Adjustments to ventilation and temperature control systems, along with one mild winter, helped net-zero-energy house at NIST quadruple surplus energy it sent to power grid during its second year-long demonstration. From February 1, 2015 to January 31, 2016, this 2-story, 4-bedroom house's rooftop solar power system generated 13,717 kW hr of electricity. This eliminated annual electricity bill of ~$3,670 and garnered ~$80 refund check from local utility for 2,139 kW-hr energy surplus.