A twinned building is likely a «physical» 
ActualPhysicalAsset . A screw used in the building is usually probably just a «physical» PhysicalEntity ; it can still be mapped by a «digital» @Entity and even be part of a control loop managed by a «twin» DigitalTwin , but need not be considered a full asset.
The distinction between «physical» PhysicalEntity and a «physical» ActualPhysicalAsset (a special case of of «physical» PhysicalEntity ) affords a way of determining how fine-grained an entire digital twin system is.