(a) In exercising its authority to zone for land uses and in revising its housing element pursuant to Article 10.6 (commencing with Section 65580) of Chapter 3, a city, county, or city and county shall designate and zone sufficient vacant land for residential use with appropriate standards, in relation to zoning for nonresidential use, and in relation to growth projections of the general plan to meet housing needs for all income categories as identified in the housing element of the general plan. For the purposes of this section:
(1) “Appropriate standards” means densities and requirements with respect to minimum floor areas, building setbacks, rear and side yards, parking, the percentage of a lot that may be occupied by a structure, amenities, and other requirements imposed on residential lots pursuant to the zoning authority which contribute significantly to the economic feasibility of producing housing at the lowest possible cost given economic and environmental factors, the public health and safety, and the need to facilitate the development of housing affordable to persons and families of low or moderate income, as defined in Section 50093 of the Health and Safety Code, and to persons and families of lower income, as defined in Section 50079.5 of the Health and Safety Code. However, nothing in this section shall be construed to enlarge or diminish the authority of a city, county, or city and county to require a developer to construct this housing.
(2) “Vacant land” does not include agricultural preserves pursuant to Chapter 7 (commencing with Section 51200) of Part 1 of Division 1 of Title 5.
(b) Nothing in this section shall be construed to require a city, county, or city and county in which less than 5 percent of the total land area is undeveloped to zone a site within an urbanized area of that city, county, or city and county for residential uses at densities that exceed those on adjoining residential parcels by 100 percent. For the purposes of this section, “urbanized area” means a central city or cities and surrounding closely settled territory, as defined by the United States Department of Commerce Bureau of the Census in the Federal Register, Volume 39, Number 85, for Wednesday, May 1, 1974, at pages 15202-15203, and as periodically updated.