Upon opening an existing model your Construction data may be missing, e.g. as in the image below.
This is likely to result in calculation errors such as that shown in the following Wiki: Error - "Bad reference : CONSTRUCTION"
This occurs when you have associated your DGN model to a different Workset.
This can be avoided by instead using the WorkSet in which the DGN model was originally created. You must take care you choose the correct WorkSet as all the data related to materials and constructions are stored in the Standards folder, within EnergyData in the original WorkSet.In future should you see a 'Mismatch Alert' message like the below when opening a model - please pay careful attention to what this states:
This tells you:1. The WorkSet the model belongs to.2. The unrelated WorkSet you are instead attempting to open it with.
To resolve:
Option 1 - Open the model via the correct WorkSet as follows:
Option 2 - If you wish to instead continue using the new Workset, you must copy the EnergyData folder from the original WorkSet and replace the same in your new WorkSet:
To learn more about the features of Workspaces and WorkSets please refer to the article here.