Cottonwood Creek Apartments is a 94-unit affordable multifamily housing complex located in Suisun City, California. The complex was designed with resource efficiency in mind and was able to exceed California’s Title 24 (2005) energy-efficiency requirements by an average of 17.6 percent. Energy-efficiency upgrades include radiant barriers on the roof, low-emissivity windows, high-efficiency HVAC equipment, Energy Star–rated appliances, efficient fluorescent overhead lighting, light-emitting diodes in exit signs, a 65-kilowatt solar photovoltaic array, high-performance building envelope material and insulation, and HVAC ducting in conditioned spaces (to reduce energy losses from duct leaks). With careful planning, the designers of Cottonwood Creek were able to secure numerous economic incentives to bring down the initial cost of these upgrades to a mere fraction of the total hard costs (0.27 percent). The apartment complex is expected to save roughly 40,000 kilowatt-hours per year relative to a similar complex built to 2005 Title 24 standards. In addition to energy savings, occupants at Cottonwood Creek report exceptional comfort, thanks to the efficient HVAC system and high-performance building envelope.