What kind of home is it?

Is the warmest room on the top floor, or in a loft conversion?

Rooms directly under the roof take the sun on the roof all day.

How much glass does that room have?

Which way does it face?

The direction its main windows point.

Can you leave windows open at night?

Without a security or noise problem.

Is there any shading outside the glass?

Trees, awnings, shutters or deep eaves — anything that stops sun before it reaches the window.