If cool air in summer or warm air in winter is leaking out of your home, you're wasting a lot of energy.

"When you've got a water leak it's obvious, but air is a colorless, odorless gas, and it's a lot sneakier," says Mark Modera, who studies indoor environments in Berkeley Lab's Environmental Energy Technologies Division. "Black streaks on the ceiling near the registers, an air conditioner that can't cool the place when there's a party going on — these can be symptoms of duct problems."

When Modera found that 20 to 40 percent of home air leakage occurs through duct systems, he set out to find a solution. Duct tape, which can do almost anything except seal ducts, was definitely not the solution.

"Most leaks are hard to reach, and the bill for labor can be steep if you try to seal them from outside, so we worked on doing it from inside. We even thought about little robots that could crawl around inside ducts. But mechanical fixes all had problems — like getting confused at intersections."

Instead, Modera invented a way to inject airborne sealant that flows through ducts, automatically sealing leaks no matter where they're located. His aerosol-based technology has won numerous honors and is now available commercially.

Modera grew up in Brooklyn, and — although it may seem odd for a city boy — it was while studying mechanical engineering at the Cooper Union in Manhattan that he designed an advanced windmill generating system for houses; it stored energy in a hydride bed that fed a fuel cell, an advanced technology for a 1970s undergraduate.

He went west to UC Berkeley and got his master's degree with a study of fireplace efficiency. Meanwhile he got a job researching the energy efficiency of buildings at Berkeley Lab, where he developed expertise in the fluid mechanics of air — the basis for his 1989 Ph.D. from the Royal Institute of Technology in Stockholm, Sweden.

Modera is a prolific inventor, a motorcycle racer, a jazz drummer, a volleyball player, and a fledgling entrepreneur. "Berkeley Lab gives you leeway to develop your ideas," he says. "If you can find funding, the Lab will help you get it done" — for example, helping Modera put together the country's largest research group dedicated to air ducts.

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