Freshwater supplies around the world are becoming increasingly scarce as time goes on, with billions of people globally now lacking safe access to drinking water… and this is expected to increase in the future unless urgent action is taken now, given the combined pressures of climate change, population growth, urbanisation, water mismanagement and more frequent extreme weather events.
Figures show that the global population is now more than three times larger than it was in the middle of the 20th century and it’s predicted that it will hit 9.7 billion by 2050, peaking at almost ten billion come the mid-2080s.
This growth is being driven in large part by the fact that more and more people are now surviving to reproductive age, coupled with a gradual increase in human lifespan, accelerating migration and increasing urbanisation.
In addition, significant changes in fertility rates have been seen alongside this growth, both of which will have big implications for future generations.
Eco impact of construction
As population numbers grow and develop, it is inevitable that an increase will be seen in demand for water and food, as well as housing and other natural resources.
As such, it will become increasingly important to consider the environmental footprint of the global construction industry so as to ensure that provisions are made for growing numbers of people, without putting even more pressure on the natural world.
Construction activity uses a significant amount of water to carry out its various operations, as well as to produce the materials required for developments and for onsite activities.
As water stress and scarcity becomes an increasingly urgent issue around the world, the onus is sure to fall on developers far and wide to assess their water footprints and introduce changes as appropriate so as to make the built environment more resilient and less water intensive.
Life cycle analysis
In order to quantify the water footprint of buildings, life cycle analysis (LCA) needs to be carried out, alongside assessments of the overall environmental impact.
By approaching the problem in this way, water use can be calculated across the construction process as a whole, covering everything from material use and extraction to the demolition of a site at the end of its life.
Whole Building Life Cycle Assessment methodologies have been growing in importance for the construction industry, representing an accurate and reliable way to assess a building’s environmental impact, used by architects, designers and manufacturers for the purposes of eco design, green building certifications and so on.
The aim of green design is to reduce the impact of the built environment and make it more sustainable, designing and constructing buildings that use less water and energy, and fewer materials – and governments and building owners are now starting to move towards LCA methods to assess climate change and other impacts that buildings have on the environment.
By adopting LCA as a performance-based approach to choosing different building materials and ways of working, significant inroads can be made where sustainability is concerned.
The water footprint of different building materials
Construction industry water consumption can be difficult to quantify, given that the amount of water used for different materials and processes will vary quite significantly, depending on what material is used and the production methods involved.
It is necessary to take into account:
Direct water use
This is the volume of water used across the construction site for the likes of cleaning, mixing concrete, drinking water supplies and irrigation.
Indirect water use
This is the volume of water that goes into the different building materials that are used across the site, including manufacture, transport and building assembly/construction.
Life cycle of the building
This is the volume of water expected to be consumed throughout the building’s entire life cycle, including potable water, equipment operation and wastewater treatment.
Steel, cement and glass are some of the most commonly used construction materials around the world, requiring significant amounts of water in production, as well as creating water pollution during the manufacturing process.
Indirect water use is also associated with the energy required across the production chain of these materials, such as for electricity and cooling.
Brick manufacturing, meanwhile, is another essential aspect of construction – and one of the most water-intensive processes of them all.
A recent study published in the Journal of Cleaner Production, for example, found that the total water consumption footprint of a brick was 2.02 litres, made up of 84.8 per cent blue water and 15.2 per cent green water.
A blue water footprint refers to the volume of surface and groundwater used in the production of a good or service, while a green water footprint refers to the rainwater consumed during the production process. A grey water footprint refers to the volume of freshwater polluted by a product over the entire supply chain.
The grey water footprint of a brick was found to be 1.3 litres, which would have been higher if wastewater treatments hadn’t been in operation prior to effluent discharge.
The researchers concluded that the most effective way to reduce the water consumption of a brick was through the adoption of sustainable water management systems, with water regeneration schemes improving brick values by 56.4 per cent.
The implications of water scarcity for the built environment
As the issues of water stress and scarcity continue to affect communities all over the world, serious changes will need to be seen throughout the built environment to ensure the sustainability of architecture projects in the future.
For example, water-sensitive design will need to come to the fore (especially in urbanised areas) to ensure that the water cycle is better integrated and managed more effectively. This could include the recycling of both storm and groundwater, for instance, or addressing the issue of urban creep and redesigning paved areas to improve water absorption rates.
And, of course, from a purely business perspective, water shortages will see an increase in associated costs, so by focusing on more sustainable water-related practices, those in the industry will be able to drive down the total costs of construction projects… so it’s a win for business, as well as the environment.