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Energy | Environment

Making The U.S. More Energy Efficient, One Building At A Time

A new, highly efficient rooftop heating and cooling unit could reduce a commercial building's energy costs by an average of 41 percent.

A new, highly efficient rooftop heating and cooling unit could reduce a commercial building’s energy costs by an average of 41 percent.

Flickr Creative Commons: Scoobyfoo


About a year ago and a half, researchers at Pacific Northwest National Laboratory found a way for commercial building owners to chop their energy bills in half. All they had to do was retrofit old heating and cooling systems — you may have seen the box-like units on top of grocery stores or strip malls.

They used computer simulations to find an average savings of 25 to 35 percent after retrofitting existing heating, ventilation and air conditioning systems, also known as HVAC. One small office building in San Francisco saved 67 percent.

Researchers will soon finish up a real-world test of this computer simulation, said Srinivas Katipamula, the study’s author.

In the meantime, Katipamula and his co-workers have been testing out a new, highly efficient rooftop heating and cooling unit that could reduce energy costs by an average of 41 percent. Katipamula said this unit could replace others that are around 10 years old.

Buildings make up about 40 percent of the energy used in the United States, said the lab’s Kim Fowler. They’re the source of most of the energy consumed here.

Researchers tested simulations of the new units in three cities: Houston, Chicago, and Los Angeles. Katipamula said they wanted to see how the units would fare in different environments.

Katipamula said these energy efficient heating and cooling systems could reduce a commercial building’s energy use by about 30 percent. He said that could add up. That’s because more than half the commercial buildings in the country use these types of units, many of which are old.

“Over time when the existing units are replaced with these high performing units, it could have a significant impact on the energy consumption of the building and overall of the commercial building stock,” Katipamula said.

The main reason the new units are so efficient: The fans don’t run at full-speed all day, every day, every season.

A couple of interesting facts he pointed out:

  • Replacing current rooftop units over a 10-year period would be the equivalent of taking 700,000 cars of the road each year, in energy saved and pollution reduced;

  • The saved energy could idle eight average coal-fired power plants every year for 10 years.

But he said it could be difficult to get building owners to replace the old units. That’s because tenants often pay the electrical bills.

— Courtney Flatt