timeline item
Here is the information we have
on the item you selected
This entry was funded by
More like this
sign up for our newsletter
© 2018 Engineering Timelines
engineering timelines
explore ... how   explore ... why   explore ... where   explore ... who  
home  •  NEWS  •  search  •  FAQs  •  references  •  about  •  sponsors + links
National Assembly for Wales (Senedd)
Cardiff Bay, Cardiff, Wales, UK
associated engineer
date  1st March 2001 - 7th February 2006, opened 1st March 2006
era  Modern  |  category  Building  |  reference  ST192745
The Senedd houses the debating chamber and committee rooms of the National Assembly for Wales. Its open design, with a suspended timber roof and glass walls, symbolises the intended transparency of Welsh government. The environmentally sustainable building was awarded a BREEAM ‘Excellent’ rating — the highest awarded in Wales at the time.
The National Assembly for Wales was formed in 1998 as a result of the 1997 referendum on devolution. In May 1999, its first elections returned 60 Assembly Members. Until the Senedd was completed in 2006, plenary sessions were held in nearby Crickhowell House (ST194746), now renamed Ty Hywel. It now contains the offices for Assembly Members and their staff, and civil servants. The Grade I listed Pierhead Building (ST192744, built 1897) is also part of the National Assembly estate.
The Senedd, meaning ‘parliament’ or ‘senate’ in Welsh, overlooks Cardiff Bay and the city’s docks. Its architect is the Richard Rogers Partnership (now Rogers Stirk Harbour + Partners), with structural engineering by Arup. The building is intended to appear open and inviting, exemplifying honest and transparent government by "making visible the inner workings of the Assembly and encouraging public participation in the democratic process". Two of its three levels are accessible to the general public. Remaining areas reserved for use by Assembly Members.
The Senedd’s immediately striking visual feature is its rectangular roof, moulded into a row of six elliptical domes, one of which is topped by a 6m high rotating wind cowl that provides natural ventilation. The upper surface of the roof is clad in aluminium sheet with standing seams. The undulating sculptural form was "inspired by the natural flow of forces within a folding plate structure".
The roof spans some 26m transversely supported by two longitudinal rows of slender, point-ended steel columns, which are anchored with raking struts. It cantilevers 8m beyond the columns on three sides, shading the glass facades.
Visitors approaching the front steps are protected from the weather by an even larger roof cantilever, and shielded from the wind by the Assembly Field, a ‘hedge’ of 32 glass panes located at the west corner of the building, designed by American sculptor Danny Lane (b.1955).
The underside of the roof, inside and outside the building, is clad with striated western red cedar. The entrance leads into the Neuadd, or atrium, a double height space with a slate and glass reception desk below a canopy designed to aid the acoustics and maintain a microclimate for reception. A flight of steps leads up to the Oriel — the area surrounding the huge cedar-clad funnel that lights and ventilates the debating chamber, or Siambr, two floors below.
The Oriel contains a cafe, exhibition space, galleries that overlook three committee rooms and a glass floor around the timber-clad funnel. The funnel is lined with 89 concentric aluminium rings, which reflect natural light down into the drum-shaped Siambr from a glazed lantern and conical mirror.
The Siambr is at the heart of the building, directly below the funnel. In the centre of its oak floor is The Heart of Wales, a 2m diameter domed glass artwork with fibre-optic lighting created by Swansea-based artist Alexander Beleschenko (b.1951). Assembly Members enter the room from the Cwrt, where they meet before and after debates.
Members sit at desks of Welsh oak arranged in concentric rows. Each desk has a computer, from which voting is displayed instantly on wall screens, and headphones for English translation of Welsh language proceedings. Activities in the Siambr may be watched from the public gallery, which seats 128 people and has disabled access.
The Senedd sits on a plinth. Deep recesses either side of the Siambr form two courtyards. These provide natural light to the ground floor and allow the public to see into the committee rooms. Glass bridges span the courtyards linking the atrium to the viewing galleries.
Except in the Siambr, the floors and parts of the walls of the Senedd are of slate. Façades are single-glazed and blast-resistant. The building’s frame is steel and exposed concrete, above a plinth of concrete and slate. Prefabrication and off-site assembly methods were used.
To simplify fabrication and construction, software modelling was used to refine the roof’s complex geometry. The timber ceiling, more than 3,000 sq m in area, was realised using 35 different panel shapes, almost all of which were transported flat and bent to shape on site.
Attention has been paid to sustainable design aspects of the building. Materials were selected for their whole-life costs, and specified to a design life of 100 years. Western red cedar was imported from sustainable forests in British Columbia, Canada, and used for its ability to resist rot and the lack of treatment it requires. The slate is from Penrhyn Quarry in Bethesda, Wales.
An earth heat exchange system is used, which uses the ground as a heat source and a heat sink. Water circulates in small pipes beneath the slate floors and around an array of 27 boreholes, each 100m deep, in the ground outside the Senedd. In winter the earth’s geothermal energy heats the water to 14 degrees Celsius.
A single 360kW Binder boiler fitted with exhaust gas recirculation and automatic heat exchange tube cleaning provides additional heating. It is fuelled from a subterranean store of wood chips or pellets produced locally.
Rainwater is harvested from the roof to two 50,000 litre storage tanks, running in piper inside the building's hollow steel columns. It passes through an ultra-violet filter and is used for flushing lavatories, landscape irrigation and window cleaning.
The reinforced insulated glass windows open and close automatically to maintain a constant temperature, minimising air conditioning use in summer and helping to retain heat in winter. The system is designed to optimise solar gain. Movement-sensitive energy efficient light bulbs are used throughout the building. The Senedd operates at well below the best practice power use average of 130kWh per sq m.
The project’s final design was approved on 18th January 2001, and the groundbreaking ceremony took place on 1st March. However, on 17th July 2001, it was announced that the architect’s contract had been terminated and the project suspended. Only the piling and a temporary site road had been completed by the contractor Skanska.
The ensuing legal dispute was not resolved until February 2002. The architect was exonerated. On 1st July 2003, a design and build contract was let to Taylor Woodrow and construction recommenced on 4th August.
On 25th November 2004, the topping-out ceremony was held. The National Assembly took control of the £67m building on 7th February 2006, six months behind schedule. On 1st March 2006, Queen Elizabeth II opened the Senedd officially. The Duke of Edinburgh, the Prince of Wales and the Duchess of Cornwall accompanied her. A ceremonial mace of gold and silver was presented to the National Assembly by the parliament of New South Wales, Australia.
The Senedd has been given ‘Excellent’ certification by the Building Research Establishment Environmental Assessment Methodology (BREEAM). It was the highest ever rating awarded in Wales. In 2006, the building won the Building Services Major Project of the Year Award, the Structural Steel Design Award, the RIBA National Award and the National Eisteddfod of Wales Gold Medal. It also received the Chicago Athenaeum International Architecture Award 2007 and the Civic Trust Award 2008.
Architect: Richard Rogers Partnership
Building services: MJN Colston
Environmental engineer: BDPS Partnership
Acoustics: Sound Research Laboratories
Fire engineering: Warrington Fire Research
Accessibility: Vin Goodwin
Bomb blast engineering: TPS Consult
Project manager: Schal International Management Ltd
Contractor (2001): Skanska
Contractor (2003-6): Taylor Woodrow Construction Ltd
Timber ceilings: BCL
IT and communications: Siemens Business Services Ltd
Biomass bolier system: Wood Energy Ltd
Research: ECPK

National Assembly for Wales (Senedd)