My award for Bullshit Of The Year 2023 goes to an email I received some time back in the summer when I was copied, snowball-style along with about 100 other people, into an email chain about a topic that had nothing to do with me.
I was about to hit delete when I spotted something interesting in the sender’s email signature. It finished with the phrase Sending thanks in advance, and a link to a blog explaining why we shouldn’t send thank you emails.
The blog is on the website of UK energy company Ovo. I’m not going to link to it here because frankly they don’t deserve any web traffic – if you really want to read it for yourself then it is, unfortunately, quite easy to find via a search engine.
Something didn’t feel right about the claim. I searched the web to try to find out more, and quickly realised that this blog post had been cited a lot elsewhere. Multiple news outlets including the BBC and the Financial Times had reported this dubious claim that sending one less thank you email per day could save equivalent carbon to 80,000 flights to Madrid.
Perhaps surprisingly, the blog includes a quote from the highly-respected scientist Mike Berners-Lee, author of How Bad are Bananas – and cited some of the data from his book as a basis for the claim. In fact Berners-Lee’s quote starts by saying “Whilst the carbon footprint of an email isn’t huge…” and goes on to suggest that thinking about the small behavioural changes can remind us to “care even more about the really big carbon decisions”. Despite essentially saying that the carbon footprint of email is insignificant, Berners-Lee’s quote inadvertently provides a degree of authority to claims in the the Ovo blog.
I had heard a lot about this book, about the interesting narrative it provides about the carbon footprint of day-to-day items and activities – but had never read it myself. So, inspired to debunk Ovo’s claim I bought the book. I read it and was in fact surprised by just how low-carbon email is. The book is ordered in chapters, with the lowest-carbon activities first. Sending an email is right at the beginning of the book – second only to drinking a pint of tap water.
As I was reading the book, though, I realised that it was difficult to get a sense of proportion about just how bad the various activities were. Each entry in the book has an associated CO₂e value, but I found them hard to compare. Just how bad is something that is 2g (e.g. drying your hands with a Dyson hand dryer) compared to something that is 2.3T (a heart bypass operation)? I needed something to help visualise and browse the data I was reading about.
So I created a zoomable graphic with all the data in the book up to 100 Tonnes CO₂e. It became clear that some activities can have a surprising range of carbon footprints – for example walking through a door can be anything between 0g (a household door when the heating/air conditioning isn’t on) up to 83g (electric doors on a cold windy day). And if you’re trying to cut carbon, there are some much easier wins than changing email habits.
When it comes to email, the book provides a range of values, between 0.03g CO₂e for the email that gets blocked by spam filters, to 26g CO₂e for an email that takes ten minutes to write, sent to 100 people, 99 of whom take 3s to realise they should ignore it. A short email sent from laptop to laptop is 0.3g CO₂e – I’ll very conservatively assume that this is the carbon footprint of a thank you email – although for reasons I’ll come on to I suspect that this is a significant over-estimate.
Here’s some choices based on data from the book that save more carbon than not sending a thank you email:
- Choosing black tea/coffee instead of adding cow’s milk: equivalent to sending 160 thank you emails
- Working at your desktop computer for 1hr less: equivalent to sending 170 thank you emails
- Washing your laundry at 30°C instead of 40°C: equivalent to sending 700 thank you emails
- Eating an 80g portion of UK-grown asparagus vs Peru-grown asparagus: equivalent to sending 4,700 thank you emails
- Choosing a veggie cheeseburger instead of a beef cheeseburger: equivalent to sending 8,500 thank you emails
- A 3hr zoom call instead of flying 800 miles for a meeting: equivalent to sending 2.4 million thank you emails
And, I’m going to call out Ovo energy here:
- Switching your home electricity provider from Ovo to another slightly greener provider who has average UK grid mix electricity*: equivalent to 210 thank you emails. Per day.
You may notice that my figure for flying has quite a different message to Ovo’s claim that one less thank you email per day could save equivalent carbon to 80,000 flights to Madrid. Their maths is bad (although they do at least include their garbled working out on the blog), and it’s based on a very high value for the carbon footprint of an email. Crucially they use the word ‘flights’ misleadingly instead of ‘passenger-journeys’. I’ve reworked their maths and in fact, if every one of the 52 million people in the UK sent one less short email every day (including weekends), then over a year this would save an amount of carbon equivalent to 10,000 one-way passenger journeys (not flights) to Madrid – about 58 fully-booked aircraft flights. Compare this to 1.8 million flights taking off and landing in the UK per year.
I’d also suggest that the 0.3g CO₂e per thank you email figure I’ve used in my maths here is much too high. In his book Berners-Lee provides a breakdown of where that carbon footprint comes from. Only around 10% of the footprint is associated with the networks and data centres – the remaining 90% is the power consumption and embodied energy of using your device. In other words, if you’d be using your computer anyway to do other work, then the carbon footprint of the email becomes even more insignificant. Work expands to fit the time available (says Parkinson’s law) – so unless you think someone will finish work that day slightly later in order to read your thank you email then there’s really no reason not to send it.
And perhaps, sending it might help motivate someone. If this causes them to work more efficiently, then it could be carbon negative. A thoughtful thank you message alongside a well-constructed piece of AID feedback might mean that next time round your colleague will be more effective giving you what you asked for.
And even if it doesn’t, it’s a thing that makes the world a little bit nicer. To paraphrase the old platitude: A thank you costs virtually no carbon but can mean a lot.
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* This is according to Ovo Energy’s own reported fuel mix of 205g CO₂e per 1kWh compared to the national average of 198g – a difference of 7g. Average UK household electricity consumption is 8kWh to 10kWh per day. 9kWh × 7g = 63g CO₂e saved per day.
Theatre Elements 