How quickly a building becomes an icon. At the annual briefing and lunch organised by building services researchers BSRIA, one of the major themes was air leakage in buildings. Between courses, delegates were invited to inflate 'a working model of Peckham Library' - a bright balloon. Only one of the 200 delegates managed it. 'One in 200 is about the proportion of buildings that don't leak, ' said the BSRIA's chief executive Andrew Eastwell.