In a recent speech Boris Johnson suggested that people could buy a new kettle in order to save money on their energy bills. Specifically, he suggested that a £20 kettle would save them £10 over the next year… A pretty small dent in the energy bills facing most families. But the kettle conundrum is actually quite interesting in terms of carbon.

When I moved into my flat, I had a very limited budget for furniture and even less for kitchen equipment and so I bought a cheap, supermarket own-brand, kettle. It got the job done and didn’t look horrific.

Now, several years on, with a little more disposable income and a lot more awareness of climate change, I had already been thinking about whether I should replace the kettle. My kettle has never been particularly efficient, sometimes it doesn’t turn off properly and continues to boil, and its full of limescale.

A new low-energy kettle would be much more efficient, but buying a new kettle has a number of issues. Firstly, the new kettle, as with anything, has a certain amount of embodied carbon. And given that kettles are usually a combination of metal and plastic, it’s unlikely to be low.

At this point I imagine you’re wondering why I’ve written quite so much about my kettle

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Secondly, I’d need to get rid of the original kettle and whilst there are plenty of places where you can take household appliances to be recycled, the process isn’t straightforward. The components would need to be separated and then a certain amount of energy would be required to re-process them into something else. Plus, I’m fairly sure that part of it would still ultimately end up in landfill.

So maybe I should hang on to my original kettle and change the way I use it? By making sure that I only fill it as much as I need and don’t get distracted while it’s boiling so that I end up boiling it twice, can I make do with what I have and hopefully achieve a small reduction in my energy use as well?

At this point I imagine you’re wondering why I’ve written quite so much about my kettle. The reason is that this dilemma is remarkably similar to considering whether to replace a building. And maybe a simple example like this can help us better explain these challenges to our clients.

If we’re considering an existing building then retaining the building is significantly better in terms of embodied carbon than demolishing it and rebuilding. We don’t send anything to landfill and we have a reduced consideration in terms of the embodied carbon of new materials.

There is often no clear answer but being able to set out the choices clearly is key to making better decisions

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A new building would have much higher embodied carbon but it would also have better insulation, new more efficient plant equipment and would require less maintenance, so the whole life carbon would be significantly lower. Retaining the existing building and upgrading it so that the energy performance is improved offers savings in terms of both embodied and whole life carbon, but is definitely a compromise in terms of performance.

Of course, all of this focuses on the carbon and ignores the costs involved and it’s easy to assume that making changes to reduce carbon have a cost impact. But is that really true? When it comes to buildings the perception is often that the lower carbon option is more expensive, and sometimes it definitely is, but that isn’t always the case.

Careful specification and well-informed designs can offer savings both in terms of carbon and in terms of cost but, just as with the kettle, it’s sometimes difficult to justify a large upfront cost even if it might offer savings in the long term. Spending £20 on a new kettle to save £10 doesn’t make much sense – unless that kettle is going to save you £10 every year for the next five years.

As well-informed professionals, a massive part of sustainable design needs to be effective communication. There is often no clear answer but being able to set out the choices clearly is key to making better decisions. Finding ways to explain complex technical problems has always been part of our role, but now more than ever it’s vital that we find ways to communicate these complexities so that they can be understood.

Something to think about while you’re waiting for the kettle to boil…

This article was originally published in Building Design