Green-building boosters are lauding the disclosure last month of private-sector building energy-use data for nearly 1.8 billion sq ft of space in New York City. The data, collected as part of the city's "Greener, Greater Buildings Plan," is seen as a positive step toward energy conservation.

The report is an eye-opener, especially for small and midsize building owners, says Kevin Hamilton, CEO of NuEnergen, a White Plains, N.Y., energy consultant. "They can see in black and white what they are consuming and … they can start to think about what to do to conserve," he adds.

The "New York City Local Law 84 Benchmarking Report" is the first analysis of city benchmarking data. The 2009 LL84 requires all owners with buildings over 50,000 sq ft or with multiple buildings over 100,000 sq ft to annually measure and report energy and water use. This is the "largest collection of benchmarking data gathered for a single jurisdiction," says the report.

In office and multifamily buildings, the data show the biggest users consume three to five times more energy than the smallest users. If all comparatively inefficient larger buildings were brought up to the median energy-use intensity in their category, New York City consumers could reduce energy consumption in large buildings by roughly 18%, says the report.

According to the data, most newer buildings use more energy than older ones. Russell Unger, executive director of the Urban Green Council, says there is a need to determine why. One difference is usage patterns, he suggests. But differences in construction, such as more glass in newer buildings, may also be a reason, he adds.

LL84 is one of four recent energy conservation laws. The others are the energy conservation building code (LL85), the energy audits and retro-commissioning law (LL87) and the lighting upgrade law (LL88).