Want fresh air? Give your house a nose job…

Central heating may keep your house warm, but it can also make the air stuffy. A new ventilation system that works like the nose of a small desert rat might let your house "breathe", freshening the air while maintaining cosiness.

So claims Steven Vogel of Duke University in Durham, North Carolina. Like some other desert creatures, the bipedal kangaroo rat, he says, helps maintain its body temperature using a clever nasal architecture.

On exhaling, the rat's nasal passageways are heated by the outgoing air. When it inhales, those warmed passageways heat the incoming air. This heat exchange ensures little body heat is lost.

Home comforts
Vogel wondered if a house or apartment could be made to breathe this way – gaining fresh air with low heat loss – and he built a model of a one-room dwelling to try it. He calls it the Nose House.

Using two fan-driven heat exchangers, he was able to mimic the rodent's trick. As one exchanger pushes air into the room, the other lets air out – then their roles reverse.

Each exchanger comprises a 40-centimetre-long plywood chamber, 5-centimetres-square in cross-section. Inside each chamber there are 17 half-millimetre thick aluminium plates that store heat as warm air leaves it, and which warm the air that is sucked in on the next "breath".

"This was as crude an analogy as I can imagine but it worked," Vogel says. "This non-optimised version saved over half the heat that would have been lost using steady-flow fans alone. "Well-sealed houses are very unpleasant and this may get around it."

Big problems
Vogel is not sure if his idea will scale up, though: to warm the average house, the chambers would need to be 6 metres long. But he plans to test whether the system might work. Patent searches have shown no similar heat exchange system working in anti-phase to mimic breathing, he notes.

Peter Gammack, concept design director for Dyson in Malmesbury, Wiltshire, UK, is impressed. "This is a very interesting biomimetics-inspired idea. Small animals have evolved to work in very efficient ways and the clever use of two alternating heat exchangers is elegant," he says. "It could be a good way of improving air quality in buildings in an energy-efficient manner."

Gammack adds that Vogel is right to be concerned about moving to full-scale machines, as Dyson discovered when developing its bladeless fan recently. "We had to extensively test even the minutest size change – it's surprising how dramatically scale affects effectiveness."

Journal reference: Bioinspiration and Biomimetics, DOI:10.1088/1748-3182/4/4/046004

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