Generally, modelers must accept either long wait times or devise clever shortcuts or simplifications. Parallel computation allows simulations to run many times faster, which often means that less involvement is required from the modeler, and graphics processing hardware is increasingly putting parallel computation in the hands of individuals. Case studies involving radiant heat exchange will be presented showing the speedup of complex simulations on highly parallel graphics processors that reduce both human and computer hours spent on simulation. The results show how parallel simulation hardware and software lead to time and cost savings in design and to more efficient buildings.