California’s commercial buildings suck up more than a third of all the electricity used in the state–and that’s too much.

That’s among the conclusions of a new report from the San Francisco-based think tank Next 10. The 12-page report points out that on average, such buildings could cut energy use by 30% just by upgrading insulation, and another 18-to-20% with more efficient lighting.

Though California leads the nation in its stingy use of electricity overall, the report notes that efficiency standards for new construction are “well below what is possible” and what standards are in place are not met by 40% of new buildings. Study co-author Tracey Grose says that’s partly because even if state-of-the-art equipment is installed, it isn’t always used as intended. There are no energy efficiency standards at all for existing buildings. In general, the study finds that energy use in most buildings could be cut by 80% with some basic upgrades.

The report, compiled by the consulting firm Collaborative Economics in Mountain View, and largely a compilation of existing work, also implies that there’s a built-in way to pay for some of these improvements. The authors cite studies showing that commercial tenants are willing to pay higher rents for “greener” space. The report also cites figures from the Building Owners & Managers Association, that some basic improvements in energy efficiency offer a three-to-one return on investment.

Power consumption varies widely within the commercial sector. Next 10 notes that restaurants are the biggest kilowatt hogs per square foot, followed by supermarkets and hospitals (when’s the last time you had to wear a sweater while grocery shopping because the frozen food section was chilling the whole store?).

According to the report, while raw consumption has continued to rise, efficiency in these buildings has leveled off in recent years. Overall, the nearly 6.8 million square feet of commercial space accounts for 37% of California’s electricity use, compared with 40% for commercial buildings nationwide. The latter accounts for more than a quarter of the nation’s carbon dioxide emissions, according to the report.

Next 10, which describes itself as an “independent, non-partisan organization” has been a vocal promoter of the economic benefits from greening the state’s economy.