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Green Homes: How to Lower the Carbon Footprint : Rammed Earth Brick

Rammed earth, as a construction technique, needs to make a comeback

Image Courtesy : Pexels

Last month, after I was done spreading awareness about the endangered sparrows on World Sparrow Day someone came up to me and said “Oh! so you are one of those environmentalists who care about the environment and nature and birds.” I just nodded and smiled not willing to go further on the discussion at that moment despite the fact my mind was so edging to say, “Well it’s about time we all must turn into environmentalist and nature lovers given the damage we have already done.”

So, being that ‘nature lover’ and ‘green energy enthusiast’ I set my mind forward on researching new methods of how to lower the carbon footprint. The construction and operation of buildings accounts for 37% of all energy use and 68% of all electricity demand. In fact, building operations are responsible for an estimated 30–40% of global greenhouse gas emissions.

John Straube in his book Green Building and Sustainability defines sustainable housing as “One that uses energy and material more effectively both in production and operation while polluting and damaging natural systems as little as possible.”

Achieving affordability by minimizing capital investment, however, has often proved to be a short-term solution that sacrifices long-term building functionality. When cheaper, lower-quality systems fail over time, building operating costs increase sharply and negatively impact both building owners and residents.

Measurable benefits

Home owners who have started to invest in solar arrays would perhaps benefit from lower hydro bills, a smaller carbon footprint and higher home value in the future. These advantages come at a high initial investment that should have you calculated potential gains.

Depending on the extent of sustainability design, the costs of green building often denote an initial capital cost investment termed “the green premium” which is higher as compared to the cost of conventional buildings. Newer technology and the requirement of special labor skills drive the cost in green building projects. However, careful planning and measured choices can minimize these upfront costs. Overall, the average green premium for affordable housing developments was found to be 2.4% above conventional development costs, although several green affordable housing developments had lower upfront capital costs than did conventional designs.

On an average, green buildings have 20–50% lower energy bills and significantly lower water expenses. Strategies to achieve these long-term savings are typically identified during the integrated design process, which is central to green building. Unlike a conventional design process, where architects, engineers, designers, builders, and owners fulfill their roles in isolation, integrated design emphasizes a team approach from the outset that involves joint performance goal setting, collaboration, and creative “outside the box” solutions.

Green Construction: Rammed Earth Brick

Rammed earth, as a construction technique, has stood the test of time. It has been used to create buildings around the world whose beauty and robustness are still visible today, like the Alhambra in Spain and the Great Wall of China, both built more than 1,000 years ago.

Traditional rammed earth is made of a mix of clay-rich soil, water and a natural stabilizer such as animal urine, plant fibers or bitumen. It is then compacted inside temporary form-works that are removed after the mix has dried and hardened. The resulting structure can withstand compressive forces of up to 2.5 megapascals (around 10% of the average compressive strength of modern bricks).

One of the major reasons for not using rammed earth more extensively is perhaps likely to be a lack of knowledge. Although rammed earth itself is old, research is quite a new field compared with other more traditional construction materials like concrete, steel, masonry and timber. Unfortunately, a lack of research means a lack of understanding of the material and its structural properties.

The good news is that the interest in environmentally friendly and affordable houses has never been bigger. Researchers from different backgrounds (engineering, materials science, architecture, chemistry, and more) are beginning to investigate the different properties of rammed earth with the aim of promoting this construction technique.

The walls can be reinforced using embedded timber beams or bamboo grids, and of course they need some architectural features to protect them from the rain and wind. Historical examples of buildings made of traditional rammed earth can be found in South America, China, India, the Middle East and North Africa.

In Europe, especially in France, Britain and Germany, traditional rammed earth is enjoying a resurgence, and several modern buildings have been constructed using the technique.

Although rammed earth does not have very good insulating properties, the walls are very thick (typically 250-800 mm), meaning that rammed earth buildings can easily produce comfortable indoor conditions in hot and arid places. Rammed earth walls breathe, hence they can regulate the indoor relative humidity, making it suitable for people with respiratory problems. The final texture of rammed earth walls is unique and beautiful, so they typically do not need any plaster or render.

Green Housing, is not a fad in next-gen housing but a step towards a sustainable future. Green affordable housing is not about the economy, the environment, or health – it is the culmination of all three.

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