Energy efficiency data from some high-profile buildings in New York City shows that some old structures, such as the Chrysler Building, have higher Energy Star scores than some newer so-called “green” buildings.
For example, the 1.7-million-sq-foot, 52-story skyscraper at 7 World Trade Center opened in May 2006 touts its LEED gold rating. But when it comes to energy efficiency, the tower scores only a 74 by the EPA’s Energy Star standards. A building must score at least 75 for the Energy Star high-efficiency-building label.
The energy data is recently mandated to be made available from the New York City Energy Benchmarking Report that shows the Energy Utilization Index and Energy Star ratings of commercial buildings. But while 7 World Trade Center falls short of Energy Star, two 1930s-era buildings – the Chrysler Building and the Empire State Building – receive an 84 and an 80, respectively, according to The New York Times.
The fine scores are attributed to extensive upgrades of insulation and mechanical systems. Also, older buildings tend to have thicker walls, fewer windows and less ventilation, resulting in better thermal envelopes.
But not all older New York buildings scored well. Most notably, the Seagram Building on Park Avenue posted a score of 3, largely due to its single-pane glass curtain walls and fluorescent lighting.
As for modern buildings with less-than-stellar scores, such as 7 World Trade Center, their lower ratings could be partly attributed to their tenants, including financial firms that use a lot of energy for computers and other high-tech gear.
The top 2 percent of New York’s largest buildings account for 45 percent of the energy expended by the total building stock (about 1 million structures) in the city, so there is considerable focus on improving the energy efficiency of these behemoths. Of the more than 2,500 commercial structures that disclosed energy use this year, the median score was 68.
More understanding of discrepancies in energy use will emerge as New York’s commercial buildings undergo required energy audits and inspections of their HVAC systems in 2013. In addition, large residential buildings, which have been exempt from the disclosure requirements, are required to begin reporting in 2013.