books business circular economy sustainability

Review: Sustainable Materials Without the Hot Air

sustainable materialsA couple of months ago I reviewed the volume on urban transport, and here’s another in the series from UIT CambridgeSustainable Materials Without the Hot Air, by Julian Allwood and Johnathan Cullen. They and their team of eight spent five years researching sustainable materials, and this is the result.

The book looks at five of the world’s most important materials – steel, aluminium, cement, plastic and paper. “We now make more than 10 times our body weight of these five materials every year, for every person alive.” The focus is very much on the first two, as the CO2 emissions from metal production are considerable.

Because it’s rooted in original research, there’s a lot of information here that is new or difficult to find elsewhere. Their work on how and where steel and aluminium is used, and in what percentages, is a valuable contribution. The climate impact of these metals and how it could be mitigated could also turn out to be important.

It’s also a cross-discipline study, with lots of consultation with industry. The authors have talked to steel producers and car manufacturers and recyclers, and discovered various solutions that wouldn’t have emerged otherwise. They advise on how to make metals production more efficient, how to reduce wastage by designing parts to tessellate, and new ways to handle scrap directly rather than having to melt it down again.

There are lots of interesting case studies about how things could be designed differently, from car doors to tin cans. For example, railway tracks tend to wear out on the upper surface first. It’s a shame to have to use effort and energy replacing them and melting down the old ones when only one surface is worn. So they highlight an idea to produce double-headed track. When one side is worn, it can be flipped over and bolted down the other way. You could even make a rail with four sides and just rotate it.

Because they are working with and not for industry, the authors can consider options the metals companies won’t – the possibility of reducing demand. They conclude that with all the efficiency measures and new design options available, we could meet demand for steel in 2050 while still meeting carbon targets. They can’t reconcile aluminium in the same way, and suggest that demand reduction will also be necessary.

The book is highly detailed and technically expert, but manages to keep a light and accessible style. There are some creative ways to introduce topics, such as a photo essay comparing jam tarts made with a round cutter and a hexagonal cutter, to show how tessellating parts make better use of materials.

Occasionally this tips over into strained analogies or gimmicks. Apparently there’s an album of songs to accompany the book. They may be great, but I think I’ll pass. My only other complaint is that the author’s research was into steel and aluminium, and paper, plastic and cement get a short chapter each at the end of the book.

Overall though, Sustainable Materials Without the Hot Air is an imaginatively presented nook that would be useful to industry and to policy makers, and can be read through or used as a reference. Like the other books in the series, it’s available to read online for free.


  1. Thanks Jeremy for another insightful pointer. This is going straight onto my reading list! I work in the rail industry myself, so I’d be very interested to explore the implications… But since the concrete and steel industries are constantly trying to prove they are the “greener” choice, I’m surprised that cement gets such a small section of the book.

  2. It sounds like a promising study with some interesting and feasible results. I would like to know if it mention Hempcrete? This is a very strong and versatile alternative to cement/concrete. There is a growing market for this and there is more use of it, my father for one is designing a house using Hempcrete, a move to the future I hope.

    1. It gets a mention, though if I remember rightly there are problems with scale – easy enough to source it for a house, but the supply networks just aren’t there if you’re building a highway or an airport. They mention a few other alternatives, including using by-products of the steel industry in the concrete mix, and re-usable concrete components that could be used again when a building reaches the end of its life. For those of us working on smaller builds, hempcrete is a great alternative.

      1. Good to hear. There a problem with growing it, as you have to buy a licence to grow it, which it expensive. This puts people off. Small steps though 🙂

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