Replacing UPVC Windows

bristolleedsfan

Choosing between two local companies, same price, same 1.3 U Value

1. Linear profile, glass from local supplier  registered with Corgi Fenestration, IBG, guarantee not transferrable

2.Rehau Profile ( not enhanced) Pilkington K K glass, Fensa registered, offers more limited guarantee

Currently 8 panes of glass Living Room and Main Bedroom, im looking to have  x 2 side opening windows opening out like a door, making mullions defunct thus more window less frame, main window effectively being like a picture window, would be 3 panes of glass, due to height of windows more than 1350mm  been told would need 6mm glass thickness instead of 4mm adding about £500 to cost of job

Any thoughts please, how much extra insulation benefit would I get from extra glass thickness, would I be more prudent having triple glazing paying bit more again, windows are south facing, free sun heat etc, would triple glazing be more beneficial when no sun heat, very windy etc

tacpot12

My thoughts; extra glass thickness won't materially improve the U value so there will be no insulation benefit. Triple glazing is unlikely to be worth it in a house that doesn't have a very large area of windows compared to the area of the walls. (The effect on the overall heat lost by the house will not be that great). A low emissivity glass (like Pilkington K) will help keep heat in and capture heat from the south facing windows.  

Rosa_Damascena

tacpot12 said:

My thoughts; extra glass thickness won't materially improve the U value so there will be no insulation benefit. Triple glazing is unlikely to be worth it in a house that doesn't have a very large area of windows compared to the area of the walls. (The effect on the overall heat lost by the house will not be that great). A low emissivity glass (like Pilkington K) will help keep heat in and capture heat from the south facing windows.  

Does it improve the sound insulation though?

168hourweek

Thicker glass   Smaller cavity  Lower insulation value  1 layer 6 mm and 1 layer  4 mm better sound attenuation