QUESTION:

I would like to define a schedule for opening and closing windows in my ECOTECT model. I understand that when an object is activated, its alternate material is used, instead of its primary material.

In the case of windows, the primary material is a window material, such as the "double glazed aluminium frame"; as for the alternate material, what should be defined for the purpose of ventilation ?

ANSWER:

If you want to simulate a 100% free flow of air we would suggest you use a material very similar in thermal characteristics to a void -- as a void is just that, an object/material that allows a complete free flow of air between zones or between inside and out.

If you wanted to represent a partially open window, then you would use an average between a void and your closed window depending on how "open" you wanted it to be.

That is, for a 50% open window you would use an exact average of the material properties of your window and the void.

Or for a 25% open window you would weight the average by 3 to 1 in favour of your window material.