The energy conservation grant fund is a special fund in the state treasury. All funds in the energy conservation grant fund are appropriated to the department on a continuing basis for the purpose of providing grants to political subdivisions for energy conservation projects in nonfederal public buildings. The department shall develop guidelines to qualify for a grant under this section which must include a requirement that projects have a combined payback period of ten years or less, a matching requirement of one dollar of matching funds for every dollar of grant funds, and a maximum grant amount of one hundred thousand dollars. Interest earned by the fund must be credited to the fund.