(D) The heating, ventilating, air conditioning, and refrigeration section consists of five members, one of whom is a heating, ventilating, air conditioning, and refrigeration inspector employed by either the department of commerce or a municipal corporation; two of whom are heating, ventilating, and air conditioning contractors or refrigeration contractors who have no affiliation with any union representing heating, ventilating, and air conditioning tradespersons or refrigeration tradespersons; and two of whom are heating, ventilating, and air conditioning contractors or refrigeration contractors who are signatories to agreements with unions representing heating, ventilating, and air conditioning tradespersons or refrigeration tradespersons. The heating, ventilating, air conditioning, and refrigeration section has primary responsibility for the licensure of heating, ventilating, and air conditioning contractors and refrigeration contractors.