Terry Macleod, a director of Mitie, said that employers should regard the recent heat wave as a warning and start to review their temperature control systems.
Macleod said Mitie had been inundated with calls for temporary air-conditioning units after the August heat wave. The company noted that under health and safety regulations it is illegal to allow an office to fall below a temperature of 16°C, but that there was no upper limit.
High temperatures will adversely affect many low-energy buildings that rely on heavyweight materials to absorb heat and cool nights to release it.
But the heat has a more serious effect on structures built with lightweight materials, leading some to question the government's commitment to timber frame and modular housing. Architect Bill Dunster said: "Climate change is the death of lightweight construction. It has not got a future in a country that will get increasingly uncomfortable in summer."
Arup engineer Gavin Davies agreed that the move to off-site manufacture was at risk. He said: "If you are looking at buildings designed for the long-term then lightweight construction is susceptible to climate change."
The increased use of indoor temperature controls could bring the UK in line with Australia and the USA, where productivity is higher, despite warmer summers.
However, the claims have provoked a strong response from some Building readers. John Prewer, research and development director at off-site manufacturer Spaceover, described the 70% figure as bogus. He said: "Those buildings will certainly require cooling, but cool air does not have to be fed into them by bulky air-handling equipment."