news
- 03.04.2008
A new building for the Welsh National Assembly
Cardiff, Wales
exterior
In March 2006 (St. David’s day, 1st of March), Her Majesty the Queen opened the Senedd building for the National Assembly for Wales (NAfW). The project, originally conceived and won in competition in 1998 with Architects Richard Rogers Partnership (RRP), BDSP Partnership and ARUP to provide a new home for the Assembly, was re-tendered in 2001 under a ‘design and build’ procurement route with the same design team lead by the Main Contractor Taylor Woodrow Construction. The Clients Brief required that the new Assembly Building meet the Assembly's constitutional responsibilities for sustainable development and achieve "Excellent" rating under the Building Research Establishment Client National Assembly for Wales Project direktor TPS Architectural design Richard Rogers Partnership Environmental Assessment Method (BREEAM).
In response, the environmental design strategy for the building as a whole was one first and foremost of reducing energy demand, followed by the application of renewable energy sources and only then covering any residual demand by using highly energy efficient technologies. This philosophy is also reflected in the lighting design and could broadly be described using the following three step approach:
1. Maximise and control natural daylight penetration;
2. Use of energy efficient light sources;
3. Link controls to deliver the best cross-over between natural and artificial.
A predominant feature is the Debating Chamber, located in the heart of the building. This space, where proceedings will be broadcast live, is unmistakably meant to be read and perceived as a daylit space by both Assembly Members and the watching public. The vision of the design team was to allow internal conditions of the Chamber to vary naturally with the passage of time, thus providing a vital psychological connection with the outside.
The space is enclosed and daylight can only enter via a glazed lantern that is seated on the domed roof beneath a rotating wind cowl and a horizontal glazed ring around the base of the funnel in the main hall events area. The most prominent daylight aperture is the glazed lantern. Daylight is reflected into the heart of the Chamber below via a combination of light shelves around the base of the lantern, a suspended conical mirror and a series of concentric aluminium rings which make up the chamber funnel.
The artificial lighting design for the debating chamber required that the artificial lighting achieve a horizontal illuminance of 500lux with a colour temperature of 5000K and colour rendering of 1A/1B, suitable for colour balancing by the host broadcaster, televising the proceedings during daylight hours. As with the daylighting studies, numerous computer modelling simulations assessing various artificial lighting strategies and luminaire configurations were undertaken by BDSP Partnership to achieve both a technically compliant and an architecturally simple yet elegant solution. Following some early investigations on CTB filters, the installed design is based on the use of 70W 4200K ceramic discharge metal halide CDM-T lamps. The fixture - Pixel Plus - was modified to accept the 70W CDM-T lamp.
This meant prototyping a new fixture, on which photometric and thermal tests were conducted in Italy at the IGuzzini laboratory. The result is a Chamber lit by a single ring of 80 fixtures with 70W CDM-T metal halide lamps, recessed into the base of the funnel and set at oblique angles, with the aluminium rings starting immediately above. A further eight floodlights are installed higher up between the tubes to illuminate the surface of the funnel. In addition, at the perimeter of the chamber, circular T5 fluorescent lamps are recessed into the acoustic panels. As the metal halide lamps cannot be dimmed, the floodlights were arranged in four banks (i.e. 25%) to achieve daylight compensation. In this manner they could be switched according to the daylight levels. In conclusion, the artificial lighting design coupled with daylight successfully complements the overall low energy concept for the whole project, enabling the Senedd to set new standards in environmental performance.
assembly chamber
client: National Assembly for Wales
project direktor: TPS
architectural design: Richard Rogers Partnership
light fittings used: Pixel Plus
Riba Stirling Prize 2006:
The Welsh National Assembly was one of the finalist projects of the prestigious british award
www.ajplus.co.uk
