AILSA CHANG, HOST:
After President Trump announced that the U.S. would leave the Paris climate deal, dozens of cities vowed to go it alone. They've signed a formal agreement to reduce carbon emissions. In fact, some have been working at this for years. But as Dan Boyce reports from Denver, many are still falling short of their ambitious goals.
DAN BOYCE, BYLINE: The city of Denver wants to reduce greenhouse gas emissions 80 percent by 2050. That means among other things, a whole slew of new building codes.
(SOUNDBITE OF ELEVATOR BEEPING)
COMPUTER-GENERATED VOICE: Floor 40.
UNIDENTIFIED MAN #1: Thank you.
UNIDENTIFIED MAN #2: Top of the world.
UNIDENTIFIED MAN #3: Forty.
BOYCE: Out onto the top floor of the city's newest skyscraper, workers in hardhats and orange vests are racing to finish up. Construction manager Michael Bjes says the city requires energy star appliances...
MICHAEL BJES: The use of LEDs in our building for our permanent light fixtures.
BOYCE: ...Water-efficient toilets, all to make the building more energy-efficient. Back in December, hundreds gathered for the third annual Sustainable Denver Summit. The city's chief sustainability officer Jerry Tinianow was upbeat. He had just returned from U.N. climate talks in Germany.
JERRY TINIANOW: We challenge each other. We challenge each other to sign pledges, to set goals and so forth.
BOYCE: Measuring progress, though, can be tough. Dave Ribeiro works with the American Council for an Energy-Efficient Economy. He credits cities for expanding public transportation, using cleaner fuels, pushing for more renewable energy. It's just when it comes to calculating how much all that is actually cutting carbon...
DAVE RIBEIRO: The data quality is poor, it's incomplete and it's tracked over different time periods.
BOYCE: The data we do have shows despite progress, many cities are still falling short. Energy consultant Sam Brooks...
SAM BROOKS: A city will set very aggressive goals, it won't meet them. And then a few or five years later, they just set new goals that are even more ambitious.
BOYCE: Some of the same cities working hardest on cutting emissions are also some of the fastest growing, cities like Denver, San Francisco and Washington, D.C. Per capita energy use may be dropping but total energy, still going up. Brooks says that's not good enough, and he takes some of the blame. A few years ago, he ran the energy division for D.C.'s government buildings. The city announced it was now powered by 100 percent renewable energy. But when Brooks testified to D.C.'s City Council last year...
(SOUNDBITE OF ARCHIVED RECORDING)
BROOKS: I am here with a very simple message and that is that what we're doing is not working.
BOYCE: He says that's because D.C. does what a lot of cities do. Instead of driving down its own carbon emissions, it pays to offset them with a slice of renewable energy generated elsewhere. He's frustrated by this and by some modern trends that end up being counterproductive even with the best intentions.
BROOKS: I think for a while we thought, more natural lighting was always good.
BOYCE: With the spread of LEDs, lighting isn't the energy suck it used to be. Now new glass-covered buildings are taking in more heat from the sun, leading to more air conditioning.
BROOKS: That very significantly increases the overall energy consumption of that building.
BOYCE: Bringing us back to that new Denver skyscraper. Its exterior, all 40-some stories, is entirely glass. Construction Manager Michael Bjes says that glass has a coating and an internal gas layer, which helps prevent that heat getting absorbed. He admits, yeah, there are building materials that could save more energy, but it has to be a balance.
BJES: The experience for our tenants is really what we're after. And we want to make sure it's, you know, it meets our tenants' needs.
BOYCE: Energy efficiency, that's important to those tenants but so, he says, are aesthetics, like floor-to-ceiling windows facing Colorado's snowcapped Front Range mountains. For NPR News, I'm Dan Boyce in Denver.
NPR transcripts are created on a rush deadline by Verb8tm, Inc., an NPR contractor, and produced using a proprietary transcription process developed with NPR. This text may not be in its final form and may be updated or revised in the future. Accuracy and availability may vary. The authoritative record of NPR’s programming is the audio record.