“I've always dreamt of contributing to a more sustainable future”

Jérémy Fleury’s research, convictions and potentially future are all concentrated on solar energy. This year, he completed his PhD thesis on smart windows – window panes equipped with a transparent, metallic nanomesh that can use solar gains more efficiently inside buildings. Five years ago, in Toronto, Fleury studied conducting materials as part of his Master’s degree; he’s long been drawn to physics, nanotechnology and renewable energy, and would like to take these interests and turn them into the foundation for his career.

“As I was finishing up my Master’s in Toronto, I came across a job posting from the Solar Energy and Building Physics Laboratory (LESO-PB) at EPFL. I felt like it was written just for me, based on my CV – I ticked every box. Prof. Schuler was looking for someone who had worked in thin films and coatings, which I’d done at the University of Basel. That’s incidentally a bilingual university, and I speak fluent German and Swiss German. Anyways, I applied and got the job right away.”

Since coming to EPFL, Fleury has focused his research on solar energy systems for buildings. He’s now a doctoral assistant in the Nanotechnology for Solar Energy Conversion group, investigating the best way to manage solar energy through the use of smart windows. These high-tech panes can reduce the amount of heat that enters buildings in the summer, and in the winter, let more heat in to lower heating costs. “We’re developing very thin, transparent coatings that can be used on windowpanes. I’m fascinated by the physics behind this technology, such as the propagation of electromagnetic waves, from the visible to the infrared spectrum.”

Solar ovens made for Switzerland

But glass panes aren’t found only on buildings. A few years ago, Fleury and his team worked on improving a solar oven that had been built by a previous PhD student. “There are many solar ovens on the market, but ours is different because it doesn’t use a parabolic dish. It’s a wooden box with a glass pane on top, and when put in a sunny, southern area, it can bake chocolate muffins in an hour. We tried to harness the greenhouse effect by placing different coatings on the glass so that a substantial amount of solar energy passes through and cooks an object inside. If the object is black, it will itself emit heat. We wanted to find a way to keep that heat within the oven. This once again gets to the physics of electromagnetic waves.”

Calculating Swiss “potato-bake days”

The research on solar ovens was published in 2019. But how useful is it to have a solar oven in Switzerland? “We calculated the energy necessary to bake enough potatoes for two people, then we took Swiss weather data and forecasted the number of days per year there’d be enough sunshine to do it,” says Fleury. “Of course, the sunnier cantons like Valais and Ticino are where it’d be the easiest. But with more than 200 sunny days per year, Vaud is definitely a place where you could bake potatoes in a solar oven. That’s when we came up with the metric of ‘potato-bake days.’”

This research led to a joint project with Makerere University – Uganda’s biggest university, located in Kampala – to develop solar ovens for refugees in areas where firewood is scarce. “Our goal is to develop an oven that uses materials which are locally available, like banana fiber and sheep’s wool for insulation. That’ll make them easy to build and repair.”

Mountain addict

Fleury spends much of his free time in the outdoors and more specifically in the mountains; he even sits on the AGEPoly Club Montagne committee. Since moving back to Switzerland five years ago, he’s been doing a lot of cross-country skiing in the winter and mountaineering in the summer. “I feel really drawn to the mountains – I’m on the slopes every weekend. As a result, the issue of global warming really hits home for me, and I’ve adapted my lifestyle to reflect my beliefs. I try not to eat much meat – I’m what you might call a Flexitarian – I use little to no plastic, and I get around on my bike or with public transport.”

With his PhD now in hand, Fleury doesn’t see himself continuing in academia. “If I could find a job that lets me help save the mountains or oceans, I’d love that. I’ve always dreamt of contributing to a more sustainable future.”