Promotional reusable mugs: green initiative or merchandising landfill?

AKA: Rich has had too much coffee on a Friday and gotten heavily sidetracked.

The university I often work for (and have two degrees from) has a pretty good reputation for environmental sustainability. De Montfort University has recently become a Global Hub for the UN Sustainable Development Goals (SDGs). The SDGs aren’t entirely focused on carbon emissions, pollution or waste but impact on the natural environment is obviously a very big part of it.

One thing they’ve done recently is a very big push towards eliminating single use plastics on campus, specifically in the realm of disposable hot drink containers. Rather than give a 25p discount for bringing a reusable mug for your hot drink, the university now charges 25p more if you *dont* bring a reusable mug. As the new academic year starts and at events like freshers week, thousands of free reusable mugs have been given away to staff and students to help encourage this.

Wow, cool! So, how many reusable mugs have been given out? 21,000 ?!?

How big is the university? Well, it has around 23,000 students and maybe another 3-4 thousand staff.

The staff intranet article in the picture above states that even more of the mugs will be made available so it is not hard to assume there would eventually be one for every staff and student of the university.

My initial reaction, if you couldn’t already tell was: ‘Bloody hell, that’s a lot of mugs

(And I do mean the drinks mugs, not staff or students *ba dum tshh*)

I was also preparing to give a lecture about the environmental impact of festivals, so it was the perfect excuse to investigate further.

There is quite a lot of info out there on how much energy it takes to create different types of hot drink containers and approximately how many times you would have to re-use them for it to break-even with using the equivalent amount of disposables. Using a paper cup and throwing it away is better than using a ceramic cup a few times, dropping and breaking it and throwing that away.

Some studies also take into account the impact of having to wash up reusable mugs and whether it is better to do so by hand or in a dishwasher. Obviously disposables don’t need to be washed up and this can be a surprisingly big energy saving. While carbon emissions (CO2e) are the most common benchmark for comparison, some studies also break up environmental impact across energy used, water used, impact on natural environment, human health impacts and so on.


Lets say the DMU reusable mug is made of 300g of stainless steel. (It clearly has some plastic in it, so we are being overly harsh to begin with)

You can buy these from any number of promotional item shops and have your logo added, I’m pretty sure it is an ‘Allen’ design which holds 450ml.

Using an estimate from another universities research on the same topic, this gave the emissions from a 16oz (454ml) stainless steel mug as 1143g of Co2e. This estimate includes raw material extraction and production. A lot of stainless steel is recycled (~70-80%) which is a lot better than new production, and (as far as I can tell) the estimate takes this into account. Coming at it another way, taking figures from the International Stainless Steel Forum gives about 3g of CO2e per 1g of stainless steel, so fairly similar = 300g mug = 900g CO2e.

Accounting for plastics then, let’s be generous and knock about 1/3rd off, call it 750g of CO2e per mug.

21,000 mugs x 750g of CO2e = 15,750kgs or 15 tons of CO2e

Even just assuming they physically weigh 300g each, that’s still 6.3 tons of mugs!

Or nearly the equivalent weight to five 2007 Vauxhall Corsa 1.7CDTi 5 door cars! (1277kg)
(I think it’s a perfectly cromulent comparison to make.)

How long might it take for this ‘fleet’ of reusable mugs to recover the energy spent in their creation?


The article states that:

“During the first week of the new drinks prices being introduced, 80 per cent of hot drinks purchased on campus were made using the new DMU reusable mug – totalling a combined 6,922 coffees, teas and hot chocolates.”

That’s handy, let’s call it 7000 hot drinks served on campus per week, or 1000 per day.

Assuming no-one was using reusable mugs before this initiative, this would mean they have replaced 800 disposable cups used per day.

Breaking even

As mentioned earlier, there are lots of studies and articles out there about the break-even needed for various types of reusable vs disposable containers. There are obviously paper and plastic types of disposable, various types of plastic, steel or bioplastic reusables to consider. I’ve taken the figures from a Canadian study which is both pretty thorough and has a nice summary.

Taking an estimate of the average between equivalent Polycarbonate and a Stainless steel mugs means we would need to reuse it 160 times to start saving against the energy required to make the equivalent amount of disposable cups. Disposable cups in this case were made of paper, with a polyethylene lining and a polystyrene lid. You can split hairs about the details, but its not a million miles off other general estimates in this area. (link)

If we’re getting 800 reusable-uses per day, and it takes 160 uses to break event, that means that we’re getting 5 ‘lifetime break-evens’ per day.

Therefore, you could say across the whole ‘fleet’ of reusable mugs at the university, we break even on 5 mugs per day.

21,000 mugs breaking even at 5 mugs per day = 4200 days until they are all accounted for.

Put another way, it might take 11.51 years to recoup that energy. (9.58 if you got up to 100% usage)

Aww. That actually sounds like a bit of a bummer :(


Let’s have some perspective.

A student using an ‘average’ computer for 1 hour creates 143g of CO2e (other estimates are lower)

750g CO2e from making a reusable mug = 5.2 hours of using a computer

The amount of time it took me to research and write this is probably equivalent to one reusable mug… so STOP READING THIS TURN OFF YOUR COMPUTER NOW STOP DOING ANYTHING AAAAARRGHHGH…

Incidentally did you know someone claims to have written their undergraduate dissertation in 16 hours? And they got a 2:1!

How will individual students be using the mugs though?

If a student has 30 weeks of university a year, and take 3 years to graduate, thats 90 weeks.

So if they would have previously bought about only 2 hot drinks in disposable mugs per week, by using a reusable mug instead they’ll have reached 160 uses by the time they graduate. That sounds a bit more positive.



It’s probably a good idea.

From personal experience, while I don’t go to the onsite cafes that often, I try to bring a (stainless steel) reusable mug with me. Not every time, to be honest, because I am only human/lazy. I probably get through more disposable cups when the free teas and coffees are brought out for staff meetings and things, you don’t see many people bringing re-usables along to these (again, myself sadly included).

I think moving from a 25p discount to a 25p charge is a good step, as long as the cafe workers don’t end up getting a load of stick for it, but I would imagine they are in favour of this scheme as well. Less rubbish to take out for one.

I wonder how it might impact the potential for theft on hot drinks? Previously you would pay and then be given your disposable cup, whereas now, really anyone could go up to the self service machines and help themselves. It’s very easy to press ‘Large’ when you only paid for a ‘Regular’ isn’t it? Oh, the buttons are so close together, I’m so clumsy!

From an engagement and awareness point of view, it’s a good point of contact with students and staff. The kind of thing that you use everyday and therefore probably makes you think a little bit more about the environment across your whole day.

Looking at the promotional costs, they could be anywhere from £2£4 per mug. It probably is better to have good quality and durable giveaways, even if they need more energy/emissions to make in the first place.

Having worked at more open days and events like this, the general amount of promotional tat that is shoveled at students is ever increasing. How many more reusable cotton tote bags could you possibly need? Are you going to reuse each one at least 131 times? (to break even versus disposable bags)

At least a decent quality, stainless steel travel mug could be more useful and outlast any of the “20 Most Unusual Promo Items”, for example.

‘Disposable-but-Recyclable’ may be better than ‘Disposable’, but it’s clearly not as good as ‘Reusable’

Getting the mugs out there and saying no to disposables is a good step.

Actually reusing them several hundred times is an important step two!

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