Written during an intensely boring conference session and dispatched via a free wi-fi node outside Liverpool St Station in London later the same day.

Between 10 and 20 years ago designers and architects made assumptions about the use of office space and people’s working practices.

Those estimates were translated into energy densities in the design of air conditioning and the square metre space allocation per head for occupancy limits. Fast-forward to today and those assumptions appear increasingly erroneous.

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In many city buildings and districts the original power distribution limits have now been reached or exceeded to the point where technology and facilities have to be limited, managed or outsourced.

What happened? Well, more IT per square metre than anyone ever imagined, new flexible work methods and hotdesking, led to greater occupancy rates than originally predicted.

A case in question is the Docklands area of London where the electricity grid is operating at full capacity and companies are having to move server farms to new areas where there is sufficient power.

But it turns out that even finding suitable outsourcing locations within the UK is also a problem. The city of Peterborough has, for example, peaked in terms of industrial power delivery to some areas. Companies are turning away.

As time and technology moves on this problem is only going to get worse. But there is significant waste that we could recoup. For example, the average server farm is generally running at less than 10 per cent capacity today.

So an obvious solution is virtualisation and facility sharing. Why do companies always need to roll their own? Clearly they do not.

Other simple energy-saving measures would involve a move to less power hungry laptops and thin clients, plus of course far more mobile, nomadic and home working.

Only 40 or 50 years ago it was not unusual to see companies and commercial sites generating a high percentage of their own electrical power.

It looks as though we may see a return to that practice as more and more companies are now critically dependent on having no-break power supplies 24/7, 365 days a year.

The most interesting aspect of this development will be to see what solutions they choose. You might think that sustainable technologies will be the obvious choice, but not so yet.

When your requirements are for megawatts of power provided with high reliability and resilience, I’m afraid it still means burning gas or oil.