Businesses may be becoming ever more reliant on their knowledge workers and their ability to do their work well - perhaps to counter the effect of work intensification as head counts are reduced - but why not skimp on their working conditions? Open-plan offices have been becoming more prevalent for decades, but these days it's not just a matter of replacing a warren of private offices with a cubicle farm. Why not get rid of the dividers and the modicum of privacy they provide - purely to encourage collaboration and break down silos, you understand - and move to ''hot-desking'' - providing fewer desks than the number of people you employ? Even more progressive is the move to the ''virtual office'', where workers are issued with their own mobile phone, a laptop and a locker, but denied a particular desk. You want them moving from desk to desk each day, even morning to afternoon. To ensure they don't break the rules and bags a particular desk, you impose a ''clean-desk policy'' where cleaners are instructed to toss away anything they find on desks overnight. They may be knowledge workers but they're not likely to need books or papers for reference, are they? That's what Google is for.

I'm sure the reduced office space required has yielded savings, but I suspect it's a false economy when you take account of the effect on workers' productivity. Indeed, there is growing evidence the costs of these policies exceed the benefits. Diane Hoskins, of Gensler, a big US office design firm, has been researching the question using surveys of more than 90,000 people from 155 companies across 10 industries. Her people found that knowledge work consists of four modes: focus (individual work involving concentration and attention devoted to a particular task), collaboration (working with another person or group to achieve a goal), learning (acquiring knowledge of a subject or skill through education or experience) and socialising (interactions that create trust, common bonds and values, collective identity and productive relationships). They found that the most significant factor in workplace effectiveness is not collaboration - the stated justification for most of the office changes - but individual focus work. Whoever would have thought being able to concentrate on your work could be so important?

They also found that focus is the thing the new-style offices make hardest. ''Co-worker interruptions, auditory and visual distractions all combine to make focus work the modern office's most compromised work mode,'' she found. Who could have known? The four work modes are highly interconnected, the researchers found, with focus as the primary component and the key predictor of all other effectiveness. So office arrangements that sacrifice individual focus in pursuit of collaboration result in decreased effectiveness for both. Other research by Gensler finds that workers who can focus effectively are 57 per cent more able to collaborate, 88 per cent more able to learn and 42 per cent more able to socialise in their workplace than their peers who are unable to focus. Justine Humphry, of Sydney University, says clean-desk policies are used as a way to prevent employees from ''nesting'': settling in one place for too long and giving it their personal stamp. This is intended to yield cost savings and productivity gains by reducing overall floor space and facilitating collaboration among staff, thereby breaking down the silos and barriers of the standard cubicle office.

Her research finds that workers continue to go about personalising and nesting in their work environments, undermining the design of a mobile and flexible office. ''Studies have highlighted identity expression and professional status as key reasons for personalisation at work,'' she says. ''But in my … research conducted on professional knowledge workers, it was found that personalising or nesting is also performed for practical reasons … to enhance wellbeing, to create opportunities for privacy or collaboration, to facilitate social interaction and to save time.'' It couldn't be that penny-pinching and fads in office design are part of the explanation for our less than sterling productivity performance since the 1990s, could it?