Measuring The Impact Of The Digital Industry

Understanding the carbon impact of your website and how you can reduce it

In the previous article of this series we explored the context of the climate emergency through the lens of the digital industry, the emissions connected to user devices, networks and data centres, and why the industry desperately needs to become more efficient. The next step is of course, how this can be done.

In this article, we’ll look at how you can calculate the emissions connected to your website or app, before examining different ways of reducing this load.

Understand the impact

In the old adage of what doesn’t get measured, doesn’t get done, the first thing to do is to understand what impact your current website has. 

At the moment I calculate this using a pretty big spreadsheet. It lists every URL on a site, the number of annual page views (not unique, actual) and the weight of that page. Multiplying the page views by the weight gives you the total data transferred in a year. 

From that you can work out the KwH needed to transfer that amount of data. This is a crucial step of the calculation and something I wish there was more consensus on (and I am working towards). 

At the moment I use the logic which takes the total amount of data transferred around the internet and the total amount of electricity the digital industry uses (minus the electricity needed to manufacture devices), figures which are available from two different reports. 

From that you can then use a carbon intensity figure (thankfully the UK’s is available for free, but sadly most other governments have monetised this data) to work out the amount of carbon a website is responsible for. 

And this is where the calculation can get very interesting. If your website has traffic from a few key countries you can use different intensities for the relative parts of your data transfer. Remember, data centres are only part of the problem when looking at electricity generation. All the switches, routers, devices etc. make a very significant part of the electricity usage. You can even look at how your website is being transferred to a device: for example, mobile data is more energy intensive than wifi. 

This calculation can be used for anything really, you just need to know how many data transfers there are and what the size of them is. I’m working on measuring the impact of ads delivered to a site, with the plan to start looking at the impact of data transfer for AI. 

Microsoft’s sustainability calculator will help to massively improve calculation transparency but it only works for the high level PowerBI/Azure licences and obviously requires a site to be on Azure to use it. But if the current opacity from data centre providers (which is driven by a paranoia that competitive advantage will be lost) continues we will have to stick with these calculations and estimates based on the data we can get. 

Reduce the load

Once you have an understanding of the emissions figures connected to your site, it’s time to consider how they might be reduced.

Obviously each website (or app) is unique and will require unique measures, but there are a few general ways to reduce carbon impact. These can broadly be divided into content and design solutions, and technical solutions.

There is a huge difference in the scale of impact of these options, but I believe it is vital to make changes right across the spectrum of impact. We shouldn’t let the small stuff distract us from addressing the big stuff, but equally we should sweat the small stuff because in a world where there will be more than 30 billion devices connected to the internet this year, every byte counts. 


  • Make sure people find the site quickly. Understand what they are looking for, what search terms they’re using and optimise content so they can complete the task they have in mind, not the one you want them to have in mind.
  • Facilitate quick content consumption. Forget about content stickiness, give people what they came for and let them leave.
  • Regularly remove content that is redundant, out of date, trivial or no longer being used. We’re working on a way to partly automate this.
  • Add in a page weight review to the editorial workflow process. We’re working on automating this as well!


  • Reduce images. Question whether they’re necessary. We’re starting to pay particular attention to the fact that one big image is better than lots of small ones; listing pages are firmly in our sights. 
  • Reduce video. Obviously autoplay is a no-go.
  • Use system fonts and as few variations as possible. Font files often contain a huge amount of styles, weights and characters you’ll never use.
  • Work hand in hand with a developer to understand how that design might be brought to life and what tweaks could be made to allow it to be created as efficiently as possible. This isn’t about spoiling anyone’s design fun, it’s just about the same level of diligence you would put in when you have a financial budget.

Technical Solutions

  • Architect the website to be as efficient as possible. There are well established practices out there such as event-driven architecture, server utilisation, extreme content delivery network use and static site generation which are extremely valuable. Ensure the architecture is also sufficiently evolveable: you need to be able to take advantage of new frameworks, software, hardware etc. when they are released to increase efficiency. Don’t close those avenues by implementing an architecture that is designed just for today’s needs. 
  • Host with an efficient, green energy powered data centre as close to the people who use your site as possible. This is a sweeping statement with not much substance behind it because there is so much to this discussion. Google buys renewable energy to 100% match the amount it uses in its data centres, is building on site renewables, is experimenting with shifting less urgent heavy compute tasks to times of low carbon intensity and leading the industry in terms of data centre efficiency. Microsoft and therefore Azure has an amazing carbon capture commitment alongside the first attempt to allow people to have access to data about the impact of what they host. AWS has done exactly what Amazon shopping has done for the majority of the public: it’s very cheap and very convenient and that isn’t to be underestimated. But sadly, it has none of the tangible evidence and commitments of its competitors despite the Bezos Earth Fund
  • Aggressively block bots to reduce server usage. Human activity on the internet accounts for only 48% of traffic on the internet. This means 52% of traffic is generated by bots. Half of that number are deemed bad bots: scraping content, increasing traffic, crashing websites, trying to find security loopholes, hoarding/bulk buying products on ecommerce sites, simulating advert clicks, etc. 
  • If images are absolutely necessary, compress and cache them and don’t load what people can’t see. Compress and zip everything you possibly can
  • Consider carbon intensity when planning when to run regular jobs. Traditionally we would run batch jobs in the middle of the night to make sure it doesn’t add to server load whilst real people are using the site. However, given that Octopus Energy recently started paying their customers to use renewable energy when it was very sunny and windy, a better way to plan these jobs is to monitor the carbon intensity of electricity and run the jobs when it is at its lowest. This concept is much better articulated as a green principle.
  • Given the mind blowing amount of data that an internet user generates every day it is vital to think about data minimisation. This is a way of thinking contrary to the tradition of harvesting as much data as possible, mining it and then defining why you needed that data. Instead, first define why you want to know something: how will knowing it help the people you serve better achieve their goals? Then define the bare minimum data you need to capture to deduce what you need to know.

Raising awareness

So there you have it – a few practical ways you can first understand, and then reduce, the carbon impact of your website or app.

In the next and final article, we’ll look at raising awareness about the climate emergency in other ways: including how to start the conversation in your business, implementing CO2e budgets, and the need to rethink KPIs.