Level of Development
A BIM specification standard that defines how precisely each model element represents the real building — from approximate massing (LoD 100) to fabrication-level detail (LoD 500).
Level of Development (LoD) is a BIM specification framework that defines how precisely each model element represents the actual building element it describes. Higher LoD means more precise geometry and more complete attribute data, but also more modelling time and higher cost.
The standard LoD scale runs from LoD 100 (conceptual massing — element is represented by a generic shape) to LoD 500 (as-built — element is verified as constructed, with installation-level accuracy and complete attribute data). For most heritage management HBIM models, LoD 300 (elements modelled to verified size and location, ±50 mm) to LoD 350 (interfaces between elements explicitly modelled) is appropriate.
In HBIM practice, LoD is adapted to include heritage-specific attribute completeness — not just geometric precision, but whether condition grades, period attributions and significance levels are assigned. A high-LoD HBIM element should be precisely modelled AND fully attributed.