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Actions » Share the carbon impact of a website

Share the carbon impact of a website

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  • hannah 
Share the carbon impact of your website

Through this action, we encourage you to reach out to others and help them understand the carbon emissions associated with visitors using their website.

Below you will find information to guide you on the most positive and effective way to do this including:

Campaign #LetsGreenTheWeb

We ran a #LetsGreenTheWeb campaign inviting the wider digital community to take this action with us on Twitter between 15 – 19 February 2021. Read more

Why this action matters

Many people don’t know that every time a website is loaded, it is responsible for carbon emissions. In fact, estimates suggest that if the internet were a country, it would be the world’s seventh-biggest polluter. Even if we can’t easily see the footprint that cyberspace leaves on our physical environment, the impact is certainly real.

Reducing the carbon emissions associated with a website boils down to reducing the amount of electricity being used to load, send, and view a web page as well as ensuring the resulting electricity needed is from clean, renewable resources.

The great thing about making a website more carbon friendly is that it often brings out additional benefits such as:

  • Making the website cheaper to run
  • Improving load times and performance
  • Providing a better content experience for users

By taking this action you are playing an important part in raising awareness about the unseen carbon emissions resulting from the world’s 1.5 billion websites.

How you can take part

  1. Choose a website to measure. Some ideas on how to choose include a site you use frequently, a favourite brand or company, or your own workplace’s site. Avoid charitable organisations where possible.
  2. Pick a page you would like to measure. A site’s homepage usually gets the most traffic so if you aren’t sure that’s a good choice.
  3. Use the Website Carbon Calculator to measure the page’s carbon emissions. Save the URL of the page that shows the results as the results can be viewed again, at any time, on the same URL. You can use this in your correspondence.
  4. Use one of our templates, or write your own and begin a conversation with the website owners. Let them know the result of your check, and what you think about the result. Remember to keep your comments positive, respectful and considerate. Not everyone will be aware of the issue or have the budget and time to make the website they want. Don’t forget to include our hashtag #LetsGreenTheWeb.
  5. Continue the conversation. You can signpost others to resources to help them take action. Remember the ClimateAction.Tech community can help with sharing good advice or articles. Just ask in our #ask-anything or #d-greener-webperf Slack channels if you are a member. You can also ask for further advice in the comments of this post.
  6. Share your experience of taking this action with us. Post in the comments section at the end of this post so we can see how you approached this action, what response you received from the website owners, and if there’s any changes we should make to this page to support others taking this action in the future.

Resources to help you

Measure the carbon emissions of a website

The Website Carbon Calculator

How to talk about website carbon emissions so people act

We’ve got a great general primer on why talking about climate change is so hard from our CAT Salon event: How to talk about climate so people act.

Below we’ve provided further ideas, inspired by advice from Deena Rosen, behaviour design expert, on how you can approach others when talking specifically about the carbon emissions resulting from websites.


Knowing that websites have a significant carbon impact is new for some people. You could help build motivation by setting the stakes.

Did you know if the internet were a country it would be the world’s seventh biggest polluter? Every click counts. See how much your site contributes #LetsGreenTheWeb Share on X Did you know it will take 300,000 Olympic-size swimming pool amounts of water this year to sustain our internet use habits? Every click counts. Find out more at #LetsGreenTheWeb Share on X

People may also be unaware of the additional benefits of efficient websites, so you can include those too.

Greening your website can often save money, improve performance, and improve UX. Learn how here #LetsGreenTheWeb Share on X

Identity, Consistency

People want to stay consistent with their own positive ideas of themselves. It can help if you remind people of their identities before asking them to take action.

I know you care about climate change, but you might not know that the internet currently produces approximately 3.8% of global carbon emissions. Find out how your clicks count and to reduce the carbon emissions of a website #LetsGreenTheWeb Share on X

Social proof

Calls to action will be more motivating if you can include social proof. You can provide credibility through trusted brands, let people know that others are doing this too, that you’re part of a larger community, and provide benchmarks of comparison.

Thousands of tech workers are checking the impacts of their favorite websites. There's easy way for you to do it too using! #LetsGreenTheWeb Share on X Join the thousands of people who are learning how their clicks impact the climate. Check your favorite sites here! #LetsGreenTheWeb Share on X

Templates for reaching out after running a check

  • Use the Website Carbon Calculator to measure a page’s carbon emissions. It will give you a percentage score which you can use in the templates.
  • Save the URL of the page that shows the results as the results can be viewed again, at any time, on the same URL. You can use this in your tweet.
  • Tweets with images are more attention grabbing. Consider including a screenshot of their score.
Hey @**brand** I’m a BIG fan of what you do, but do you know the carbon emissions of your website could be reduced? I ran a test of your site and you scored **insert%**. Get your results at **insert carbon calc URL** #LetsGreenTheWeb Share on X Hey @**insertbrand**! Did you know that your website could have a smaller climate impact? I ran a test of your site and you scored **insert%**, see your results here **insert carbon calc URL**. Find out how to improve at #LetsGreenTheWeb Share on X Hey @**brand** Great job on your website! I ran a test through and you scored **insert%**. Great job! 🙌 #LetsGreenTheWeb Share on X

Where to get further advice

Our hashtag #LetsGreenTheWeb has plenty more inspiration on how others are reaching out to others to spread awareness. Take a look for yourself and join the conversations.

Our CAT Action Guide: Reduce the carbon emissions of your website provides plenty of ideas and resources on how to take action if you are a website owner or content creator.

Not a Twitter user? How about an email instead?

Subject: Let’s green [company’s] website

Dear [person if you know it or simply just write the company name],

I’m writing to you as a proud [customer / consumer of your products], and I want to highlight how [company] can continue to improve. I’m participating in the #LetsGreenTheWeb campaign launched by, which aims to raise awareness about the unseen carbon emissions resulting from the world’s 1.5 billion websites. 

Every time a website is loaded, it’s responsible for carbon emissions. In fact, it’s estimated that if the Internet were a country, it would be the world’s seventh-biggest polluter. But it doesn’t have to be that way. There are many easy ways to make sure that the Internet is having a much smaller impact on energy consumption and climate change – including by reducing the emissions generated by websites.

In fact, low-carbon sites can actually provide a better user experience as they are often faster, more lightweight, and cheaper to run.

As part of our #LetsGreenTheWeb campaign, I wanted to test your site using the Website Carbon Calculator to see how it could improve. You scored [insert percent and hyperlink to the Carbon Calculator URL].

There’s always room for improvement, so we encourage you to share our resources, frequently asked questions, and ways to reduce the carbon emissions of your website with your communications/web development team(s).

I appreciate how committed to sustainability [the company] is, and I can only encourage you to continue standing with us in our mission to make the Internet better for both people and the planet.

Sincerely, your customer,


Note clicking the “Click to email” button will open your email program. You’ll need to copy and paste our suggested email text and amend as you see fit before sending.

Frequently asked questions

Is it OK to measure the carbon emissions of a website using a different tool?

Of course! We specifically recommend the Website Carbon Calculator because we know it is easy for someone with little or no technical knowledge on this topic to use, and the calculations being used behind the scenes are well researched. We list some further measuring tools in our Action Guide: How to Reduce the Carbon Emissions of Your Website. If you know of a tool you think does the job as well, please let us know in the comments.

I’m not on Twitter, can I still take part in the campaign?

Absolutely! The reason why this action focuses on Twitter only, is simply because we are staffed by volunteers, and we don’t want to stretch ourselves too thin by trying to cater for too many different social media platforms.

You’ll find graphics for Facebook, Instagram and Twitter in our #LetsGreenTheWeb Media Package – which you are very welcome to make use of if you want to post on social media.

You can also reach out to your chosen website via old fashioned email too 😁

Why do we suggest your favourite company? 

Because there’s an established base of research that shows companies are more likely to take on board feedback from actual customers rather than from those with no real connection to the company. Also, by choosing one of your favourite companies, you are more likely to approach the conversation in a constructive manner. By helping them to improve and succeed, they can keep providing you with your favourite products or services with a lesser environmental impact.

Why do you suggest we don’t reach out to charitable organisations?

As budgets and resources are limited for charitable organisations, we think that their time would be better spent serving their main mission, rather than responding to requests to update their website. There are hundreds of thousands of companies that have the funds and access to expertise to update their website, and we believe reaching out to them is a more pragmatic and effective starting point.


  • Hannah Smith
  • Michael J. Oghia
  • Stefanie Mühlbacher
  • Deena Rosen
  • Noel Anthony

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What others are saying

    1. I got a response in the email I sent and they replied saying that they forwarded the resources & information to the relevant teams in the company! 💚 Very excited to see what they do with this new information!

  1. I had another company whose website I tried to measure didn’t have a Twitter account — NL based “The Good Roll” They didn’t score too well so I sent an email linking a few resources for their engineering team to get started. 😌

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