What are Sustainable Materials?

We’re starting to realise the importance of building for the future without condemning it to the effects of climate change. You've probably heard about what you can do personally to reduce your environmental impact, but what else? The construction industry can also make a difference by committing to sustainable building. 

But if you’ve never put much thought into it before, you might not know how to tell how sustainable your work already is. One place to start your exploration is with the materials you use - literally the building bricks of sustainable construction.

Some materials are highly sustainable. Others are less so. But how is this decided? Well, there are several things that are considered when deciding how sustainable a material is, including:

• Origin - is it locally produced? You might think it doesn’t matter where you buy your materials from, but it can have a significant impact. Choosinglocal suppliers and manufacturers reduces the amount of transportation needed to get the material to your construction site, reducing the carbon footprint of the whole operation.

• Composite materials - does it consist of natural, sustainable resources? If the resources can be regrown, such as in the case of wood, this makes it a more sustainable material for use by future generations.

• Manufacturing process - is it energy efficient and carbon neutral? If the manufacturing process uses up a lot of energy and releases carbon into the atmosphere, this counts towards the environmental impact of using it in a building project. Manufacturing processes might also have byproducts which can be harmful to the environment, or they might be useful for other purposes or industries.

• Durability - will the material last a long time? A material that needs to be replaced every couple of years might have a greater environmental impact over a given time period than another material that is more durable.

• Afterlife - can the material be reused or recycled? In the event of the original building project being deconstructed or the components replaced, what happens to the material? If it can be reused or recycled, this extends its lifespan, spreading its carbon footprint over a greater length of time.

• Disposal - will the eventual disposal of the material add to its environmental impact? Biodegradable materials can break down and enrich the soil, whereas others might end up in landfill and pollute the environment for thousands of years to come.

These are just some of the ways we can evaluate how sustainable a material is. We might also consider how a particular material might reduce the environmental impacts of using the building in the future. For example, some materials are more energy efficient and insulating than others, which improves the overall energy efficiency of the occupants of the building in years to come. 

In addition, it’s important to remember that the use of sustainable materials can be combined with efforts to reduce pollution. For example, by installing energy or carbon capturing technologies, we can offset the impacts we have in other areas, thereby creating a more sustainable construction industry overall.

It’s clear that the building industry uses a great many different materials, all with varying levels of sustainability. In the sections below, we take a look at some common construction materials and evaluate their sustainability. 

It can be tempting to think that bricks must be pretty outdated in terms of sustainability, given that they’ve been around for thousands of years. They might have lasted this long because they’re useful, but are they still relevant as we focus on becoming more sustainable in the construction industry? 

The answer is yes. While there are some impacts caused by the manufacturing process - both in the mining of clay and the firing process which makes bricks strong - these are generally viewed to be outweighed by the good points. For starters, bricks are highly durable and don’t require much maintenance. Some brick buildings can stay standing for hundreds of years - and even when a brick building comes down, that’s not necessarily the end of the brick’s lifespan. There’s a market for reclaimed bricks, where the mortar is removed and the bricks used again in a new building project.

Additionally, the clay which is used to make bricks is a reasonably abundant resource available in many parts of the world. This means bricks can often be made with local clay, cutting down on transportation pollution. Furthermore, clay is usually found close to the top soil, which makes it less resource-intensive to mine for. Bricks are also one of the most energy efficient building materials around, meaning they help to keep heat inside homes. This therefore reduces the need for excessive heat generation.

Glass is an essential component of most buildings, as without it we wouldn’t have windows. But heat is lost more easily through glass than through walls - that’s part of the reason why we have curtains. So how does it rank as a sustainable material?

In fact, it ranks pretty highly. Glass is made from superheated sand, ash and limestone, all of which are abundant natural resources in most areas of the world. More importantly, once you have a piece of glass, you can simply melt it down, remould it and you have a new one. Because of this, glass is an infinitely recyclable material. This means that even glass which has broken - for example, a shattered window - can be made into a new sheet of glass for use in another project. And while it’s easy to break glass, it’s a reasonably durable material the rest of the time because it doesn’t rot or degrade.

Timber may seem like an easy one to consider. After all, it literally grows on trees. However, not all timber is made to the same levels of sustainability. The type of timber you choose can have a huge impact on how sustainable your building project is as a whole. Sustainable timber - i.e. timber that’s sourced from responsibly managed forests - is an excellent building material that retains all the carbon stored in the wood. Therefore, so long as the wood doesn’t burn and the forest owners plant new trees to replace the felled ones, the end result is more carbon removed from the atmosphere. 

It’s also reasonably durable, with some timber buildings lasting for hundreds of years. In terms of recycling and reuse, if timber can’t be reused in large beams for construction, it can be repurposed. For example, it can be used for building a fence, making wooden furniture or fueling log burner fires to heat homes. Even removing the stumps of felled trees allows them to be turned into wood chips for kindling or decorative bark.