National Museums Scotland aims to take a whole organisation view of sustainability, and this commitment now extends to their digital operations. Working with our partner, Supercool, National Museums Scotland rebuilt their entire website with the intention of both improving the usability and reducing the carbon footprint of their website – aligning their digital presence with their broader sustainability goals.
In order to develop a picture of before and after, Digital Carbon Online was installed on on the old nms.ac.uk website while the new site was being built by Supercool.
This is the story of what happened.
Journey to a lower-carbon website
The National Museums Scotland story
As a national institution, National Museums Scotland recognised the environmental impact of their high-traffic website. They faced the challenge of maintaining an engaging user experience while reducing emissions. Their goal was to ensure their website reflected their aim to work sustainably and responsibly in achieving carbon reduction across their activities.
The project began with a comprehensive website rebuild by Supercool, a digital agency renowned for their work in the arts and culture sector. Supercool delivered a high-performing, user-friendly website which leveraged the latest sustainable web design best-practices.
The National Museums Scotland team were highly focused during this project. And we did a lot of user testing to test site architecture and content. All this meant we were able to design a website that’s easy to use, so users can find what they need quickly.
From a technical point of view we used modern image formats, reduced font files and minimised code. We’ve been efficient with the code, ensure only what’s needed is on the website. This reduces the weight of each page.
At Supercool, we track the time spent on every project, and we’ve estimated our carbon footprint. This means we were able to offset the carbon footprint of the project, so the research, design and build of the new website was carbon negative.
– Supercool
In parallel to this, Digital Carbon Online was installed on the existing website to capture a carbon emissions baseline that would be used to measure the efficacy of the lower-carbon web design.
Baseline – before migration
The pre-migration baseline determined that between May 2024 and July 2024 their average website carbon emission was around 0.5g CO2e per page per view, which is roughly on par with the global average. However, the worst pages on the website were significantly worse at 1.78g CO2e per page per view or more.
Headline Statistics
Before optimisation
gCO2e per page per view
gCO2e per page per view
gCO2e per page per view
The outcome
The results of this collaboration were impressive.
National Museums Scotland achieved a significant reduction in their website’s carbon emissions, with the average page emission dropping from 0.5g CO2e per view to 0.12g CO2e per view.
Not only this, but their worst pages became significantly better, resulting in lower emissions across every single page of their website.
Headline Statistics
After optimisation
gCO2e per page per view
gCO2e per page per view
gCO2e per page per view
The numbers above are a bit of a simplification as they don’t represent the month-by-month data across both of our assessment methodologies. If we look at a specific month we can get a more granular understanding of their accomplishments.
| Month | All page average (model 1) | All page average (model 2) |
|---|---|---|
| July | 0.93 gCO2e | 1.51 gCO2e |
| November | 0.84 gCO2e | 1.30 gCO2e |
| Reduction | 10% | 14% |
This alone is impressive, but if we look at the total reduction in carbon footprint between the two months we see a reduction of approximately 72%.
Explaining the 72% monthly carbon emission reduction
To understand the difference between the monthly all page average numbers and the overall monthly reduction we must take into consideration three other factors:
- The distribution of pages weights across the website (as per the worst/best page charts)
- The frequency visits across the distribution of pages
- The total number of page views per month
In the case of National Museums Scotland, the focus on both reducing the carbon footprint of individual pages combined with improved site design and navigation architecture culminated in a huge decrease in monthly carbon emissions across the entire site.
Not only did this work reduce the environmental impact of their digital operations but also enhanced website performance, creating a faster and more efficient user experience.
How they reduced website carbon emissions
Commenting on their optimisation work, National Museums Scotland said:
We used the initial data from Digital Carbon Online to inform a complete review of our asset library. We discovered that there were a lot of very large files that had never been optimised for the web. These were the clear cause of the poor performance of many of our heaviest pages.
Our first approach was to target the worst offenders to knock those high numbers down by deleting unnecessary images and optimising all the others. The move to WebP image formats is also new for us, and makes a big difference overall.
To help us maintain a lower website carbon footprint, we created new content design guidelines which includes factors for managing the carbon footprint of assets and content.
These include:
– Defining maximum file sizes for images
– Limiting video embeds per page, and,
– Questioning the number of images necessary for collections stories to make sure everything we include has a unique purpose.
We’ve also streamlined some of our more complex sections of our website – particularly Collections, Schools, and About us – by taking out unnecessary levels in the structure.
Focusing on our most visited areas of the website, we completely reworked the Visit pages, to make user journeys shorter, more efficient and therefore reducing the number of pages per user visit.
Lastly, we deleted well over 400 pages and merged the content of over 140 others. This covers both the elimination of broken content and incorrect, out-of-date, or unnecessary information, as well as the retiring, archiving, or reworking of collections story content.
Work in all these areas is ongoing, and we aim to make further improvements as we go.
It’s been so useful to have this data to inform and track our progress.
– National Museums Scotland
Ongoing commitment
National Museums Scotland’s commitment to website carbon management sets an inspiring example for other cultural institutions. With almost 50% of websites still not using green hosting, their actions highlight the importance of integrating sustainability into digital strategies. By making these changes, they demonstrated that it is possible to achieve both environmental and operational goals.
Follow their progress
Looking ahead, the organisation plans to continue monitoring and optimising their website’s carbon footprint. Their partnership with Digital Carbon Online and Supercool underscores their dedication to innovation and sustainability, positioning them as leaders in the field of digital sustainability.
Every Digital Carbon Online user receives a public dashboard that they can use to publicly demonstrate their progress. Not all organisations choose to publish these, but National Museums Scotland have and it can be found below.
Follow their lead
If your organisation wants to learn how to reduce its website carbon footprint, Digital Carbon Online offers free website carbon footprint assessments.
These reports provide insights into your website’s emissions, including comparisons to real-world activities like miles driven or coal burned.
Visit https://digitalcarbon.online/test to get started.