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Innovative waste management practices on construction sites in Brussels: Lessons learned from pilots
Romnée A.1, Vrijders J.2 1,2
Belgian Building Research Institute, Laboratory of Sustainable Development, Brussels, Belgium, (+32) 26 55 78 37, E-Mail: ar@bbri.be, jvr@bbri.be
Abstract
In recent years, waste prevention and management have gained importance due to the economic and environmental impact of waste on construction sites. Although some innovative practices have already been experimentally put in practice, it remains difficult to apply them in densely built regions due to lack of space and time, and lack of knowledge regarding quantities produced and new solutions.
In order to improve the knowledge of the construction sector on waste management and to improve the environmental impact of construction works, several innovative practices, focusing on prevention and waste management, have been implemented and validated on ten pilot construction sites in Brussels.
For each of the pilot projects, an estimation of the amount and type of waste arising has been made, before the beginning of the construction works, in order to establish an economical and environmental optimized waste management scenario to be applied on site. Based on the quantities, several innovative approaches were implemented by contractors in collaboration with the supply chain actors of the construction site (waste collectors, material suppliers, material producers, architects and clients): the commitment of social economy enterprises to the sorting out and collection of waste on site ; the quantification and monitoring of arising waste ; the industrial symbiosis between contractors and other local economic actors; the reuse of materials salvaged on site ; specific recovery channels for closed-loop recycling. The paper describes the lessons learned from the experiments of these innovative practices and highlights on the conditions that need to be fulfilled in order to repeat the good practices on other construction sites. These pilot construction sites show that innovative waste management practices can provide large practical, economic and environmental advantages.
Keywords: innovative practices, waste management, pilot projects, construction sites,
circular economy.
Circular economy and construction waste management
Circular economy in the construction sector has gained huge interest given that the sector has to focus on minimizing raw materials exploitation and waste arising on construction site. Among other principles regarding construction design for flexibility and development of new business models, the circular economy considers waste as resources and asks to smartly prevent and manage waste. In practice, the circular economy minimizes the production of waste by repairing, maintaining, reusing products, remanufacturing and recycling materials (WEF, 2016).
A study in Great Britain shows that the main causes of construction waste production are: failing work methods, material over-ordering, inadequate storage of unprotected materials (weather and theft) and work that must be executed several times due to drawings or conceptual specifications not being clear enough (Zakar, 2008).
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Designing and building within a circular economy perspective is not just about building without waste, but about transforming the concept of waste into resources. This means, firstly that waste must be avoided, both in the design and in the implementation of products and materials on site, avoiding overproduction, overstocking, inefficient transport, redundant work, waiting times, and improper performance; and secondly, to find opportunities to turn waste into a resource.
The Brussels Capital-Region is a densely built region, generating more than 600000 tons of construction and demolition (C&D) waste each year. The Brussels Capital-Region government engaged in 2016 in favour of implementing a Regional action Plan for Circular Economy (PREC), with focus on prevention and management of construction waste, especially in renovation and construction projects (be.brussels, 2016). One concrete action in this plan is to implement and validate several innovative waste management practices on ten pilot construction or renovation sites in Brussels. The authors of this paper coordinate the realization of this concrete action of the PREC.
Summary of innovative waste management practices on pilot sites
Before the beginning of the construction works, an estimation of the amount and type of waste expected to arise on site has been made for each of the pilot projects. The aim of this estimation was to establish an economical and environmental optimized waste management scenario to be applied on site.
The estimation is based on the analysis of the technical drawings and specifications and on waste production ratios. These waste production ratios are extremely variable since they depend on many factors such as the type of material, the type and design of the building or the constructive processes. Nonetheless, based on several references (ADEME, 2001, GEDEC, 2004, WRAP, 2012), on site monitoring experiments, own experience and on discussions with contractors and material producers, a database was established of waste production ratios for many construction materials that was used to estimate the type and amount of waste (see Figure 1).
Figure 1. Extract from the wastage rate database.
Based on the types and the quantities of waste expected to arise on site, several innovative approaches were developed in order to optimize both economic and environmental aspects of
Wastage Rate
Wastage Rate
Concrete - Block, Slab, Paving stone 4% Gypsum / Plaster - Plastering 3%
Concrete - Poured 2% Gypsum / Plaster - Plasterboard 7%
Concrete - Prefab 1% Insulation - Rock wool 5%
Cellular concrete - Block 7% Insulation - Glass wool 5%
Cellular concrete - Lintels 2% Insulation - EPS 5%
Wood - (other) 8% Metal frame 3%
Wood - Carpentry 8% Bituminous asphalt steamer 3%
Wood - Formwork 90% Floor tile 5%
Wood - Panel 5% Gypsum / Plaster - Plaster block 8%
Wood - Outside covering 8% Plastic - piping PVC, PE 2%
Wood - Inside covering 8% Silico-limestone - Block 7%
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waste management. On each pilot site, a monitoring of waste production is established in order to validate the waste estimation.
On relatively small projects, innovative approaches focused mainly on selective waste management in order to reduce the waste management cost due to mixing waste containers. Some renovation projects went further and put into practice deconstruction and reuse on site (see Figure 2).
Figure 2. Deconstruction and selective waste management applied as waste management on small
projects (pictures: BBRI).
On larger and very large projects (up to 60000 m²), innovative approaches mainly focused on management of specific waste fractions for which innovative recycling or reuse processes exist. Several material producers set up collecting systems for the collection of cut-offsin the implementation of their products to reintroduce them into production cycles. These collection methods are tested on several pilot sites (see Figure 3). Other pilot sites are setting up industrial symbiosis with other local economic actors for the reuse of certain waste from the site (mainly formwork) as resources for the production of new products. Collaboration with social economy enterprises is also being tested for sorting, storing containers and maintaining a clean building site.
Figure 3. Specific waste fraction collection, industrial symbiosis and social economy applied as waste
management on huge projects (pictures: BBRI and LEVANTO). Lessons learned from pilot sites
Innovative waste management practices, experimented on these ten pilot sites, can take many forms. First of all, the waste production must be predicted before the beginning of the construction works and follow up by a waste production monitoring during the construction. Despite estimates recognized by contractors as reliable, there are often significant discrepancies between these estimates and monitoring. The reasons of these discrepancies rely mainly to the bulking factors of materials thrown into a container (measurement of the vacuum part in a container) and to construction processes that may consume a large amount of materials not preliminary mentioned into the technical specification (for example, formwork, packaging, protective covering materials, etc.)Secondly, innovative waste management practices also refer to the existence of recycling channels for certain specific wastes. Many materials such as rock wool, glass wool, plastic wrap, bituminous roofing, etc. may be sorted on site to be to be recycled in closed loop by the producer. On one hand, these
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specific treatment streams require sufficient available place on site to be implemented and large volumes of waste in order to be profitable. Therefore, small-scale projects cannot implement such practices. In addition, the number of on-site sorted waste fractions is directly linked to the size of the project and by the way to the amount of waste produced. For large-scale projects, if there is no place to install many containers and since the price of the mixed container is not sufficiently dissuasive, contractors are not encouraged to sort several fractions. Nonetheless, for small-scale projects, in order to reduce its management costs, the contractor often sorts several fractions on site that he collects in small bags before personally evacuating them to a consolidation centre.
Thirdly, the innovation may also consider the human resource management. Nowadays, many languages are spoken on construction site and the waste management is not always usual for many nationalities. It is therefore important to train and to inform every worker on site with simple and comprehensive waste collecting signage.
Since sorting waste, storing containers and maintaining a clean building site represent a cost for the contractor, he may be interested to subcontract on-site waste management to a social economy enterprise. For large-scale projects, a social economy enterprise may install on-site a kind of waste disposal centre in order to sort numerous waste fractions. Since the cost of a social is lower than the price of a skilled worker, the benefit of this action may be found in the sorting and the storing of the containers. In order to be really efficient, social workers have to be considered on site as common subcontractors in charge of the implementation of the waste management plan.
Fourthly, consider waste as a resource, in a circular economy perspective, is a form of innovative waste management practice. For renovation projects, the deconstruction of the constructed elements can not only reduce the amount of waste produced but also encourage reuse on-site or off-site. The deconstruction with a view to reuse has to be carefully planned before the beginning of the demolition part of the renovation project. Moreover, waste that arise on-site during construction works may interest other economic activities surrounding the construction site. An industrial symbiosis may therefore be implemented in order to give or to sale what it is considered as waste for the site and as a resource for someone else. This kind of sharing economy represents economic benefits for both actors since the site does not have to pay to get rid of some waste types and the purchaser receives or pays a lower cost compared to virgin materials. This application of the sharing economy principle is really efficient if both actors are located nearly from each other in order to reduce transport costs and if they are not competitors in the same market sector.
The implementation of these innovative approaches depends on a lot of factors relative to the size of the site and the contractor. Mostly, contractors will implement these practices if they can save money on waste management. The realization of a waste management plan prior to the start of the project is therefore essential to evaluate the benefit of each action.
These pilot construction sites show that innovative waste management practices can provide large practical, economic and environmental advantages.
Funding
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References
- Agence de l’Environnement et de la Maitrise de l’Energie (ADEME), Gestion sélective des déchets sur les chantiers de construction : Ratios techniques et économiques, ADEME, 2001 - be.brussels, Programme Régional en Economie Circulaire 2016-2020 - Mobiliser les ressources et minimiser les richesses perdues : Pour une économie régionale innovante, Brussels, march 2016,
- GEDEC, Déclaration de gestion des déchets de chantier : mini-guide pour une estimation rapide du volume de déchets générés sur le chantier, Genève, 2004
- World Economic Forum, Shaping the Future of Construction – A breakthrough in Mindset and technology, World Economic Forum, 2016
- Waste and Ressources Action Programme (WRAP), BRE SMARTWASTE Summary Data, WRAP, London, 2012
