Portcullis House, London

Portcullis House is a 17,000 sq.m complex for Members of Parliament of the British Government in London and is located opposite the Houses of Parliament � a World Heritage Site - and the design, with its rows of tall chimneys, is intended to recall the Victorian Gothic design of the Palace of Westminster.

The building has a design life of 125 years and the brief from the client was that the building should "leave as little impact on the planet as possible". The building is designed to use less than 30% of the energy consumed by a similar building of conventional design which equates to 70% energy savings and an annual saving of 2,600 tonnes of carbon dioxide.

To achieve this the building incorporates a "living wall" fa�ade which collects the sun's heat via dark blinds (to avoid solar gain) and maximises daylight through reflective lightshelves which project light into the interior of the office. An unpowered air conditioning system which draws air through the building by exploiting natural convection flows and uses water from two boreholes sunk 150 metres below the building's basement level for summer cooling.

The lighting design and controls are also optimised to reduce energy consumption � critical in a building where there is no mechanical air-conditioning. To minimise the use of artificial lighting, light shelves with reflective upper surfaces, three-quarters of the way up each window, reflect outside light into the depth of the rooms and also provide shade from low level sun. The light fittings within each office are mounted to reflect lighting deep into the room and the Delmatic lighting management system reduces the artificial light output to take account of the amount of reflected daylight. Integrated control of the window blinds enables the extent of daylight penetration to be optimised while also taking into account possible solar heat gain.

Consultant � Arup

Back