1. A computer based method for evaluating different building designs, the method comprising: generating a first set of different building massing configurations using a shape grammar; storing the generated first set of different building massing configurations in a building massing library; reducing the first set of different building massing configurations according to a parameter search to form a second set of different building massing configurations, the second set being a subset of the first set; using the second set of different building massing configurations to evaluate an aspect of a building system.