Not later than 4 years after December 19, 2007, the Secretary shall by regulation establish standards for energy efficiency in manufactured housing.
The energy conservation standards established under this section shall be based on the most recent version of the International Energy Conservation Code (including supplements), except in cases in which the Secretary finds that the code [1] is not cost-effective, or a more stringent standard would be more cost-effective, based on the impact of the code [1] on the purchase price of manufactured housing and on total life-cycle construction and operating costs.