Sealed double glazed window or single glazed openable window in bathroom?

[raininwinter]

Moving into a place with two skylights/roof domes in the bathroom. The skylights are both poorly insulated, but it's too expensive to replace them with proper double glazed windows that open easily. The most affordable options are as follows:

1. Replace both windows with sealed double glazed units. These are more energy efficient, but can't be opened. The extractor fan in the bathroom is good, but obviously not as nice as getting some fresh air through the room.
2. Replace one window with the sealed unit, and leave the other window as is so that I can air the room. The downside is this will be colder, and it's slightly awkward to open the window anyway.

Any thoughts? The other decision is how to avoid baking in the summer - I think I'm going with the light reflecting paint/obscured glass, but this will also have the effect of keeping out the sun warmth in winter. Not sure this is a huge issue though.

I would always ( no exceptions) want a way to air a bathroom that is not an electric extractor, so at least one of the windows would have to be openable for me.
Replace one with double glazing and save up to replace the second one at a later date?

You need a window that opens in the bathroom. It would be grim without one.

I’ve had several windowless bathroom and as long as the extractor is adequate then I haven’t notice any real difference versus windowed ones

If money is the issue, replace one at a time with double glazed opening units.

What's the price difference between single and double glazed units that open?

Opening a window is free! 😁