Section 9C. As used in this section, the term ''child care facility'' shall mean a child care center or a school-aged child care program, as defined in section 1A of chapter 15D.

When any zoning ordinance or bylaw in any city or town limits the floor area of any structure, such floor area shall be measured exclusive of any portion of such structure in which a child care facility is to be operated as an accessory or incidental use, and the otherwise allowable floor area of such structure shall be increased by an amount equal to the floor area of such child care facility up to a maximum increase of ten per cent. In any case where the otherwise allowable floor area of a structure has been increased pursuant to the provisions of this section, the portion of such structure in which a child care facility is to be operated as an accessory or incidental use shall not be used for any other purpose unless, following the completion of such structure, the board authorized to grant variances under such zoning ordinance or bylaw shall have determined, with the written concurrence of the office for children, that the public interest and convenience do not require the operation of such facility. The procedures governing the granting of variances, including all rights of appeal, shall apply to any such determination.

The owner of a building as to which the allowable floor area has been increased pursuant to this section shall be allowed to charge the operator of the child care facility for the following: the cost of utilities used by the child care facility, a reasonable building operating fee for the costs of maintenance, cleaning and security, and real estate taxes for the portion of the building which is the child care facility, if such facility is operated by a for-profit provider. The owner shall not impose a charge for the cost of alterations necessary to meet the requirements of the office for children regarding the physical facility of a day care center. Any person operating a child care facility in a portion of a structure which is to be used only for such purpose pursuant to the provisions of this section shall use best efforts to assure that at least fifty per cent of the children utilizing such facility are from families whose income is not more than one hundred and ten per cent of the median family income of the commonwealth.