Toughened Glass Measurements

Zandimos

Hi all, I've got a fair few misted up double glazing units which I'm looking at getting replaced. I know that the regulations state that any window lower than 800mm should be toughened glass. However it doesn't specify where that measurement should be taken from. As if I measure it from the outside it is approx 1 metre to the bottom of the glass, if I measure inside it's roughly 780mm to the bottom of the glass. 

Is anyone able to advise me on which way to measure as it determines whether I need toughened glass or not.

Also, this is our first time getting new windows or units... Does Argon gas really make that much different or is a marketing thing?

Thanks in advance

FreeBear

One normally measures from the floor internally - This is where people are running around and more likely to go through a window.

Jeepers_Creepers

There speaks experience... :-)  

Elmer_BeFuddled

Argon is an inert gas. As far as I am aware double glazed units have always been filled with inert gases, I may be wrong as I often am.

Zandimos

Thanks all

EssexExile

Elmer_BeFuddled said:

Argon is an inert gas. As far as I am aware double glazed units have always been filled with inert gases, I may be wrong as I often am.

I'm afraid this is one of those instances Elmer.

princeofpounds

Yes, argon gas makes a difference. It has a lower thermal conductivity than air. The fact that it's inert is a separate issue (not that you'd want anything that wasn't inert!). Most sources suggest something like 15-30% improvement over air-filled cavity windows (the upper end being lab test performance, the lower end probably more realistic as it's not the only factor in a window!). 

The technical literature seems to suggest that low-emissivity coatings are even better, performance-wise. 

So no it's not a marketing thing. But as always, there's a cost trade-off here. So it may be better, but is the improvement worth it? I would say yes, if you are having significant areas of glazing. There's also the issue of the specific effects of performance - having a cheaper, less insulating window can create draughts, cold zones, condensation etc. French doors or bifold doors feel very different, much colder in the space around them, if they aren't sufficiently insulated.

All the data you'd want on thermal performance of different gases, cavities and coatings (All the way up to Decuple Glazing!)

https://techhub.uk.saint-gobain-building-glass.com/sites/default/files/document-files/Solar & Thermal 1E - Thermal Insulation - 19-09-2018.pdf

Elmer_BeFuddled

EssexExile said:

I'm afraid this is one of those instances Elmer.

DOH!!! Ah well.