By Mike Dunn

PHILADELPHIA (CBS) — A Philadelphia law that requires that owners of large office buildings keep track of energy usage is being expanded to include larger apartment buildings.

It was two year ago that the city began requiring what’s called ‘energy benchmarking’ of about two-thousand larger office buildings.

The owners have to use an EPA website to track their building’s energy usage, then report the findings to the city.

This coming week City Council is expected to approve an expansion of that law, so that about 800 apartment buildings also have to benchmark.

Katherine Gajewski, the city’s Director of Sustainability, says the data will also give each owner a sense of how their buildings are doing:

“It helps you to understand where you fall on that spectrum, and it also compares you to like buildings. So you can see whether you’re performing with the pack, ahead of the pack, or behind the pack.”

The hope, she says, is that this tracking will prod building owners to become more energy efficient:

“Approximately 64 percent of the city’s greenhouse gas emissions come from buildings, and so if we’re going to do something to reduce greenhouse gas emissions, we need to deal with building efficiency. And that starts with education and transparency in the marketplace.”

Owners whose buildings fall under the law’s scope face fines if they don’t comply.