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A Guide to Designing Out Waste
September 27, 2020
| Leila Nattagh

This guide demonstrates the importance of design decisions in the generation of waste. In construction projects, waste can be significantly reduced by the use of established techniques and by working closely with clients and contractors as an integrated project team. This guide is suited for designers and engineers working on new construction or refurbishment projects.

Overview

This guide is a summary of WRAP’s guide on designing out waste (Found here).
WRAP (Waste & Resource Action Programme) is a British charity of circular economy experts. They work with businesses, individuals, and communities to reduce waste, develop sustainable products, and use resources efficiently.
This guide was created to help reduce waste on projects through intentional design. Through their research, WRAP has identified 5 basic principles that allow for minimal waste generation.

These principles are:

  • Design for Reuse & Recovery
  • Design for Off-site Construction
  • Design for Materials Optimization
  • Design for Waste Efficient Procurement
  • Design for Deconstruction & Flexibility

These principles should be applied as early as possible in the project life cycle, ideally starting at the feasibility study stage.

This gives the highest chance for achieving efficiencies in waste and cost reductions. These design principles are not to be added on at a later stage. By then, design options will be limited and there may be insufficient information or time to properly evaluate new options. It should be noted that these principles are applicable for both new construction and refurbishment projects.  

 

 

 

Design for Reuse and Recovery Questions:

  • Can any components of existing site be reused in the new development?
  • Can unsuitable soils be used for soil manufacture with PAS 100 compost?
  • Can a cut and fill balance be achieved with the ground conditions on site?
  • Can contaminated soils be remediated or encapsulated on site?
  • Can existing pavement be recycled into new pavement using cold recycling techniques?

Design for Reuse & Recovery

This is one of the most fundamental principles as it sets the stage for resource management throughout the life cycle of the project. Design for Reuse and Recovery aims to maximize efficient use of materials available on site. 

The first thought regarding this principle may be to import materials with high recycling content. Of course, this is true. However, it also includes other opportunities that relate to reuse and recycling of products on site such as those outlines in the highlighted box, Questions to Consider.

Design for Off-site Construction Questions:

  • Can any part of the design be manufactured off site?
  • Can site activities become a process of assembly rather than construction?

Design for Off-Site Construction.

The benefits of off-site production in the construction industry have the potential to considerably reduce waste on site. Its application can also reduce the amount of on-site activities, allowing the project to advance more efficiently.

Often called Modern Methods of Construction, off-site construction is part of a group of approaches to more efficient construction. Examples in civil engineering, include use of prefabricated units such as manholes; use of precast components for retaining walls, bridges and other structures; use of precast piles rather than cast in-situ; and use of precast tunnel segments rather than cast in-situ tunnel linings.

Yes, these examples all involve concrete. Applications where precast concrete can be used instead of cast in-situ will often save waste and speed up work. This is because it eliminates the need to wait for concrete to gain strength before placing subsequent lifts. This can be particularly helpful in projects with severely strict deadlines.

 

 

Design for Materials Optimization Questions:

  • Can the amount of excavation be avoided by using ground improvement techniques?
  • Can the overall use of materials be reduced by use of geosystems?
  • Can the working platform (if required) be incorporated in the final structure?
  • Can innovative designs or materials be used for structures to reduce material use?
  • Can the design, form and layout be simplified without compromising the design concept?

Design for Materials Optimization

 Materials Optimization means lean design or value engineering. It is an approach that focuses on materials resource efficiency so that less material is used in the design and/or less waste is produced in the construction process.

A key application of this principle is the use of various ground improvement techniques to avoid having to excavate soft foundation soils. This may because of its inability to support proposed loading. Some techniques to overcome this include: foundation drains to accelerate settlement; geosystems to reinforce weak foundation soils; vibrocolumns and dynamic consolidation to strengthen the foundation soils; lightweight fill to reduce loading; and staged construction to allow consolidation of the foundation before construction of the structure or pavement.

Design for Waste Efficient Procurement Questions:

  • Have the project specifications been reviewed to select elements/ components/materials and construction processes that reduce waste?
  • Has the timeline been developed to include opportunities for reuse or recycling of materials on site?
  • Have appropriate KPIs and targets for waste been set and included in contracts for the whole supply chain?

Design for Waste Efficient Procurement

Until recently, designers of projects mostly regarded waste as “a contractor responsibility”. With the increase in integrated project teams, waste is becoming the responsibility of the entire team. This allows for early contractor involvement so that areas where waste is to be generated are identified and deliberately reduced. This will involve liaison with the principal contractor and specialist subcontractors.

One of the most important ways in which procurement can be used to promote waste reduction is by including commitments to reducing waste in contracts throughout the supply chain, including those for designers.

Appropriate KPIs and targets for waste can also be included in contracts. The designer should be involved in the setting of these at the earliest stage in the project. While there is a wide range of KPIs relating to construction waste available, the most common ones are as follows:

 

  • Waste to landfill KPI: reduction in ‘tonnes of waste to landfill per unit of construction output’ relative to baseline year;
  • Waste reduction KPI: reduction in ‘tonnes of waste per unit of construction output’ relative to baseline year;
  • Waste recovery KPI: percentage of waste diverted from landfill during the last year.

Design for Deconstruction & Flexibility Questions:

  • Have the project specifications been reviewed to select elements/ components/materials and construction processes that reduce waste?
  • Has the timeline been developed to include opportunities for reuse or recycling of materials on site?
  • Have appropriate KPIs and targets for waste been set and included in contracts for the whole supply chain?

Design for Deconstruction and Flexibility

In projects where future expansion and alterations are expected, flexible design is crucial. This may be the case for widening of a road, bridge, or expanding facilities. Here, components and elements manufactured off-site are advantageous as they can be easily disassembled versus the cast in-situ elements. This also allows those elements to potentially be reused in the new construction.

This illustrates how Design for Deconstruction connects directly with Design for Reuse and Recovery. Thus, the design should anticipate the future expansion; both by integrating ways to make this easier and by avoiding anything that would make it difficult. 

 

    Overall, the principles in this guide are based on proactively targeting options which allow for the biggest waste reduction opportunities. A common approach is recognizing that a few key solutions on each project are likely to achieve significant waste reduction, along with cost savings and other benefits. These will be different for every project so it is important to have a process for prioritizing these actions. 

    Leila Nattagh
    Leila Nattagh
    Obsessed with creating a circular future, Leila is a part-time writer for Companies for Zero Waste. When she's not writing, she’s helping businesses assess the environmental impact of their products at W2R Solutions. You can connect with her on LinkedIn by checking out her profile here.