The idea of requiring commercial properties to meet more stringent energy efficiency standards received a warm reception Tuesday night from the Boulder City Council during a study session on energy and climate issues.

Energy use accounts for 76 percent of Boulder's greenhouse gas emissions, and industrial and commercial electricity use makes up nearly 83 percent of the community's energy use, according to a city analysis in 2006. So far, programs aimed at reducing energy use in the commercial sector have been voluntary, but they haven't achieved the energy savings necessary for the city to meet its climate goals.

In response, city officials have proposed a program similar to SmartRegs, which created energy-efficiency standards for residential rental properties. A three-phased approach would start with expanding the incentives available for business owners who voluntarily take on energy-efficiency improvements, followed by mandatory energy rating and reporting.

Businesses would have to rate their building's energy performance using a standardized tool and make that information publicly available for potential tenants, the same way consumers know the Energy Star rating on their washing machines or how many miles per gallon their cars get. The information learned through that process would be used to set commercial energy-efficiency goals and a timeline to meet them.

Though the proposal includes a transitional period, city officials hope to move quickly, putting the new mandatory standards in place by late next year.

"I know that's a heavy hand, but given how much the commercial sector contributes to our greenhouse gases, I think it's necessary," Councilman Tim Plass said.

Mayor Matt Appelbaum said he'd like to see the standards become mandatory even sooner.

However, the city may need to get new legislation passed through the General Assembly to require Xcel Energy to turn over more detailed information about commercial energy use. Right now, the city needs to collect waivers from individual businesses to grant the city access to energy information, and those requests need to be mailed to a central processing center out of state.

Business owners and advocacy groups who have met with city officials have said they would prefer for voluntary programs to continue, said Elizabeth Vasatka, business sustainability coordinator for the city's Local Environmental Action Division.

Councilman Ken Wilson said coming up with energy standards for widely varied commercial uses might be more complicated than doing so for residential properties.

"This is going to be complicated by what businesses do," Wilson said. "The building is one thing, but what the business does in the building is another."

He also said the city needs to be able to offer significant incentives and rebates to help businesses reach the new standards.

Councilman Macon Cowles suggested that the city might be able to require changes to commercial leases that would allow property owners to amortize the cost of energy-efficiency improvements through rent. That would shift some of the cost of improvements to tenants, who also see the benefits in reduced utility bills.

"This would be nearly painless to do, and over a period of three or four years, we could get green leases on nearly every tenancy in the city," Cowles said. "This would have anticipated benefits that are both immediate and long-term."

Other council members balked at the idea of inserting the city into the contractual relationship between landlords and tenants, but they supported the idea of making model lease language available to landlords so that they could include it when leases are renewed.

Councilwoman Lisa Morzel said if businesses want the programs to remain voluntary, they need to increase participation and bring new ideas.

"If they want to see more voluntary programs, let them come up with ideas, and if they can't, then we go toward phase 3," she said.