When erecting a scaffold around a house, what if any are the requirements for the residents window ventilation? In terms of how far must they be allowed to open etc.

Forget ventilation - focus on means of escape. Domestic fires take hold very quickly and residents may be trapped upstairs. Too many tragedies without causing more. I'm also routienly perturbed by some pictures on the news of such tragedies where large replacement d.g. units have been installed with no openings to allow escape.