When importing a Hevacomp Design Database project into OpenBuildings Energy Simulator the Ground Floor Uvalue may appear altered.
OpenBuildings takes the Ground floor Uvalue from your Hevacomp Ground floor data, selected in Fabric Data:
To ensure consistent data please ensure that the above figure is set to the same Uvalue entered when setting up your Ground Floors as below:
*UPDATE*
Please note that the above applied to version OpenBuildings Energy Simulator update 7, and earlier. This has since been resolved in Update 8.
So, should you be encountering the above issue please install the latest version, as shown here.