Skip to content
So how do we measure sustainability?

So how do we measure sustainability?

Continuing on from last week’s blog post on what sustainability means to me, I wanted to continue to explore how to measure how sustainable something is. It’s something I keen to develop a working theory on because ultimately it’s how I’ll be able to recommend which products (and, in time, services) are the most sustainable. But can a formula be worked out that will provide a quantitative answer, or is it more complicated than that?


Determining the sustainability of something is multi-faceted, because focusing too much on one particular outcome can have unintended consequences.  Pretty much everything we produce or do has some impact on the planet, so to my mind what we are trying to do is reduce that impact. To work through all the considerations let’s continue with the example of buying a cup of coffee.


When you go to buy a cup of coffee you’ve got three options, drink it at the café, use a reusable takeaway cup, or get it to go in a single use cup. Leaving aside what kind of coffee you order – that opens up a whole other raft of sustainability considerations depending on whether you take your coffee black or with milk (and then if it’s dairy or plant-based) – which is the most sustainable option?


We could look at the energy required to make and keep a coffee mug clean. We could look at the carbon footprint of coffee mugs vs single use cups. But looking at those in isolation doesn’t work, because as a one off a paper cup requires the least energy to produce and has the lowest carbon footprint. Obviously the idea of the ceramic coffee mugs and reusable takeaway cups is to use them over and over again. So at a certain point you have reused them enough to make up for the initial extra energy or carbon emissions. According to CIRAIG that point is reached between at between 100 and 250 uses, reasonably easy for a ceramic cup used in a café but that could take a while to reach for your own reusable cup so is worth bearing in mind when considering how big your keep cup collection is.


Those aren’t the only factors to consider though. The raw materials used to produce the product matter too, clay in the case of ceramic mugs, a combination of steel, glass, and plastic for reusable coffee mugs, and wood pulp and plastic in single use cups, or food-based ingredients in the case of so-called compostable coffee cups. How the products are disposed of is important too – can they be recycled, or do they end up in landfill (as is the case with almost all single use cups, including the compostable ones given they aren’t collected separately). Whether the energy used to produce and keep a product clean could well make a difference too.


The answer to my original question - can a formula be worked out that will provide a quantitative answer to sustainability – is maybe, but it’s complicated. There are a few common factors to consider when assessing a product’s sustainability though, for example whether the raw materials used are renewable or non-renewable, how durable the product is vs how frequently it is used, whether and how easily the product can be recycled, as well as the energy required to produce it and the product’s overall carbon footprint. Often how ethical a product is falls within a similar remit to sustainability so things like organic, fairtrade, vegan and animal cruelty-free are additional considerations. Assessing each factor individually and then considering overall sustainability looks to be the best approach to determining how sustainable a product is. How we go about this here a Buy Sustainably will be a work in progress so any feedback is welcome.


And in case you were wondering, the most sustainable way to have your coffee is in the café using their ceramic cups due to the frequency with which they are used as well as the efficiency of their industrial dishwashers. So next time you need a caffeine hit take a bit of time out and drink in, you’ll be doing yourself and the planet a favour.


Image credit: Time Out

Next article What sustainability means to me, revisited

Leave a comment

Comments must be approved before appearing

* Required fields