Description

The New Parliamentary Building is one of the most controversial and disputed of England’s new office buildings. The English press calls it the most expensive office building in Europe while, at the same time, the most energy-efficient and ecological of England’s office buildings. The name “Portcullis House” with its connotations of exclusion, together with its inhospitable appearance, has made it a symbol of politics conducted behind closed doors, contradicting the image of open and aboveboard politics in a twenty-first century democracy.

Portcullis House directly faces the Palace of Westminster, home of the Houses of Parliament. It is part of the so-called parliamentary ‘campus’ north of the Palace of Westminster. In 1989, Michael Hopkins Partners was appointed to carry out a study on the space requirements of the Members of Parliament and their spatial conditions in the Palace of Westminster. According to the study, the existing buildings on site were to be adapted to the MPs’ new requirements. However, due to the Jubilee Line extension linking London’s Docklands, the Westminster underground station had to be enlarged. It was decided that the above ground area over the station would be refurbished, and the existing buildings demolished and replaced with a new structure. The contract for renovation and extension of the underground station was also awarded to MHP. This enabled the building of Portcullis House to be integrated with the construction of the underground station. The new building adapts itself to what is certainly the most difficult site in London, more in the public eye than any other. It holds its own – not least through its striking chimney-turrets – yet without dominating its surroundings. It was modelled on both the vertical structure and the façade of the Palace of Westminster opposite and on the form of a building with a courtyard. In contrast to Westminster Hall, the courtyard in Portcullis House has a glazed roof constructed of oak and steel above the first floor. In the courtyard, MPs, members of staff and invited voters can meet and talk, casually or more formally. On the ground floor around the central courtyard lie general-purpose facilities such as the restaurant, cafes, e-library, post office and voting offices, with access to the entire building at the corners. A wide stairway leads from the courtyard directly to the first level, to the committee and meeting rooms. These are oriented towards the outside and accessed via a broad corridor running around the inside. Resembling cloisters, the passage serves to give MPs an opportunity for informal exchanges. On the three levels above and the first roof level, there are offices for 210 MPs and their staff. The size of the offices was fixed at 20 m² apiece. The maximum room depth that still allows natural lighting, while providing the required number of offices per level, resulted in bays of 3.60 metres. Each MP’s office has been allotted rooms for staff and assistants – who may have to be shared by two Members, depending on their status. Lavatories and staff kitchens are situated in the corner areas, together with the access cores.

The engineers Ove Arup were charged with planning the construction and the climate management. It is a fine example of integrated building planning. To enable the erection of the new building while the underground station was still under construction, it was 95% pre­fabricated, incorporating the building services.

The underground station forms the basement. In order to transmit the load of the building to the 30-meter-deep foundation, the outer perimeter is supported by the reinforced concrete walls of the station. The courtyard façade is supported by a reinforced concrete structure comprising six tied arches bearing on six columns, ‘threaded’ between the converging Underground lines beneath. The façades are developed as frames that integrate the floor slabs as structural elements while leaving them exposed on the outside. The vertical columns are massive sandstone piers that decrease in diameter due to load reduction as they ascend and are held in place by post-stressed struts within the structure. The ceiling is constructed of reinforced concrete elements prefabricated in gull-wing form in order to span the 13.8 metres between the walls. The resulting wave-form becomes the offices’ ceiling and also provides for ventilation via the space under the floor. The vertical air ducts are integrated into the bronze elements between the sandstone piers and the window elements; as the piers decrease in size with height with reducing structural load, the ducts increase in size and flow capacity towards the roof-mounted air handling plant. These ducts also play a principal role in the roof construction. They are gathered in groups of 4 pairs per side above level 5, and continue up to straddle the building forming the primary roof structure, the “spider”. These structures support the building’s fourteen chimney-turrets that contain the air handling units. In the turrets, the energy from waste air is used to bring in fresh air via “Thermal Wheels” – regenerative heat exchangers. The building manages without air conditioning, being ventilated 100% by outside air and using 25% of the energy used by the refrigeration plant of a conventional office building of the same size. The precondition for this was the uncompromising reduction of the cooling loads through triple-glazing with adjustable bronze blinds in the inner cavity. Exhaust air from the rooms is drawn through the inner cavity, reducing the heat gain to the room in summer and heat loss in winter. The dark blinds act as solar collectors in winter. Air is supplied to the rooms through the raised floor; at night, cold air circulates to cool off the concrete slabs and concrete internal partitions. Additional cooling is achieved by water drawn from boreholes 200 meters deep.The offices’ natural lighting is supplemented by horizontal reflectors in the window area and the use of a micaceous sand to give a light coloured raw concrete finish. The entire load-bearing structure and the façade are blast-resistant.

With a required life of 120 years and a projected life of 200-400 years, Portcullis House earns its reputation as one of the most sustainable new buildings in Great Britain. The comprehensive detailing and careful workmanship through every aspect of the building project as regards conception, construction and detail was, however, only possible in a project that was not subject to the limits imposed by the commercial office market.

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Originally published in: Rainer Hascher, Simone Jeska, Birgit Klauck, Office Buildings: A Design Manual, Birkhäuser, 2002.