Double Facade - Cooling Demands study


I am currently working on a project where I want to assess the cooling demands of a double facade system and compare it with the single facade version of it and to evaluate the impact of different glazing ratios and cavity widths. I followed the example in Hydrashare for Double Vented facades and Energy Box simulations, however, I have some questions, because the cooling demands I get from the single facade seem to be lower that the double skin one.

I think that the problem is in the way I have set the natural ventilation and air flows in the single facade, but I am not quite sure. I cannot attach the Rhino and Grasshopper files yet, because I am a new user, but if someone could help me out on this to understand what the problem is, that would be great.

Some of my questions are:

  • In the SolveAdjacencies component between the cavity and the inner facade, if the Air wall is off, then the Cavity Air flow doesn’t affect the results, but if Air Wall is on, then the glazing ratio changes don’t have any impact on the cooling loads.
  • Also, is it right to set the wind coefficient to zero inside the cavity?
  • And is it valid to have the room as an adiabatic one, considering it part of a building?
  • In the natural ventilation in the single facade scenario what should be the min and max indoor and outdoor temperatures?

Thanks a lot for your help.