The legislative body of any municipality or, in a municipality where the legislative body is a town meeting, the board of selectmen may, by ordinance, exempt from real property tax any workforce housing development project, as defined in section 8-395, to the extent of seventy per cent of its valuation for purposes of assessment in each of the seven full assessment years following the assessment year in which the construction or substantial rehabilitation, as defined in section 8-395, is completed.