Cheaper fuel bills, improved working conditions and reduced m&e maintenance make a persuasive argument that is resulting in an increasing number of office developments incorporating exposed structural concrete in order to capitalise on the material's inherent thermal capacity for passive cooling.
Passive cooling uses a combination of natural ventilation and high-mass exposed structure as a thermal sink to influence internal ambient temperatures. This can eliminate the need for air conditioning and reduces the requirement for heating. Concrete is best for this approach as, unlike steel, it stores rather than conducts energy.
However, the move towards exposed concrete structures also allows architects to realise concrete's potential for designing a building that is structurally honest. To put it crudely, it is the 'what you see is what you get' aesthetic. There is no cover up. This is demonstrated to dramatic effect at the new cae Electronics headquarters, designed by architect Lifschutz Davidson.
The building provides both discreet elegance and a sense of permanence. The design objective was to use concrete to express the difference between speculative industrial buildings and corporate headquarters. This is a building that has no need for superfluous flamboyance.
The main office is a low linear structure clad in red brick to reflect the local building materials. Behind the offices is a large lightweight steel double-height workshop building for product assembly. The client envisages that eventually the workshop will link two office blocks. A striking feature of the building is the series of perforated vertical aluminium solar shutters, extending the height of the building. Apart from being a distinctive design feature, the fins function as part of the control of the building's internal environment. Solar sensors track the position of the sun, causing the fins to rotate through 120degrees. This reduces the impact of solar gain and glare on the interior office space.
The building makes full use of its exposed precast-concrete double-T units, formed using a recycled mould floor and 200mm precast-concrete external wall panels to provide a high- quality fair-face finish. A rigorous quality-control procedure by structural contractor Composite Structures maintained the finish of the exposed concrete, which was simply painted. The finish is complemented by the simple yet effective detailing of the exposed elements.
The 13.5m long span of the concrete beams provides a column-free office environment which allows flexibility of space. Form and layout of the building are governed by the desire to provide a comfortable and productive workplace while allowing natural ventilation. During the day, heat is absorbed by the exposed concrete frame. At night, a flow of cool air in the floor voids removes heat from the concrete in a process called 'purging'. Windows can also be opened manually for extra ventilation, giving the occupants more direct control over their immediate environment.
The exposed structure of the cae building demonstrates how form, function and aesthetics can complement each other. Its structural honesty is, like the natural ventilation used for cooling the concrete, a breath of fresh air.
Ben Knight is project architect at architect Liftschutz Davidson
R T James
Ove Arup Partners