90 Long Acre. Credit Gensler; 90 Long Acre. Credit Gensler;

The Acre, London

Turning an iconic building into one of the healthiest and greenest developments in Central London

When Northwood Investors wanted to repurpose an iconic but obsolete Brutalist building, designed by noted architect Richard Siefert, they approached trusted advisor Arup for multidisciplinary services. Working closely with the architect, Gensler, we engineered a series of interventions to retain as much of the existing structure as possible, while transforming building performance.

Originally built in the 1970s, and formerly known as 90 Long Acre, the Acre is a 240,000 sq ft landmark in Covent Garden, London. Set to complete in 2023, the refurbishment will revitalise existing office areas, add floor space, upgrade the building’s performance and provide new public space and retail opportunities at ground level.

How do you transform energy performance in a 1970s building?

Impactful interventions are set to reduce operational energy use in the building by over 70%, enabling the refurbished older building to outperform new-build energy standards.

‘Infill’ extensions make the building’s thermal envelope more effective, reducing heating and cooling loads. Other passive improvements include internal insulation fitted to existing façades and high performance new façades.

A new, all-electric heating and cooling system uses high-efficiency pumps that reclaim heat for hot water. During extreme temperatures, Cat A space will be conditioned via Artus fan coil units, an award-winning technology developed by Arup, which uses 50% less power than traditional units. Their smaller dimensions also create an extra 150mm of floor to ceiling height, maximising the value of the Cat A office space.

The Acre will be fitted with a smart platform that allows real time energy analysis and predictive maintenance of the plant, along with live monitoring of window operations. This will give the property team and occupiers valuable insights and empower them to manage the building for efficiency and wellbeing. 


Project Summary

70% saving on operational energy

80%of the existing building retained

4850tonnesof CO2 saved

© VMI Studio

How do you create one of London's healthiest buildings?

The Acre is targeting WELL Platinum certification and Fitwel 3 Star – the highest levels on the leading international frameworks for health and wellbeing in buildings. This includes:

  • Openable windows on every façade allow office workers to control internal temperatures for their comfort.

  • Extensive greenery increases opportunities for them to enjoy nature and enhances biodiversity.

  • Over 350 cycle spaces and a new pedestrian route through the building support active lifestyles and green travel.

  • Spectacular roof terraces offer inspiring views.

  • Reshaping the ground floor opens up public access and adds retail space, connecting the building to the wider Covent Garden area. 

For a safer building, Arup brought together a multidisciplinary team to complete rigorous fire risk assessments. Their insights influenced the ‘frangible’ atrium roof system, designed to disintegrate in a controlled fashion at high temperatures, so heat escapes from the building. In addition to creating a safer building by reducing the risk of fire to spread to multiple levels, this design also allows existing floors to be connected to the atrium, an intrinsic part of the natural ventilation strategy. 

We look forward to giving this Richard Seifert landmark a new lease of life. We’ve listened to the needs of contemporary business and designed The Acre to be Covent Garden’s greenest and healthiest workplace, reducing embodied and operational carbon and placing employee wellness at its heart. ” Richard Strachan Senior Vice President of Asset Management, Northwood Investors

How do you make the greatest sustainability impacts?

Arup led the sustainability strategy for the Acre, starting with a UN Sustainable Development Goals workshop to identify the greatest potential environmental and social benefits at the outset. The decision to retain and reimagine the existing building halved embodied carbon, compared to the previously consented new build scheme. 

With substantial whole life carbon savings, wellbeing interventions, natural ventilation, biodiverse terraces, public spaces and green travel features, the Acre has already achieved a SCORS: A+ and it is on track to achieve BREEAM Outstanding, 4.5 NABERS UK Star and RIBA 2030 embodied carbon targets on completion.

Learn more about how we are shaping resilient and sustainable places

Mel Allwood, Director at Arup, talks about the design of the Acre.
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