Scheme A: Under this scheme the F Hall is used for gallery space, gallery support and the new building to the north of F Hall contains gallery space and the support facilities, including part of the central plant rooms, (such as cooling towers and chiller plant, which provide chilled water to the whole Site. This scheme envisaged the retention but modification to the Laundry Yard steel structure with the yard used as a multi-purpose space and the upper open deck at the level of the Prison Yard used as a sculpture exhibition area.

Scheme B: Under this scheme, the F Hall is used for gallery space, gallery support and some portions would be retained for interpretation of its former role as a reception area of the Prison. The new building to the north of F Hall (the Old-Bailey Wing) provides the main gallery spaces and a new art themed restaurant. The old Laundry Yard is used as a site for another new building (the Arbuthnot Wing) to be used as a new multipurpose space/hall, which acts as a proper introduction/linkage to the arts educational/ arts related facilities in D/E Halls. The top floor of Arbuthnot Wing also accommodates the major space for central plant rooms to serve the overall Site.

These schemes were evaluated taking into account their ability to satisfy the demand for the cultural and mechanical plant spaces needed, the level of intervention at the existing historic buildings, integration with other buildings at the upper courtyard, engineering constraints and the potential environmental impacts.  Although the scale and building mass of Scheme A is smaller than that of Scheme B, Scheme A is shortcoming in that if F Hall is to be taken alone to function as a top international gallery, drastic alterations that would compromise its heritage value would be needed: the Laundry Yard would require extensive architectural and structural alterations and strengthening to make it minimally workable multi-purpose space, and the space on top of the new building would be insufficient for the necessary cooling towers and chillers to provide the chilled water for the whole Site.

On the other hand, Scheme B offers several merits, including the new building along Old Bailey Street (the Old Bailey Wing) will have a bulk size substantially effective to meet multiple demands that is vital to the revitalisation and long term sustainability of the Site; the Arbuthnot Wing provides an excellent multi-purpose space; the Arbuthnot Wing allows a complete deck of plant space for cooling towers and chillers; and the Arbuthnot Wing will work well with the D and E Halls. 

Hence, having considered and balanced the demand for the cultural space needed, the level of intervention within the existing historic buildings, integration with other buildings at the upper courtyard, engineering constraints and the potential environmental impacts while achieving the vision of the Project, the implementation of Scheme B is more preferable.

Architectural Style and Massing of the New Building

The architectural style to be adopted could broadly take either a historical or a modern approach.  The use of a modern approach over a historical approach has been recommended for the following two key considerations:

Firstly, it is a well-established concept in conservation,that new interventions, whether they are internal alterations in an historical building, or whole new buildings on an historical site, should be “of their time”.  This is because all generations of people have expressed their culture through their buildings (among other things), and to copy a style of the past would be to devalue it, and indeed the culture of today.  By constructing new buildings that speak of today, another chapter in the biography of the site is added.  This then can be viewed by later generations and understood within the context of the site and its history.

Secondly, if the existing buildings cannot accommodate the new uses, any new building cannot be made to look like an historical one within the current footprint.  The forms of historical building would require more ground area than is available at the CPS Site unless one was to build on the Parade Ground or Prison Yard.

The massing and style of the new buildings was dictated by the zoning envelope and height restriction set for potential new buildings under the OZP and the internal space (floor area and ceiling height) needed for the proposed uses.  The design takes the approach to set back from the maximum building envelope so as to minimise disturbance to the adjacent historic buildings and leave them intact.  The new buildings have allowed approximately 1.5m setback from the adjacent historic buildings.  Hence, in terms of the massing of the building, it is compatible in terms of both visual and cultural heritage perspective. 

Façade Treatment of the New Building

Different façade treatments have been considered for the new building.  These include a fully glazed façade, a corten metal panel façade, a polished aluminium metal panel façade and a cast aluminium unitized façade.  A fully glazed façade was considered but rejected because of the apparent lack of association with the immediate building material fabric as well as the potential to pose glare impact.  A corten metal panel façade was also considered but rejected because of concerns weather-related premature aging.  A polished aluminium metal panel façade was also considered but rejected over the potential for glare impact.  A cast aluminium unitized façade system has been considered suitable for the new building.  Such proposal was the results from a study of existing site material textures and scales, such as porous masonry, traditional brick and granite wall constructions.  The versatility of aluminium in terms of texture, malleability, light weight, lifecycle and general aesthetic makes it the preferred material for the distinctive integration of new construction within the historical heritage compound.  The composition of the new building façades will register their respective interior layout and general façade technical requirements.