Reducing carbon emissions from our websites

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Why we are measuring our digital carbon emissions

All online activity generates carbon emissions. Every image downloaded, every click, server call and visit to our site. These types of interactions generate Scope 3 emissions. Lowering these emissions helps Scottish Enterprise towards achieving our Net Zero targets. And, for our users, the user experience is improved, along with SEO, because pages load faster and they use less data interacting with our sites.

Screenshot showing a snapshot of the Beacon report.
Beacon calculation of the SDI home page

Getting started on our journey

We first looked at the impact of our sites in February 2021 where we ran some calculations using a tool highlighted by Climate Action.

You can read more about this in my earlier post Let’s green the web​

Several members of the team also registered for Gerry McGovern’s  digital waste webinar, he’s leading the conversation and raising awareness about the impact of digital on the environment.​

It was clear to see through learnings and data that we could make some improvements in how we develop and create our websites.​ Work on our new Design System was the perfect opportunity to start putting our learnings into practice.

Working with Yard

We were introduced to Yard in February 2022. They are a sustainable driven digital company committed to reducing theirs and other businesses carbon impact. 

Along with Aline and their  Digital Beacon tool which enables capture, analysis and calculation of website data, it was suggested we run an audit of SDI, SE and FBS.

We had a particular focus on SDI as this was the first site to migrate to our new Design System. The plan was to run an audit with the existing site then analyse again once the site had re-launched.​

What we did next​

Aline conducted an audit of the site using analytics data we provided from March 2021 March 2022. Using their Beacon calculation to measure the impact of first visit and return visit.​

The audit outlined results and recommendations ranging from quick wins to more complex changes required.​


A screenshot from the audit results includes Thanks Helen. Is the plan to keep the failure on the same URL then and we’d continue to track via element visibility?
Results of the initial audit on SDI

The results are in grams of carbon released. For reference a gram of carbon for a first page visit is the equivalent of:

  • Average emissions per page view: 1.958g
  • Annual emissions: 1.155T

This also equivalent to:

  • Driving an average car for 2,903 miles
  • Consuming 2.7 barrels of oil
  • Swapping 44 incandescent bulbs for LED bulbs

Recommendations – quick wins

Better image compression

Compressing images before uploading them can vastly reduce the asset size, meaning they will load quicker when requested. 

Action – We have asked the content team to compress images before uploading to Umbraco. This has been included in wider training to raise awareness of the impact of content added to the site.

Ensure all images have size attributes

Height and width attributes helps with placement when rendering the rest of the page. 

Action – We have recently updated most of our code to reflect this. There are still some gaps to improve.

Recommendations – complex

Code optimisation

Optimising front end code and removing what isn’t used can save significantly on file size

Action – The Design System is a rewrite of the GDL codebase — by focussing on code performance, reuse and quality, code size was reduced. TypeScript and Webpack optimisation helped with this. 

Rather than our old GDL’s – Global Design Language “include everything” approach, our new Design System breaks packages into smaller items of required component(s) code — this extends to brand site specific optimisations. 

Also, dropping support for legacy browsers such as Internet Explorer, means less backwards-compatible code is required, reducing code size further. 

In addition to recommendations

When reviewing some data we noticed that there was a significant decrease in calls to the server. Our old processor for responsive images generated redirects to cached versions, and the new processor returns cached versions directly so there’s only one call per image, significantly reducing the number.

Screenshot showing the comparison of calls to the server on the old site and the new site.
Breakdown of calls to the server

Responsive images with appropriate dimensions

Different devices are served appropriately sized images for their screen-size, reducing the size of image requests

Action – We have recently updated most of our code to reflect this. There are still some gaps to improve.

Content audit and reduction in content

Looking at where we can reduce content, out of date, duplicated and look at where we can streamline journeys.

Action – The content team conducted a full content review of the SDI site, this helped to reduce some content, optimise journeys which also benefits the user experience.

We migrated SDI to our new Design System in Jan 2023 and to help us analyse our data we created this dashboard For a real time view of SDI we have created this dashboard

Screenshot of the SDI dashboard showing the reduction in CO2 over several months
SE website estate carbon dashboard

View our SE web estate carbon dashboard and read more about this in a previous blog article Measuring our carbon output.

Comparison between our old and new site

Average emissions per page view on the old SDI site at the time of the audit taking place : 1.958g. Average emissions per page view on the new SDI site : 0.678g

Overall this is a reduction of 56.95%

Screenshot showing the CO2 comparison between the old and new site. A reduction of 56.95% overall.
Comparison between the old and new site. A reduction of 56.95 overall

Comparison with a selection of our competitors

We did some comparison with some of our competitor sites , SDI carbon footprint is considerably less than other competitor sites.

Screenshot showing the carbon comparison with some of our competitors. SDI carbon footprint is considerably less than other competitor sites​.
A comparison with some of our competitors

Further findings from 2021 – 2023

Screenshot showing 2 graphs with further reductions from 2021 - 2023.
Further analysis from 2021

What’s next

We will continue to review the data we have available, improve where we can and add any learnings to our future migrations.

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