It’s time to move the net zero debate beyond ‘retrofit’ versus ‘new build’

This is a personal reaction to last week’s decision and of course it will take time to digest the detail of the findings and to understand their longer-term impact.

After five year’s work and three planning decisions in favour of our scheme, the most recent by the Planning Inspector, we learnt on Thursday that Michael Gove had taken a contrary view and the proposals were to be refused. This protracted process may beg the question whether the planning process itself is broken and whether the rigour and cost of the inquiry process is justified if an experienced inspector’s findings are simply to be put aside.

As an architect, I believe compact, efficient, and humane cities, well served by public transport, are fundamental to our journey to net zero. Sites like M&S’ Marble Arch flagship, five minutes from the Elizabeth Line, must fully deliver their potential for sustainable good growth. A doctrinaire orthodoxy to the contrary, which retains every existing structure irrespective of merit, freezes the city and robs it of vital potential for adaptation and growth.

We approached the project with care and the final new build proposals were evaluated against more than a dozen alternatives, including refurbishment. We (and M&S) love retrofit, and I was able to show David Nicholson, the inquiry inspector, over our recently completed Kensington Building as an example of our experience and approach in this field. (The building has recently been awarded the British Council of Offices’ 2023 retrofit of the year award.) Retrofit first, but not retrofit only: it seems no more than common sense to acknowledge that the quality of existing buildings must inform their potential for refurbishment.

Two visions for the site’s future were under scrutiny at the inquiry.

We made the case for transformational change that would secure M&S’ long-term presence on the nation’s high street. An environmentally advanced new building would optimise the site’s employment potential, delivering 4000 jobs right on top of the Elizabeth Line. The existing public realm is dire. The new building offered new public space, new permeability and the chance to create a St Christophers Place West – an oasis in place of the current service yard. All this was closely aligned to Westminster’s and the Mayor’s policy objectives for the site and both authorities backed our proposals.

The existing public realm shortcomings remained unaddressed

Our opponents, SAVE, tabled a very different vision. They judged the three buildings, all unlisted and all excluded from the conservation areas that surrounded the site, as having sufficient merit to make the compromises required to retain them, worthwhile. The severity of these compromises only became clear through the inquiry, when Simon Sturgis’ scheme showed how poor the result would be. Mr Sturgis agreed with us that change was required and that the existing buildings are not fit for purpose.

He proposed to demolish all nine structural cores and to create a new central core cut through the existing fabric. New roof extensions, given the foundation constraints of the existing buildings, would require carbon-intensive steel. The embodied carbon impacts would be very similar to the new building, as has been our experience on the Kensington Building, which has a slightly higher embodied carbon level than the new building proposed at Marble Arch.

Yet notwithstanding this carbon investment, the retrofit offered only compromised ceiling heights, floors that misaligned between buildings, and dense and irregular columns grids. The existing public realm shortcomings remained unaddressed – the dark undercroft on Orchard Street and the ugly bridge over Portman Mews were retained, the new permeability and public spaces foregone.

The space would be unsuitable for M&S’ occupation (they have said they will leave the site if it cannot be redeveloped) and it’s doubtful that its quality would attract many tenants for the offices above. Operational energy efficiency would be markedly inferior and the ongoing embodied carbon investment higher, given the uncertain design life of the existing buildings.

At the inquiry, and only at the inquiry, were these competing visions rigorously tested with both parties subject to cross examination. This evidence led the inspector to conclude that the SAVE scheme was unlikely to be deliverable.

I believe therefore the Secretary of States’ refusal is misjudged and that it will have long-term, and profoundly negative, impacts on Oxford Street, the wider economy and our transition to net zero.

Beyond ‘new build’ versus ‘retrofit’

At the inquiry, I stated our ambition to reduce the embodied carbon of the new building by 20% before construction. We had achieved a similar reduction for our Edge London Bridge project currently on site next to the Shard (the building will be London’s most environmentally efficient multi-let office).

We’ve begun researching how the new building could re-utilise more of the existing building fabric with innovative construction techniques that draw on the latest advances in robotic fabrication. This work promises to move the debate on from ‘new build’ or ‘retrofit’ to the richer possibilities of adaptive reuse.

>> Also read: Is the M&S decision the start of a new era, or a fig leaf to conceal government backsliding on net zero?

>> Also read: Gove refuses M&S Oxford Street redevelopment in landmark ruling