(a) When the principal amount of the loan is $100,000 or less, the form of contract between the borrower and the contractor shall be in accordance with the following:

1. (1) The contract between the borrower and the general contractor may be in the form of either a lump sum contract or a cost plus contract. Either form of contract shall include the cost of the energy conserving improvements, their installation, and such other work to be performed by the contractor as necessary to meet the requirements of the Secretary. A lump sum contract shall provide for the payment of a specified amount. A cost plus contract shall provide for the payment of the contractor's actual cost of compliance with the requirements of the contract, plus such allowances for overhead and profit as may be approved by the Commissioner and shall provide that the total cost under the contract shall not exceed the upset price as approved by the Commissioner.
2. (2) If agreed to by the general contractor and borrower, a lump sum form of contract between the borrower and the general contractor may be used unless the Commissioner determines that a cost plus contract with a maximum upset price is necessary to protect the interest of the borrower or the Commissioner.

(b) When the principal amount of the loan is over $100,000, the form of contract between the borrower and the contractor shall be in accordance with the following:

1. (1) Lump sum contract. If the Commissioner determines that there is no identity of interest between the borrower or any of the officers, directors or stockholders of the borrower and the contractor, there may be used a lump sum contract providing for payment of the specified amount.

2. (2) Cost plus fixed fee contract.

   1. (i) If the Commissioner determines that there is any identity of interest (financial or otherwise) between the borrower, its officers, directors or stockholders and the contractor, the form of contract shall provide for payment of the actual cost of construction not to exceed an upset price and may provide for payment of a fixed fee not exceeding a reasonable allowance as established by the Commissioner in accordance with customary practices in the area.
   2. (ii) In any case where the borrower is a nonprofit entity, a cost plus fixed fee contract shall be used unless it is established to the Commissioner's satisfaction that such form of contract is not required to protect his/her interests and the interests of the borrower, in which case, a lump sum form of contract may be used.