Defining a sustainable workplace – the BCO’s climate emergency challenge

刊登 02.08.2023

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The British Council for Offices (BCO) Guide to Specification is seen as the bible for office design in the UK, providing a clear reference point for designers, clients, contractors, agents and, most importantly, occupiers to refer to when sourcing and commissioning new workspaces – large and small.

The Guide to Specification is often seen as both the minimum acceptable requirement and the maximum affordable limit for office design. Therefore, it’s imperative the guide remains ahead of the curve.

The guide is updated every five years based on industry best practice and feedback from a range of industry experts. Much of what becomes best practice is only adopted into collective knowledge when it has been evidenced through exemplary buildings; however, a typical commercial office project can take up to five years from inception to occupation. As such, what was considered the benchmark for Grade A office design in the 2019 update was in fact conceived in the mid-2010s.

In 2020, some six months after the 2019 guide was released, the commercial office sector was turned on its head (along with the rest of the world) by COVID-19 and the rapid change to remote, hybrid, and even nomadic working practices. This seismic shift led workers to reflect on what they need from their workplace and caused businesses to reassess how their physical spaces align with their culture. It was clear the BCO needed to move fast to address these two new perspectives.

An interim update of the Guide to Specification was launched in early 2023, which incorporates some of the most significant changes the guide has seen. These key changes reflect the world of hybrid work, rapidly changing technology, and guidance on how the office sector can move towards zero carbon.

A healthier office

When designing new office buildings, the eventual occupiers and their specific needs are often unknown to architects. Pre-2020 it was relatively straightforward to make assumptions about how an organisation may utilise a workspace, but following COVID-19, the change to a hybrid work environment raises many risks. For example, over-specifying systems that cater to a hypothetical user group (which may not physically be there) has a tangible impact on the embodied and operation carbon of the building, as well as construction and fit-out costs.

In response to this, the latest update to the guide places increased focus on occupant health and wellbeing through a loosening of occupation density to one user per 10m² of tenant area. This provides greater scope for the variety of workplace settings needed to support hybrid working. It also avoids the overdesign of core services, improves floorplate efficiencies and reduces carbon emissions. However, this must be studied in practice, as many workspaces see huge changes in occupational density over a working week, with particularly low densities on Mondays and Fridays. This will undoubtedly be addressed in the next update.

A fully retractable glass door allows the ground floor at Cunningham Street to be easily opened up to the street, creating opportunities for pop-ups or exhibitions that welcome the public in.

While these allowances for shifting densities improve operational efficiency, the impact of COVID-19 and the heightened focus on occupant wellbeing has seen a drive for increased fresh air rates: changing from 12 litres per second/per person to 14 litres per second/per person. This improvement to indoor air quality (CO₂ concentration of 800ppmv, down from 1000ppmv) cancels out the energy saving associated with the reduced density air supply.

Along with lower densities, the change of working styles has seen a significant reduction in power and lighting loads associated with previously held standards on large, open-plan offices with fixed computers, monitors, task lights and peripherals, such as printers. The guide’s update sees a massive reduction in on-floor equipment loads, reducing the equipment requirements from 100W to 60W per workspace. When factoring in lower densities, this results in a 50% reduction in plug loads, which cuts associated cooling requirements from 20W/m² to 6W/m² – lowering operational energy as well as the associated embodied carbon from the cooling plant.

Light levels have also been updated in the guide, with a maximum lighting allowance of 300 lux, down from 500 lux, to improve visual comfort. The daylight definition has also changed from ‘average daylight factor’ (ADF) to ‘spatial daylight autonomy’ (sDA), reflecting a more balanced occupant-comfort approach that follows the WELL Building Standard, which has been sweeping the sector due to its focus on occupant wellbeing.

The green wall in the full-height atrium of HSBC's Quai des Bergues office brings nature indoors to boost tenants' wellbeing.

Energy and carbon

BREEAM has often been seen as the sustainability rubber stamp for the office sector and has been the BCO’s go-to, with the minimum standard now set at ‘Excellent’. Societal awareness of the climate emergency and the transition to net zero carbon means the BCO has made a significant leap by introducing a net zero carbon pathway for operational energy consumption – 70kWh/m² per year for the base build and 45kWh/m² for tenant fit-out (net lettable area) – in line with the UKGBC base build 2025–2030 target. These targets will likely tighten to a combined 70kWh/m² in the next guide to meet the Paris-proof target requirement for the sector.

The relatively recent introduction of the NABERS Design for Performance standard in the UK has been embraced by the BCO. This is a game-changing move, as NABERS fosters a collaborative energy design approach to designing, building and commissioning, with a focus on project-specific energy reduction. This approach aims to reduce the performance gap between generic system design and building operations, which often results in supposed low-energy buildings operating poorly.

Beyond these targets, the BCO’s embodied energy pathway target (RICS A1–A5) of 350–600kgCO₂/m²presents a further challenge. There are several industry-recognised targets for embodied carbon from the RIBA, LETI and UKGBC, but these vary. There is a common standard called the Net Zero Carbon Buildings Standard (NZCBS) currently being developed, but this isn’t yet available. The lower 350CO₂/m² (GIA) target meets the LETI 2030 target; however, few buildings can currently achieve this. It’s worth noting that a single target is unlikely to be appropriate for all projects, for example tall buildings in high-density areas like London necessitate higher upfront embodied carbon than office buildings in low-density cities and towns.

There are various changes in the guide which can help facilitate this pathway, including the reduced structural grid from a minimum span of 9m to 6m. This change enables more efficient beam and slab design, and also addresses the span limitations of timber frames. In practice, the tighter 6m x 9m grid in our 80 Charlotte Street scheme resulted in a tangible carbon reduction, leading to reduced structural depths, a lighter frame and increased building area.

80 Charlotte Street is all-electric and runs on renewable electricity, operating at net zero operational carbon.

What’s next?

While the BCO Guide to Specification was once the panacea for office design, it should now be considered the minimum standard, a starting point for designs to challenge and adapt. Other BCO documents, such as the Circular Economy in Offices document and the upcoming Fit Out Specification, are crucially addressing climate-conscious workplace design and hybrid working patterns. However, given the rate of change over the past four years, designers, owners and users shouldn’t blindly accept the status quo but be curious and think ahead, beyond the guides.