Section 3A. (a) The secretary shall, in consultation with the secretary of housing and economic development and the secretary of transportation, adopt sector-based statewide greenhouse gas emissions sublimits as components of each statewide greenhouse gas emissions limit adopted pursuant to subsection (b) of section 3 for the sectors of electric power, transportation, commercial and industrial heating and cooling, residential heating and cooling, industrial processes, and natural gas distribution and service. In order to achieve the greenhouse gas emissions limits established by this chapter, the secretary may adopt sector-based statewide greenhouse gas emissions sublimits for any other sector or source the secretary may designate.

(b) Sector-based statewide greenhouse gas emissions sublimits for a given year shall not, in the aggregate, exceed the statewide greenhouse gas emissions limit for the year and shall be designed to maximize the ability of the commonwealth to meet the 2050 statewide greenhouse gas emissions limit established in subsection (b) of section 3; provided, however, that a sublimit shall not be found to have been binding for a given prior year if the commonwealth is found to have complied with the statewide greenhouse gas limit adopted pursuant to said subsection (b) of said section 3 for the same year.