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Laboratory conditions

Arup’s lighting design for the newly developed Sainsbury Laboratory at Cambridge University makes intelligent use of natural light to achieve large energy savings. Amanda Allen talks to Arfon Davies, associate director at Arup Lighting, about the Breeam Excellent-rated building

The Sainsbury Laboratory is an 11,000m² plant science research centre set in the University of Cambridge’s Botanic Garden. Rated Breeam ‘Excellent’, the building’s main laboratory spaces incorporate specially designed rooflights that significantly reduce the need for electrical lighting within the space. This ability to light the space using daylight for the majority of the working day will lead to huge reductions in energy consumption for the client, as Arfon Davies explains.

“The ability to light the space using daylight for the majority of the working day will lead to huge reductions in energy consumption” Arfon Davies, associate director, Arup Lighting

“The daylighting system can achieve sufficient general illumination for more than 80 per cent of the typical working day. No electrical lighting is required during these hours, representing a significant energy saving for the laboratory.”

The design brief for the Sainsbury Laboratory was to achieve a high-quality working environment that would attract leading scientists from around the world. Central to this aim was to provide a working environment lit by daylight, and with strong visual connections to the garden outside. “The client wanted to create a world-class laboratory working environment. In response to this, Stanton Williams were very keen to provide a generously daylit space to set it apart from the majority of laboratory spaces, and our early design discussions led us to introduce daylight from above rather than just through windows,” says Davies.

Light by day

Considering the different options, Arup initially studied a typical sawtooth northlight solution, but reconsidered given the shape of the laboratory spaces. Davies says, “The geometry of the laboratories meant that the scale of northlights would have been too small to allow the desired, uniform distribution of light in the space.” This desire for uniformity of daylight throughout the space led Arup to a flat rooflight system incorporating a carefully selected diffusing element.

The rooflight design comprises of flat, glazed rooflights above 3m deep GFRG light wells, with the bases of the wells 3.2m above floor level. The light-well shape, which fans outwards from the rooflights, was carefully designed to maximise uniformity of daylight. Glass in the rooflight incorporates a translucent interlayer acting to diffuse and scatter daylight and prevent direct sunlight from reaching the laboratory work benches. “This was the best solution for the space,” says Davies, “as it provides the greatest overall daylight penetration for all weather conditions and diffuses sunlight without the need for exterior shading elements.”

Due to the use of the space, adequate shading was also an important consideration. “There was a need to exclude sun from the laboratory spaces to ensure the visual comfort of scientists and to protect some highly sensitive machines which cannot be exposed to direct sunlight,” says Davies.

Helping hand

While natural light illuminates the laboratory for the majority of the working day, a combination of task and ambient lighting is also used to supplement light levels when necessary. This lighting is linked to photocells and activated when daylight levels fall below 750 lux.

In total, there are three layers of electric lighting within the laboratory space, the first of which is the ambient lighting system installed at the top of the rooflight. Davies says, “Because the rooflights are quite deep, we didn’t want them to appear like a black hole at night so we introduced custom-designed, linear T5 fluorescent luminaires from Aether Lighting, which are installed at the top of the rooflight.” According to Davies, the aim here was to provide a distribution of light that was almost equal to daytime. “We wanted the first ambient layer to produce something that is very diffuse and uniform, almost like it’s originating from the sky.” This ambient lighting system provides general lighting for the space, of 200 to 300 lux, with the continuous linear luminaires arranged to cross-light, so as to evenly illuminate the curved walls of the GFRG light wells.

A second layer of ambient lighting was also introduced to meet the client’s desire for increased ambient lighting. This secondary layer consists of a continuous Slotlight II from Zumtobel installed at the base of the light-wells. The third layer of lighting is composed of custom-designed T5 task lights integrated within the laboratory benches, which were designed by Arup and Stanton Williams, and supplied directly by the bench suppliers.

Other elements

While the design of the laboratory space was a key element of the project, Arup also designed the lighting in the auditorium, which has a coffered ceiling concealing T5 fluorescent lighting within it. “We wanted the ceiling to be a bit more defined in this space, and worked very closely with the architects to refine the form and shape of these ceiling elements,” says Davies.

Another key interior space is the internal circulation area – a public and communal area spaced over two floors. Here the materials are glass and stone, in keeping with the natural theme of the building. Eager to minimise clutter on the ceiling, Arup wanted the lighting to be integrated with the architecture and other building services. They achieved this using a Modular profile system, which also incorporated other elements of building services such as the smoke detectors, photocells, and the PA system. “Co-ordination wise, this was a big undertaking for the design team,” says Davies.

A key design consideration for the exterior of the building was to minimise light pollution, while still providing a secure and visually interesting night time scene.With the exception of uplighting the trees at the entrance, all of the exterior lighting is low-level and controlled. “We wanted to give the entrance a focal point for when people approach the building either at night or during the winter so we did that by uplighting the trees,” says Davies.

Another key element of lighting the exterior was to link it to the interior, which was achieved through the use of a recessed linear light in the ground on both sides of the glazed entrance façade. “We wanted a consistent and uncluttered language of light throughout the building and achieved this by using linear lighting systems carefully integrated with the architecture. We wanted a continuous language of light throughout the whole public space.”

PROJECT DETAILS

Project: Sainsbury Laboratory

Client: The University of Cambridge

Lighting specialists: Arup Lighting – Arfon Davies and Melissa Mak

Architecture: Stanton Williams

Suppliers: Aether, Modular, Se’Lux, Simmtronic, Zumtobel

Botanic boffins

Cambridge University Botanic Garden, home to the Sainsbury Laboratory, was conceived in 1831 by Professor John Henslow who was Charles Darwin’s guide and mentor.

The Garden was developed as a working research tool in which the diversity of plant species could be systematically ordered and catalogued. The Laboratory further develops Henslow’s research principles, and central to its identity is the way in which it operates as a sequence of spaces, conceived in terms of their relationship with the surrounding garden. The way in which the laboratory’s different functions are connected by a continuous route recalls the ‘thinking path’ described by Darwin, a way to reconcile nature and thought through the activity of walking.

The building also acts as a home to the University Herbarium, which contains over one million pressed and dried plant specimens, including the great majority of those collected by Charles Darwin on the Beagle voyage which set sail from Plymouth on 27 December, 1831.

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