What about a window with an opening at the bottom?

Thanks for the suggestion Jonathan. The window reaches down almost to floor level so not sure this would work but certainly hadn’t thought of splitting it this way.

Trickle vents? Or a tilt and turn window?

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So you say an opening would look awful.... most windows open so is this going to be one single pane then? Most windows have trickle vents as carolina suggeted.

How much ventilation do you want ?? if its only background venting then you could possibly fit retro trickle vents ..

Thanks for the above comments. It is basically a large picture window so a glazing bar or opening section would spoil the appearance. I don’t think a trickle vent would be sufficient. A tilt and turn would be ideal but it is such a large window that I understand it would be difficult to source and prohibitively expensive. If this is not an option for us then I wondered if there was any sort of manual or electric ventilator which could be inserted/incorporated into the window. We just want something that looks smart. The window and French doors are aluminium in anthracite. Hope that clarifies as is probably obvious I don’t understand the technicalities 🙄. Really appreciating all your responses though 😊

what is the frame made of and what does it look like from the outside ??

The frame is aluminium and in the plans it is just a large rectangle 2m high equi distant between floor and ceiling. From inside there is a run of units down the left hand side and an island to the right. From outside, the big picture window is on the right with matching French windows about 2 m to the left of it. Hope that helps - Claire

Is there anywhere else you could put a small opening window, eg if you are detached or semi could you use a side wall. Or if terraced you could perhaps add a small electric opening skylight to the roof, not a cheap option but in a s facing extension with lots of glass you may well find it’s worth it to let hot air out.

just wondering if there is space for a controllable ventilation slot above the frame ..

Thank you everyone for all your comments and particularly for the ventilation slot idea. We need to make a decision tomorrow morning and are veering towards putting in an opening skylight at the mo - not ideal but we suspect cheaper than a swivel opening for the picture window.

I have designed tilt and turn windows of that dimension. They are neither especially difficult to source or expensive. The picture below is from one of my projects and the window opens outward pivoting around the upper side.

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You might also consider a Heat Recovery vent system