The demand for coloured glass in architecture is becoming more and more prevalent. Developing technologies have allowed large expanses of glass to be used structurally, encouraging architects to turn to the vibrant material to create modern buildings that can tell a story through their design.
When the design team for the new Stoke-on-Trent City Council offices was enlisted to draw up plans for the building in the heart of the new Smithfield leisure and cultural quarter, they wanted to create a landmark that combined modern design with references to the rich history of pottery manufacturing in the city.
Since the 17th century, the area has been almost exclusively known for its industrial-scale pottery manufacturing, and is home to some of the world’s most influential ceramic designers, including Wedgewood and Royal Doulton.
It was, however, the work of world-renowned ceramic artist Clarice Cliff, who was born and worked in Stoke-on-Trent that the designers turned to for inspiration. Taking the simple form of a ceramic tile, the team tessellated panels of green, blue, red, yellow and white glass, drawn from the artist’s colour palette, into a continuous grid of pentagons and hexagons along all of the facades of the building. This design is reminiscent of the potter’s most iconic pieces.
The coloured panels were then supported by black anodised aluminium frame elements, which mimicked the black outlines Cliff employed in her designs.
In creating such a visually striking facade, the top priority was to ensure that the colours were as vibrant as possible. Standard practice when creating coloured double glazing units is to apply the colour to surface four – on the inner pane of glass. However, this can reduce the vibrancy of the colour, due to added reflections from the outer pane.
In order to create maximum brightness, Pilkington United Kingdom Limited digitally screen printed the colours onto surface two – the inside of the outer sheet of glass. Pilkington Optiwhite, true low-iron glass was used for the outer pane, which has an extremely high level of clarity and therefore allows the colours to be seen in their truest form.
To ensure the colour in the glass panes was completely opaque, a second layer of ceramic paint was applied to the inside of the glass, creating a richly coloured, highly pigmented facade.
The architects wanted the colours to not only be as bright as possible, but to also project out of the facade on three sides of the building, lending them further emphasis. This was achieved by building a step into the modular system whereby the coloured glass stood forward of the clear panes.
For this, an advanced glazing system supplied by German manufacturer Schüco was used, which allowed the facade to be constructed off-site in 3m by 1.5m sections. A total of 4300m² of glass was installed in the building, 2300m² of it transparent and 2000m2 featuring the screen-printed colours.
The units that make up the facades all needed to be custom designed and manufactured to deliver the required pattern. Similarly, the variation in colours across the building’s face and its structural formation meant that few units were identical to each other, and as a result had to be installed in a very specific order.
The jigsaw-like installation was further complicated by the inclusion of electronic-opening vents to allow occupants to control the temperature inside the building, as well as the use of different levels of solar control coating on different parts of the facades.
For those sides of the building with the most exposure to the sun – the south west and south east elevations – glass with higher solar control performance was used. This reduces the amount of energy allowed into the building, in order to prevent overheating during the summer.
To lower the risk of overheating in the south-facing units, which are more exposed to direct sunlight, Pilkington Insulight Sun 60/33 was used, while on the north-facing sides, for which solar gain is less of an issue, the design team opted for Pilkington Insulight Sun 70/39.
At the front of the building on the ground floor, where double-height, single-unit windows are located, preventing overheating from excess sunlight is vital, so Pilkington Insulight Sun 40/22 was used.
Solar control and sustainability
Not only do the solar control glazing units used within the council building form an attractive feature, but they are also important for saving energy.
Over the past few decades, advances in structural glass technologies have undergone radical changes with the introduction of modern coating techniques, meaning that solar control glass is now an essential ingredient in the design and construction of low-energy buildings.
The coating added during the manufacturing process allows for the maximum amount of natural daylight to enter the building and can also maximise or limit solar heat gains where necessary. This helps to keep the structure cool and also limits the need for electricity powered artificial lighting.
The resulting effect enables the space to reduce its reliance on fuel powered systems. This could not only improve the building’s carbon foot-print but it will also provide council employees and visitors with optimum comfort levels all-year round.
A new landmark
The exterior appearance of this building is entirely defined by its glazing. The facade not only delivers the architect’s vision but it also helps provide a comfortable, efficient and light-filled environment.
The tessellated glass skin combines pattern with performance, while celebrating the most iconic product of Stoke-on-Trent’s heritage. The finished structure is a vibrant kaleidoscope of coloured glass, which creates a building with a strong civic presence and provides a new landmark for the city.