Heat loss through windows

For some windows, draughtproofing is the most important action. If your windows are draughty this might affect your glazing choices and point towards the more extensive options.

If you are replacing the windows and not just the glass, think about what you want users to be able to do with them. Should they be able to open them all the way, given that they might then leave them open? Is the way they open suitable for the kinds of users that you have?