October 25, 2021

I, Science

The science magazine of Imperial College

Enjoying that cup of coffee? That’ll be 21g of CO2 emissions, please. The sandwich is 40g, the crisps 15g, and the banana 80g. And while 3g for flushing the toilet is thankfully a bargain, washing and drying your hands will cost another 35g. How do I know this? My phone told me. And if David Stefan gets to extend his recent stunt beyond the Chelsea College of Art and Design, yours would tell you too.

Stefan is probably best described as a software engineer, but he splits his time between University College London’s Department of Computer Science and the Urban Sustainability & Resilience Centre where he is working towards a doctorate. For the last month, though, he has been creating an art installation with a team of design students that he hopes will amount to a fresh way of thinking about urban sustainability.

Most of us are used to food coming with a breakdown of dietary information – calories, salt content, saturated fats – so why not add a carbon cost to the list? “Because that number doesn’t tell you much,” says Stefan. “Do you know what 80 grams of CO2 is? I wouldn’t know what it means.” But that is exactly what he and his collaborators wanted to get people asking.

They hit on the idea of sticking QR codes – square barcodes easily read by most of our phones – to as many consumable items as they could. In case these eye-catching yellow and black stickers were not intriguing enough, they finished off the installation by digging up the turf of Chelsea College’s parade ground to make a QR code 12 metres square and viewable only from the sky.

“We somehow came to the idea of a QR code because you can use that idea to basically encode any sort of information,” says Stefan. “If you scan a banana it will take you to a website that tells you the CO2 that’s produced by eating a banana. Growing it, shipping it over to Europe, distributing it to the shops, getting it to the college… We can’t just think in terms of price or how many calories we get by eating a banana – there’s also how big an impact it makes on the environment. That was the main message I think.”

Information is power, they say. Good thing my phone also comes with a calculator.

Image: David Stefan