Chapter Two, Three Years Later

When I sat down to read through Chapter 2 of my book again, I noticed something I did not expect. The chapter is called What is carbon footprint, and at the time I wrote it, I thought of it as the technical foundation chapter, the one that gives the reader a vocabulary and a few tools so they can start measuring what they are building. Reading it now, three years later, I see something different. I see a chapter that was, without me fully realising it at the time, asking a much harder question underneath the technical one. The harder question is not how do you measure a website’s carbon footprint. The harder question is what do you actually do with a number that is never going to be precise, in a conversation with someone who does not care about the environment, in an industry that is still optimising for speed and feature count.

That is the question I have spent the last three years trying to answer in practice, and the answer has shifted what I think the measurement chapter is really for. So I want to walk through Chapter 2 honestly, the way I did with Chapter 1, and I want to tell you what I have learned since then about what these numbers can and cannot do, and how I have learned to make them useful even when the people I am talking to do not share my values.

In Chapter 2 I introduced websitecarbon.com and EcoGrader, and I was upfront about the fact that the results these tools give you are not one hundred percent accurate. I argued that even an imprecise estimate is valuable, because it shows direction, and because for every adjustment you make, the numbers move in a way that teaches you something about what you have just done.

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Three years on, I still believe that, and I want to defend it more strongly than I did in 2023. The tools have not become dramatically more accurate, and I do not think they will, because the kind of accuracy people sometimes ask for is more or less impossible to achieve. To calculate the precise footprint of a single website, you would need to know how many visitors it has, what devices they are using, how far they are from the data center, what connection type they are on, what the carbon intensity of the electricity is at every hop in between, and how the visitor’s device was manufactured and powered. Some of that information exists in fragments. Most of it is impossible to get without violating privacy laws, and the rest is so context-dependent that any single number you produced would be wrong the moment the next visitor loaded the page.

So when people ask me whether websitecarbon.com gives you the real number, the honest answer is no, and that has not changed since 2023. The dirty secret of carbon measurement in web design is that the precision people want is not available, and it probably never will be. What is available is a guideline, a sense of direction, a way of seeing whether the choices you are making are pulling the project lighter or heavier. That is what the tools were always for, and three years of working with them has confirmed that for me rather than weakened it.