Cost effective total window replacement

[Oz07]

8 hours ago, Mike said:

A key benefit of triple glazing is that the inside air temperature next to the glass will be a few degrees higher than it would be next to a similar double glazed unit. If you have underfloor heating, then the closer that temperature is to the target room temperature, the slower the convection currents are in the room. Which creates a more uniform temperature gradient from floor to ceiling, so you don't need the thermostat as high (which is where there's a cost saving). It also removes condensation risk even when temperatures drop well below zero.

 

However, if you don't have UFCH then the first of these benefits goes 'out of the window' as you'll have significant convection currents anyway. And if you do have UFCH + well-specified double glazing (argon filled, low-e, good weather seals, well-insulated frame), then the temperature gradient can still be very good.

 

In short, it's preferable to choose double glazing in a well-insulated frame, rather than a triple glazing in a standard / poorly insulated frame. U_w is the best guide for that.

 

And what is a reasonable target to aim for? Excluding passive house craziness