A hot topic at a symposium focusing on commercial-building energy use I attended earlier this year was the strong need for benchmarking building performance. The consensus of the 20 or so consulting engineers and commercial-building owners and managers at the event was that without benchmarking it is almost impossible to determine if a building is energy-efficient or "green." It is one thing to say a building is energy-efficient, but quite another to measure and prove it.

It all made sense to me. Apparently, it made sense to California Gov. Arnold Schwarzenegger and the state's Legislature, too. On Oct. 12, Schwarzenegger signed a bill making California the first state to mandate the disclosure of commercial-building energy-consumption data and benchmarks.

The legislation requires electric and gas utilities to maintain energy-consumption records for all non-residential buildings for which they provide service. By January 2009, utilities must have the data in a format compatible with the U.S. Environmental Protection Agency's (EPA's) Energy Star Portfolio Manager online tool and ready for upload at a customer's request.

The bill further mandates that starting in January 2010 commercial-building owners and operators will be required to disclose a building's benchmarking data and EPA energy-performance rating to a prospective buyer or lessee of an entire building or a lender that would finance an entire building.

California Assembly member Lori Saldana, the bill's primary sponsor, noted that the legislation would make it easier for building owners and operators to compare their buildings' performance with that of similar buildings and manage their buildings' energy costs over time.

"This information will help motivate building managers to make their buildings more energy-efficient," Saldana said. "It also will help them to establish investment priorities and to take advantage of energy-investment opportunities offered by utilities and governments."

The law is a major boost for the green-building movement because it gives measuring building performance a sense of urgency that currently does not exist in the world of voluntary efficiency. If the program succeeds in California, I am confident other states will follow suit and adopt similar legislation. "Green" and good business are a tough combination to ignore.