{"id":920897,"date":"2026-10-05T00:42:20","date_gmt":"2026-10-05T00:42:20","guid":{"rendered":"https:\/\/www.newsbeep.com\/ca\/920897\/"},"modified":"2026-10-05T00:42:20","modified_gmt":"2026-10-05T00:42:20","slug":"the-pigment-shifting-window-that-responds-to-light-and-could-help-slash-energy-costs-2","status":"publish","type":"post","link":"https:\/\/www.newsbeep.com\/ca\/920897\/","title":{"rendered":"The pigment-shifting window that responds to light \u2014 and could help slash energy costs"},"content":{"rendered":"

Inspired by squids, U of T researchers designed a window that lets winter light and heat in \u2014 but blocks out heat in the summer<\/p>\n

Reprinted with permission from Be Giant<\/a>, a non-profit, non-partisan media outlet reporting on the people, places, ideas and breakthroughs shaping Canada’s future. Sign up for their weekly newsletter<\/a>.<\/p>\n

Benjamin Hatton spends a lot of time contemplating the perfect window.<\/p>\n

In the summer, it would keep out the sun\u2019s heat while letting in light. In winter, it would let in both light and heat. It would scatter and evenly distribute light on overly bright days to keep a building naturally lit.<\/p>\n

In short, the perfect window would act a little like a squid.<\/p>\n

Hatton is a University of Toronto materials science and engineering professor who leads the Hatton Lab for bio-inspired materials and design. A few years ago, he and a team of researchers created panels that dynamically shade in response to the sun\u2019s rays, mimicking the way squids, octopuses, krill and other sea creatures move pigments within their cell structures to change their coloration. The panels move liquids containing additives such as carbon black (to absorb light) and titanium dioxide (to scatter it) through channels carved into thin plastic sheets.<\/p>\n

Hatton says the next challenge is to scale that idea by turning it into a tool that can be used to retrofit old buildings.<\/p>\n

\u201cWe can improve the performance of a window without having to replace the entire [thing],\u201d says Raphael Kay, who began working with Hatton\u2019s research group while doing his master\u2019s degree in mechanical engineering at U of T; he\u2019s currently working on his PhD at Harvard. Kay was the lead author on two papers about the team\u2019s panel system, released in 2023 and May of this year.<\/p>\n

In the 2023 paper, the researchers\u2019 simulations estimated that one version of their dynamic windows with three fluid layers could help buildings slash their heating<\/a> energy use by 75 per cent, electric lighting use by 20 per cent and total operational energy<\/a> use by 43 per cent compared to the best available electrochromic technology<\/a> of the sort used in airplanes.<\/p>\n

About 80 per cent of the world\u2019s buildings will still be in use by 2050. And those structures are energy hogs. Currently, buildings consume about one-third of the world\u2019s energy supply, and that\u2019s projected to double by mid-century.<\/p>\n

The reason? \u201cThe buildings we design today are kind of dumb,\u201d Hatton says. More than a quarter of a typical building\u2019s energy is used to offset the heat that enters or escapes through its windows: the ramped-up air conditioning in the summer to combat greenhouse-effect warming from the sun and the blasting of heat in winter to counter the chill let in through glass panes.<\/p>\n

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\nAn artist’s impression of the multi-layered prototype window. (Supplied by the University of Toronto\/Raphael Kay, Adrian So) <\/p>\n

Research attention to windows is overdue, despite their outsized role in a building\u2019s energy use.<\/p>\n

In the 1970s and \u201980s, researchers collaborated with industry in the U.S. and Germany to develop coatings that limited the amount of thermal radiation that entered through windowpanes on buildings. Today, most commercial buildings have windows manufactured with these films in them, but their light-blocking properties are fixed, meaning they aren\u2019t well suited to a country with a variable climate. Electrochromic windows, first developed in the 1980s, have advanced the concept of dynamic facades \u2013 if you\u2019ve been on a newer airplane with windows that can brighten or darken with digital control, you\u2019ve seen them. But, at the moment, they\u2019re \u201cway too expensive\u201d for a whole building to adopt, Hatton says.<\/p>\n

Then there\u2019s good old-fashioned roller shades, he adds: \u201cMore or less, that\u2019s all we have.\u201d<\/p>\n

Hatton and Kay are currently testing separate prototypes to fill the gap. At Harvard, Kay and fellow researchers have installed a commercial-scale prototype window in a historic house on campus that students can conduct experiments on. The two-foot-square window has a reservoir for liquids that can be pumped into an air gap between two glass panes. The solutions can variously make the window change from clear to blurry, control heating and cooling, and filter light.<\/p>\n

Kay sees the path to market running through commercial real estate, given that cities are implementing higher benchmarks for energy efficiency in commercial buildings. Kay says he\u2019s envisioning a thin application for existing windows that basically acts like a giant sticker with fluids inside. That would allow building owners to retrofit their windows rather than replace them entirely. Such a sticker system, he says, could be controlled by artificial intelligence to respond to weather conditions outside.<\/p>\n

At U of T, Hatton is in the midst of setting up a lab with a dedicated simulation room where tests will determine whether two-metre-tall prototypes can regulate the room\u2019s temperature as sunlight shines through them.<\/p>\n

\u201cIf you can make a layer two metres tall, it means it\u2019s suitable for a big storey-height window,\u201d he says. \u201cIt\u2019s the height of these things that\u2019s most difficult because of the gravitational effects on the fluid.\u201d Depending on how the prototypes perform in the lab, the next step will be to test them across the university campus.<\/p>\n

Hatton envisions a final product that can be targeted at the retrofit market. But \u201chow that ends up technologically, we\u2019re still working on,\u201d he says. \u201cWhere we\u2019re at right now is just trying to figure out how to best fabricate these layers to be large scale and inexpensive but also reliable, and to test their performance in different conditions.\u201d<\/p>\n

Kelsey Rolfe is an award-winning freelance business journalist in Toronto, covering personal finance, technology and mining. Her work has appeared in the Globe and Mail, Canadian Business and The Logic, among other publications. She has worked for the Financial Post as a staff reporter and was an editor at Benefits Canada and CIM Magazine.<\/p>\n

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