Key West, Florida, has toughened residential building requirements with a new provision making green certification mandatory.

In 1993, the city adopted the Building Permit Allocation System Ordinance that limited development, and in November the City Commission updated the ordinance green building provisions.

New residential projects will have to be LEED-certified or meet the standards of the Florida Green Building Coalition, according to a post at Green Building Law Update.

The change is part of an effort to address several sustainability issues, including potable water supply limits and a rise in sea levels.

The new requirements were developed by city staffers in conjunction with builders and architects. The object was to find a green building standard “that was easy to measure and use, and has been proven successful,” the website said.

All new residential projects, including additions valued at more than 50% of the original building, will be required to have a rainwater catchment system. Even renovations that don’t trigger the new green building requirements will have to demonstrate water and energy consumption 15% below that of Florida building codes, the article said.