Housing

CRISIS MODE

Widespread commitment to lowering our construction carbon footprint is the only way to avoid the impending crisis. Hari Phillips, Director of Bell Phillips Architects, explores further.

It is not easy to find any positives in the appalling pandemic that has consumed us over the past 18 months or so, but if there is one it is the incredible speed with which vaccines have been developed, approved and distributed across the majority of the population. It is a remarkable demonstration of how effectively Government, private businesses and the public sector can galvanise itself and work together in the face of a catastrophic crisis.

One wonders how severe the climate crisis needs to get before we see a similar response. Do we need daily televised updates from a Chris Whitty-like figure talking us through graphs of temperature change, carbon emissions, sea levels and daily climate change-related deaths? The problem with climate change is it is intangible and insidious, barely perceptible and distant. Except that it is starting to feel increasingly immediate. Extreme weather events are becoming ever-more regular occurrences; the extraordinary recent flooding in Belgium, Germany and China, heat waves in the US and forest fires in the US and Australia to name a few.

While the Government chooses to fiddle around with notions of beauty while the world burns, it is good to see that public sector clients are picking up the baton to push the envelope for operational carbon. There is no doubt that the attention focused on Norwich City Council’s Passivhaus development at Goldsmith Street, which won the Stirling Prize for architect firm Mikhail Riches last year, has demonstrated what can be achieved and raised interest in low-energy design.

For example, we have designed 134 mixed-tenure homes across six sites for Ealing Council designed to meet Passivhaus. Achieving this standard will see the homes exceed Part L by 61%, meeting Ealing’s commitment to delivering net-zero-carbon homes. Meanwhile, we are working on a major estate regeneration with Westminster Council that will deliver a mix of uses, including over 1100 new homes. These will meet the London Energy Transformation Initiative (LETI) definition of net-zero operational carbon.

It is encouraging to see more and more clients seeing these challenging targets as the norm rather than the exception. However, operational carbon is only part of the story. If we want to keep pushing the boundaries and being ambitious, we need to urgently turn our attention towards embodied carbon. Embodied carbon is defined as the carbon emissions emitted producing a building’s materials, their transport and installation on site as well as their disposal at end of life. With significant steps being taken to reduce operational carbon, LETI estimates that embodied carbon can represent 40 to 70% of the whole-life carbon in a new building. Yet Building Regulations makes no mention of it, nor will you find it in planning guidance, with the exception of projects that are referable to the London Mayor. Hence it falls on the construction industry to drive standards for embodied carbon forwards.

So, how do we go about reducing embodied carbon? One way is to limit new-build construction by refurbishing and extending existing properties, thereby making use of the embodied carbon already inherent within existing structures. Some argue that we should not be demolishing any existing buildings at all. In some cases this is an appropriate strategy, however, it is difficult to see how we can realistically deliver the number of homes required through this approach alone. However, I would argue that we do need to be challenging each other more robustly about the relative merits of retention/refurbishment/ extension versus demolition and new build.

Sequential testing should be undertaken to assess the relative merits of retention vs demolition and the respective whole-life carbon calculation should be part of this analysis. Planning authorities should be requesting this analysis as a central component of planning applications. Currently, these conversations are notable by their absence.

We also need to reduce the amount of carbon used in new-build construction. The obvious way to approach the former is to build in timber. However, the kneejerk reaction to timber construction precipitated by the Grenfell disaster has sent the industry into a tailspin. Even the most modest timber construction is undermined by a lack of coordination between certification, the regulatory framework and demands of insurers. Our approach to timber construction is dogged by a mentality of fear. Compare this with the bold approach being adopted on the continent. For example, the new Centro Direzionale subway station in Naples constructed in mass timber or proposals in France that require publicly-funded buildings to be 50% timber.

To work around the regulatory system in the UK, we need to be inventive. For a new 14-storey community housing project in Southwark, we are working with structural engineer Morph on a hybrid steel frame with cross-laminated timber (CLT) floors that reduces embodied carbon whilst meeting Building Regulations on non-combustible materials. The structure results in a lighter building reducing the amount of concrete required in foundations.

It’s been an exhausting 18 months, but perhaps there is light at the end of the tunnel. COVID shows us what we can achieve under extreme circumstances. There are positive signs that we’re making headway with the issue of operational carbon, but it’s not the time to pat ourselves on the back. We need to push embodied carbon up the agenda. Let’s not wait until Chris Whitty is giving daily briefings on climate change.  www.bellphillips.com