- This article was originally written by Mr. Howard Button, chief executive of the National Federation of Demolition Contractors (NFDC), and Ms. Katherine Adams, independent consultant and director of Reusefully, for the EDI Special Publication 2021 – Decontamination of hazardous substances.
In the UK the role of the Pre-Demolition Audit is to identify and formalise options for reuse and recycling of products and materials involved within the demolition or refurbishment process and so divert them from landfill where possible. It comes under the umbrella of Pre-Redevelopment Audits, which can also include Pre-Refurbishment Audits.
Where hazardous materials such as asbestos may be present, they are dealt with by a Demolition & Refurbishment survey which is a legal requirement that stands separately from the Pre-Demolition Audit, which by contrast is not yet a legal requirement.
The Pre-Demolition Audit is, in practice, the formalisation of a process that demolition contractors themselves have done for years since such contractors will price jobs subject to how they will manage the materials from it.
And recycling is already a strong focus for members NFDC members, who boast an average 96% by weight recycling rate.
But the increased focus on sustainability and the environment by all parties involved in the construction process – from designer to demolition contractor through to the construction client – means that the value of the Pre-Demolition Audit is now greater than ever, particularly helping with project planning and providing sustainability information to include in tenders.
And although not yet mandatory for all, the Pre-Demolition Audit is increasingly on the agenda as stakeholders look to focus on the value of the circular economy. It’s already included within BREEAM, as part of its sustainability assessment process for buildings, for project holders to obtain credits relating to demolition waste management.
And it also now forms part of the London Plan, the statutory spatial development strategy for the Greater London area, as part of its Circular Economy Statements that are required for the larger developments that are referred to the Greater London Authority.
In both initiatives, the Pre-Demolition Audit is done at the design stage, which allows the opportunity to identify any materials that could be used within the new development in the case of demolition or retained in the case of a refurbishment. Carrying out the Pre-Demolition Audit as early in the process as possible helps to provide more opportunities for reuse of materials in the new development as well as maximising the time available to find suitable reuse and recycling options for materials that can’t be reused on site.
What does the Pre-Demolition Audit process involve?
In the UK the Pre-Demolition Audit is usually carried out by an independent party to the project to advise on the products and materials that can be reused or recycled before demolition or a major refurbishment.
The process involves a detailed analysis of the building and the products and materials it contains. Ideally, this will be informed by an assessment of existing information available, such as scaled plans of the structure, as well as any other supporting evidence about the property that may be available. These help to give more accurate estimates of what the building comprises, as well as measurements that will help the assessor more accurately estimate the amount of materials it contains.
These will then be supplemented by a site visit to estimate the types and amounts of materials likely to arise from the project. Where possible the interior of the building will be surveyed in person, with the assessor taking measurements and photographs to inform the audit more fully.
The assessor will then quantify the materials from the demolition, working out the tonnage of each material and producing a report of these, along with recommendations of reuse and recycling options for them. The assessor can also set targets and recommendations for reuse and recycling which should ideally then be incorporated into the tenders for demolition contractors.
It will estimate the value of materials to be collected, as well as suggesting routes for disposal of materials, such as reusing them in the new development itself, using them in other projects by the same client or selling or giving away locally.
Best practise then sees a post-completion analysis after the demolition process has been carried out to identify what happened, compared to what was recommended. The value of this is in helping to develop and track the audit process, since materials estimates may not always be 100% accurate if detailed building information isn’t available when the Pre-Demolition Audit is carried out.
Why it’s increasing in prominence
The Pre-Demolition Audit has been around for many years and many demolition contractors will point out that it’s part of how they work already. But the formalisation of the process in the form of a Pre-Demolition Audit document means that clearer targets and goals are set for all – with designers and contractors far more aware and accountable for the environmental impact of their projects as a result.
The Pre-Demolition Audit also helps to focus thinking on how materials can be best managed, especially as clients get more demanding and ask more questions about how materials are being used.
For instance, in the case of designers helping to put together a building project design the Pre-Demolition Audit encourages them to consider what is already in place, rather than starting with a completely blank piece of paper. This consideration means that the existing building can inform their design throughout – for instance the materials available which could be reused in the next project and maybe even retaining the structure of existing buildings where applicable.
Meanwhile, it can also help demolition contractors to consider new, more innovative ways of recycling and reuse too, identifying new recovery routes as a result and getting a step ahead of competitors as environmental obligations increase.
The Pre-Demolition Audit may be a largely voluntary process currently but it’s certainly best practice and it’s likely we will see increasing adoption of it going forward. Encouraging more recovery routes and highlighting the need for minimal environmental impact is key in all building projects, especially as they focus on minimising carbon footprints with the aim of being net-zero. With the growing prominence of sustainability within the built environment and the net-zero ambition it’s a requirement that isn’t going away anytime soon.