While those in the Western world may not think twice about flipping the light switch on at night, off-grid communities such as those in sub–Saharan African have come to rely on dangerous and expensive kerosene to keep the lights on after dark. This kerosene can cost 20% or more of an individual’s income and have a drastic effect on their (and their family’s) health. Alternatively, solar-powered lamps and wind-up devices that rely on rechargeable batteries are typically much more expensive and have a short shelf life.

Taking this impact design challenge head-on, British designers Jim Reeves and Martin Ridiford have developed a simple, low-cost gear-train and generator that uses a descending weight to power a perpetual light source called the GravityLight.

Designed in SOLIDWORKS, the low-cost ($7) light takes its inspiration from an old grandfather clock and uses a 22-pound bag of sand to generate 176 joules per lift – or enough LED light to illuminate a 100-square-foot room for half an hour. To keep the kinetic energy-based light on, all a user needs to do is repeat the cycle all over again.

Having raised nearly $400,000 for the light through an Indiegogo campaign back in 2013, today the GravityLight has evolved into its own nonprofit foundation committed to bringing the sustainable lighting solution to over 15% of the world’s population.

In this recently released mini-doc about the GravityLight, Reeves delves deeper into the design process and what it means to design for impact:

