Cities and states on the West Coast are teaming up to tackle one of the biggest sources of urban emissions: energy use in buildings.

Three governors, six mayors, and the environment minister of British Columbia adopted the Pacific North America Climate Leadership Agreement this month at the Clean Energy Ministerial in San Francisco. The leaders of British Columbia, California, Los Angeles, Oakland, Oregon, Portland, San Francisco, Seattle, Vancouver, and Washington state agreed to work together to address the energy use and greenhouse gas emissions from buildings.

Energy use in buildings is one of the largest sources of emissions in most cities. Buildings account for 52 percent of emissions in San Francisco, and 33 percent in Seattle. Even in smaller cities, the building sector remains a significant source of emissions. If cities can cut energy use in buildings, it can help them deliver on their ambitious climate mitigation commitments.

Since cities are already filled with buildings, improvements must be made to those that are already in use, rather than waiting for newer, more efficient buildings to be constructed.

A place to start is with benchmarking and disclosure policies, which are in place in 15 cities. Cities require building managers to record and report their energy use with the help of EPA tools. The resulting database can help identify opportunities for reducing energy use. And city officials can use the information to guide policy and create long-term strategies to reduce energy use and emissions.

To ensure that buildings achieve reductions in energy use, cities are complementing benchmarking and disclosure policies with additional actions, including: retro-commissioning, a process that assesses buildings to uncover low-cost operational improvements; supporting buildings through retrofit processes; and ensuring that buildings undergoing major renovations are brought up to current code.

Examples of these policies can be found throughout the West Coast and the U.S. at large. Seattle recently required commercial buildings 50,000 square feet or larger to undertake retro-commissioning processes every five years. Los Angeles is supporting property owners and managers to execute building performance upgrades to achieve 20 percent reductions in energy usage. And Washington, D.C., like many cities, requires major upgrades to existing buildings to meet current, more energy-efficient building codes.

With a comprehensive suite of policies aimed at commercial building efficiency, cities can take action to address one of their largest sources of emissions. We are heartened to see that the Western states and cities have committed to work together on this challenge, and look forward to seeing the local progress that might be accelerated with supportive state policies. By working together, cities and states can help shape policy, investment, and behavior change strategies that can become models for broader action.