Palo Alto's environmental activists gathered in a parking lot near the Baylands on Wednesday afternoon for an unusual activity: watching a crane lift boxes and heave them onto the roof of an East Bayshore building.

The building was the Peninsula Conservation Center, which houses eco-friendly nonprofits such as Acterra and Green Foothills. The eight boxes, each about the size of a large washing machine, were its new all-electric heating, ventilation and air conditioning units, a technology that the city is banking on to help meet its ambitious climate goals.

For the city, the installation represented a milestone of sorts. While Palo Alto's new green building rules require all new commercial buildings to be "all electric" when it comes to space and water heating, existing commercial buildings by and large rely on gas for their heating needs. Phil Bobel, former assistant director at the city's Public Works Department, said the project at the Peninsula Conservation Center is the first instance in which an existing commercial building received permits and replaced its existing gas-fired, roof-top HVAC units with all-electric heat pumps that provide both heating and cooling.

Bobel, who serves on the board of directors at the Peninsula Conservation Center, said the project is important because existing buildings account for about 30% of the city's greenhouse gas emissions. Yet most of the debates currently taking place in Palo Alto and elsewhere pertain to bans of gas-powered appliances for new construction.

"Obviously, were going to have to make some inroads on existing stuff," Bobel said. "It's not going to be enough to just deal with new stuff unless you want to wait 100 years for everything to be replaced."

So far, the city has been cautious about moving ahead with any programs to encourage widespread conversion of space heating from gas to electric appliances. While the City Council has recently adopted a goal of getting to carbon neutrality by 2030, its only major new program focuses exclusively on water heaters. The program, which the council approved in late September, aims to convert 1,000 local homes from gas to electric water heaters, a conversion that the city is facilitating through a "turnkey" installation process and on-bill financing, which allows customers to pay for the new appliances gradually through their utility bills. While it is still in its early phases, about 190 people have already signed up for the switch, according to Christine Luong, the city's sustainability manager.

The city has not been nearly as aggressive on space heating. Partly, that's because in many cases these conversions are more complex and more costly. Partly, it's because Utilities Department officials are concerned about the city's ability to accommodate both the increasing electric load and staff workload that these conversions would entail.

During an October discussion of the city's new building code, Jonathan Abendschein, assistant director at the Utilities Department, said that space heating programs that rely on heat pumps are something that the city is looking to ramp up in the coming years.

"The concern is avoiding a situation where we put a mandate in and our engineering team gets overwhelmed and it delays occupancy on projects while people wait for transformers," Abendschein said at that time.

But if Palo Alto were to meet its climate change goals, projects like the one the Peninsula Conservation Center is undertaking would be essential. Brad Eggleston, the city's Public Works Director, said that to meet its sustainability targets, Palo Alto would need to see about 100% of the existing gas-powered rooftop HVAC units get replaced with electric ones.

Though such conversions are still new, Eggleston said they are starting to become "more common and more cost effective." He underscored the environmental benefits of the switch.

"Most generally, you're going from using devices that burn natural gas and create greenhouse gas emissions for heating to more energy efficient devices that use our 100% carbon neutral electricity," Eggleston said. "That contributes directly to reducing greenhouse gas emissions and getting to our climate goals."

For the Peninsula Conservation Center, the installation was a long time coming. Bobel said the group has been reserving about $20,000 a year for the past eight years to purchase the eight units, which cost about $160,000. It has also spent about a year dealing with the Planning Department to get the needed permitting for the work.

The length of the permitting process, a frequent source of frustration for installers of green technologies, surprised Richard Izmirian, the heat pump contractor on the project.

"If Palo Alto is trying to encourage them, they better tell the Planning Department," he quipped.