DAVIS, Calif. — University of California-Davis has issued the Western Cooling Challenge, an effort to replace air conditioners throughout the western United States with new units designed specifically for the region's climate.

The challenge is looking for more efficient rooftop air conditioning units for new and existing low-rise, nonresidential buildings such as retail stores and office buildings.

The UC Davis Western Cooling Efficiency Center is sponsoring the challenge, part of its push to improve the energy efficiency of cooling throughout the western states of Arizona, California, Colorado, Idaho, Montana, Nevada, New Mexico, Oregon, Utah, Washington and Wyoming.

The challenge's goal is to reduce the energy consumed by cooling units by 40 percent. The Western Cooling Efficiency Center is attempting to help the development of technologies that both reduce total energy use of cooling as well as peak-demand energy use.

UC Davis has laid out voluntary cooling unit performance specifications and is including cooling system manufacturers, building owners and operators, utilities, energy regulators, universities and nonprofit groups in the challenge.