In order to accurately simulate HVR performance, any room you want to assign to an HVR unit group must meet the following pre-requisites:
-The room must haveone HVR Integrated Louvre for each HVR unit in a room. For example, if an HVR unit group defines the Number Of Units property as 2, the room must have two HVR Integrated Louvres. All HVR louvres are modelled using external doors.
-Each HVR louvre must have aminimum size of 0.27m2 at 900mm x 300mm.
It is the user’s responsibility to model the louvres at an appropriate size and position to reflect real-world conditions.
If the Automatically identify HVR® openings on room assignment setting (see previous section for details) is active for the unit group and a room is assigned to that group, any wall-based external door in the room that is assigned a MacroFlo opening type using a Degree of Opening profile other than off continuously will be considered as being available to be used as an HVR integrated louvre. Note that only the required number of suitable external doors (i.e. the # of Units value from the unit group properties) will be automatically used – any additional doors will be left as-is. In addition to handling external doors, all wall-based external windows that are assigned a MacroFlo opening type using a Degree of Opening profile other than off continuously will be automatically used as HVR Natural Vent. Windows.
You will generally set up your model in the normal way beforehand, ensuring that you have defined suitably sized (see the sizing guidance above) and positioned external doors and windows, and with sensible MacroFlo assignments applied. If you need to add on new doors or windows to rooms you are planning on using with HVR, you can use the standard Add Door () and Add Window () features in ModelIT – simply set a suitable width, height and base height and add the openings.
) and 
) features in ModelIT – simply set a suitable width, height and base height and add the openings.