Does your office cafe have a bring-your-own cup discount? And does this make you feel pretty good about the café’s priorities? Well, it turns,out, although well meaning, a discount doesn’t actually incentivize the intended behavior (i.e. bringing your own cup).
We’ve reviewed the evidence (all linked below), and what studies have found is the optics of charging MORE for a single use cup, not a discount, is what changes a person’s behaviour.
“While a charge on disposable cups increased [the use of reusable cups]…, a discount on reusable cups did not.” — Poortinga & Whitaker (2018), Sustainability
Their field experiment ran across UK university and workplace cafés, testing messaging, free cups, a charge and a discount. The cost-neutral charge shifted behaviour, but the discount didn’t.
What we mean by ‘the optics’ of charging more
What do we mean – ‘the optics’ of charging more? This means introducing a cost-neutral charge.
Say a coffee is £3.00. You relabel it £2.80 — the reusable cup price — and add 20p to the price for a disposable cup. Nobody pays more than they did yesterday. But now the cup has a visible price tag.
Here’s the evidence:
- Swapping a $0.15 discount for a $0.25 cost-neutral charge took reusable cup sales from 4.8% to 23.7% across four University of British Columbia cafés. (Sidhu et al., 2018)
- At Tufts, a $0.10 discount replaced by a $0.17 charge moved sales from 3.1% to 8.1%. Meanwhile a second campus café that kept the discount went from 0.37% to 0.34%. (Fisher, 2008)
- A $0.15 cost-neutral charge at a UC Berkeley café increased sales from 0.8% to 6.2%. (Latimer, 2016)
- A £0.10 charge at NHS Crosshouse Hospital took staff reusable cup use from 1% to 43% — though free cups and a loyalty card came with it. (Zero Waste Scotland, 2018)
(Actual sales of coffee were unharmed with cost-neutral charges).
Messaging helps too
Messaging helps too, on top of a charge. Environmental signage — the number of cups going to landfill, that sort of thing — added around two percentage points in the Poortinga study. But the strongest result came from a different framing: a pre-registered German study across nearly 24,000 hot drink sales found that telling customers “more and more people are switching to reusable cups” beat both moral appeals and straight factual messaging, adding closer to four percentage points. Describing where behaviour is heading works better than describing where it should be. Perhaps it’s the power of peer pressure?
Studies carried out in office environments (and campuses) actually had better results than other settings, like the high street.
But this is only part of the story. Do we actually WANT people to use a reusable cup?
This gets murky, because where will customers get their reusable cups? Giving out new reusable cups for free, or having customers buy them, complicates matters.
The production and transport of a new reusable cup is more carbon intensive than producing a disposable cup. Studies have shown that customers would need to keep reusing their cup for the longer term (between 10 and hundreds of uses, depending on materials, washing methods and more – research REALLY varies here) for the environmental impacts to break even and to start to pay off, when compared to a disposable cup.
What are the chances the new reusable cup will end up collecting dust with all the others, in a cupboard somewhere?
How you wash it matters as much as what it’s made of
Also, it sounds like splitting hairs, but how you wash your reusable cup can also matter as much as what it’s made of. One assessment found a lidded ceramic cup washed by hand never breaks even at all with the environmental impact of using a disposable paper cup. This is mostly because of the electricity needed to heat the water for washing, so washing via a modern dishwasher or by hand in cold water is best for the environment. (This is also highly dependent on whether you’re using renewable energy, or not).
So what should you advise your café to do?
- If you’re brave, tweak your café prices to display the discounted reusable cup price, and make it look like you’re charging ‘extra’ for a disposable cup drink. But it must be at least £0.15 – £0.20 (roughly) to be effective.
- If you’re going to give your staff free reusable cups, support them to keep them and use them for the long term. Ensure there is a convenient place to store them and wash them, advise them to wash in cold water.
- If you’re opting for compostable cups, ensure there is infrastructure in place to properly compost them, and folks know how to dispose of the cups correctly. Make it convenient. Otherwise the cups just end up in the landfill leaking methane or incinerated.
And as an individual looking to make a good choice
- If you already have a reusable cup, bring it, use it. It’s already been manufactured, so using it for the long term is the most environmentally friendly thing you can do. You should also ideally wash it in a dishwasher rather than by hand, or in cold water if by hand.
- For folks who know they won’t realistically use their reusable cup regularly for months, drop the guilt and just use a disposable cup. In the end this would actually be less carbon intensive than periodically getting new reusable cups.
One life cycle assessment we came across concluded the same — use a ceramic cup for a long time, wash it in a dishwasher or by hand without hot water, but “to enjoy an occasional coffee-to-go, the paper cup remains a greener option.”
— Martin, Bunsen & Ciroth (2018), openLCA case study
What has been your experience with your office café and disposable cups? We’d love to hear your experiences.
Sources and further reading
Poortinga, W. & Whitaker, L. (2018). Promoting the Use of Reusable Coffee Cups through Environmental Messaging, the Provision of Alternatives and Financial Incentives. Sustainability, 10(3), 873.
https://doi.org/10.3390/su10030873
Poortinga, W., Nash, N. & Hoeijmakers, L. (2019). Rapid Review of Charging for Disposable Coffee Cups and Other Waste Minimisation Measures. Scottish Government, on behalf of the Expert Panel on Environmental Charging and Other Measures.
Sidhu, M., Mehrotra, K. & Hu, K. (2018). Single-Use Items Reduction: Disposable Cups. UBC SEEDS Sustainability Program.
https://doi.org/10.14288/1.0387025
Zero Waste Scotland (2018). NHS Reusable Cups Trial (Lenaghan, M. & Kowalski, J.).
Zero Waste Scotland (2019). Cups Sold Separately: Field Trial and Evidence Review of Disposable Cup Charges (Lenaghan, M., Clark, W. & Middlemass, T.).
Loschelder, D. D., Siepelmeyer, H., Fischer, D. & Rubel, J. A. (2019). Dynamic Norms Drive Sustainable Consumption: Norm-Based Nudging Helps Café Customers to Avoid Disposable To-Go-Cups. Journal of Economic Psychology, 75, 102146.
https://doi.org/10.1016/j.joep.2019.02.002
Zero Waste Scotland. The Environmental Benefits of Reusable Plastic over Single-Use Products.
https://www.zerowastescotland.org.uk/resources/environmental-benefits-reusable-plastic
UNEP Life Cycle Initiative (2021). Single-Use Beverage Cups and Their Alternatives: Recommendations from Life Cycle Assessments.
House of Commons Environmental Audit Committee (2018). Disposable Packaging: Coffee Cups. HC 657.
https://publications.parliament.uk/pa/cm201719/cmselect/cmenvaud/657/657.pdf
Martin, S., Bunsen, J. & Ciroth, A. (2018). Ceramic Cup vs. Paper Cup. openLCA Case Study v1.1. GreenDelta GmbH, Berlin.
https://www.openlca.org/wp-content/uploads/2025/01/Report_Ceramic_cup_vs_Paper_cup.pdf
https://www.zerowastescotland.org.uk/resources/cups-sold-separately-report
