Section 8. A city or town shall submit to the department, concurrently with the city or town's application for a letter of eligibility, either an existing comprehensive housing plan, an existing housing production plan, or a housing production summary. The plan or summary shall include an estimate of the projected number of units of new construction that could be built in the proposed smart growth zoning district or starter home zoning district. If a city or town has already completed a comprehensive housing plan or housing production plan, the city or town shall submit with its application to the department a description of how the proposed smart growth zoning district or starter home zoning district relates to and will further the goals of its comprehensive housing plan or housing production plan, as well as an estimate of the projected number of units of new construction that could be built within the district.