Burlington Danes, one of the government’s flagship City Academies, has undergone major extension work to the existing campus on its eleven acre site in West London. The original art deco building, with its imposing 1930s façade, was extended to accommodate sixteen classrooms, four laboratories and a number of ancillary offices, staff rooms and breakout areas. The external finish features a mixture of concrete panels and large areas of glazing, plus a full-height, glazed and faceted rotunda at each end, equipped with large brise soleil to minimise solar gain. It is a large steel frame structure, three-storeys high, one hundred metres long and fifteen metres wide – and with steel being such a highly conductive material, combating the problems caused by thermal bridges was a critical consideration early in the planning stage.

There are very few effective solutions to combating the various negative aspects of thermal bridges, particularly in steel structures, but one proven answer is the Schöck Isokorb type KST thermal break module. It has excellent thermal insulation properties and dramatically reduces energy loss by guaranteeing the homogeneity of the thermal envelope between cantilever structures and the internal floor; while also transferring load and maintaining full structural integrity. Just as importantly, it also enables the inner surface area temperatures to remain well in excess of those likely to cause condensation and mould formation.

Mould is not a new phenomenon of course, but a combination of circumstances is elevating interest in the problem. Primarily these are better insulated and more airtight buildings, improved energy efficiency requirements, plus much greater environmental awareness. Local relative humidity in a building needs only be sustained at above 80% for mould growth to accelerate appreciably, and in some quarters the problem is being compared with the ‘asbestos experience’ of two decades ago.

In the USA, claims from workers and users of affected buildings are becoming more prevalent because of the rapidly growing publicity, hype and litigation, involving allegations of mould damage and there is concern that this could set a precedent for the UK. The Institute for International Research in New York has predicted that insurance premiums in the US could rise significantly to offset claims for mould damage – with insurance companies more concerned about the health aspects of mould rather than property damage.