The world's largest net zero energy building did not happen overnight, but it did start with an ambitious vision. The National Renewable Energy Laboratory (NREL) stipulated an annual energy consumption of 25 kBtu/ft2 (79 kWh/m2) for its new Research Support Facility. Rather than just meeting this aggressive requirement, the designers submitted a plan to deliver what NREL had on their wish list, a building that would use as much energy as it would produce—a net zero design. The idea was to do this within a typical design-build (DB) schedule and a rigid $64.3 million budget.