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Buildings

What we build and the way we build it makes a massive impact on the environment. Globally, the construction sector accounts for an estimated 11 per cent of greenhouse gas emissions, not just through the use of heavy machinery such as cranes and drills, but also because of the carbon cost of extracting and processing materials such as steel and concrete. When those materials reach the end of their lives, that generates a huge amount of waste.

The most effective way to reduce construction鈥檚 impact is to avoid building afresh wherever possible by retrofitting old buildings. This is the aim of initiatives such as the Re:fit scheme, originally developed by the Greater London Authority in 2009 and . In London, its aim is to introduce energy-efficiency retrofits in 40 per cent of the city鈥檚 publicly owned buildings by 2025. When buildings do need to be knocked down, we must move away from the current practice where everything, including concrete foundations, is ripped out 鈥� something that often isn鈥檛 necessary, says engineer at the University of Strathclyde, UK. And what is removed needs to be reused where possible. One organisation working on this is the Dutch non-profit Madaster Foundation. It has created a 鈥渕aterial passport鈥� that registers the materials used in a building, meaning people can plan to reuse them at the end of the building鈥檚 life.

Using more sustainable construction materials in the first place would also help. Low-carbon concrete, high-tech wood products and even are among the alternatives being developed. Finnish company Betolar makes bricks and other materials from mining and forestry waste. It gets around the varying composition of these waste streams by using a machine-learning algorithm to constantly tweak its recipe.

But there is a major hurdle to using new, sustainable building materials, says Lunn. Insurance companies are often loath to cover buildings made with innovative materials whose long-term performance isn鈥檛 guaranteed. Lunn reckons the way forward is to install sensors in buildings that monitor the performance of materials in real time, and give early warning of any degradation. 鈥淲e need an insurance industry that will accept some level of risk,鈥� she says.

Clothing

The number of garments produced worldwide , according to a report by the Ellen MacArthur Foundation, which works towards a more circular economy (see 鈥淭he end of waste: The grand plan to build a truly circular economy鈥�). That was driven by more people wearing more clothes, but also by the rise of cheap 鈥渇ast fashion鈥�, which has led to the average garment being worn fewer times before being discarded.

Some 73 per cent of the materials used to make them end up being sent to landfill or incinerated 鈥� a truckload of clothes every second. And making them is resource-intensive, whether they are artificial fibres derived largely from hydrocarbons, or cotton, which takes a lot of land, water and fertiliser to grow. In 2015, the equivalent of 1.2 gigatonnes of carbon dioxide came from producing fibres and turning them into clothes, more than 2 per cent of global greenhouse gas emissions.

How can we slow fast fashion down? One way is to view clothes not as a one-off purchase, but as a service you draw on as needed. A few years ago, Reima, a Finnish children鈥檚 clothing company, launched an initiative called return clothes when they are outgrown. Reima sells them again, and the parents got some money back. While this scheme is no longer open to new subscribers, similar rental models are springing up elsewhere.

Even rented clothes eventually wear out though, and recycling clothes is no cakewalk, particularly those made of cotton. Old garments can be shredded to give strands of cotton, but these are shorter than the original ones, making clothing spun from them lower quality. , a company based near Helsinki in Finland, uses a chemical process to break down cotton fibres into a solution of cellulose that can be crystallised into new ones. Clothing firm H&M is an investor, and the company behind the Tommy Hilfiger brand is a customer. 鈥淲e estimate that we can be 20 per cent cheaper than cotton grown in the conventional way,鈥� says Petri Alava, the firm鈥檚 co-founder.

Scaling it up, though, would require much better-organised systems for collecting used textiles. This is beginning to happen: in 2018, for example, the European Union ruled that member states will have to separate textiles from other waste by 2025.

A longer-term solution might be not to use cotton or hydrocarbon-derived materials for clothes at all, but bio-based polymers grown by vats of microbes. One UK-based company called that can be extruded from a gel into a silk-like fibre.

Electronics

In 2019, researchers at the University of Plymouth, UK, minced a smartphone to a fine powder in a blender. They found 33 grams of iron, 13 grams of silicon and a plethora of other rare and expensive elements, including 36 milligrams of gold. All in all, the average smartphone contains more than 30 different elements, from lithium and cobalt in its battery to rare earth elements in its screen. Recycling this complex cocktail requires sorting the phone鈥檚 components out by hand, followed by the use of magnets and energy-intensive chemical processes.

Few people bother to hand over their old phones anyway. In the UK alone, 125 million used phones are estimated to be languishing in drawers. And we generate shocking amounts of electronic waste: the countries of North and South America, for example, . Only 9 per cent of this was recycled.

There are ways to do things better. Apple has developed a robot, called Daisy, that carefully sorts the different components of each phone, enabling it to recover more metal than the traditional e-waste recycling process. The company says the robot can take apart 200 iPhones per hour.

New laws aimed at increasing the repairability of goods (see 鈥淭he end of waste: The grand plan to build a truly circular economy鈥�) might also help make it easier for people to replace screens and batteries and upgrade memories in their phones.

In November 2021, Apple, which has historically been resistant to its customers tinkering with their phones, announced a scheme to allow people to , screens and cameras for self-service repair.

Redesigning phones with greater modularity in mind would also help. Google took on Phonebloks, a modular phone concept developed by the Dutch designer Dave Hakkens, rebilling it as Project Ara, but then binned it in 2016. Other, slightly less modular smartphones have since been developed by companies espousing more circular principles, including the Dutch-based Fairphone, whose

Plastics

Many everyday objects are made of plastic, a material derived from crude oil. If we want to build a circular economy, wouldn鈥檛 it be better to make crisp packets, bottles, computer cases and so on from plant-derived materials?

Of course, oil is itself plant-derived 鈥� it鈥檚 just that the plants it is derived from lived hundreds of millions of years ago, making it a non-renewable resource. The argument with materials based on plants living now is that you can return the organic molecules they are made from to the soil in relatively short order, where they can be used to grow new plants 鈥� and avoid the scourge of long-lived microplastic pollution to boot.

But the idea of biodegradability that this is based on is a slippery concept. 鈥淧eople consider these biodegradable materials environmentally 鈥極K鈥� like, they magically disappear,鈥� says . 鈥淏ut that is absolutely not the case.鈥� Many materials labelled as biodegradable or compostable typically won鈥檛 break down unless they are subjected to industrial composting conditions, meaning high humidity, temperatures of up to 70掳C and a special cocktail of microbes. Biodegradable plastics tossed into landfill can still last a very long time.

Whether such materials really are environmentally friendly depends on how they are sourced, how intensively they must be processed and whether they are eventually recycled or end up as waste. A rare few come up trumps, says Fabbri, such as biopolyethylene, a material derived from plants such as corn that is chemically identical to the stuff made from crude oil. In most cases, things are less clear-cut. In 2018, Fabbri completed a two-year study for the European Union that , including nanocellulose, which can be used for applications ranging from antimicrobial films to medical scaffolds, and lignin, the main molecular component of wood. Several companies already make things like pots for cosmetics from wood industry waste streams.

An alternative might be 鈥渋nfinitely鈥� recyclable plastics. What鈥檚 thought to be the first example, called PBTL, was developed by Eugene Chen at Colorado State University in 2020. Suitable for things like packaging, car parts and construction materials, at the end of its useful life, it can be heated to 100掳C in the presence of a catalyst to break it down into fresh polymer. With efficient waste collection systems 鈥� far from a given 鈥� such materials would be a truly circular solution.