisation providing window energy ratings is the BFRC. Does the second document you received have a BFRC logo on it? If it does then you should contact them and point out the anomaly in the documentation. If their documentation is being misused I would definitely expect they will take action.
If the document is not a BFRC certificate and is being represented as a Window Energy Rating then I think the Trading Standards service closest to the supplier should be contacted.
Can you post a picture of the document.


This situation is akin to being sold 1000 litres of heating oil and having about 930 litres delivered. It is not that difficult to assign a monetary value to your loss in this instance. The difference in heat loss between 1.4 and 1.5 can be calculated, multiplied by the area of windows installed. The cost of your heating is then factored into derive an annual loss. Multiply the yearly amount by 35 (the nominal service life of a pvc window) and you have a reasonable assessment of how much the ‘misleading’ information has cost you. If there is no argon in the IGU’s the loss will be greater still.

ammc

fatty pang wrote: »

I had understood that you had an NSAI certificate. If the windows come from a UK supplier, their organisation providing window energy ratings is the BFRC. Does the second document you received have a BFRC logo on it? If it does then you should contact them and point out the anomaly in the documentation. If their documentation is being misused I would definitely expect they will take action.
If the document is not a BFRC certificate and is being represented as a Window Energy Rating then I think the Trading Standards service closest to the supplier should be contacted.
Can you post a picture of the document.


This situation is akin to being sold 1000 litres of heating oil and having about 930 litres delivered. It is not that difficult to assign a monetary value to your loss in this instance. The difference in heat loss between 1.4 and 1.5 can be calculated, multiplied by the area of windows installed. The cost of your heating is then factored into derive an annual loss. Multiply the yearly amount by 35 (the nominal service life of a pvc window) and you have a reasonable assessment of how much the ‘misleading’ information has cost you. If there is no argon in the IGU’s the loss will be greater still.

I can't post a picture as I don't have the required amount of posts.

There's no BFRC Logo but a Kitemark symbol. I just 'googled' it and see it's operated by the British Standards Institute. I will try and make contact with them tomorrow and see if they can throw any light on it. However, there is no certificate number on the cert like on other certs from the same manufacturer so I don't know if I need this for them to investigate or if this is specific to the manufacturer. Also, other certs I've seen from the same manufacturer have also been signed-off with a signature but not on mine. My cert also takes a different format than the others as well.

How could I investigate the Argon issue further? Don't know if there's any point getting onto the manufacturer as while I'm the end customer the supplier is the direct customer and there is a relationship there.

fatty pang

My apologies, BSI Kitemark also operate a window energy rating scheme which I had forgotten about –it’s virtually identical to the BFRC scheme. The Kitemark certificate should also have a licence number on it. If your document/certificate has no licence number you should point this out to BSI Kitemark and ask them for an explanation. The argon issue should also be addressed to BSI Kitemark. You have been presented with a document/certificate with the Kitemark logo that covers the entire product.
The Kitemark is a trusted symbol of quality. BSI will want to ensure the integrity of their certification.

braddun

get triple glazed

and don't put in vuelux

ammc

fatty pang wrote: »

My apologies, BSI Kitemark also operate a window energy rating scheme which I had forgotten about –it’s virtually identical to the BFRC scheme. The Kitemark certificate should also have a licence number on it. If your document/certificate has no licence number you should point this out to BSI Kitemark and ask them for an explanation. The argon issue should also be addressed to BSI Kitemark. You have been presented with a document/certificate with the Kitemark logo that covers the entire product.
The Kitemark is a trusted symbol of quality. BSI will want to ensure the integrity of their certification.

There is a licence number under the Kitemark logo and this licence number is specific to the manufacturer and there name is beside it and all would seem to be in order.... but how can I confirm what is on the certificate is the same as the windows in my house? Can the BSI distinguish if they are only going by the licence number or can they ask the manufacturer for the certificate number and details relevant to my order? The kitemark logo and same licence number is on all the certs that I have seen but what is omitted on my cert is the certificate number of the manufacturer and a signature signing-off by the Managing Director on the said product.

fatty pang

The manufacturer would have to have a quality management system in place in order to provide WER labels with their product so there should be records of what was produced. The licencing body should have access to those records for auditing purposes.
If your ’cert’ has no licence number that suggests to me it’s counterfeit and should be taken up with BSI Kitemark

ammc

fatty pang wrote: »

The manufacturer would have to have a quality management system in place in order to provide WER labels with their product so there should be records of what was produced. The licencing body should have access to those records for auditing purposes.
If your ’cert’ has no licence number that suggests to me it’s counterfeit and should be taken up with BSI Kitemark

Just to clarify, there is a kitemark licence number on the manufacturer's certificate. This same licence number (e.g. KM567422) appears on all the manufacturers certificates regardless. But there should also be a unique certificate number on all the manufacturer's certificates which differs for each order. This is omitted from my cert along with the other things mentioned earlier.

I contacted BSI today. They confirmed the kitemark licence number was valid which I had assumed they would as this is a licence to manufacture windows to their standards. But they don't seem to have a mechanism for verifying that what is shipped by the manufacturer is what it says on the cert. Although they do a yearly audit, they say they do not have access to the records of what was produced. Well, that's what the BSI rep told me anyways before qualifying that he never dealt with this kind of issue before.

To put it bluntly, what is to stop a supplier sourcing B-rated windows from a manufacturer and passing them off to the customer as A-rated windows. These same B-rated windows would have the same kitemark licence number as the A-rated ones.

I will try BSI again tomorrow and after that I will have to try the manufacturer but as they told me already they wont deal with the public only the supplier....