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Topics: Sustainability

Managing Low Carbon Design in Commercial Buildings

Over the last two years we have seen an increasing recognition of the climate crisis as a fundamental briefing issue for a number of clients who now identify the net zero/low carbon agenda as an opportunity to positively contribute to the identity of their building and provide a point of differentiation relative to other competing developments. Whilst this is not yet a universal approach, it is becoming a subject that cannot be ignored if your development is to secure the highest rents with the best tenants and ultimately deliver a better commercial return. It is also a planning requirement for all schemes evaluated by the GLA.

This approach to low carbon asks different questions of us as project managers. What specialist advice do we need? At what stage of the design process do you begin to consider low carbon alternatives? What does this even mean in the context of the numerous standards that seek to categorise and measure low carbon design? Perhaps most importantly how does this change established approaches to managing an already complex design process?

Establish a Clear Brief

The first question to answer is what is your carbon strategy? Up until recently standards like BREEAM and LEED set a range of targets around sustainability but neither of these deals very specifically with the emerging principal objective – to drive down carbon emissions. There are several emerging and somewhat competing objective standards that seek to establish and define what ‘low carbon’ means in the context of the built environment. These include London Energy Transformation Initiative (LETI) and the RIBA Sustainable Development Goals. Whilst they are all aiming to encourage the same objective – to design, build and operate buildings generating less carbon emissions than a current generation building – they all approach the measurement and importantly the stated objectives slightly differently. As a broad principle – the two commonly accepted goals are to lower both embodied carbon and operational carbon. Embodied carbon being the carbon that it is used in the manufacture, transport and construction of a building1 and operational carbon which is the carbon that is used in the operation of a building in running the central plant and supporting the occupants’ and tenants’ activities.

How do you navigate this complex set of competing targets and ensure that your low carbon brief is both aspirational and deliverable? You are part way there if you have appointed Gardiner & Theobald but you also need to ensure you appoint a carbon confident team. As buildings have become more efficient in operation the importance of focussing on the embodied carbon (sometimes referred to as capital carbon) has come to the fore. Every member of a design team will be making decisions that impact embodied carbon and this is where clear and informed project management is vital. This is not a bolt on service and requires your full design team to be versed in understanding the various targets and importantly, understanding what is achievable in the context of your project and where this sits relative to its competitive peer group product. We would also recommend a specialist sustainability consultant to support this journey from establishing the brief through all stages of design and construction.

Designing for Low Embodied Carbon

Once you have set the strategic brief how do you progress the design? Importantly the decision to deliver a low embodied carbon building should be taken at Stage 1. Whilst material selection and building services design contribute to the embodied carbon, the height, depth, grids and massing have a larger overall impact. What we have learned is that this requires a more integrated approach with the carbon cost of all design decisions being measured and understood in real time as the building design is progressed through Stage 1 & 2. Secondly, that you cannot meaningfully re-engineer a low carbon building once the fundamentals of height, depth, grid and massing have been fixed. We have established a methodology on our projects that seeks to treat the carbon content of all decisions as you would monetary costs. You establish a ‘Carbon Plan’ at the outset and you measure all design decisions against this carbon plan as the design evolves.

Procurement

We have learned a lot organisationally over the last two years in regard to low carbon materials and products. It is also true that the materials and products supply market is continuing to evolve how it measures and reports products in response to demands for ‘lower carbon’ materials and assemblies. Until now there has been limited auditable information available from suppliers to inform material selection, but this is changing and there is a wealth of data out there that needs to be managed and corralled to allow unambiguous reporting to our clients. As an example, steel that has been produced by a supplier in a traditional coal fired process will have a much higher carbon emission figure than steel that has been manufactured in an electric furnace powered by renewable hydro-electric energy. This is one example but highlights that your design team needs to be knowledgeable as to the provenance and carbon performance of individual materials.

This also suggests that clients may need to be willing to engage with the supply chain at a much earlier stage in the design and procurement process than they have perhaps been comfortable to do previously. This has consequences in terms of main contractor risk transfer and competitive tendering, that all need to be carefully navigated and managed. Whilst it is true that adopting a low embodied carbon design has the potential to increase the capital cost of your development the relationship between capital cost and low carbon design is more nuanced. As referenced earlier, careful consideration of building fundamentals such as grid, height, depth and form married with informed material section can support a value driven approach to sustainability that aligns low carbon decisions to drivers of enhanced value.

Operational Carbon

The carbon emitted in the day-to-day operation of a commercial building is made up of two main components. The first of these are the emissions from the energy used to manage and operate the base build plant and support the landlord areas – the lifts, services to common parts and central plant supporting the building. This is part of the operational energy that we as a design team can control through the adoption of passive design measures, highly efficient plant and progressive HVAC solutions. By these means it is possible to significantly reduce the base loads to a level that enables challenging operational carbon targets to be achieved. The second part is more difficult and relates to the tenant specific loads, in particular the small power allowances. These are often driven by BCO guidelines or historic energy usage experience that predate cloud computing and include allowances for significant on site data rooms. Early engagement with tenants to truly understand their energy usage will be key if we as a sector are to achieve ambitious operational carbon targets in the buildings we are currently designing.

Conclusions

Embracing low carbon design is no longer a tick box exercise and for many clients it is a way to truly differentiate their development. Our recommendation is to adopt the following approach:

  • Appoint a carbon confident team including a specialist sustainability consultant
  • Define your targets and strategy for low carbon design at Stage 1
  • Manage project carbon in the same way as cost
  • Understand the role of the supply chain in achieving your carbon targets
  • Engage with tenants as early as possible

1 - RIBA also recommends measuring the carbon used in the maintenance and end of life of a building