By optimizing the wavelength, intensity, and dispersion of light transmitted through windows, researchers at the T Faculty of Engineering have developed a multi-layer fluid system that can reduce energy costs for heating, cooling, and lighting buildings.
The platform was inspired by the dynamically color-changing skin of creatures such as squid. Compared to existing technology, it uses simple off-the-shelf components, thus keeping costs low while offering far greater control.
“Buildings use large amounts of energy to heat, cool, and illuminate the spaces within them,” says a recent graduate. Rafael Kay (MIE MASc 2T2), first author of a new paper published in 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, which affects the lighting of buildings, but it also contains other invisible wavelengths, such as infrared, which can be considered heat in nature,” he says. says.
“In the daytime in winter you might want both in, but in the daytime in the summer you want only visible light and not heat. Either it does or it blocks neither, nor does it have the ability to direct or scatter light in any useful way.”
System developed by Kay and team — led by Professor Ben Hutton (MSE), including Ph.D. Charlie Catholics (MSE) and Professor Alstan Jakubiec (Daniels Architecture) — Harnessing the power of microfluidics to provide an alternative.
Their 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 a different type of optical function, such as controlling intensity, filtering wavelengths, or 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.
This work was developed by the same team earlier this year, Nature CommunicationsWhile 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, such as chromatophores, which control light absorption, and iridophores, which 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.
These models were informed by physical properties measured from prototypes. The team also simulated different control algorithms to activate or deactivate layers in response to changing ambient conditions.
“If we had just one layer that focused on modulating the transmission of near-infrared light—that is, not even touching the visible part of the spectrum—it would use more heating, cooling, and lighting energy 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%. Those are huge savings.”
In this study, the control algorithms were designed by humans, but Hutton says the task of optimizing them is an ideal task for artificial intelligence and a potential future direction for research. I am pointing out.
“The idea of a building that can learn, a building that can uniquely tune this dynamic array to optimize for changing seasons and lighting conditions, is very exciting for us,” he says.
“We are also working on how to effectively scale this up so that we can actually cover the entire building. It is a problem that can be solved.”
Hutton 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.”
Original: Squid skin-inspired ‘liquid windows’ help buildings react to their changing environment and save energy costs
Than: University of Toronto
