Mercury House
Achieving more by doing less
Evaluating the options Sometimes our projects are as much about what we’re not doing as what we are. When we started looking at options for the refurbishment of Mercury House in 2020, we investigated the relative benefits of options ranging from a very light touch refurbishment through to a full demolition and new-build scheme. It was a rigorous process, but our underlying principle remained the same throughout: how could we make minimum intervention for maximum impact?
The original building in the 1950s.
As found in the 2020s.
Our proposed design, which will take the building back closer to its original form.
Midtown headquarters During the second world war, many of the Georgian terraces immediately north of Red Lion Square in central London were damaged beyond repair by bombing. In their place, much larger office structures were built along Theobald’s Road in the postwar years, including Mercury House. Designed by architect Gordon Jeeves as a headquarters for Cable and Wireless and completed in 1955, most of the Portland stone facades have remained intact, while inside frequent alterations and an unsympathetic 1990s refurbishment have limited its potential.
The 1916 map shows the site divided into small residential plots.
This 1944 map shows that the buildings on the site were almost completely destroyed by wartime bombs.
The nearby Tybalds Estate was developed in response to an urgent need for post-war housing, shown here under construction in 1949.
Ground floor plan of the original building (Gordon Jeeves Architects, 1954).
A working community Mercury House sits at an axial point of routes east-west between Clerkenwell and Bloomsbury, and north-south between Holborn and the hospitals. With such a broad range of industries in the area, the vision of our clients is that the building will become a working community. Rather than a new headquarters, there will be multiple SME tenants co-existing under the same roof, signalling a need for both flexibility and high-quality shared space.
Refurbishment strategy Our feasibility studies led us to opt for a heavy-ish refurbishment, taking advantage of the good bones of the existing structure and focusing most of our attention to the front of the building. The poor quality extensions added in the 1990s will be removed and the central bay extended outwards towards the street to add more area. By infilling the non-original atrium we have created additional space. At ground level, blocked windows will be reinstated and space given to a café which will bring activity to the street.
Clarify original massing by removing low-quality 1990s additions, restoring the building closer to its original form.
Consolidate the cores and infill the atrium on the upper levels.
Revitalise the building and improve its street presence.
Maximise building setbacks and landscaping and add a rooftop pavilion.
Activate the ground floor with a feature entrance and introduce glazing to enhance natural light and permeability.
Using what we find We estimate that, despite this being a fairly deep refurbishment, around 80% of the building’s structural elements will be retained – and with them their embodied carbon. As we deconstruct the existing façade to allow for the front extension, we will retain the Portland stone so it can be reused on the new front elevation. Similarly, internal stone removed during the build will be repurposed as terrazzo. Where we do use new stone, this will have a slightly different texture so our changes to the building can be clearly read.
Diespeker sample options: our intent is to re-use deconstructed Portland stone from the facades for new feature flooring.
Sample of Portland stone pieces from site placed with selected binder tile (Bianco Verona).
Initial large format terrazzo sample - the stone did not seal properly!
Alternative terrazzo sample using small chippings for the aggregate.
Selected sample terrazzo to be used as floor tiles.
Selected sample terrazzo format to be placed using an in-situ method. Stone off-cuts from site will be hand placed and sanded down with the binder poured over.
Reading the room We’ve thought carefully about what the new community of tenants will occupy the building and what will work best for them in term of internal space and finish. There is generous amenity space – lounges, a gym, meeting rooms and so on – which can be shared by tenants, meaning they need only focus on the desk space they need. Each floor is divisible into 3 parts, so they can potentially grow within the building. Knowing that the tenants will set the character of the space, we have opted for calm detailing that will act as a simple backdrop to their activity.
Renewable energy (kWh/m² building footprint)
Upfront carbon (kgC02e/m² GIA of whole building)
Operational energy (kWh/m² NIA)
Refrigerant usage (kgC02e/kg)
Location
Holborn, London
Client
Theobald Investment Limited
Date
Under construction
Borough
Camden