Optimum Energy Wants Buildings to Use More Software, Waste Less Power

4/6/09

If you work in a commercial building, you’re probably familiar with the vagaries of large-scale heating and cooling systems. Hear that whir click on and cold air suddenly gusting through the vents? That’s the sound of your building hemorrhaging money and energy.

Seattle cleantech software company Optimum Energy wants to stanch the energy drain of the U.S. commercial sector, one building at a time—and soon, hundreds of buildings at a time—by slowing down the motors that power those buildings’ heating and cooling systems.

I traveled down to Optimum’s Georgetown office, which houses 22 of the three-year-old company’s 30 employees, to find out from founder and CEO Nathan Rothman how Optimum plans to save companies hundreds of thousands of dollars every year with a simple software program.

The company’s software products have the potential to halve the heating and cooling bills of about 110,000 large buildings in the U.S., Rothman said. That’s no small potatoes, when you consider that commercial buildings use 18 to 20 percent of the country’s energy, and that in hot climates like California or Texas, air conditioning accounts for more than half of their energy bill.

“If we implemented our technology just in Manhattan, we’d save enough electricity to light the other four boroughs all the time,” Rothman said. “And that doesn’t include the CO2 and greenhouse gases you’re saving.”

Large buildings maintain temperature control (or HVAC, for heating, ventilating, and air conditioning) using a massive network of cold water that courses through the building, absorbing heat and venting it through steam. That cold water is generally kept at a chilly 44 degrees Fahrenheit by a large machine aptly dubbed the “chiller.” High-powered motors and pumps drive the water around the building.

So what happens when a hot building cools down to, say, 70 degrees? The motors shut off, but then power back on the second it bumps up to 71—an incredibly inefficient process, Rothman said, as powering down and up uses a lot of energy.

That process starts to sound even more inefficient when you take into account … Next Page »

Rachel Tompa is a freelance journalist based in Seattle. She can be reached at rmtompa@yahoo.com. Follow @

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  • http://www.keepcomfy.com/ Utah heating

    a certain physical property of hydraulic pumps called an affinity law, where slowing the motors in the HVAC system by a certain amount results in triple that amount of energy saved. So if you reduce how hard the chiller runs from 100 percent to 70 percent of its full capacity—using a special piece of equipment that feeds electricity to the motors and other equipment in short bursts so as to run them at slower speeds—you’d only be using a third of the original energy, Rothman said. But nobody took this property into account in the days when modern HVAC systems were designed and energy was dirt cheap.