ST. PAUL — Minnesota cities are using and sharing data on their energy use to help reduce their impact on the environment.

They’ve joined the Regional Indicators Initiative, which aims to help cities determine whether their environmental measures are really working. Twenty-three cities representing a quarter of the state’s population are studying data through the initiative, a project funded by the state and the Urban Land Institute of Minnesota.

The project has data from 2008 onward that include vehicle miles traveled, waste generation, water use, and the amount of electricity, natural gas and other fuels being used by everyone within city limits.

“It says, ‘All right, we have these best practices, now are they actually making a difference in your community, in your neighborhood?”’ Falcon Heights Mayor Peter Lindstrom said. “Can we measure?”

The St. Paul suburb of 5,000 installed solar panels on its City Hall and signed up for a discount program that makes solar panels more affordable for homeowners.

“I think the worst thing any city can do is greenwashing — to say you’re making a difference but then not really making a difference at all,” he said. “So through the Regional Indicators Initiative, it’s going to tell us whether our programs are making a difference.”

The cities that signed up agreed to make their data public, said Rick Carter, a Minneapolis architect who’s managing the project.

“You can’t manage what you don’t measure,” Carter said. “If somebody’s not looking at the data, it doesn’t matter that you have it. And if everybody’s looking at the data, it’s better.”

Carter said it could lead to a little friendly competition. Studies have shown that if homeowners’ electricity bills show how they’re doing compared with their neighbors, it can motivate them to use a little less power.

“You naturally use less because we’re all a little bit naturally competitive and because you know,” Carter said. “The question of whether that scales up to a city remains to be seen.”

Cities will need several years of data to decide what new policies or actions will help them reach the next level of being green.