Complying with the 2012 International Energy Conservation Code (IECC) could be prohibitively expensive for the multifamily industry, according to research conducted on behalf of the National Apartment Association and the National Multi Housing Council.

The construction cost per unit could increase by thousands of dollars, the analysis indicates. Apartment design and construction might have to be changed significantly in many areas of the nation to accommodate alterations such as thicker exterior insulation. The expense of compliance would depend on climate zone and building size, among other factors.

"Apartments are by definition more energy efficient than other residential options, such as single-family houses," said Paula Cino, NMHC Director of Energy and Environmental Policy. "But these codes are meant to set minimum requirements, and they set a very expensive minimum. In some cases it would take more than 200 years for the energy savings produced by the codes to pay for the required upgrades."

As a result, the organizations are urging policymakers to consider the cost of adopting these codes before making any decision and seek to strike a balance between mandating energy efficiency and affordability. If the cost of constructing and operating apartments increases past a certain point, landlords and rental property management firms may be compelled to pass that on to tenants.