Research confirms clay brick’s reputation as the building material of choice in an environmentally-conscious industry due to its sustainable nature.
Currently there is growing pressure on enhancing the sustainability of new buildings, facilitated by consumers’ increasing awareness of energy efficiency in lowering environmental impacts. Furthermore, new regulations and legislations that target energy usage in buildings, such as SANS 10400XA and SANS 204, are adding to this pressure.
Heating and cooling consumes between 20% and 40% of the total operational energy of buildings in South Africa.
South Africa’s extreme climate presents a unique challenge for walling and roofing in terms of moderating temperatures, which makes clay brick an especially suitable option, as it has the natural ability to absorb heat during the day and release it at night. With the continuously rising energy costs, this is not only an environmentally-friendly solution, but also a cost-effective one in the long term.
More recently, and in an effort to avoid greenwashing in the marketplace, the Clay Brick Association of South Africa (ClayBrick.org) commissioned the University of Pretoria’s Department of Architecture to prove the life cycle value of Clay Brick products in a ground-breaking study titled “A lifecycle assessment for clay brick masonry walling in South Africa”.
At Coetzee, executive director of the CBA, says: “Through this lifecycle assessment (LCA), we will be able to calculate the environmental impact of a clay brick building, from the initial production of the material to construction and overall operation, in terms of energy usage, water consumption, resultant greenhouse gas emissions and recyclability, among others. The thermal performance of clay brick walling structures will also be compared to newer industrialised methods, such as the light-steel framed building systems.”
The clay brick LCA will be rolled out as a two-phased approach. The first stage will include a detailed assessment to determine the environmental impact of clay brick from raw material extraction through to manufacturing, transportation, construction, operational life of the building, and also the demolition, disposal and recycling thereof. The second phase will see a thermal modelling study offering comparative data between the thermal performance of clay brick walling and other alternate walling structures.
“What this research means to the clay brick industry is that we will be able to maintain the high ground when we talk about our products. We are proud of the partnering relationship established with the University of Pretoria and look forward to working with Professor Vosloo and his team in proving the sustainability of clay brick,” says Coetzee.
Clay brick’s longevity stems from its performance properties, widespread availability of clay and the fundamental simplicity in application.
While fired clay brick has definitive sustainable properties, the industry is continuously exploring new technologies and processes to reduce their carbon footprint. Some manufacturers have incorporated recycled content into their clay brick products. Others like Corobrik have converted six major brick plants to natural gas, which virtually halves the CO2 emissions per megajoule of energy, while others have invested in energy efficient firing technologies such as Langkloof Bricks, who recently adopted the Vertical Shaft Brick Kiln (SA-VSBK), which reduces the coal consumption required to fire the kilns by as much as 50%.
According to Pieter Blake, production director of Langkloof Bricks, the company has reduced wastage from 10% to less than 3%. “Langkloof Bricks monitored and met all of the emissions criteria as set out by the Department of Environmental Affairs’ Air Quality Management Directorate, which enabled us to register for carbon credits under the Clean Development Mechanism of the United Nations (UN),” says Blake. The company pioneered the technology in South Africa and won two coveted Eastern Cape Top Green Awards in 2012.
Modern brickmaking techniques ensure that clay brick products are stronger and more durable than ever.
The appeal of clay brick
The design flexibility and ageless appeal of clay brick makes it a popular choice for architects and specifiers, more so by its strength, durability, thermal performance and long-term cost-saving benefits.
Stephan van Niekerk, site manager at Dalmar Construction in Pretoria, says: “Materials used in the construction of buildings, as well as the lifestyle phases consume the most energy – and adds or subtracts significant value to the thermal efficiency of the building. From a risk point of view, the fact that clay brick is incombustible makes it an even better and safer option.”
Van Niekerk identifies a broad range of classifications when it comes to clay bricks, and mentions that its variety and flexibility simply add to its reputation as a quality building material. According to Van Niekerk, clay bricks can be classified as common bricks, face bricks, load-bearing bricks and engineering bricks.
The advantages of using clay bricks
Colour retention: Brick never fades – colour is fired at over 1000°C.
Energy saving: Clay brick homes stay cooler in the summer and warmer in winter.
Impact resistance: Resists man-made or natural impacts.
Maintenance: Little or no maintenance is required with proper design detailing and good clay brick practice.
Texture: Available in wide range of natural colours and textures, clay brick allows flexibility in design and aesthetic appearance.
A natural complement
Clay bricks feature an earthy richness, blending towards deeper reds and earthy browns, warm terracotta’s, as well as sandy and autumn brick colour tones. Their advantage is in the life they bring to buildings, and their local surrounds.
Occupancy Comfort and Energy-Efficient Design
When it comes to occupancy comfort and energy efficient design, recent research undertaken by WSP ‘Green by Design’ has validated double skin clay brick walls as a “best fit both economically and environmentally, and the appropriate solution for sustainable low cost housing in South Africa”.
The study was based on a 40m² house and compared the performance of different walling methods, including concrete blocks, which are typically used in the construction of low cost housing, as well as clay brick in two leaf and cavity wall formats and the light-steel frame building (LSFB) method.
Dirk Meyer, managing director of Corobrik says: “WSP’s brief was to evaluate which building methodology provided a ‘best fit’ for South African low cost housing in terms of initial cost, lifecycle cost, lifecycle energy cost and the upliftment of disadvantaged communities.”
The study found that, in each of the six climate zones, the clay brick masonry house required the lowest heating energy per annum in comparison to LSFB insulated lightweight walled houses. In each of the six climatic zones the clay brick masonry house was found to experience less time that occupants might get to experience significant thermal discomfort compared to the LSFB insulated lightweight walled alternatives.
Peter Kidger, director of marketing at Corobrik, says clay brick in South Africa’s modern design context is firmly on track. Many organisations around the world are fast subscribing to principles like the Green Building Council of South Africa’s (GBCSA) Green Star rating and the Carbon Disclosure Project (CDP) as a means of emphasising their commitment to best practice in sustainable development. While the full Lifecycle Assessment by Energetics in Australia found that the embodied energy of a house was less than 10 percent of total energy consumed no matter the construction type it also found that double-skin clay brick with insulation in the cavity outperformed insulated lightweight walls in terms of thermal comfort and lower heating and cooling energy to afford lower ‘total’ [embodied plus operational] greenhouse gas emissions over a 50 year lifecycle. The LCA commissioned by ClayBrick.org will hopefully reaffirm the comparisons found in the Australian study.”
Not only do clay bricks ensure significant savings on maintenance and replacement of less durable materials over a building’s lifecycle, but as face bricks they mitigate future carbon debt associated with maintenance reducing greenhouse gas emissions. They are also both reusable and fully recyclable, thereby also minimising waste. According to www.claybrick.org clay brick is confirmed as intrinsically “perfect” for defining a sustainable and more energy-efficient future.
Full thanks and acknowledgement are given to Corobrik, the Clay Brick Association (CBA), the University of Pretoria, Stephan van Niekerk (Dalmar Construction), Langkloof Bricks and Michael Chusid, RA, FCSI, Steven H Miller, CSI, and Julie Rapoport, PhD, PE, LEED AP: “The building bricks of sustainability”, for the information given to write this article.