Squid-inspired smart windows may make buildings more energy-efficient

Raphael Kay/Adrian So/U of T Engineering/Cover Images

A new type of smart window could help you cut down on your energy use - and it's all thanks to the humble squid.

Researchers at the University of Toronto have developed a squid skin-inspired fluidic system that could reduce the energy costs of heating, cooling, and lighting buildings.

Compared with existing technologies, it offers much greater control while keeping costs low due to its use of simple, off-the-shelf components.

"If we can strategically control the amount, type, and direction of solar energy that enters our buildings, we can massively reduce the amount of work that we ask heaters, coolers, and lights to do," recent graduate Raphael Kay, lead author on a new paper published in PNAS, explained.

Currently, certain 'smart' building technologies such as automatic blinds or electrochromic windows - which change their opacity in response to an electric current - can be used to control the amount of sunlight that enters. But these systems are limited - they cannot discriminate between different wavelengths of light, nor can they control how that light gets distributed spatially.

"Sunlight contains visible light, which impacts the illumination in the building, but it also contains other invisible wavelengths, such as infrared light, which we can think of essentially as heat," he continued. "In the middle of the day in winter, you'd probably want to let in both, but in the middle of the day in summer, you'd want to let in just the visible light and not the heat. Current systems typically can't do this: they either block both or neither. "

The system developed by Kay and the team - led by Professor Ben Hatton - leverages the power of microfluidics to offer an alternative. Their prototypes consist of flat sheets of plastic that are permeated with an array of millimetre-thick channels through which fluids can be pumped. Customised pigments, particles, or other molecules can be mixed into the fluids to control what kind of light gets through - such as visible vs. near-infrared wavelengths - and in which direction this light is then distributed. By using small, digitally-controlled pumps to add or remove fluids from each layer of multi-layered stacks, the system can optimise light transmission.