The city won that prize, not to mention global recognition, with an idea to lower the cost of utilities for affordable housing using sustainable energy.
In particular, Mayor Lauren McLean and staffers relied on the city’s well-known — at least locally — geothermal energy capability to come up with a unique entry in the Bloomberg Philanthropies 2025 Mayors Challenge: using that geothermal to heat affordable-housing units.
The city will use the $1 million for a project with up to 300 apartments in an area adjacent to Boise State University, complete with geothermal heating. The city says residents in those units should see drastically lower utility bills.
“This idea takes our direct source geothermal system and allows us, when it’s implemented, to use it to heat affordable housing in the Lusk District,” McLean told the Idaho Statesman in an interview. “This will be the first instance of its kind where anybody’s using direct source geothermal heat to warm multifamily and, importantly, affordable housing in their community.”
Geothermal energy exists in Boise because of the city’s location near so many underground sites, and it has been a leader in that field since the late 19th century, when the city established the Warm Springs Water District and built a system that uses natural hot springs to heat homes, according to the city’s website. The city has its own system now that heats City Hall and more than 90 buildings downtown; several Boise State University buildings; and even the Idaho Statehouse.
McLean said the reward for Boise illustrates the dedication of a city team working on sustainable energy and affordable housing.
“This recognizes the quality of the idea and the belief in the city of Boise team that they’ll be able to do this or deliver, and then share with others how to do the same,” McLean said.
Boise was named a top 24 city among 630 in the competition run by former New York City Mayor Michael Bloomberg’s philanthropic foundation, which challenges cities to find innovative and creative solutions to prominent issues — things such as affordable housing, waste management, emergency services and environmental problems.
Idaho’s capital wound up being one of three U.S. cities to win a $1 million award, the others being Lafayette, Louisiana, and South Bend, Indiana. Among cities around the world to get prizes were Barcelona, Budapest, Cape Town, South Africa, and Fez, Morocco.
Aparna Ramanan, who leads the Mayors Challenge for the Government Innovation program at Bloomberg Philanthropies, said in a statement that Boise’s idea was “the kind of innovation the Mayors Challenge was built to back.”
Boise Goes From Finalist to Big Winner
In July 2025, Bloomberg Philanthropies announced that Boise was among 50 finalist cities. All of those were invited to a conference to workshop ideas and create a prototype of their project, and Boise was one of five cities chosen to present its plan to the other cities.
Katie O’Neil, the city’s energy program manager, told the Statesman that the team was able to learn from experts with the foundation and from cities around the world, which came up with “grassroots solutions to real local problems,” she said.
O’Neil noted that in Boise, geothermal energy is something that can be utilized to transform the way the entire city is run.
“We’re the only city in the United States that has this, one of only a handful in the world, and this has never been applied to an affordable housing structure,” she told the Statesman when Boise was announced a finalist.
O’Neil said city staff went to the community with this idea and spoke to residents about utility bills while they were researching the project. She said the level of savings on utility costs for residents in the affordable housing units would be drastic, with estimates of up to 80% lower bills.
The city is now looking at its next steps in the process, and Bloomberg Philanthropies will continue to aid Boise with operational support. In addition, two employees whose positions will be funded by Bloomberg will join the city of Boise and be dedicated to the project.
The affordable housing will be constructed by J. Fisher Companies, which won the bid on the project, McLean said. The city entered into a public-private partnership with the company to construct the building on Lusk District land that was chosen for its location near the geothermal system.
Part of the $1 million grant will allow the city to start extending the necessary geothermal infrastructure to be connected to the housing complex, which the city hopes to complete by 2028.
O’Neil told the Statesman that because of this competition, Boise was “put on the map.”
“It’s a big testament to our mayor, actually, who has done a lot of work to bring Boise’s energy and climate goals to the forefront,” O’Neil said.
McLean told the Statesman that completing this project would be a foundation to expanding sustainable energy around the city.
“This grant is a big deal,” McLean said. “It will provide us with the tools that we need to do this again ... so we can continue to build out the innovation and to meet Boise’s goals of being a clean city, a safe and welcoming city that’s affordable for everyone.”
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