Do you deliberately avoid visiting friends who live in multi-story buildings without an elevator? No one would fault you — having to climb even just a single flight of stairs is like being forced to work out against your will. But thanks to engineers at Georgia Tech and Emory University, stairs might one day do all the hard work for you.
In a paper published today in the journal PLOS ONE, that team details their energy-recycling stairs, which store energy when you descend, and then release it to make the ascent easier on the way back up.
You probably don't stop to think about it while you race down a flight of stairs, but your body expends a considerable amount of energy in the process to prevent you from falling. It's usually wasted energy, but these energy-recycling stairs take advantage of those forces using a spring-loaded mechanism that compresses each step and locks it down as you descend.
This leaves every step charged with potential energy once you've hit the bottom. When you go to climb back up, pressure sensors on each tread release the locking mechanism on the step below it, turning that stored potential energy into kinetic energy that helps lift a climber's leg as the spring-powered step raises again.
As the stairs compress on your descent, the engineers have calculated they save around 26 per cent of the energy you normally use to brace yourself as each foot makes contact. And on the way back up, the energy-recycling stairs make it around 37 per cent easier on the knee, making these stairs ideal for people who are pregnant, dealing with mobility issues, or are just simply out of shape.
The stair's unique mechanisms can be retrofitted to existing steps, so the technology isn't only for new buildings, necessarily. And installing them would be cheaper, and require less space, than an escalator or elevator. There's no word on when this technology will be commercialised, but anyone living in an elevator-less building will certainly be hoping it's as soon as possible.