The mayor and city council of Chandler, AZ adopted Resolution 4199 in June 2008, establishing a requirement for all new occupied city buildings larger than 5,000 square feet to be designed and built to achieve the Silver level of the Leadership in Energy and Environmental Design (LEED) certification program, and to strive for higher levels of certification whenever project resources and conditions permit. To maintain cost control, city building projects may be exempt from the requirement if the payback period necessary to recover the initial costs is more than ten years.