A point-based green-building rating system (from the US Green Building Council) that certifies a project across categories like energy performance, water use, materials, and indoor air quality, awarding a level from Certified up to Platinum. LEED does not require BIM, but in practice BIM makes pursuing it dramatically easier: energy analysis, daylight studies, and material quantities that LEED documentation demands can be extracted or simulated directly from the model instead of calculated by hand.

This is essentially what 6D BIM is for in practice - LEED (or its regional equivalents like BREEAM) is often the actual target that 6D energy and environmental analysis is being done to satisfy.