Energy-saving inspiration from squid skin

Inspired by the dynamically color-changing skin of creatures such as squid, researchers at the University of Toronto have developed a multi-layered fluid system that can reduce the energy costs of heating, cooling, and lighting buildings.

Optimizing the wavelength, intensity and dispersion of light transmitted through the window, the platform keeps costs low through the use of simple off-the-shelf components while offering far greater control than existing technology.

“Buildings use large amounts of energy to heat, cool, and illuminate the spaces within them. mechanical engineering He holds a PhD in Applied Science and Engineering and is the lead author of a new paper published in a journal. PNAS.

“If we can strategically control the amount, type and direction of solar energy entering a building, we can significantly reduce the amount of work required for heating, cooling and lighting.”

Certain “smart” building technologies, such as automatic blinds and electrochromic windows that change opacity depending on current, can now be used to control the amount of sunlight entering a room. But Kay says these systems have limitations. It cannot distinguish between different wavelengths of light, nor can it control how light is distributed spatially.

“Sunlight contains visible light that influences the lighting of buildings, but it also contains other invisible wavelengths. infrared lightwhich can be thought of as heat in nature,” he says.

“I want to put both in the daytime in winter, but it’s better to put both in the daytime in summer.” visible light And not heat. Current systems typically cannot do this. Either block both or block neither. They also lack the ability to direct or scatter light in useful ways. ”

Developed by a team led by Kay and Associate Professor Ben Hatton, the system harnesses the power of microfluidics to provide an alternative. The team also included a Ph.D. Candidate Charlie Katrycz is in both the Materials Science and Engineering departments and Alstan Jakubiec is an Assistant Professor in the John H. Daniels School of Architecture, Landscape and Design.

The prototype consists of a flat sheet of plastic permeated with a series of millimeter-thick channels through which liquids can be pumped. Customized pigments, particles, or other molecules can be mixed into fluids to control the type of light that passes through, such as visible and near-infrared wavelengths, and the direction in which this light is distributed.

These sheets can be combined into multi-layer stacks, with each layer responsible for different types of optical functions, such as controlling intensity, filtering wavelengths, and adjusting scattering of transmitted light indoors. By adding or removing fluid from each layer using a small digitally controlled pump, the system can optimize light transmission.

“It’s simple and low-cost, but it also allows for incredible combinatorial control. You can basically design dynamic building facades in the liquid state that you can do whatever you want with respect to their optical properties,” says Kay. say.

This work is based on another system that uses infused pigments. Developed by the same team earlier this yearWhile that research was inspired by the color-changing ability of sea arthropods, the current system more closely resembles the multi-layered skin of squid.

Many species of squid have skins containing stacked layers of specialized organs, including chromatophores that control light absorption and iridophores that affect reflection and iridescence. These individually addressable elements work together to produce unique optical behaviors that are only possible through combined manipulation.

While T engineering researchers focused on the prototype, Jakubiec built a detailed computer model to analyze the potential energy impacts of cladding a fictional building with this type of dynamic façade.

The model was informed by physical properties measured from the prototype. The team also simulated different control algorithms to activate or deactivate layers in response to changing ambient conditions.

“If we had just one layer focused on modulating the transmission of near-infrared light, that is, not even touching the visible part of the spectrum, it would use more energy for heating, cooling, and lighting than a static one. We can see that we can save about 25% a year.Baseline,” says Kay.

“If you have two layers, infrared and visible, it’s closer to 50%. That’s a huge savings.”

The most recent study found that control algorithms were designed by humans, but Hutton says the task of optimizing them is an ideal task for artificial intelligence and could be a future direction for research. points out.

“The idea of ​​having a building that can learn, or this dynamic array, that can be uniquely tuned to optimize for seasonal and diurnal variations in solar conditions is really exciting for us,” says Hatton.

“We are also working on how to effectively scale this up to cover everything. buildingIt takes work, but it’s a solvable challenge considering it can all be done with simple, non-toxic, and low-cost materials. ”

Hutton also hopes the research will inspire other researchers to think more creatively about new ways to manage energy in buildings.

“Globally, buildings consume a huge amount of energy, even more than they spend in manufacturing and transportation,” he says. “I think making smart materials for construction is a much more noteworthy challenge.”