sentences:  Recent studies have found that roughly 30% of LEED certified buildings perform substantially better than anticipated, while 25% perform substantially worse than anticipated.In general, LEED certified buildings perform 25-30% better than non-LEED certified buildings with regards to energy use.It is ultimately difficult or impossible for customers to construct a single integrated picture that correlates energy usage and maintenance costs to control system performance, space usage, conservation measures, and the behavior of those using the facility space.