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Surprising Science

To Cool Buildings, Run Water Through The Windows

Harvard researchers took inspiration from the cooling ability of skin for their microfluidic circulatory system, which can save energy and lower air-conditioning bills.

What’s the Latest Development?

Researchers at Harvard’s Wyss Institute for Biologically Inspired Engineering have created a cooling system for windows that involves passing water through ultrathin channels embedded into a thin “skin” of clear silicone rubber. The water takes the sun’s heat with it, reducing the amount of air conditioning needed to cool the room. The channels become transparent when filled, so they are invisible to the naked eye. A mathematical model was created to determine the system’s efficiency on normal-sized windows; it predicted that “just half a soda can’s worth of water…would cool a full-size window pane by a full 8°C (14°F).”

What’s the Big Idea?

In buildings, heat flowing through windows often hinders improved energy efficiency efforts. The system combines the science of microfluidics with bioadaptive technology — specifically, the way the circulatory systems of humans and animals work to cool the body by expanding a network of tiny blood vessels near the skin to increase blood flow and heat transfer. The team’s next task is to combine their mathematical model with architectural energy models to determine the total energy savings for an entire building outfitted with modified windows.

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