Five buildings totaling 1.2 million square feet of space in the Hillwood-developed Interchange Business Center in San Bernardino, Calif., have earned LEED Silver certification from the U.S. Green Building Council.It is the largest speculative industrial project in the U.S., one of the largest industrial projects in the U.S., and one of the largest overall projects in California to receive LEED certification, said Hillwood, the Fort Worth-based developer of Alliance Airport and the surrounding residential and industrial developments. The buildings were completed in 2008 but have since been sold to CB Richard Ellis Investors. The buildings received the Leadership in Energy and Environmental Design certification in June. The Interchange Business Center was done in partnership with the city of San Bernardino’s Economic Development Agency. The 144-acre site once housed a pre-World War II silica gel manufacturer.