It is the purpose of this chapter to encourage increased residential opportunities, including affordable housing opportunities, in cities that are required to plan or choose to plan under the growth management act within urban centers where the governing authority of the affected city has found there is insufficient housing opportunities, including affordable housing opportunities. It is further the purpose of this chapter to stimulate the construction of new multifamily housing and the rehabilitation of existing vacant and underutilized buildings for multifamily housing in urban centers having insufficient housing opportunities that will increase and improve residential opportunities, including affordable housing opportunities, within these urban centers. To achieve these purposes, this chapter provides for special valuations in residentially deficient urban centers for eligible improvements associated with multiunit housing, which includes affordable housing. It is an additional purpose of this chapter to allow unincorporated areas of rural counties that are within urban growth areas to stimulate housing opportunities and for certain counties to stimulate housing opportunities near college campuses to promote dense, transit-oriented, walkable college communities.