Design to minimise waste

This Issue This is a part of the Cleaning up feature

, Build 164

While construction and demolition waste is created by contractors on site, decisions made by designers influence the type and amount of waste throughout a building’s life.

DECIDING WHAT and how to build, whether to demolish or renovate, what materials to use and the design specifications all impact on the project waste.

Get the client onboard from the start

During the initial client consultation, discuss incorporating waste minimisation in the project by:

  • highlighting the environmental, financial and social benefits of minimising waste
  • explaining how a detailed brief and comprehensive design detailing will minimise waste
  • explaining the potential for lower whole-life building costs. Materials that are more durable, for example, reduce waste and repair and maintenance costs.

The initial consultation is also an opportunity to influence the client brief. This can help avoid full-scale demolition and overdesign. Discuss:

  • repairing and refurbishing instead of demolition and reconstruction or specifying deconstruction to recover a high proportion of materials
  • using materials that last longer and require less maintenance
  • using salvaged building materials
  • designing the building to be flexible for future uses
  • including space for waste sorting and storage during occupancy
  • sizing spaces to suit specific material dimensions, for example a 1200 mm grid will suit plywood sheet lining.

Build a team that values waste minimisation

A team approach is the best way to implement waste reduction. When building a team:

  • choose design professionals interested in waste minimisation
  • include the main contractor and key subcontractors in the design team or a team member with expertise in construction methods and planning
  • if possible, include suppliers – they can help ensure specified materials save unnecessary waste, cost and labour
  • establish roles and responsibilities for minimising waste
  • encourage ongoing communication about waste minimisation. Obtain agreement from the entire design team on goals and objectives to reduce waste at different stages of the building’s life.

Gather information

Research new building practices and materials that reduce wastage such as off-site prefabrication. Keep up with product information and changes in materials standards. Develop a set of standard details for use on projects and a preferred specification list including materials and components with recycled or reused constituents.

Identify local infrastructure for recycling of construction and demolition waste.

Use the Resource Efficiency in the Building Related Industries (REBRI) resource routing calculator to review the use of salvaged material on project costs.

Concept design

Minimise waste when defining the building type, function, core materials and core design:

  • Plan for end use and deconstruction so the structure can be taken apart and reused or recycled with minimal waste.
  • Check the design concept matches the actual needs to avoid overdesign and use of excess materials.
  • Keep the design simple so that it will be easier to build and less likely to have things go wrong.
  • Select materials that reduce waste and include recycled content. Consider durability and reuse and recycling options. Use materials consistent with the expected life of the building.
  • Design dimensions to suit standard modular construction sizes so the floor, ceiling and wall surfaces conform to the size of sheet materials, reducing unusable off-cuts.
  • Investigate reusing existing buildings and materials to reduce demand for resources, lower waste volumes and save money. Renovating a structurally sound building is usually more material efficient than starting from scratch.
  • Use prefabricated and precut components where possible. Off-site fabrication can reduce waste, facilitate separation of waste and improve recovery rates.
  • Prescribe techniques that reduce maintenance, fixing or replacing of components.
  • Plan the building to reduce vegetation clearing and earthworks.

Design for future flexibility

A building may change ownership several times and be used for many different purposes.

The original design dictates how easy it is to retrofit and how much waste is created during each renovation. Some detailed design considerations include:

  • maximising distances between loadbearing components or design these to the edge of the building to allow flexibility with the internal arrangement of partitions or temporary walls
  • using modular design techniques so that adding on to, or altering, the building is easier in future
  • designing for a greater load on the foundations and lower-storey supports to allow for upper storeys to be added in future
  • allowing good access to wall and ceiling spaces to allow for service upgrades and modifications
  • allowing flexibility with lighting, heating and ventilation wiring and controls for changing building uses.

Design for deconstruction

The largest contribution to the landfill and cleanfill is at the end of the building’s life. Consider the durability or recyclability of components. Simple things can make a big difference to wastage in the demolition phase:

  • Design entrances wide enough for deconstruction machinery.
  • Specify fixing mechanisms that can be reversed without damage, for example, screws, clips, bolts and gaskets in preference to rivets, mastics, adhesives and tapes.
  • Use components and equipment that have a long life and are easily maintained so they can be reconditioned for reuse.
  • Specify materials that can be easily recycled.
  • Use reversible construction and assembly sequences.

Building material and product selection

Building materials are often selected based on lowest cost, aesthetics and short-term needs. To identify the most effective materials to reduce waste, use a broader set of criteria, including:

  • recyclability – can the product or material be easily reprocessed back into a useful product or material
  • resource efficiency – less materials have been used to produce the same product
  • future salvage and reuse – whether there is a useful life for the product and material following its original use
  • durability – how quickly a product or material will need to be replaced.

Avoid overspecifying, for example specifying 13 mm plasterboard when 10 mm is suitable. Lower standards or performance specifications may be appropriate if waste can be reduced as a result.

For more

See www.branz.co.nz/REBRI.

Download the PDF

More articles about these topics

Articles are correct at the time of publication but may have since become outdated.

Advertisement

Advertisement