First of all let me say, you probably shouldn't be deleting your work emails because they don't belong to you. Your company has a legal obligation to keep them for a certain number of years and your emails are probably archived by the company anyway.

Let's get to the real substance of what was so misguided about the advice to delete emails. The intended outcome was to reduce:

• space in data centres
• hardware needed to store emails
• energy consumption
• water for cooling (it's not just water)

On the surface it may would seem that less of anything would achieve all of the above.

It feels intuitive; less is better.

But here's why it's wrong.

1. emails are tiny, so if space is your concern, it's really the wrong priority
2. data at rest uses very little energy and doesn't create heat/need for cooling.
3. what's done is done. Changes in future behaviour are more impactful.

Scale

I stated that emails are tiny. They are. A 250 word email comprises around 1,400-1,500 characters including spaces and punctuation. 1 character typically requires 8 bits (1 byte) in standard encoding like ASCII or UTF-8. So our basic 250 word email has about 1.5 kilobytes. Throw in some HTML for styling and headers (hidden info needed to move the emails around) and it's maybe 2.5 kilobytes. 400 emails are about 1MB, 400,000 emails 1GB and 400,000,000 emails (four hundred million) in one terabyte (TB).

I have a USB key in my pocket that stores 256GB, so that's about 100 million emails worth of storage OR only 64 GoPro videos each of about 20 minutes.

So if we accept that we can store about 400 million emails on one single terabyte and that 1TB takes up less space than your mobile phone, what happens if we gave every person on the planet and inbox with 10,000 two hundred and fifty word long emails?

80 trillion emails! OR 200,000 TB. The hardware to store all this would fit into your living room (It's a total of 200 Petabytes or 0.2 Exabytes).

Now of course, people email attachments etc so emails are often way bigger than a couple of kilobytes, but if you look at the majority of your inbox it's really just text and usually way shorter than 250 words. So even if we multiplied the numbers by 100, 100 living rooms aren't going to wipe out habitats and destroy the livelihoods of farmers.

That one hour Zoom meeting that you recorded, well that's a different case. Every photo taken and shared when the sun sets or the first snow of the year falls, every TikTok craze and video of your first born's first words or steps. Every update for the 200 apps on your phone, every post showing you lifting a beer or the food you're about to eat. The "weight" of each of these items is thousands of times more than an email.

I'm not denying storage is a problem, and believe me, I'd love to have fewer emails, but focussing on emails is sooooo off the mark.

So why did I say deleting your emails could make matters worse? Because creating or deleting emails takes energy.

Energy

Computer activity uses energy and creates heat which in turn requires cooling. Energy use is highest when creating data, performing actions on it, moving or transforming it. Dormant emails are stored and not really using much energy, why wake them up?

When you delete emails, there's an action on your computer and then a whole series of machines swing into action between your computer and where the emails are actually stored. Lights flicker on and off, just like in the old movies, beep-beep, boop-boop.

So what can you do?

If you're still set on a war on email ... send shorter and fewer emails I guess. But I hope I got across that it won't make that much difference even if everyone did it (and they won't). Human behaviour is very hard to change en masse which makes individual action on this matter kind of useless (sorry). We're not going to stop moving video, TV, photos and voice around the world at an astonishing rate and these files probably won't get smaller in the near term.

From an energy perspective, it's much easier to ensure that the electricity that powers the underlying systems is renewable. Speak up for renewables, put your money where your mouth is if you can and let local politicians know that you're in favour of renewables because they hear from some very loud voices against them.

In terms of space and land-use for data centres and the general infrastructure of our online lives then it is much easier to get change mandated at the political and planning level than it is for individuals to save so much storage space that it would have a real impact. If you're genuinely passionate about you need to get into the weeds of planning policy and figure out how to win concessions from data centre operators to ensure that their energy and cooling needs align with the communities in which they are situated. Don't just fight the good fight locally because you may just be making a problem that moves down the road.

Maybe we all just need to have a offline day every week.

[Apologies to tech folks for my back of a beer mat calculations. I know we divide by 1024 not 1000.]

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