IES-VE User Forum

Hi,
I am modelling a window 1000mm x 450mm high including frame with an opening area of 900mm x 400mm ie an 80% openable area.
The window is top hung. When fully open at 90deg Macroflo gives an equivalent orifice area of 82.58% and I am not sure why this is?

If the window cannot be opened more than 150mm for security is there a simple method of applying that?

Hope you can help

Hi,

Remember this represents the equivalent orifice area i.e. the area of a sharp edge orifice which allows identical air flow under identical pressure difference to the window you have described in the other inputs. In general the equivalent orifice area will be less than the opening area drawn but for some cases, such as this one, it can be greater.

The Cv factors used in the calculation are based on the best test data we had available but you are free to use the Custom Sharp Edge orifice opening type if you wish to adjust this. With this opening type you are able to directly input the equivalent orifice area (the Openable Area input is only to be used to represent any frame or non-moving parts of the window) so you have more control of the area passed into the MacroFlo calculations at simulation time.

Phil

Thanks for that Phil, I understand now.

To be able to alter the opening angle to suit the security 150mm restriction I will stick with the top hung window type.