OK, this may sound like a silly question but:
Got a large bay sash window in the bedroom of my flat. I'm having some work done on the windows so I've got the option of putting some double glazing in.
I like the idea of double glazing because of the energy efficiencies with heating etc. Noise is not a problem so I'm not so bothered about the noise reduction.
However generally when we sleep we keep the window open a couple of inches anyway, for air. Also we need to keep the window slightly open now and again to prevent condensation build up.
So the question is:
Does a 'slightly open' double glazed window still save me anything on my energy bills?
My memory of A-level physics tells me it might, as even though warm air can escape through the open bit of the window, the rest of the (rather large) window will still help keep heat in fairly well.
Advice from glaziers, DIYers and fluid thermodynamics experts welcome.