Mass. Gen. Laws ch. 40C § 7
In passing upon matters before it the commission shall consider, among other things, the historic and architectural value and significance of the site, building or structure, the general design, arrangement, texture, material and color of the features involved, and the relation of such features to similar features of buildings and structures in the surrounding area. In the case of new construction or additions to existing buildings or structures the commission shall consider the appropriateness of the size and shape of the building or structure both in relation to the land area upon which the building or structure is situated and to buildings and structures in the vicinity, and the commission may in appropriate cases impose dimensional and set-back requirements in addition to those required by applicable ordinance or by-law. When ruling on applications for certificates of appropriateness for solar energy systems, as defined in section one A of chapter forty A, the commission shall also consider the policy of the commonwealth to encourage the use of solar energy systems and to protect solar access. The commission shall not consider interior arrangements or architectural features not subject to public view.
The commission shall not make any recommendation or requirement except for the purpose of preventing developments incongruous to the historic aspects or the architectural characteristics of the surroundings and of the historic district.
Mass. Gen. Laws ch. 40C, § 7