Five things you didn’t think of as having a CO2 footprint

Five things you didn’t think of as having a CO2 footprint

Shocking lessons from the book “How Bad Are Bananas?”

Lottie Coltman

Jan 27, 2020



min read

Just a quick note before we start: In the book that this blog is based on, Mike Berners-Lee uses the term CO2e. This is what is called “carbon dioxide equivalent”, a way to talk about all of the greenhouse gasses and their climate change impact in the terms of the amount CO2 that would have the same effect. So, in keeping with his wisdom, we will do the same.

We all know that when we get into our petrol thirsty cars and cruise along the motorway/highway/autobahn for a road trip, that our CO2e footprint is going as quickly as the mileage on the dashboard.

While thinking about it too much can be a bit of a buzzkill, knowing that something has an impact allows you to be more conscious about how often you do it/use it. For example, if we follow on from the example above, if you’re feeling particularly climate-conscious, instead of renting a sports car for your holidays, you might choose to hop on the train (which brings the added bonus of being able to enjoy a glass of wine as you go).

But what about those things from our day-to-day lives that we just don’t think about as having a CO2e footprint? Well, I’m afraid that list is probably pretty long as, sadly, the truth is that pretty much everything has a footprint of some sort — even getting a dog (but you’ll never hear me making a recommendation against dogs. Never.). The key is to pick the areas where your choices can make the biggest difference. To do that, however, you need to know what is having an effect and by how much...

Luckily, one of the Cooler Future team recently gifted me the book “How Bad Are Bananas?”, by Mike Berners-Lee. If you are looking for a day to day guide on all things CO2e, this is a brilliant place to start...

Below, are 5 things that shocked me:

Walking through a door

Ok, look, I’m not saying you should give up walking through doors (although if you attempt this please @ me on Twitter and let me know how it goes). But I did say we were going to cover the things that you just don’t think about, right? So, here we are. The good news is that according to Berners-Lee, walking through a normal door in your house on a summer's day produces 0 CO2e. So, if you’re reading this in August, knock yourself out and go door crazy.

But, on a cold winter’s day? 3 grams of CO2e! This, of course, comes down to escaping heat and energy. Still, it’s not so big a deal.

If you work in an office block, however, with big electric doors that open into a large, heated foyer — well, that figure could sky-rocket to 84g. That’s the same CO2e cost as the production and transportation of a banana.

The takeaway? Well, first of all definitely don’t leave your door open on a cold day. And secondly, while we can’t personally control the type of door our office has, the choices that architects and building planners make do matter and as a society, we should hold them to account.

A thank you email


I’m British so far be it for me to rally against over-politeness, but it turns out it could be doing more harm than good from an environmental point of view. Of course, it’s not that thank you emails use more energy than other types of email (well, except emotional energy maybe), in fact, Berners-Lee only looked at spam emails (0.3g CO2e), “proper emails” (4g CO2e) and emails with long and tiresome attachments that you have to read ( a whopping 50g CO2e).

From this, we could come to the conclusion that it is long emails with attachments that should be the subject of scrutiny but, let’s face it, if you’re going to the trouble of sending a long email with an attachment there is probably a good reason for it. Thank you emails, however, as a recent article from Statista pointed out, are sometimes… well, a bit unnecessary.

In fact, in the UK alone over 64 million unnecessary thank you emails are sent every single day. If every Brit sent one less thank you email a day, we would save 16,433 tonnes of carbon a year — the equivalent to 81,152 flights to Madrid.

And there were our mothers saying that manners cost nothing...

A heart bypass operation:

Before people start sending me hate email (which, by the way, would just be undoing all the good you’d done by giving up thank you emails) let me state the obvious: Heart bypass operations are a good and worthy thing for us to use our CO2e allowance on. They are very serious and not a frivolity, unlike… I dunno, that novelty T-shirt you got in the office secret Santa (I actually love secret Santa but I think we have to admit that 99% of that stuff ends up straight in the trash).

Anyway, I just had never thought about the fact that things like operations have a CO2e footprint. Until I read the book. Curious? Let me (by directly quoting Berners-Lee), break it down for you… The average carbon cost of Healthcare in the UK per pound spent = 170g. The typical cost of a heart bypass to the National Health Service = £6,324 Therefore, the carbon footprint of this operation is about 1.1 tonnes. Which, if you were to aim for a 10 tonne a year lifestyle (which apparently we should), would blow about 6 weeks of your budget.

Of course, as we highlighted at the start this is the important stuff that we should prioritise. That said, if we were all to be a little bit healthier the carbon footprint of our health services could quite possibly go down. Luckily, a low CO2e lifestyle goes hand in hand with a healthier lifestyle (less meat, more walking/cycling, not having that third bottle of wine in a night) and so it’s possible that with the correct steps we could look after ourselves and the planet at the same time.

Cycling a mile

As someone that has recently moved to Amsterdam and has, therefore, adapted the Dutch habit of cycling everywhere, in all types of weather, this one confused and dismayed me. Why the hell am I publicly shaming myself with my very slow, clumsy cycling style if I’m not even helping the environment while doing it?

But, of course, cycling IS better for the environment than driving a car or hopping on the bus. That said, the matter is a little more complicated (and, in my humble opinion, interesting) than you might have first thought.

Put it like this;

If your bike is the mode of transport, what is powering it?


And what is your energy source?


So, in the same way, that we can calculate different CO2e footprints for cars depending on whether they are running on diesel or electricity, so can we (by which, I again mean Berners-Lee) calculate the different CO2e footprints of your bike ride depending on what you have put in your mouth. His calculations also include 50g a mile for the emissions of making the bike and any cycling safety equipment.

A mile of cycling powered by:

- Bananas: 65g CO2e

- Cereal with milk: 90g CO2e

- Bacon: 200g CO2e

- Cheeseburgers: 260g CO2e

- Air-freighted asparagus 2800g CO2e

As Berners-Lee then goes on to state, “if your cycling calories come from cheeseburgers, the emissions per mile are about the same as two people driving an efficient car”

And the asparagus?

“You’d be better off in a hummer”.

Spending 1 pound

Now, I don't know about you, but when I spend I’m generally thinking of the impact it is going to have on my bank balance and not so much its effects on the wider world. That’s not because I am a selfish, heartless witch (although perhaps I have exes that would say otherwise) but more that the fact that every single pound/euro/dollar/yen we spend has an impact on the world, well, it just isn’t something that was drilled into me. When I see a pound in my hand, I didn’t (before joining Cooler Future and reading this book) tend to see all the potential CO2e it could unleash.

Which is why I would argue that this is probably the most important and potentially world-saving lesson that this book contains, since often we don’t realise the impact of what we are doing.

Anyway, down to the calculations…

1 pound spent on:

- A well-executed rainforest preservation project = - 330kg C02e

- Solar panel = - 3kg CO2e

- Financial, legal or professional advice = 160g C02e

- A car = 720g CO2e

- A typical supermarket trolley of food = 930g CO2e

- Petrol for your car = 1.7kg CO2e

- Flights = 4.6kg CO2e

- The electricity bill = 6kg CO2e

- Budget flights = 10kg CO2e (and up)

Bad news for me and my low-cost holiday addiction, but also an eye-opener for any of us that do want to do better and something to think about next time you whip out that potentially world-damaging plastic. By which, I mean your bank card, not a straw.

So, there we have it. Five things that you might not have thought about as having a CO2e footprint.

And as I have said, there is a whole host more. Want to lead a lifestyle that is more considerate of CO2e production? Then despite the fact that the money you pay for it will have its own CO2e footprint, Mike Berners-Lee's book is an excellent place to start…

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