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The Potterrow site lies just to the north of George Square in central Edinburgh and, apart from its use as a surface car park, it has lain empty for many years. As such, it is the legacy of Edinburgh University’s struggle to consolidate its town centre campus - a process that began with incursions into George Square a century or so ago and continued throughout the 20th century, leading to major redevelopment of the south, east and north sides of the square in the 1960s and ‘70s and the acquisition of land between Potterrow and the McEwan Hall.
The tenements on Potterrow were demolished and Edinburgh Corporation re-routed traffic around its outer edges, only the northern part of the site was developed with new buildings, with the effect that the group of white concrete structures known as the Health Centre seem isolated and incomplete.
The masterplan framework prepared by RMJM Architects to repair this fragmented part of the University’s estate, in a way that also integrates any new development with the City as a whole. It goes without saying that, because of its proximity to a World Heritage Site, any new development must be to the highest architectural and urban design standards.
Examination of old street maps confirms that, whilst the Potterrow site is now broadly rectangular, it was once dissected across its diagonal by the continuation of Bristo Place. In consequence, the morphology of the area was dense and tight with buildings, with glimpses into George Square or towards the steeple further south on Potterrow. Clearly, any substantial new buildings are going to radically alter for the better the perception of what is presently a windswept, open area.
Bennetts Associates and Reiach and Hall were appointed jointly in Autumn 2003 to design the new Informatics building on the Potterrow site, together with future accommodation for other departments as described in the Introduction.
The masterplan identifies the Potterrow car park as the largest of several University development sites, measuring approximately 70m x 85.m, with pedestrian or vehicular streets on all four sides. Because it is unencumbered with existing buildings, it is in effect a "standalone" plot that can proceed at any time, although its physical relationship with the context of the existing Student Centre and Management School Buildings and with the future masterplan buildings that will eventually replace it are equally important considerations.
To the north of the site, therefore, is a primarily pedestrian route, Marshall Street, connecting Bristo Square to Nicholson Square that passes by the service entrance of the Health Centre in the short term and a potential new building of around five or six floors in the long term. To the east is Potterrow itself - a relatively busy street that adopts the alien character of a dual carriageway as it passes the Student Centre and Management School. The buildings on Potterrow itself comprise a mixed bag of tenement-type housing above shops and a new mosque that tends to underline the fragmented nature of the area. To the south is Crichton Street and the 1960s Appleton Tower, academically an extremely functional and effective University slab-block that rises well above the natural skyline to 11 floors. On the west side of the site is Charles Street, which adopts the role of a major pedestrian route between George Square, Bristo Square, the McEwan Hall, the Health Centre and other prominent landmarks beyond the immediate area such as the Old Quadrangle and Chambers Street.
The four corners of the site also have particular significance. The combination of Charles Street, with the increasing use of Crichton Street (as nearby developments east of George Square come on stream,) means that the corner of the site at the intersection of these two routes has a high level of prominence, not only for pedestrian traffic but also from George Square itself, making it an obvious location for a major entrance. The opposite end of Charles Street has a similar level of importance, being highly visible from Bristo Square, albeit with a backdrop of the Appleton Tower, and the point that can provide the first impression of any new buildings when approached from the Old Town via Bristo Place. The north-east corner has the potential to form a pivot in the alignment of any new route between Nicholson Square and Bristo Square, whereas the south-east corner announces both the site and the point of entry to George Square on the approach from the south. This latter connection has further significance in that it represents the main link to the University’s suburban campus at King’s Buildings.
At high level, the views are exceptional. With Salisbury Crags to the east, the Pentland Hills to the south (somewhat obscured by the Appleton Tower) and the Castle to the north-west, the roofscape is not only an important resource but will also be visible from many surrounding points.
The Architects’ approach to the project is intended to balance the functional needs of the University’s estate and its occupiers with those of urban design and the external community.
Like many academic institutions, the focus of the University is on teaching and research, but only a modest proportion of its accommodation is purpose-made for lectures or unique activities such as science labs. The basic requirement for most purposes is more akin to regular office space, in that it can accommodate research, administration, small teaching or tutorial spaces, academic staff offices, meeting rooms and so on. Edinburgh University’s own experience suggests that simple, flexible, daylit space such as the Appleton Tower is of greater value in functional terms than, say, the converted Georgian houses in Buccleuch St.
In consequence, the basic form of construction for most of the Potterrow development is a relatively standardised unit of floorspace that can be used for a range of academic purposes and can be readily adapted to a variety of non-academic uses over its lifespan. It has a generous floor-to-floor dimension consistent with modern office standards, its width is generally constant for ease of internal layout and good daylighting, and it is planned on a square module of 1.5m in common with most buildings in the commercial sector. Quite apart from its inherent economy of construction, this approach places a high priority on future adaptability, in recognition of the University estate’s need to accommodate continual change in its departmental occupiers.
Therefore, whilst the site layout must adapt to a wide variety of external conditions such as views, adjacent buildings, routes, points of entry and so on, the internal arrangements of the project are of necessity repetitive and functional. The means of creating spatial interest and visual stimulus within this setting are described more fully below.
The design concept for the site as a whole comprises a family group of linked buildings, as opposed to one, single, large building or "superblock". There are several reasons for this.
First, the urban "grain" of Potterrow was historically far smaller (at least on plan, if not in height) than could be achieved by a single building. Second, the scale of a single building on this site has the potential to be unduly monolithic, overpowering other buildings in the area that might be considered to be more important. This is particularly true of the Old Quad - the architectural jewel in the University’s crown and the centre of its governing functions. Third, the former street pattern indicated a public route across the site and there is evidence of a strong desire-line across the site today, with pedestrians picking their way between parked cars. Fourth, other urban blocks that survive in the immediate area (e.g.; the medical school) are characterised by routes, courtyards or alleys rather than a single building. Fifth, the Brief requires a development that can be phased, which can be problematic with a single building.
By using the standard unit of floorspace, each of two major buildings are arranged around a rectangular courtyard or atrium, one placed towards the north east and the other towards the south west extremity of the site. Each major building is supplemented by a further wing of space, running parallel either to Charles St or to Potterrow respectively, thereby creating an irregular geometry in the spaces between different elements of the site’s composition. When viewed externally, the plan-forms created by these devices give the impression of two interlocking buildings of some complexity, in contrast to the simplicity of their internal organisation.
Whilst the atria of the two major buildings are enclosed and, therefore, private, the other spaces within the site are open to the sky, forming a diagonal pedestrian network that rekindles the memory of the street that once traversed the site. Each private atrium has a strong visual and physical link to the open courtyard at the centre of the pedestrian route in order to create a strong sense of focus and a memorable public space. The intention is that certain activities within each building can spill out into the courtyard when appropriate, such that a new threshold is formed between the University and the general public.
In broad terms, this network of spaces follows the slope of the ground, with its high point at Bristo Square and the low point at the south-east corner by Potterrow. Each major space is a level plateau, with gentle ramps forming the connections. It is therefore completely accessible to all, although the University will wish to control entry at designated times.
Studies have been undertaken to ensure that the form of the surrounding buildings takes account of the need for direct sunlight in the central courtyard and atria at key times of year.
In terms of massing, complexity on plan is mirrored by variations in overall height. Whilst there is a general datum of six floors, most of the Potterrow elevation is reduced to four floors in response to the scale of the buildings opposite. Conversely, the northern end of the Charles St block is raised to eight floors so that it can hold its own beside Bristo Square and occupy the foreground in the view from Bristo Place currently dominated by the Appleton Tower. In between the taller volumes the height is reduced to three floors on the west side to allow sunlight to penetrate into the courtyard and provide visual punctuation in what would otherwise be a long façade. The skyline is further enlivened by pavilions, terraces or atrium roofs.
In order to provide flexibility for different room partition locations in future a 1500mm planning grid has been used and the smallest room width of 2 bays, 3000mm, therefore always has to accommodate a window.
It was not thought appropriate to utilise curtain walling or a horizontal fenestration approach as Edinburgh facades tend to have a vertical emphasis with a high percentage of solid to void. Thus the Potterrow fenestration pattern also tends to have windows with a vertical emphasis and a percentage of solid to void in the order of 60:40 to provide a relationship to the surrounding buildings and to reduce solar heat gain and achieve good daylighting to the interior.
We have stated elsewhere in this report that a monolithic superblock with similar elevations on all sides seemed a crude response to a very varied surrounding streetscape. It is also arguable that too much variation in terms of pattern and materials denies the function of the building and could be overly whimsical. Therefore the building strikes a balance between a consistency of overall approach whilst responding to the primary events in the context.
Thus the Charles Street elevation utilises a similar sandstone to that of George Square providing continuity but signals itself as a city block with its own identity by using an irregular window rhythm. The same materials and rhythm is used along the majority of Crichton Street and the north west portion of Marshall Street to provide not only continuity to the urban block but also emphasis the strong diagonal pedestrian route through the middle.
The Potterrow elevation uses a more regular orthogonal window rhythm and a different material, grey cast stone panels to calm down an existing street pattern which is very haphazard in terms of scale and materials. The same elevational treatment turns the corners into both Marshall Street and Crichton Street to emphasise the shape of the city block in exactly the same way as in Charles Street.
The internal courtyard facing elevations tend to have greater percentages of glazing, although with the same basic rhythm, as the courtyard context is different from the surrounding streets. The deliberately lighter cast stone panels are used to maximise light and provide a certain surprise and different feel to the more civic street facades.
Key events such as entrances, the café, special meeting rooms and roof terraces provide emphasis and contrast to all elevations.
The larger, southernmost of the two major buildings is the Informatics department, whilst the northernmost is allocated at present to Humanities, the Student Centre, incubator space and a new Health Centre. The location of each activity and its principle entrance reflects its identity and the need for interaction either with the University or with the public. In particular, the atrium of the Informatics building is seen as its "Forum" - a busy space in which to demonstrate its research programme and illustrate the meaning of Informatics to the wider public.
Internally, the atrium or Forum provides a strong departmental identity as well as a source of daylight. A series of double-height spaces at different positions around the perimeter of the atrium provide a sense of changing direction, encouraging vertical as well as horizontal connections. In other respects, the plan of each floor caters for a highly cellular arrangement, but with unbroken corridors kept to a minimum for visual and orientation reasons. One of these corridors is brought to the edge of the atrium and straight across the link to Potterrow, to increase legibility and add drama to the pattern of circulation.
The first phase of construction, for which funding is largely secured, is to be the Informatics building, including its associated wing on Potterrow, plus a portion of the central pedestrian courtyard.
The timing of the second phase will depend on the availability of funding. The University is anxious to complete the full development and it is a possibility, for example, that Phase 2A, the student hub facing Charles Street will be constructed at the same time as Phase 1. The Application drawings indicate the phasing Options and the use of the residual land prior to the construction of the next phase.
Samples of all external materials will be submitted prior to the end of September.
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