(a) A governmental unit may enter into a guaranteed energy cost savings contract in order to reduce energy consumption or operating costs of government facilities in accordance with this article.
(b) All energy cost savings measures shall comply with current local, state, and federal construction and environmental codes and regulations. Notwithstanding anything to the contrary, a guaranteed energy cost savings contract does not include improvements or equipment that allow or cause water from any condensing, cooling, or industrial process or any system of nonpotable usage over which public water supply system officials do not have sanitary control, to be returned to the potable water supply.