Concrete and the circular economy

Chris Stanley of the Concrete Block Association explains where concrete can fit into a circular economy, and help to boost sustainable housebuilding.

Talk of the circular economy has penetrated every part of the construction industry recently, and rightly so. The phrase is perhaps not used widely enough, but the concept is essential to transforming our methods and practices.

Taking environmental concerns into account is no longer optional – they are as important as capital costs in propelling the housebuilding industry forward. Whether new build or renovation, flexibility is key, as we should be building to allow room for future retrofit, not future demolition.

Particularly for manufacturers of building products, the circular economic model is a proven way to achieve greater sustainability. Reducing, reusing, recycling, and recovering energy from products at end-of-life and beyond is now central to the business strategies of our members at the Concrete Block Association (CBA).

Masonry structures are well-known to be robust – a fundamental property for whole-life performance. Yet, masonry also possesses unique attributes which minimise CO2 emissions. Concrete blocks can considerably minimise embodied CO2 when specified correctly, for example. Operational emissions from heating and cooling a building can also be notably reduced due to the materials’ thermal mass qualities, and without compromising on comfort.

This is merely one example of how concrete blocks can aid the transition towards a greener, environmentally friendly built environment. There are however more direct actions being taken within the building products sector in order to ensure best practice and a better future.

The fact of the matter

In the past decade, the industry has made considerable headway in significantly lowering emissions resulting from the production of concrete blocks. We’ve achieved a reduction of 13 per cent carbon intensity since 2008 for example, facilitated by improvements to the manufacturing process itself.

The impact of emissions through the transportation of goods is equally low in relation to other building products, due to the fact blocks rarely need to travel far. A wide variety of concrete blocks are produced in the UK, made in local production facilities from constituents delivered locally, thus minimising their environmental footprint.

There’s no denying that cement accounts for much of a concrete block’s impact. While it remains an indispensable part of the composition, it can now be blended with lower impact cementitious materials to reduce the overall embodied CO2. In the UK, this is now standard practice, with two of the most commonly used substances, fly ash and ground granulated blast furnace slag (GGBS), being industry by-products finding a new purpose.

Critical mass

Adapting to the inconvenient truth of climate change, we need to double our efforts to ensure the homes we build are comfortable and energy efficient. The core materials used are vastly influential in this regard. Providing inertia against temperature fluctuations is key, as it will help homeowners by potentially reducing energy bills through improved energy efficiency.

One of the most important ways the whole-life performance of a building can be improved is through taking advantage of a concrete block’s thermal mass. The material absorbs and stores heat during the day, which is then removed overnight, passively through ventilation. This gives the structure a natural, alternative method to control temperature. When heat is released gradually, the need to resort to air conditioning or central heating is minimised. This also reduces the overheating risk.

Second nature

Of course, fundamental to the concept of the circular economy is casting our eyes beyond end of life and finding ways to reuse and recycle products. After their initial lifespan, concrete blocks can find a second life in groundworks, piling mats and landscaping. Crushed, they can be used as recycled aggregate. In fact, CBA members have publicly committed to only manufacturing blocks that are fully recyclable.

Further CO2 is released in deconstruction and waste processing at the end of a building’s life, therefore improving how building products are manufactured and specified is everyone’s responsibility.

It is vitally important that producers introduce measures to reduce energy consumption, focusing on the elimination of waste and the adoption of environmental and sustainable management systems that go further than what is legally required.

Lean & flexible design

The wider housebuilding and architectural industries need to also be fully invested in order for the circular economy concept to be effective. Everybody needs to be on board with the message of material efficiency and lean design, whereby we use less resources and use them in a smarter way.

Luckily, our technologies have been swiftly improving, and innovation is helping us to achieve this. Calculating the optimal build-up of structures needed for best energy efficiency is now possible.

For a building to be able to assume new uses, incorporating new technologies and the changing climate, flexibility must be built in from the outset. We have not yet arrived at a point where construction and manufacturing are truly ‘circular,’ but we have taken leaps towards it. Maintaining the momentum is key, even through these economically uncertain times.

Chris Stanley is housing manager at the Concrete Block Association