Save the Planet, One Redevelopment at a Time
The world’s scientists concur that climate change is real; the challenge for humanity is to urgently and dramatically reduce global carbon emissions. Responsibility for a large proportion of that challenge sits squarely on the shoulders of those who develop, design and construct the built environment, as the construction and operation of new and existing buildings is estimated to make up a combined 40% of global carbon dioxide emissions (data source: Global ABC Global Status Report 2018, EIA).
Given this scenario, there is a heated debate within the built environment industry at the moment – should we be continuing to knock down existing buildings as part of the redevelopment cycle of our cities and communities? Or should demolition of existing buildings now be considered a crime against the planet?
There is a rational approach available to assess this dilemma – approval for the redevelopment of existing buildings and sites could be partially based on a sustainability business case. The business case would consider all the key impacts on carbon emissions that the redevelopment would generate – both positive and negative – and would be compared to other building retention options.
What would this sustainability business case consider? In the negative corner would be the significant carbon emissions generated by the demolition process, and construction of the new development, including extraction, manufacture, transport and assembly of all the built form components. However, many existing buildings generate excessive carbon through the continued operation of old and inefficient heating and cooling systems, made worse by outdated, inefficient façades and insulation systems. So retaining existing buildings isn’t necessarily going to generate the best outcomes for the planet, in the long-term.
In the positive corner, the demolition process offers the opportunity to recycle and re-use building materials, lowering carbon emissions as the demand for new materials is subsequently reduced. In addition, a new building – designed sustainably with low-carbon or carbon-sequestering materials such as timber or low-carbon concrete, and designed to operate efficiently throughout its enhanced life – could offer substantially lower carbon emissions over the life of the building, compared to continued operation of the existing building stock.
There is another less obvious but significant metric to consider in the redevelopment business case – the positive impact that redevelopment can have by reducing the need to create more and more urban infrastructure. The densification of urban areas – by building taller in our cities – actually reduces our need to build more roads, more rail systems, more power and water distribution networks – it even reduces our reliance on cars as we gain better access to integrated public transport, cycling, and walking.
Only when all of these key metrics are considered and measured in a holistic business case, will we be able to understand whether sustainable redevelopment actually favours retention and/or retrofit of an existing building, or demolition and reconstruction of a new building. An immediate opportunity exists for urban planning authorities around the world to introduce a requirement for a sustainability business case as part of any redevelopment proposal, with approvals highly dependant on the findings of that business case.
A recent and excellent example of achieving sustainability through consideration of the aforementioned metrics, is the Greenland Centre Sydney project, in the heart of the Sydney CBD. This pioneering project took an existing, empty, 31-storey office building – constructed in the 1960’s – and converted it into a high-quality 67-level residential tower featuring a community arts hub.
The design retained as much of the original 1960’s structure as possible, and incorporated this into the new design. Materials recovered from the partial demolition (mostly precast concrete panels) were recycled for re-use wherever possible. The construction methodology was developed to minimise the extent of temporary works required during construction, again reducing the amount of carbon emitted. And the final development achieved a density increase of more than 100% on the previous development, but all within local planning limits. The project is an exemplar of how redevelopment can drive sustainable outcomes.
The outstanding achievements of this project were made possible by many, but critically by the client Greenland Group who believed in and supported the vision, structural engineers ARUP, construction engineers Robert Bird Group, and architects Crone (Stage 1 DA), BVN and Woods Bagot (Stage 2 DA and delivery).
Keeping the original structural frame stable and safe during the highly complex partial demolition and rebuild process was a critical key that unlocked the feasibility and delivery of the entire project. Robert Bird Group were proud to be significant contributors to this project, having completed the original structural feasibility assessment on the existing building back in 2013, contributing to the structural design solution as peer reviewers, and optimising a safe and efficient demolition and construction sequence as construction engineers. We are even more proud to be the recent recipients of a CTBUH Award of Excellence for our works on the project.
Structural engineers have a critical role to play in the determination of sustainability business cases for any urban redevelopment project, as no two structures are typically alike in condition and capacity. We have the skills and are keen to help save the planet – one redevelopment at a time.
Group Managing Director – Projects