Building sustainably means consuming less water
As global warming disrupts the water cycle through a succession of droughts and flooding, one question arises – will we run out of water one day? This is a valid concern, since human activities are only adding to this water stress. So how can we use this resource more sustainably in the construction sector?
Construction and water scarcity
There is a good reason we call the Earth the “blue planet”. Composed of 70% water, our beautiful world reminds us what a precious and essential resource it is – and one we must preserve. And yet our Earth is thirsty. According to the WHO (World Health Organization), one in three people in the world today do not have access to drinking water. And two-thirds of the world’s population will face water shortages by 2025, according to the United Nations.
Among the regions of the world most affected by this water stress are the Near East, the Middle East, Africa and Asia, as they suffer increasingly intense periods of drought. The paradox is that while three billion people experience a severe lack of water, others act as if this resource were inexhaustible. It is not… Water stress needs to be taken very seriously. In 2019, the World Economic Forum even identified the phenomenon as one of the greatest risks facing the world in the coming years. This is the result of increasingly violent climatic episodes, which permanently degrade our water reserves and exacerbate global social inequalities. And the situation is likely to worsen, as some experts expect the planet to become more than two degrees warmer by 2040. So, are we heading for a water shortage? Many experts are sounding the alarm, especially in the industrial and construction sectors, both of which consume large quantities of water.
Dry or wet construction?
From materials design to concrete production and use on worksites, construction consumes a lot of water. Too much. Yet to be truly sustainable, our construction sectors need to promote water resilience, both in their design and their uses. So how do we achieve this?
At the forefront of this growing awareness, dry construction is becoming increasingly popular. As its name suggests, this approach uses no water on worksites, and therefore no poured cement or concrete. Dry construction favors wood or steel walls and frameworks, ready to be assembled on site, without the need for a single drop of water. Other “dry” approaches include prefabrication of components in the factory, dry screeds and lightweight partitions, which significantly reduce water consumption during their manufacture. The results are extremely positive, including better control of the resource, optimal cost management and simple and rapid implementation.
Hard times for concrete
Could this be the end of wet construction? Let’s not jump to conclusions, as this is far from the end of the road for concrete. Long singled out for its environmentally suspect production methods, concrete is having a makeover as cement manufacturers innovate with new formulations designed to minimize their environmental footprint and more especially their water consumption. For instance, Chryso – a Saint-Gobain subsidiary – has developed Chryso® AMT 2, a grinding agent that significantly reduces the amount of mixing water required to produce concrete. This is the water incorporated into the binder and aggregate mixture, activating the setting of the concrete and giving it its plasticity.
Although concrete is now becoming more virtuous, other solutions stand out for their low water consumption. This is particularly true of many environmentally-friendly materials, which are part of a comprehensive approach to sustainable construction. Take adobe, for instance, which is widely used in Africa and desert areas. This age-old construction method uses unprocessed local earth to build the walls of a house. It is simple, healthy and above all very economical in terms of energy and water. Another alternative is hemp. Grown without any pesticides or irrigation, it is used in construction as natural insulation or in the form of hemp concrete to replace concrete blocks. These are laid dry, simply by interlocking the blocks like a Lego© set.
Best practice on worksites
Saving water therefore means taking an overall life-cycle approach (production/manufacturing of products, use, then recycling), while trying to consume as little water as possible throughout the process. But that is not enough. Because to win the battle for water, everyone must take action, including on worksites. There can be no question of pouring concrete in hot weather, for example, which would involve frequent watering of the screed. We are in an era of greater responsibility and it is important for worksites to minimize all their impacts by taking a more ecological approach, whether in terms of discharges into or adduction from the natural environment.
Preserving drinking water
Reuse of TWW (treated waste water), which was adopted by the European Union in 2020, provides one practical response to the risk of water shortages.
This method involves treating, filtering and disinfecting used water in a treatment plant, before returning it to the site or using it for agricultural irrigation. This is an effective solution, fully in line with the circular economy, while preserving drinking water resources.
As well as wastewater, there is also “unconventional” water, such as rainwater and runoff water, which are also resources to be exploited. In Chennai, India, for example, the Saint-Gobain Glass and Sekurit plants collect rainwater from roofs in collection containers to irrigate an urban forest. During the monsoon, water tanks also store excess water to supply the plants.
These types of industrial initiatives are now echoed in cities and residential housing. Some municipalities have established rainwater harvesting systems, for example.
As you will have understood, faced with the climate challenge and the impact of human activities, it is urgent to adopt a more frugal use of water, at national level as well as the level of a building. New smart-sensor, smart-building and digital-twin technologies could come to the rescue, to ensure more virtuous management of water, as is already the case with energy.
* source document from Sispea (the French National Observatory of Public Water and Sanitation Services) and the OFB (French Biodiversity Office)
Photos Credits : Eyeem/tomasz zajda