How Sustainable is your External Wall Cladding?

When it comes to designing and building a home, there’s plenty you can do to make the process as eco-friendly as possible. Choosing the right external wall cladding can reduce the embodied energy in your building materials, improve your home’s energy efficiency and more. So, let’s have a look at how different wall cladding products perform in terms of sustainability.

Sustainability Factors

When you examine a wall cladding material in terms of sustainability, you need to consider four factors.

• Embodied Energy

Embodied energy refers to the energy used to manufacture the product. This can vary greatly between cladding materials, but you ideally want something that requires little energy to make. It’s also worth researching if and what waste products are created during the manufacturing process. These may mean the cladding has a further impact on the environment.

• Sourcing

All wall claddings have to come from somewhere. Raw materials will be harvested and processed in order to create the final product. Research where these raw materials come from, including how they are harvested and if they are renewable. Ideally, you want a cladding that is sourced in a sustainable fashion from renewable materials, although that isn’t always possible.

• Recycling

No cladding lasts forever and it will eventually need to be replaced. A sustainable cladding though can be recycled. It may be turned into other products or reused as cladding again. You always want to find out if your cladding is made from recycled materials.

• Energy Reductions

The sustainability factor most homeowners are concerned with is energy reductions. Some claddings have insulating properties, which can mean reduced power bills. However, not all claddings are effective insulators and some provide no insulation benefits at all.

Common Cladding Materials

• Timber

Timber external cladding can include a number of cladding styles, including weatherboards and reconstituted timber. As a result, the sustainability of timber cladding does differ according to the specific type, as well as any treatments needed to maintain the cladding.

In general, timber generally has a low embodied energy and is a renewable product. However, manufactured timber products like MDF and plywood can have an embodied energy five times higher than kiln dried hardwoods. If sourced from forest waste or designated plantations, it can also be fairly sustainable.

Unfortunately, it can be difficult to recycle timber cladding. This is often because the finishes and fixings used, as well as the existing joins, limit the reuse options. Chipping for mulch is an option but paint and treatments can make this unfeasible as the chemicals may leach into the surrounding environment.

Timber won’t do much for your home insulation, but it may provide some slight benefits depending on how thick the timber is and how it is sealed. It’s still recommended to use interior insulation to insulate your home effectively.

• Fibre Cement

In general, fibre cement has a fairly low embodied energy. According to YourHome.gov, it’s about on par with plasterboard, and significantly lower than materials like glass, engineered timber products and galvanised steel.

While the materials for cement are abundant and will be for many years to come, they aren’t renewable. It is also difficult to use recycled cement for cladding. Finishes can leave it unsuitable for new purposes and the removal or destruction process can leave the cladding damaged. So even though the raw materials aren’t renewable, it’s often cheaper to make new cement cladding than attempt to reuse or recycle it.

Further, fibre cement is not a strong insulator, so you will need to find other means to save power at home.

• Brick

Brick is a traditionally popular wall cladding material, but it isn’t the most sustainable available. It requires significant energy to convert the raw materials, like sand and clay, into bricks. However, brick still has a much lower embodied energy than metals like aluminium and steel.

The raw materials required for bricks are plentiful, but they aren’t renewable. Additionally, the removal of these materials from their natural environment can impact the local ecosystem. For instance, removing sand from riverbeds for bricks can change how rivers flow and drastically change the local landscape.

Thankfully, bricks can often be recycled. They can be reused in other projects, or turned into new bricks or fill, although this can depend on the strength of mortar used. If a lower-strength mortar is used, the brick is more likely to be recycled.

Finally, bricks aren’t particularly good insulators. While they provide some insulation effects, you will need to choose a suitable internal insulation material to do the majority of this work.

• Aluminium

Aluminium has the highest embodied energy of any cladding readily available on the market. This is because extracting raw aluminium and processing it for use is extremely complicated. There are many steps involved and a great deal of power is needed.

The raw aluminium ore, also known as bauxite, is the primary component of aluminium cladding. However, aluminium is incredibly easy to recycle without losing tensile strength and structural integrity. Most aluminium building products are made from recycled materials and can be further recycled once they reach the end of their useful life. The high embodied energy resulting from the manufacturing process can be offset by the opportunities for recycling and reuse.

• Steel

If you want a highly durable cladding, steel is an excellent choice. However, it’s not the most sustainable. It has a high embodied energy, with the extraction and refining process requiring large amounts of energy. Steel can also be quite heavy, which can increase the transport energy required.

Like other metals, steel is made from finite raw materials. While the required iron ore to create this iron-carbon alloy is plentiful now, it is required for a range of other products, creating an increasing demand.

Luckily, steel products, including steel cladding, are highly reusable and recyclable. You’ll even find that the majority of steel cladding is made from 40% recycled steel.

There are a range of wall claddings readily available, but if you want a highly sustainable option, you will need to do your research. Consider what is right for your home and fits within your budget. You may need to choose a product that is more sustainable in one area, rather than an all-round excellent performer.