I would like to model, preferably in EnergyPlus, horizontal black out insulating curtains in a greenhouse application.

To me this is an interesting modelling challenge as it creates a space with a vaulted ceiling going from essentially from 1 zone to 2 zones when the horizontal curtains at the roof hip level are closed with the interface having a U-value step change. Since these curtains are horizontal and the roof is sloping, they are not parallel to the glazing. The curtains would be controlled by a time of day schedule as a function of sunrise, sunset.

In the same application, I will model horizontal reflective curtains, which are also not parallel to the roof glazing using the EnergyPlus daylight algorithm.

Your suggestions are most welcome.