A study was conducted to examine the effects induced by a greenroof installation on a typical roof in various climate types of the United States. Initially, heat and moisture transport parameters of a modular greenroof system were evaluated based on physical measurements and simulated soil hydraulics. Using climatic data, the greenroof system was then evaluated to determine the stormwater runoff reduction potential compared to a BUR (Built-Up Roof) and overall energy load effects compared to a BUR and a reflective, cool roof in seven U.S. evaluation cities. Runoff simulations were run in HYDRUS-1D, while energy load simulations were run for a hypothetical office building in the evaluation cities using eQuest, a DOE-developed building energy load simulation. Simulation results were validated based upon in situ observations at a greenroof installation in Athens, Georgia. Simulated runoff and cooling load reductions for the evaluation cities ranged from 17-81 % and 2.5-6.9 %, respectively.