The state, acting by and in the discretion of the Commissioner of Housing, may enter into a contract with a municipality for state financial assistance to initiate, expand or improve housing code enforcement programs to promote the preservation or rehabilitation of housing, in the form of a state grant-in-aid equal to two-thirds of the cost of the program, as approved by the commissioner, for two years after execution of the state assistance agreement, one-half of such cost for an additional period not to exceed three years and thereafter one-third the cost of the program. To facilitate the effective enforcement of housing codes throughout the state, the commissioner may prepare a model State Housing Code. Any municipality may adopt such code by ordinance.