We all use images in education. They’re used everywhere—presentations, online courses, blogs, websites, and social media. But do we ever think about the hidden cost of using images in teaching and learning?
This post comes from a Jisc project exploring how to promote sustainable digital practices in teaching and learning. Images help communicate ideas, enrich content, and support learning. Using images more efficiently also helps institutions tackle student and organisational concerns about reaching net zero.
There are many choices we can make when using images. Let’s explore how the right choices can reduce the environmental impact and also bring wider benefits to our learners.
Defining Image Optimisation
Image optimisation can mean different things, depending on your role. For example:
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Accessibility specialists may focus on alt text, colour contrast, and avoiding seizure-triggering visuals.
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Marketing professionals will likely prioritise brand consistency and visual impact.
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Student-facing staff (teachers, librarians, etc) aim to support understanding and enrich content.
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Web developers focus on user experience, load times and responsiveness.
All these are valid considerations, but how often do we assess the carbon cost of using images? Every byte of image data contributes to energy use across networks, servers, and devices. Optimisation reduces this footprint.
Why Does This Matter?
According to a recent Jisc Learner Digital Experience Insights Survey, 71% of Further Education and 73% of Higher Education students regularly use smartphones for learning. Our VLE review service has shown that more students are accessing learning content via mobile, often struggling with content that doesn’t load efficiently. This unfairly affects those with limited data plans or older devices.
Research by Google suggests that 53% of mobile site visits are abandoned if a page takes more than three seconds to load. With mobile as the dominant platform, speed and efficiency are now central to the user experience.
We may not know how many students have disengaged due to slow loading from large images, but it makes sense to keep access as smooth as possible.
Guidance
There is a lot to unpack, and image optimisation is a rich area to explore, but there are resources out there to help.
Depending on your role, your knowledge of images and techniques to optimise will vary. For example, do you understand the differences between Raster images and Vector images and in what context you would use them? Are you aware of the tools available to compress images that can have a big impact on File size with negligible loss to image quality?
Some tools are built into Office apps like PowerPoint and are easy to use. Others, like Adobe Photoshop, may need a subscription. You don’t need to know all the details about image compression—start small and learn as you go.
This video gives a deeper look at what to consider and suggests activities you can try with learners or staff.
Why It Matters
By optimising the images in a recent presentation, I was able to reduce its file size by 75%. That’s a substantial saving in digital resources. While we know compressing a few images won’t save the planet, this is about modelling good digital habits.
Ask yourself: “What kind of digital practitioner do I want to be?” Do you want to be the person who shrugs off small changes? Or the person who makes thoughtful, sustainable choices that lead to meaningful change?
By being more thoughtful about how we use images in our digital work, we can make small changes that add up to meaningful improvements over time.
