Habtoor Leighton Group’s senior sustainability engineer, Wissam Yassine PQP LEED AP PMP, shares his case study reusing the waste created in construction and demolition; a sector accounting for 60% of the UAE’s total waste generation
The UAE infamously has one of the highest per capita waste generation rates in the world. To put it in numbers, an average UAE resident produces 3150 kg of waste annually, 6 times the amount of waste generated by an average French resident.
Currently more than 75% of that waste ends up in landfill; this constitutes an important lost opportunity for recycling waste and gaining environmental and economic benefits. The Center of Waste Management in Abu Dhabi estimates that the UAE economy losses AED 1.5 billion a year due to landfilling valuable waste which can be otherwise recycled into useful products.
Figure 1: Breakdown of waste in Abu Dhabi (Source: Statistics Center, Abu Dhabi)
Tapping into this lost opportunity starts by understanding the breakdown of waste in the UAE. Figure 1 demonstrates that the construction and demolition sector is responsible for more than 60% of the total waste generated in the UAE, far more than any other sector. Clearly, the construction industry can reveal great benefits by developing programs that segregate and recycle construction waste.
Construction recycling at Arzanah Medical Complex
One such pilot program was developed by Habtoor Leighton Group (HLG) for the Arzanah Medical Complex construction project in Abu Dhabi, a project aiming to be the first LEED Gold certified health care facility in the Middle East.
The program was an instant success and resulted in diverting 70% of construction waste from landfill.
In total 3061 tons of construction waste was generated during the 20 month period since HLG started working on the project. Of this, 2148 tons were recycled or reused and only 913 tons were sent to landfill. The breakdown of waste generated and how it was handled is demonstrated in figure 2 below.
Life cycle assessment
To fully appreciate the environmental benefits of the recycling program, we modeled the outcomes of the program using Life Cycle Assessment. LCA is a technique to assess environmental impacts associated with all the stages of a product or a process life from-cradle-to-grave (i.e., from raw material extraction through materials processing, manufacture, distribution, use, repair and maintenance, and disposal or recycling).
The power of LCA lies in its ability to quantify the environmental benefits achieved by a certain environmental program by comparing it to the business as usual scenario. Many tools are available that help conduct an LCA of processes or products, these make use of readily available environmental impact databases of all possible “unit processes”.
The benefits of our waste recycling program mainly stems from avoiding the extraction of the virgin material which the recycled material replaces and avoiding the impacts of landfilling the waste material. To quantify these benefits used an LCA software (SimaPro 7.3) to model both the recycling process and the business as usual process whereby waste is sent to landfill. Comparing the lifecycle impacts of these two processes we were able to determine the reduced impacts achieved by the recycling program.
Environmental benefits
The results of the LCA (Figure 3) demonstrate that the recycling program had significant environmental benefits across the four impacts categories which are: human health, ecosystem quality, climate change and resource use. The most significant benefits are in the human health category. This can attributed to the fact that recycling avoids the extraction and processing of virgin material, processes with detrimental health impacts on workers.
Another significant result is that recycling of steel is responsible for most of the environmental benefits, although in terms of weight it represents only 10% of the total recycled material. This demonstrates that per unit weight, recycling steel has a significantly higher environmental and human health benefits compared to recycling other materials. It is fortunate that the economics of recycling steel are also very strong, thus most waste steel in the majority of construction sites around the world is captured and reintroduced into the supply chain, resulting in an average of 80% recycled content in a typical steel product.
Green buildings
The total climate change benefits of the construction waste recycling program are equivalent to avoiding 108,120 kg of CO2 emissions. That is equivalent to the CO2 emitted in producing 180,200 kWh of electricity, enough to power a typical UAE apartment for 5 years!
Yet, construction waste recycling is often viewed as just another point collected in a green building rating system, with the focus often on optimizing the building energy and water performance.
While the energy and water consumption are indeed important, we believe greater emphasis should be placed by construction and engineering professionals on recycling construction waste, as this study demonstrates the significant environmental and human health benefits achieved by recycling.
This should also be complemented by governmental investments in modern and efficient construction waste recycling facilities, and legislation to ban dumping construction waste in landfills, which is something we are starting to see in the UAE.
Finally, an important challenge facing construction waste recycling going forward is the wrong perception about the quality and reliability of construction material made from recycled content.
This is leaving recycling plants with enormous quantities of recycled materials which are not being taken back by the market; this often leads to halting the operations of the recycling plants and sending recyclables to landfills, thus losing economic value and environmental benefits in the process.
The solution would be to increase awareness of the performance of recycled material and to build trust through third part independent testing of the performance of such material. Authorities should also play a role by requiring the use of a certain percentage of recycled material in all new construction, this will increase demand for recycled construction material and close the cycle so that the environmental and human health impacts of the construction industry are minimized.
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