It was a requirement of the brief that the building should set an example in energy saving and this has had a profound effect on its structure and features.
Fourteen tall, bronze chimneys crown the ridge line, echoing the chimneys of the Norman Shaw building and the pinnacles (which are also chimneys) of the Palace of Westminster. They are not just decorative embellishments, however, but the terminals of a vertical duct system that embraces the whole building.
Each sandstone pier is flanked by bronze clad ducts which expand upwards in proportion to the tapering of the pier and connect at cornice level with the spider's legs of the roof structure. Fresh air introduced at the bases of the chimneys travels down the supply ducts into plenums beneath the raised floors. Exhaust air enters the return ducts through the inward projections of the light shelves.