Address: St Pancras Hospital, Kings Cross, London UK
Area: 23, 000 sqm
Client: Argent LLP

Design Team:
Architect: HNNA
Structural Engineer: Webb Yates
Landscape Designer: BBUK
Services Engineer: Skelly + Couch
Cost Consultant: Artelia
Delivery Architect: John Robertson Architects

Copyright:
Design, visualisations and drawings: HNNA Ltd

[ URBAN DESIGN / WORKPLACE ]
[ 2206 ]

The scheme is for a new 23,000 sqm lab-enabled workspace on the site of the old St Pancras Hospital in Kings Cross. The design retains the existing water tower and chimney stack on the site as both historic reference and navigation tools. The mass of the building has been broken into 3 parts and stepped down toward the residential development and St. Pancras Gardens to the south. The proposed plan, including the double atrium provision, ensures double-sided natural lighting and ventilation throughout the building. The structure is hybrid consisting of a composite CLT floor slab, concrete/stone or raised service floors, an LVL/glulam column and beam, with a precast concrete, insulated sandwich, structural exoskeleton and cylindrical cores made from lean, green concrete.

Heritage and Context

A key aspect of the scheme is the retention of both the existing water tower and chimney stack as icons of the site’s industrial past, both as navigation tools and as historic references. These pieces of infrastructure work as wayfinding to navigate pedestrians approaching the city block from the north and west as well as those from the south setting up an alternative axis within the masterplan away from the original residential spine that results in a dead-end at the rail tracks. Instead the proposed building massing directs pedestrians through newly created public realm enveloping the heritage icons, adjacent to the new workspaces and Oriel building and toward the canal allowing the ground plane to the new residential development to remain more private. As well as being integrated into the servicing strategy these elements are referenced in the building’s façade and internally in the vertical cores. This retained heritage holds the NW corner the same way that the retained brick buildings announce the site from the SE.

The Oriel building which dominates 1/3 of the block is also referenced in the horizontality and cellular rhythm of the proposed cladding as are the faceted/rounded corners and massing of the new building.

Massing and Circulation

The mass of the building has been broken into 3 parts and stepped down toward the residential development and St. Pancras Gardens to the south.

The overall massing has been reduced from the upper limit of 16 storeys to 13 storeys (plus basement) to ensure that it sits more sympathetically within its context with an overall height of <80m AOD including plant. This means that the height of the offices adjacent to the residential development align with it and the overall visual impact of the scheme from St. Pancras Gardens is greatly reduced from the masterplanning massing.

The two main entrances to the new workplace mirror the Oriel building and the open mouth to the west emulates massing on the opposite side of Granary Street, inviting people into both entrances. The side access also allows public facilities to be focussed on the NW corner facing the canal and small scale start up, coworking and residential facilities to embrace the more private square to the east, encouraging active ground floors of a different nature.

The public realm therefore takes on a distinct public/private nature with skylights servicing the basement acting as navigation beacons at night together with the water tower/chimney. Corners are left open in the façade to enable the vertical chimney cores within to be visualised and to encourage a feeling of transparency.

Lab-enabled Workspace Massing and Circulation Diagram © HNNA Ltd

KEY

1 Workspace

2 Lab-enabled space

3 Leisure, wellness and retail

3b [scaleable active ground floor units]

4 F&B [left] and community facilities [right]

4b [scaleable active ground floor units]

5 Landscaping - commercial roof terrace

6 Landscaping - commercial

7 Landscaping - residential

8 Plant and services

9 External terrace [level 04]

10 Retained water tower

11 Retained chimney

12 Atrium

13 Ground level skylights [white hatch]

14 Service risers [orange]

15 Service cores [WC, left, kitchenette, stair]

Structure

The proposed building has a hybrid structure which consists of a composite CLT floor slab [200mm] with concrete/stone or raised service floors as required, a LVL/glulam column [400mm reducing to 250mm] and beam [within floor depth] frame, with a precast concrete, insulated sandwich, structural exoskeleton and cylindrical cores made from lean green concrete [“New ways to design carbon-friendly, fire-safe towers” RIBA Journal]. The chosen structural grid is 4.8m by 6.25m with a 7.2m span between buildings. The reduced 4.8m span maximises floor to ceiling heights and reduces the need for 2 directional large beams (that are common to CLT buildings) and interrupt service runs. The internal concrete cores reference the retained chimney stack and together with the composite floors provide thermal mass. The structural, precast concrete exoskeleton references the structure of the watertower and introduced horizontal datums within the elevation which differentiate the building mass and create a synthesis with the facade of the Oriel building.

Services

The proposed plan, including the double atrium provision, ensures double-sided natural ventilation throughout the building. With floor plan depth <12.5m natural day lighting is also possible to all of the proposed office spaces and the majority of the main lab-enabled floor plans at lower level. The systematised 4.8m main facade panels include ventilation louvres with mechanical ventilation allowed for all of the lower lab-enabled spaces. The lab-enabled spaces have been located to the north allowing a greater than 4m floor to floor provision if required (an 800mm ceiling void is usually required) whilst ensuring the massing still aligns with the proposed residential development to the south. The proposal includes the incorporation of a ground source heat pump as part of the basement construction with a heat share provision between the cooled labs and the heated residences. The basement design includes smoke venting for disaster situations which would naturally ventilation daily. The chimney stack is also used for the heavy lab provision to the basement to ensure no stale air in the public realm. Plant, PV and accessible terraces are distributed at roof level and within the water tower.

Kerri is an Associate Director at John Robertson Architects. She has particular expertise in workplace and her portfolio includes the flagship headquarters for Saipem, One Southampton Street, Bermondsey Yards and the new TJX Headquarters. She has extensive knowledge of architectural legal and technical requirements, fire reform, Quality Management Systems and Construction Design and Management. Kerri and Hannah have known each other for 28 years and HNNA & JRA worked toward collaboration on a number of projects including the Iraq Parliament Complex.

As a Senior Civil and Structural Engineer, Eleonora is a key member of Webb Yates contributing to a wide range of projects across a variety of different scales. Eleonora has extensive experience in the design of large scale buildings and structural reinforced design of large industrial CLT, steel and concrete buildings. She brings a wealth of experience to the team and has a passion for fostering strong working relationships with all members of the design team.

Natasha is a Principal Engineer with Skelly & Couch. Since joining in 2011, Natasha has contributed to a wide range of outstanding projects, honing her environmental engineering expertise across many sectors. Natasha has a particular focus on the provision of carbon zero servicing solutions she is presently working on a science teaching, lab-enabled new-build development within a World Heritage Site with Grade I-listed surrounds in Canterbury for the King’s School.

Skelly & Couch worked directly with HNNA on the Greenwich Design District as the Services engineer for of of the 16 new build workspaces.

After a career in fashion, Harriet Bourne studied landscape architecture and worked in urban design and landscape architecture practices before setting up BBUK. Since the inception of the practice Harriet has run projects ranging in size from large scale urban design and landscape strategy and master planning projects through to detailed design and implementation of a range of schemes both in the United Kingdom and abroad. She is currently working with HNNA on the West Kentish Town Estate redevelopment.