Chimneys traditionally had a triple function: to ventilate rooms as well as getting rid of smoke, and to create a vertical emphasis to the external architecture. Some architects and builders chose to exaggerate them, some tried to hide them in parapets and battlements, but they were always there. Until the Clean Air Acts of the 1950s, it was common even for offices in older blocks to have open coal fires. The Victorians – obsessive about fresh air since they polluted so much of it – often incorporated separate ventilation flues into their chimneystacks, using the warmth set up by fires to get the air moving.

Long before the days of airconditioning, architects and engineers experimented with ways to air and cool theatres and public buildings using this "chimney effect" – sometimes successfully, sometimes not, as at the Houses of Parliament, where the chimney-effect ventilation system, concealed in various turrets and spires, was always dodgy. Then, there was no option. Today, it is an alternative that is rapidly reviving for two reasons: environmental and economical. Over the long term you save lots of money in energy costs: if enough people do it, you also reduce the amount of "greenhouse gases" given off by power stations. That at any rate is the theory. But does the appearance of these new buildings have to be quite so in-your-face as the Contact Theatre in Manchester?

Alan Short of Short Associates - who apart from being an architect is Dean of Art and Design at De Montfort University - says that he is "more and more convinced that the next generation of naturally conditioned buildings will be materially different from those existing." The internal climate of the last generation of buildings, he argues, had nothing to do with their architecture: now, all that has been reversed. Obviously Short is something of an extreme case. His earlier Queen's building at De Montfort in Leicester, which made a much more retro architectural virtue out of its greenness, got the modernists spluttering in anger. He likes colour, decoration, little flourishes for their own sake: he is by no means immune to the whimsy that Hopkins so sternly resists. Having a theatre to do suits him perfectly, since there he can indulge his taste for drama without fear of reprisal, and the vivid interior colour scheme and repeated use of the curtain-metaphor in the architecture is something he just wouldn't get away with in your average office block. True, the galvanised steel curtain of the entrance facade, or the rigid red plaster side curtains in the auditorium, have a function - the first acts as another airflow regulator, the second acoustically kills side echoes - but the fact remains that he could have had those functions in a different style, had he wished.