SONOMA – The newly completed O'Neill Passive House in Sonoma will be open for public tours this weekend. It is the state's first certified passive house and the first retrofit passive house in the U.S. Passive design reduces energy usage by up to 90 percent of a traditional house through a combination of high levels of insulation, efficient windows, optimized passive solar gain, airtight construction, heat recovery ventilation and energy modeling. Tours will be conducted Saturday, Oct. 23, and Sunday, Oct. 24 from noon to 4 p.m. Tickets are $25, and proceeds will benefit Habitat for Humanity of Sonoma County.