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 a lot of energy to heat, cool and light the spaces inside,” he said. Rafael KayRecently graduated with a Master’s Degree in Mechanical Engineering from the Faculty of Applied Science and Engineering, New paper published in the 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 in response to electrical 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 includes visible light that affects lighting in buildings, but it also includes other invisible wavelengths, such as infrared light, which can be considered heat in nature.” he says.
“During winter days you would want both, but during summer days you would 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.”
Fluid multi-layered biological inspiration. (A) Color change in a panther chameleon. Realized using a multilayer architecture of active photonic crystals. (B) Squid color change achieved using coordinated actuation within multiple layers of pigments and structural elements. The upper image is Sepiotheutis lessensiana and the lower image is Lorigo Piley.
Developed by a team led by Kay and Associate Professor Ben Hutton, the system harnesses the power of microfluidics to provide an alternative.The team also included a Ph.D. Charlie Catholicsboth departments of materials science and engineering, and Arstan JakubiekAssistant Professor, 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.
The work is based on another system using infused pigments developed by the same team earlier this year. That study was inspired by the color-changing ability of marine arthropods, but 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.
“With just one layer focused on modulating the transmission of near-infrared light, that is, without even touching the visible part of the spectrum, we could save about 25% of energy per year in heating, cooling and lighting. It’s a static baseline,” says Kay.
“If you have two layers, infrared and visible, it’s closer to 50%. Those are huge savings.”
In the most recent study, control algorithms were designed by humans, but Hutton points out that the task of optimizing them is an ideal task for artificial intelligence and a future direction for research. increase.
“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 the entire building. It is a solvable problem.”
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.”