Total energy consumption by com. and residential buildings in the US nears 40 Quads. Approx. 1/3 of that energy use is due to space heating and cooling. Recent anal. of materials that comprise the building envelope would benefit from smarter windows that more effectively managed heat. We will describe recent efforts in using doped metal oxide nanocrystals in electrochromic windows to manage solar heat gain in buildings. These nanocrystals show switchable absorption properties in the IR due to their dynamically tunable surface plasmon resonances. We will describe the impact of different mesoscale nanocrystal architectures on the switching, optical properties, etc - which are controllable by block copolymer-directed assembly.