The city of Vancouver is “very seriously” considering consolidating most of its staff into one large building, a move intended to save $1 million a year, Mayor Tim Leavitt said Monday.Vancouver spends about $2 million a year to house its 1,000 employees in six buildings spread over downtown and as far out as Northeast 77th Avenue. The idea of buying or leasing one large building has long been part of the city’s long-term goals.“We are considering very seriously a large transaction that will save the taxpayers of our community significant dollars,” Leavitt said. “Taxpayers continue to demand that we find ways to become more efficient.”There aren’t many structures around Vancouver that would be able to house the city’s staff. But the former Columbian building, now owned by Bank of America, would have adequate space.No Vancouver official would confirm the city is interested in the former Columbian building.The city council Monday night spent just under an hour in a closed executive session to discuss real estate property acquisition, according to the council agenda. Only the seven-member council and relevant city officials may attend executive sessions.