K Glass

[Anonymous]

In the upstairs of our Edwardian house, every window has been replaced with lovely aluminium framed windows (though the boxes have survived). We have had a company quote to re make all the box sashes to match the neighbouring houses. The company are Fensa registered and as such all windows have to be made to a particular specification. This includes using Pilkington K glass which I understand is more environmentally friendly etc, but that it also has a greyish tint to it.

Does anyone have any experience of this? Does it look hugely different and will it look odd in an Edwardian house with very pretty windows?

Any advice gratefully received. Thanks very much.

 

[Anonymous]

Any deviation from the 3mm plain glass of the very late Victorian/Edwardian era, as you know, is a compromise. Nevetheless sometimes these have got to be made.

From your ( internally) viewing point you will notice hardly any difference, viewed externally the glass tends to look darker and has this " mirror " type reflection of the surroundings.

Look at it on the bright side, you may not need any curtains.

 

[Anonymous]

We have K Glass and, to be honest, there's no noticeable cast in it. Where colour casts can show up is if you have a mixture of glasses, but if all the windows are the same tock, then bo-obe's going to notice.

 

[Anonymous]

Pilkington K (I guess we'll be calling it Nipon K soon) does have a faint blueish-grey colour but you wouldn't notice it unless you were really looking for it. It's most easily detected in bright sunlight shining from an angle so a shadow is cast by the window frame. You can then see the colour difference between the lit and shaded part. I've supplied a lot windows with Pilk K and none of my customers has ever mentioned it so either they havn't noticed or they're too polite. Pilk K has what is called a 'hard coat' low-e coating. There is an alternative, known as 'soft coat'. As far as I know Pilkington doesn't supply it in Britain but St Gobain, the French company, does. It is actually more widely used on the continent. Soft coat functions better in terms of reducing the U-value of a window and so is better. It is also even clearer. It is more delicate so needs careful handling before being installed in the dg unit. This means more expensive equipment at the glaziers so most dg unit makers in Britain don't use it. There is a reluctance on the part of our glazing industry to make the investment until forced by stiffer Part-L type legislation. In France and Germany they seem to have a different attitude.

To sum up, yes, Pilkington K does have a grey/blue tint but it is so slight most people don't notice it. If you can find dg units made with 'soft coat' low-e glass you will have a clearer window and lose less heat, but you may have difficulty finding it and it may cost a little more.

 

[Anonymous]

Thank you for this. Very useful. I have heard that if the glass is toughened, the process takes some of the colour out. Have you heard of this being the case?
My only worry with all this is that the downstairs windows are original and its only the upstairs that are having to be changed so if the difference was obvious, then it would look a bit odd. The house is in a conservation area but I am assuming this doesn't make a difference to the glass used?
Thanks for your help with this.

 

[Anonymous]

Etoile
You may find that being in a conservation area places
some constraints on what you are able to do when
changing windows. In my case it has worked to my
advantage in allowing me to keep the original Georgian
windows and glazing despite them not conforming to
modern standards of insulation. We have installed
secondary double glazing to reduce heat loss.
regards
Phil

 

[Anonymous]

It is a shame that the previous responses have not really addressed your question, save to comment on Pilkington K glass.

The firm offering to manufacture your new sashes may well be FENSA registered, but they are not giving you best advice by telling you that because they are FENSA registered that they are obliged to manufactue to certain standards.

You have said that you are retaining the existing box frames. Therefore the replacement of the sashes is a REPAIR and is not covered by Doc L! The replacement sashes can be glazed with any glass that conforms to the current safety standards that cover glazing for dwellings.

So unless you particularly want double glazing, it is not an option that you are forced to take.

 

[Anonymous]

I've not heard that toughening alters the appearance. I don't know but I rather doubt it. I do think you are worrying too much about the appearance. It really is quite difficult to see. The industry has developed a little metal detecting gadget that is capable of detecting whether or not a low-e coating is present because it is so difficult to see.