As construction accelerates globally, implementing sustainable building practices is critical

Global building floor space is projected to double by 2060. This is the equivalent of adding an entire New York City to the world, every month, for 40 years. While most advocates focus on carbon reduction emissions to mitigate climate change, another pollution issue goes largely unnoticed. During construction, finishing trades need to wash their tools regularly. This everyday task uses large volumes of fresh water, turning it into liquid waste pollution that most sites discharge into sewage systems.

The world is facing a fresh-water shortage and a rapidly growing pollution problem from the environmental discharge of liquids and solids from wastewater treatment plants. Eliminating this pollution at the source can deliver transformational benefits to construction site productivity and safety.

Technological innovation has the power to transform construction site productivity and environmental impact at the same time. The construction industry is burdened with many legacy practices that must be addressed as the industry pivots to a green building economy.

Historically, green building efforts have been geared towards sustainable material choices and building technologies that create efficiency during the operational life of the building, while site-based construction practices have been of lesser concern. For this reason, many project teams have been slow to recognise the impact of legacy construction practices on productivity, health and the environment.

From office fit-outs at 40 square feet per gallon, to high-rise residential construction at five square feet per gallon, the pollution generated is extreme. But the biggest impact isn't just the volume of water wasted, it’s also the liquid waste pollution and the volume of solids that are washed from tools and discharged into local watersheds. This amounts to 7-10% of the liquid volume and up to 40 tonnes on a large construction project.

How do we know this? A recent study by Western Sydney and Deakin Universities verified and highlighted the waste volumes that are being recorded and eliminated by Washbox, one of the winners of the World Economic Forum’s Yes SF Uplink innovator challenge.

This waste contains microplastics, PFAS, titanium dioxide, dyes and various chemicals and toxins that originate from the resin and masonry-based finishes used in buildings, such as paint, stain, plaster, grout, adhesives and patching compounds.

The construction industry either directs trades to self-manage this waste or to install sewer-connected drums or slop sinks for trades to use, which discharge this waste directly into the sewer.

In simple terms, wastewater treatment plants are waste-separating facilities, removing solids from liquids before they each re-enter the environment. They do this primarily by letting solids settle before the wastewater is discharged back to the closest river or ocean as a liquid. This liquid is loaded with all the contaminants that were not removed by the process. Anything that was removed as a solid is called biomass and becomes fertiliser or landfill.

Making matters worse is the prevalence of combined sewer overflow systems that co-mingle both stormwater and wastewater in a single wastewater plant. When stormwater exceeds the plant’s capacity, raw wastewater from all points of source, including commercial and industrial sources, is diverted to the nearest waterway, without passing through the plant.

These discharges are having a significant impact on the quality of rivers and oceans around the world's major cities. As an example, Sydney Water in Sydney, Australia discharges 62% of wastewater after only a primary screening.

To mitigate pollution from entering the watershed, a large construction site called One Sydney Harbour, being built by Lendlease, has replaced the sewer-connected wastewater drums with Washbox. This closed-loop, multi-trade wash station continuously recycles a small batch of water from its holding tank to provide daily washing for trades' tools. The water is purified by the system after the automatic removal of the waste solids that have been washed off the tools. The waste solids dry in a series of filter bags and are responsibly disposed of as a solid.

Washbox records usage metrics, which in this case amounts to the equivalent of 735,000 litres of water, and the capture of over 35 tonnes of washed-in solids, such as paint, plaster and grout. Without Washbox this total volume of 735,000 litres of pollution would be discharged to the sewer.

Through innovative design thinking and the adoption of technology solutions, the construction industry has a big opportunity to change the way things have traditionally been done. By inspiring interdisciplinary knowledge-sharing and collaboration between diverse stakeholders, including the water and waste industry, environmentalists and construction professionals, we can drive transformative change.