As a prototype, HouseZero works to address one of the biggest energy problems in the world today—inefficient existing buildings. The U.S. building stock is responsible for around 40 percent of energy consumption, with housing nearly a quarter of that use. Property owners spend more than $230 billion annually heating, cooling and powering its 113.6 million homes. Addressing the energy-inefficiencies locked into this problematic building stock offers tremendous opportunity for curbing its impact on climate change. Paving the way through ultra-efficient retrofit strategies, HouseZero creates a blueprint for reducing energy demands and increasing cost savings for property owners.