When organisations talk about sustainability, the focus tends to land on familiar ground. Energy usage, supply chains, procurement, travel policies and waste reduction are usually at the centre of the conversation. These are visible, measurable and well understood. Websites, despite being one of the most widely used and frequently accessed assets any organisation owns, rarely receive the same level of attention in sustainability discussions.
Digital sustainability is still a relatively emerging area. While awareness is growing, it has not yet become a mainstream consideration in most organisations, including those that have already made sustainability a core part of their identity. That raises a simple but important question. If we look at organisations that have already demonstrated a strong commitment to social and environmental responsibility, what does their approach to digital sustainability look like in practice?
To explore this, we carried out original research analysing the websites of B Corp certified businesses at scale.
B Corp certification is awarded to businesses that meet high standards of social and environmental performance, accountability and transparency. It is widely seen as a marker of responsible business practice and is often used as an indicator that a company is actively committed to sustainability. This makes B Corp organisations a useful reference point for understanding how sustainability principles are being translated into digital practice.
The aim of this research was not to assess the overall sustainability performance of these organisations, nor to evaluate the certification itself. Instead, the focus was specifically on digital sustainability and the extent to which recognised best practices are being adopted across their websites.
Methodology
For this study, we analysed the home page of 4,677 B Corp websites using our digital sustainability audit process.
The dataset included organisations across multiple sectors and sizes, providing a broad overview of how sustainability-focused businesses approach their digital presence in practice. Websites were assessed based on a consistent framework of metrics linked to performance efficiency and resource usage.
The specific indicators used in the analysis included:
- Page size (MB)
- Carbon dioxide created per page load
- HTML size
- Image size
- CSS size
- JavaScript size
- Font size
- Media size
- Performance score
These metrics were chosen because they act as practical proxies for digital sustainability. Together they provide a useful view of how efficiently a site is built and delivered, and how much unnecessary resource consumption may be occurring as a result.
Key findings
The results revealed a clear gap between broader sustainability leadership and the adoption of digital sustainability practices. We observed data across the following ranges:
- Page size (MB) – 0.0003 to 333.24
- Performance score – 3 to 100
- HTML size (MB) – 0.0003 to 2.34
- Image size (MB) – 0 to 331.49
- CSS size (MB) – 0 to 3.33
- JavaScript size (MB) – 0 to 30.39
- Font size (MB) – 0 to 20.50
- Media size (MB) – 0 to 203.86
- Carbon dioxide produced per page load (g) – 0.00008 to 98.24
These ranges help to demonstrate the huge variance on show, but to get a useful overview of how the 4,677 home pages perform overall, we have distilled the data into a set of averages, and calculated an indication of the weighting of each metric:
- Avg total page size (MB) – 6.96
- Avg HTML size (MB) – 0.08 (1.09% of total)
- Avg image size (MB) – 2.76 (39.65% of total)
- Avg CSS size (MB) – 0.13 (1.82% of total)
- Avg JavaScript size (MB) – 1.27 (18.18% of total)
- Avg font size (MB) – 0.27 (3.83% of total)
- Avg media size (MB) – 2.02 (28.94% of total)
- Avg “other” size (MB) – 0.45 (6.48% of total)
- Avg carbon dioxide emissions per page load (g) – 2.11
The suggested target set by the sustainable web design community is 0.5g of carbon dioxide produced per page load. As you can see, across the dataset, the majority of websites did not meet the benchmarks used within this analysis for efficient and sustainable digital design. While there were examples of strong implementation and some organisations clearly demonstrated careful attention to performance and efficiency, these were not representative of the wider picture.
One of the most notable patterns was the inconsistency of implementation. Even within organisations that are actively engaged in sustainability across other areas of their operations, digital sustainability appeared to be unevenly applied or not formally considered at all in website development and maintenance.
This creates an interesting tension. Many of the organisations analysed are already investing significant time and resources into reducing their environmental impact in other areas, yet their digital presence does not always reflect the same level of consideration.
One limitation of this research is that the analysis was conducted using the homepage of each website rather than a complete crawl of every page. In some cases, organisations may have sections of their websites that perform differently from their homepage, whether positively or negatively. However, the homepage remains the most visible and strategically important entry point for most websites and is often the page that receives the greatest level of design and development attention.
However, given the scale of the dataset and the consistency of the methodology applied across every site analysed, the findings still provide a meaningful indication of how digital sustainability is being approached. While a deeper page-by-page analysis may reveal additional nuances, it is unlikely to alter the broader patterns observed within the research.
Why digital sustainability gets overlooked
One of the most interesting interpretations of these findings isn’t about performance itself, but about visibility.
Sustainability efforts tend to focus on areas that are easy to see and measure. Buildings, transport fleets, manufacturing processes and physical waste streams are tangible and well defined. They can be audited, reported and improved in structured ways. Digital infrastructure, by contrast, is largely invisible. It exists as code, hosting environments and third-party services that rarely appear in day-to-day operational conversations.
As a result, even organisations that are highly committed to sustainability can unintentionally overlook their digital footprint. Websites are often owned by marketing or development teams rather than sustainability teams, which means responsibility is fragmented. In many cases, there is no clear ownership of digital sustainability at all.
There is also a wider lack of knowledge to consider. Most organisations are familiar with concepts like carbon reporting or energy efficiency ratings for buildings, but there is much less visibility of how the same concepts can be applied to websites. Without that visibility, it becomes difficult for digital sustainability to compete for attention alongside more established sustainability priorities.
Why this matters
Although the environmental impact of a single website visit is relatively small, websites are not static assets. They’re accessed repeatedly, often at scale, across large and distributed audiences. Over time, small inefficiencies in design and delivery accumulate into significant resource consumption.
The importance of digital sustainability becomes clearer when viewed through this lens of scale and repetition. A slightly heavier page, unnecessary scripts or inefficient media delivery may seem minor in isolation, but multiplied across thousands or millions of visits, the impact becomes far more meaningful.
Digital sustainability also occupies a unique position within the broader sustainability landscape because it is highly visible to end users. A website is often the first point of contact between an organisation and its audience. Unlike many sustainability initiatives that take place behind the scenes, the digital experience is directly experienced by customers, employees and stakeholders every day.
The business case for digital sustainability
One of the most compelling aspects of digital sustainability is that it often aligns closely with existing commercial objectives.
A more sustainable website is typically a more efficient website. Improvements that reduce environmental impact often also improve performance, usability and accessibility. Faster load times, reduced page weight and cleaner code can all contribute to better user experiences, improved search visibility and stronger conversion rates.
For example, even a 0.1 second improvement in page load time can result in measurable gains, including:
- 9.2% increase in average order value
- 5.5% increase in lead generation
- 8.4% increase in user transactions
- 5.7% decrease in bounce rates
- 5.2% increase in page views/session
This creates a situation where environmental improvements are not necessarily in conflict with business goals. In many cases they reinforce each other. That makes digital sustainability one of the more accessible areas of sustainability for organisations that are also focused on performance and growth.
For example, with images representing an average of 39.65% of average total page size, and image optimisation often being as simple (on a WordPress website, at least) as installing an image optimisation plugin and letting it run, improving the digital sustainability of a website often requires very little effort, time and cost to implement.
For many teams, this means digital sustainability does not require a fundamental shift in strategy. Instead, it often emerges from better decision-making within existing processes, particularly in design, development and content production.
What good looks like
At its core, a sustainable website is purposeful. It delivers what the user needs without unnecessary complexity or waste. It loads efficiently across devices and networks. It avoids unnecessary duplication and prioritises clarity over excess. It respects the time, attention and resources of the people using it.
This approach does not require minimalism for its own sake. Rather, it focuses on ensuring that every element of a website serves a clear purpose and contributes meaningfully to the overall experience.
To fully understand the impact of digital sustainability, let’s look at the data we have. If each home page in the dataset is visited 10 times a day for an entire year (based on the current real-world performance of each site), that’s 36,053,245g of carbon dioxide, or 36 tonnes, released a year.
However, adjust that formula to assume that every website in the list achieved the target of 0.5g of CO2 produced per page load, and the level of emissions based on the same number of visits falls to 7,979,254g (7.9 tonnes) a year. A reduction of just over 78%.
Remember: That’s just the home page of each site. With more pages on each website, each receiving traffic of their own, the actual current figure is much, much larger.
Looking ahead
If digital sustainability is currently underrepresented even among sustainability-focused organisations, it raises an important question about how the landscape will evolve.
Websites are becoming increasingly complex. The use of rich media, third-party integrations and dynamically generated content continues to grow. At the same time, new tools are making it easier to produce and publish content at scale. These trends are not inherently negative, but they do increase the importance of considering efficiency and resource usage in digital design.
As sustainability reporting becomes more common and more formalised across industries, it is likely that digital assets will begin to receive greater scrutiny. Organisations that begin developing better practices now may find themselves better positioned as expectations evolve.
A broader blind spot in sustainability thinking
Perhaps the most important takeaway from this research is not about websites specifically, but about how organisations prioritise sustainability efforts.
Sustainability initiatives often focus on areas that are visible, measurable and traditionally associated with environmental impact. This can create blind spots in areas that are less tangible but still widely used. Digital infrastructure is a clear example of this. It is deeply embedded in almost every organisation, yet it does not always sit within the core scope of sustainability planning.
This suggests that the challenge is not simply technical. It is organisational. As sustainability becomes more embedded in business strategy, there is an opportunity to broaden the scope of what is considered relevant. Digital sustainability is one part of that wider shift.
Conclusion
The findings from this research highlight a clear gap between sustainability leadership and digital sustainability adoption. However, they also point to something more nuanced. The issue is not necessarily a lack of intent, but a lack of visibility and shared understanding.
Organisations that have already demonstrated a strong commitment to sustainability appear to be well positioned to lead in this area as awareness grows. The opportunity now is not only to improve digital practices, but to expand the way sustainability is understood within organisations so that digital infrastructure is included alongside more traditional focus areas.
If sustainability is about reducing unnecessary impact while maintaining or improving outcomes, then digital sustainability is not a separate conversation. It is part of the same one.
What next, then? We’ve looked at businesses that have already demonstrated a commitment to good causes, but there are another set of businesses we can learn a lot from. Huge corporations that put sustainability messages across their sites and advertising – how do the FTSE 100 perform? Find out very soon…
