This 725-square-foot residence’s sustainable elements—a small building footprint, living roof, water catchment system, and recycled building materials—combine for high performance and low energy bills. A living roof and spray-foam insulation in the walls minimize energy losses due to air infiltration and conduction through the building frame, while a 1.7 kW PV array provides pollution-free electricity. Well-placed windows allow ample natural light to permeate the home, reducing the need for artificial lighting during daylight hours, while LED lighting fixtures maximize energy efficiency at night. Water-saving fixtures include low-flow showerheads and faucets, and a dual-flush toilet, as well as a greywater recycling system. As a result, the mkLotus exceeds California’s GreenPoint rating system, an independent certification sponsored by the nonprofit Build It Green, by 300%.