The boiler house at Guy's and Saint Thomas' Hospital is located next to the main entrance. An important building, but regarded as ugly. It has long been held that the environment often influences how you feel: therefore having attractive hospitals is important. Recognising this, the hospital decided upon an upgrade and, with the collaboration of the Crafts Council, commissioned Thomas Heatherwick to refurbish the exterior. The solution he arrived at consists of 108 almost identical square panels or tiles, the edges of which have an uniform 'S'-shape, which are then infilled with woven stainless steel mesh. Individually, this gives each frame an appearance akin to a hyperbolic paraboloid, but combined together the effect is that of a rippling surface. All the panels are demountable to allow access for maintenance. The building is specially illuminated for night-time appreciation. A distinctive and welcoming icon for both staff, patients and visitors.