Doube glazing - A-Rated and Trickle Vents

[wainy]

I know new regulations are in force where in new builds all windows need to have trickle vents.

Speaking of a couple of companies one mentioned that having the trickle in the "opening unit" reduces the energy efficiency of that pane and it should not be A-rated. The vent should be in the "main frame". Seen lots of new build with it in the opening frame.

Can anyone confirm this or is it a bit of marketing spin, or does it not make any difference?

[mk1fan]

No the regulations don't say you HAVE to have trickle vents. They say that a building requires background ventilation and ONE way of providing this is by have trickle vents in windows. Also, back ground ventilation isn't needed constantly.

A trickle vent through the frame would be the most inefficient as it would provide a cold bridge across the frame. Having a casement that can be secured partially open would be more efficient as when the the window is fully closed (ie not giving background ventilation) then there is no cold bridge over the frame. Well, that's my thought's on it.