CEDAR RAPIDS — A group of Linn County human services agencies has settled on the building that will serve this winter as an overflow shelter for those who are homeless.The space, a vacant office building located at 505 33rd Ave. SW, has been offered for use by a local businessman who wishes to remain anonymous, said Phoebe Trepp, executive director of the Willis Dady Homeless Shelter, one of 15 agencies involved in the Linn County Continuum of Care.