Designing a better box for global data
On the bottom of many emails are words suggesting the recipient NOT print the email to minimise the environmental footprint of paper consumption. But the footprint of the email itself in terms of resources and embodied carbon is invisible to most eyes.
Every byte of data has a footprint. It has an operational energy footprint, and it has an embodied carbon impact in the form of the materials used to construct the growing number of data centres that host and transfer all the world’s digital communications and information.
Because energy-efficiency in operations is becoming standard practice and the energy supply in many regions has an increasing proportion of renewable energy instead fossil fuel-generated electricity, currently the cradle to gate emissions from construction comprises around 50% of the carbon footprint of a Data Centre. The opportunity for us as structural engineering designers is to find creative and evidence-based ways to reduce this impact.
In other building typologies such as commercial buildings and residential, the use of mass timber has become an increasingly popular option for low-carbon construction. However, because data halls involve long span structural members and data centres have significant weight due to all the equipment packed into the spatial footprint, timber is generally not a suitable solution.
The way we reduce embodied carbon on these projects is through an integrated, lifecycle thinking design approach. We assess embodied carbon throughout each iteration of Data Centre design, using an international database of embodied carbon data for each material and element to support our calculations within the digital model.
Through a process of both structural optimisation and rationalising the layout of spaces and systems within the building envelope, we can reduce the quantity of materials required while still meeting client objectives and structural soundness and suitability requirements.
We are also able to specify low-carbon materials or less impactful materials such as high-strength, lightweight materials. Using parametric design we can demonstrate options to clients and show where the optimal balance is between cost, functionality and environmental impact. The use of digital modelling also enables us to design for construction approaches including prefabrication that reduce construction material waste.
Lifecycle thinking means our design also considers end-of-use for each material and structural element, incorporating eventual deconstruction and re-use. For example, using bolted connections for steel structures, rather than designing for welding in place. The technical specifications of structural members become proprietary information within the project BIM model, to ensure information is available at end of life to facilitate disassembly and re-use in new construction.
Longevity is crucial for reducing embodied carbon impacts, so ensuring buildings are designed for re-use either whole or in part is fundamental.
With data centres, we also cannot see where the future might lead in terms of technology and demand, so planning for flexibility and adaptability is part of our approach. One-way spanning slabs, for example, allow for penetrations to be cut in the slab to reconfigure space or add new equipment. Removable facades, modular building systems and foundations specified for the maximum potential weight all facilitate adaptation of the DC building through future decades.
Another re-use approach is to undertake due diligence with clients and understand whether the best solution is in fact a whole new hyperscale data centre built from the ground up. How big a centre do they need? Can they meet their goals with smaller data centres located close to where the main data customer such as a financial services organisation will be? Can a data centre or data hall be scaled to suit an existing and unoccupied industrial building which is then renovated to suit?
Industrial buildings are a good candidate for repurposing because they already often have long span internal areas and very strong foundations due to the weight of plant and equipment they originally housed.
There is always a series of trade-offs involved in the project development process. Space and how it is allocated is one of those trade-offs. DCs are very cooling intensive due to the heat generated by the racks and associated computer systems. In a small DC, up to half the floorspace may be needed for the plant providing cooling, which reduces the floorspace available for the primary function of hosting data racks. For DCs being commissioned by clients who aim to maximise the data hall space available to lease to organisations such as servers or internet providers or cloud platform developers, larger DCs deliver a greater return, as the space required for the plant is a smaller proportion of a large footprint.
Independent of scale, the use of digital modelling can ensure the space required for mechanical, electrical and hydraulic systems is as efficient as possible. Collaboration between the engineering disciplines optimises the planning and configurations and eliminates clashes or buildability issues. This in turn can reduce the embodied carbon footprint by minimising waste and maximising materials and construction program efficiency.
In general, for structural engineers there is an education process involved in developing expertise and knowledge in low-carbon approaches. The learning is something we also need to share with clients, through explaining how the right design and specification decisions help them achieve carbon neutrality as an asset owner or investor.
