Before originating or purchasing or participating in the purchase of a senior housing mortgage loan, the corporation may have or may require the borrower to have an appraisal made of the fair market value of the real property, including structures on the real property, for which the loan is made. In conducting an appraisal under this section, the appraiser shall give full value to insulation and other features of construction in structures on the real property that add to the energy efficiency of the structures.