Typical climate conditions of the 20th century may not provide adequate design parameters for the built environment of the 21st century due to changing climate. The conventional practice in the engineering community is to use past climate observations to provide climate input for building design to function into the middle of the 21st century. Recent studies have used global climate models together with statistical downscaling techniques to develop site-specific climates for future energy demands on buildings. An alternative method is to use "dynamical" downscaling by use of regional climate models as is being done under the North American Regional Climate Change Assessment Program (NARCCAP). This technique uses results of global climate models to drive regional climate models which give higher resolution results over specific locations, thereby more robustly representing features such as mountains, coastal areas, and fine scale dynamical processes of the atmosphere that create regionally unique climates. We use seven global/regional climate model combinations in conjunction with the solar radiation analyses method of Wilcox and Marion to produce scenarios of future typical meteorological years for the middle of the 21st century for Mason City, IA. Our method goes beyond previous results in that (1) we use dynamical downscaling rather than statistical downscaling, (2) our results are applicable to all US locations available in the TMY3 database, and (3) our use of multiple global and multiple regional models enables us to present strong evidence that, for our test location, the magnitude of climate change in meteorological variables of high importance to building energy considerations by the middle of the 21st century will be of greater magnitude than both the natural variation in these variables during last three decades of the 20th century and the inter-model variation of the model combinations used to project this change. In future work these results will be used in building design and building energy modeling, starting with the U.S. DOE Commercial Reference Buildings.