By Gordon Brown
According to the World Green Building Council the construction sector accounts for up to 40% of waste in landfill sites worldwide, and while this figure may be lower in South Africa construction remains a significant contributor to landfill content. The National Waste Information Baseline Report (DEA2012) indicates that the construction sector is responsible for 8% of all waste generated, although it is unclear whether this number includes the waste from product suppliers during production, which is significant. Importantly this statistic also excludes the ongoing operational waste generated in all occupied buildings, and so is understated.
Construction waste is made up of aggregates (concrete, stones, bricks) and soils, wood, metals, glass, biodegradable waste, plastic, insulation and gypsum based materials, paper and cardboard, a very high percentage of which are reusable or recyclable if separated at source. Currently 16% of construction waste is recycled in South Africa (NWIBR).
Trends and forces for change
The green building movement is being spearheaded by the CSIR and the Green Building Council of South Africa, the latter having set up rating tools that award points for, amongst other green building aspects, resource efficiency for designs which reduce waste.
Construction waste emanates due in some part to inconsiderate design, construction, maintenance, renovation and demolition, as well as supplier considerations such as packaging. Intelligent design and best practices during each phase can significantly reduce waste.
Architects and engineers have a very significant opportunity to affect the waste generated through the life cycle of a building by determining the method of construction and the materials specified. From simple strategies like utilising building rubble onsite as fill for instance, or reusing items from demolished buildings such as wooden window frames, by specifying materials with recycled content, and adopting strategies and building methods geared to dismantling and designed for deconstruction – design affects everything, and with careful planning and consideration given to waste and reusing materials at concept stage, much waste to landfill can be avoided. An example of this is modular construction.
It is also very important at design stage to consider how the building is going to manage operational waste while the building is occupied – sufficient space will be required for recycling storage and sorting, as well as the access to various floors and of course for collection.
At a waste management level, there are a number of best practices to ensure maximum recyclability of materials on site:
- Make this consideration a key performance criterion when appointing contractors
- Set targets for % of waste not to go to landfill (refer to Green Star SA for achievable best practice)
- Have a waste management plan drawn up according to best practice prior to beginning the project(ie. Part of the tender/brief document)
- Have correctly marked skips for certain waste streams
- Ensure that the correct paper work is filed for all items removed from site
- Safe disposal tickets for hazardous waste must be kept
Keep a monthly and overall project reports of all waste and at the conclusion of the project –confirm whether targets are being achieved
There are many great examples of achieving excellent standards in construction waste management, one of these was the first Green Star SA certified project in South Africa, the Nedbank Phase II building in Sandton – in 2008 the contractor was initially concerned about the high standards set within Green Star SA for waste diverted from landfill (30, 50, or 70% of construction waste). By the end of the project, with the good waste management programme they employed, they were surprised at the incredible success – they were able to divert over 90% of their construction waste from landfill. This is a significant achievement, and is replicable across all construction projects by implementing good waste management programmes.
Product and Material Suppliers suppliers have huge potential to reduce the amount of waste going to landfill. Many suppliers could provide their materials to site in a way that requires less or no ‘packaging’, or packaging that is recyclable, and also ensure that their contract with the construction contractors is such that their packaging is returned to them directly for recycling or reuse. ‘Packaging’ is a significant waste source. (Packaging refers to anything that is not the actual material that will be used and left installed on site.) Besides the ‘packaging’ referred to, the product suppliers are also responsible for a significant amount of waste at their own factory or storage houses – the contractors and design team can have a significant influence on the downstream waste impacts by contracting only with suppliers that minimise their waste production and maximise recycling and reuse of waste.
The building in operation
During the course of a buildings life it will require multiple new light bulbs, new carpets and flooring, painting, filling, stripping, windows due to breakages etc. Good building managers and operators can make the necessary effort to separate materials.
The Green Star SA rating tools will reward designers for making provision for separation operations within the utilities area of the building, and building maintenance would utilise these facilities for its waste streams. It is important to have both the space designed to store and sort the waste for collection, but also to have waste management policies in place for the ongoing operation while the building is occupied.
As the market places a greater value on sustainability, products with recyclable content become more sought after. Masonry bricks made from crushed aggregates, tiles made from recycled plastics, are just two examples of products gaining traction.
On the waste disposal side, costs are rising but it remains relatively cheap to dispose of construction waste to landfill, cheaper in fact than general waste disposal which costs R272.00 per ton.
As costs increase so too does illegal dumping, which poses an environmental problem, and municipalities need to consider increasing the penalties imposed on transgressors and to find ways of policing illegal dumping more effectively. Perhaps funds from increased charges for legal dumping can be directed in part to policing illegal dumping.
The construction sector has a massive impact and a commensurate opportunity to effect positive and meaningful change. Through a combination of product design and innovation, building design and methods, and through best practice waste management on site the sector can radically reduce the amount of waste created and significantly improve on the rate of recycling.
Source: Green Building Handbook Volume 6
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The City of Joburg and Pikitup are rolling out a project to produce energy from landfill waste to alleviate pressure on the national grid.
The idea is to extract gas from waste generated from your trash, to produce electricity as an alternate source of energy to ease strain on the overburdened national grid.
The city anticipates that by 2016, around 19 megawatts of electricity will be produced – enough electricity to power 16 500 medium-sized houses, The Star reports. The project will become the biggest landfill gas-to-energy project in the country once completed.
A similar project being piloted at the Robinson Deep landfill in the south of Joburg has already shown good results, Pikitup GM for disposals David Harris said.
“We will install connectors to our infrastructure and within the next year or two we want to start generating power from this gas. Five operational landfill sites [Robinson Deep, Marie Louise, Linbro Park, Ennerdale, Goudkoppies and Witkoppies] will produce electricity for the city from converting gas,” he said.
The gas is currently being extracted and the toxic gasses burnt through a flare to minimise exposure to methane.
While methane gas is a handy alternative to conventional energy, energy analyst Roger Lilley says it hasn’t always been a popular choice given the significant costs involved in storing and distributing it.
“The gas in question is methane, which is commonly obtained from landfill sites when vegetables or any biodegradable waste degrade and it produces methane. But it must be stored properly and distributed, and there are considerable costs involved,” he told Business Day.
Further than a tool to help alleviate the power crisis, retrieving the methane gas from waste means harmful biogases aren’t being emitted into the environment – an initiative that could earn the city carbon credits on international markets.
Harris said there was enough gas in reserve to run the project for the next 15-20 years, but that gas production rates could vary depending on influencing factors including age and composition of waste, the temperature and moisture content of each site.
Source: The Star, Business Day