double or triple glazing for new extension roof window

[New2022]

Please may I get some suggestion of the windows selection. our house currently have double glazing windows, we are going to build a back extension kitchen and living area, in the new pitched roof, will have four roof window 780*980, if chose triple glazing window there, whether it will make any better heat protection. or it wont make different to use double glazing there.
thanks you

 

[RonnyRaygun]

What percentage of the roof area is it? If a large proportion it'll make more difference than if a small proportion of the total roof area. On average, you will save some energy by using triple glazing (but it will be a long time before it saves you any money).

Also, not all double or triple glazing is the same. The U-value will vary related to several factors including the external frame, thickness of glass, overall thickness of glazed unit, and type of gas the glazed unit is filled with.

If cost is an issue you might be better off increasing the amount of insulation in your roof (or elsewhere). It might be cheaper to do that to achieve the same overall result than spend a fortune on triple glazing. If money is no object, get the best standard of glazing possible AND stick more insulation in.

As of June 15th you are going to have to meet more stringent Part L requirements anyway. Take a look at https://www.quadrantai.co.uk/latest-news/industry/part-l-transitional-provisions-for-domestic-extensions-2022/#:~:text=The new edition of the,thickness of insulation within extensions.

 

[New2022]

What percentage of the roof area is it? If a large proportion it'll make more difference than if a small proportion of the total roof area. On average, you will save some energy by using triple glazing (but it will be a long time before it saves you any money).

Also, not all double or triple glazing is the same. The U-value will vary related to several factors including the external frame, thickness of glass, overall thickness of glazed unit, and type of gas the glazed unit is filled with.

If cost is an issue you might be better off increasing the amount of insulation in your roof (or elsewhere). It might be cheaper to do that to achieve the same overall result than spend a fortune on triple glazing. If money is no object, get the best standard of glazing possible AND stick more insulation in.

As of June 15th you are going to have to meet more stringent Part L requirements anyway. Take a look at https://www.quadrantai.co.uk/latest-news/industry/part-l-transitional-provisions-for-domestic-extensions-2022/#:~:text=The new edition of the,thickness of insulation within extensions.

many thanks for those info, It is roughly 20% of the roof area. electric VELUX GGL MK04 centre pivot roof window is considering now. since the patio door and kitchen window is double glazing. so we are advised to use triple glazing just for roof window wont improve the heat pretention? so can not make up mind now.

 

[^woody^]

It's not a random decision to make.

The extension, and more so the roof should be designed as one and the thermal calculations done to determine where it's needed or best to spend the money. The extra heat retention may well be on paper, not in real life.

If it's just a few quid difference in price then go for it, but it's not.

There are loading issues to take account of for the roof, and replacement costs in 10 years or so.