The owners of more than 450 buildings in Honolulu will have to report their yearly energy and water use this summer under a new city ordinance that aims to cut down on the use of natural resources and greenhouse gas emissions.

Ordinance 20-17 was passed by the Honolulu City Council in 2022 after the program was identified in the city’s Climate Action Plan as a key step in reaching net negative emissions by 2045.

City officials say the building sector accounts for roughly one-third of Oahu’s greenhouse gas emissions, and the Better Building Benchmarking program is projected to reduce the electricity consumption of the island’s largest buildings by nearly 7% by 2030 while curbing greenhouse emissions.

By moving to this policy, Honolulu is following the lead of dozens of other U.S. cities, counties and states with similar ordinances, according to the National Resources Defense Council.

Minneapolis, Denver and Chicago are among the cities that have seen energy savings of 3% to 5% soon after policy passage, the NRDC said.

The policy, which eventually will be required of nearly 1,900 buildings in Honolulu, is intended to make owners fully aware of the resources they consume and allow them to compare their energy and water use with similar buildings.

The comparisons will allow owners and managers to see the potential for reducing one of their largest ongoing expenses and aim for lowering costs.

“That’s the goal,” said business owner Adrian Hong, who is also a consultant helping building owners comply with the city’s program. “Building owners can learn to use less electricity and less water — and save money.”

Hong said that to cut down on energy and water use, building owners can do any number of things, including switching to LED lighting, automatic light controls and energy-efficient fixtures. Other ideas include window tinting and shading, roof insulation and solar hot water heating.

But first, owners have to determine how much electricity, gas and water their buildings are using.

“You can’t improve what you don’t measure. You have to see where you are so that you’re able to compare to other buildings,” he said.

Hong, whose primary business, Island Plastic Bags Inc. in Aiea, recently underwent a similar “benchmarking” process, said he’s talked to potential clients and realized not a lot of people know about the new requirement.

“But the time for reporting is coming up,” he said.

In 2020 the Honolulu City Council approved a similar ordinance that established a municipal benchmarking policy to measure and report the energy and water use of all city facilities over 10,000 square feet in size.

The benchmarked data is already informing plans to retrofit and implement energy-saving upgrades in several municipal buildings, officials said.

The nonmunicipal benchmarking program, signed into law in July by Mayor Rick Blangiardi, is being phased in with covered buildings 100,000 square feet or larger required to report energy and water performance annually to the city by June 30.

According to city Real Property Division tax data, there are an estimated 466 buildings 100,000 square feet or larger, including most of the city’s skyscrapers, shopping centers, hotels, larger condominiums and hospitals. A list of these buildings can be found at the program’s website at resilientoahu.org/benchmarking.

Buildings between 50,000 and 100,000 square feet will be required to report on June 30, 2024, and those between 25,000 and 50,000 square feet must do it by June 30, 2025.

All told, there are nearly 1,900 Oahu buildings 25,000 square feet in size or greater that qualify for the benchmarking program.

Buildings exempt from the ordinance include single-family, duplex, triplex and fourplex residential homes, most industrial properties and structures less than 25,000 square feet.

The Honolulu Resilience Office will hold a Better Buildings Benchmarking online training Wednesday from 11:30 a.m. to 1 p.m. to help building owners and property managers comply with the new law.

The meeting agenda, according to the city, will include background information on benchmarking, plus how to use Energy Star Portfolio Manager, a free online tool created by the Environmental Protection Agency for measuring and tracking energy, water consumption and greenhouse gas emissions.

The training will feature Portfolio Manager experts who will go through a step-by-step demo that covers everything from building details to uploading utility data and responding to a data request from the city.

For more information can be found at the city’s benchmarking web page at resilientoahu.org/benchmarking.