The definition of “Consistent with local needs” in section 20 of chapter 40B of the General Laws, as appearing in the 2016 Official Edition, is hereby amended by striking out the second sentence and inserting in place thereof the following sentence:- Requirements or regulations shall be consistent with local needs when imposed by a board of zoning appeals after comprehensive hearing in a city or town where: (1) low or moderate income housing exists which is in excess of ten per cent of the housing units reported in the latest federal decennial census of the city or town or on sites comprising one and one half per cent or more of the total land area zoned for residential, commercial or industrial use; (2) such city or town is a member of a regional school district established pursuant to section 15 of chapter 71, and low or moderate housing exists in member cities and towns, which are in their total in excess of 10 per cent of the housing units as reported in the latest federal decennial census; provided, that such percentage shall be calculated by adding up the total number of low or moderate housing units of each member city or town as the numerator and then divided by adding up the total number of housing units of each member city or town as the denominator and then multiplying the resulting decimal by 100; or (3) the application before the board would result in the commencement of construction of such housing on sites comprising more than three tenths of one per cent of such land area or ten acres, whichever is larger, in any one calendar year; provided, however, that land area owned by the United States, the commonwealth or any political subdivision thereof, or any public authority shall be excluded from the total land area referred to above when making such determination of consistency with local needs.