As a result, environmentally-conscious occupiers are starting to insist that development agreements include the highest BREEAM rating for new-builds, and much has been written on "green leases" which promote energy efficiency through the landlord and tenant relationship.

However, promoting and implementing energy efficiency comes at a cost. For example, a "green lease" will invariably increase upfront transaction costs, such as the legal costs of developing the lease itself.

And, developers are likely to find the cost of proving that a scheme has a BREEAM "outstanding" rating will rise considerably, especially in light of more stringent assessment criteria within BREEAM 2008.

Inevitably, developers will seek to pass on these costs to occupiers and buyers. But is the market sufficiently robust to bear them? This will depend on the extent to which these additional costs are matched by the reduced running costs of more energy efficient buildings.

There has been much talk of a two tier market developing with some occupiers insisting on the highest environmental rating and being prepared to pay a premium for the most energy efficient buildings.

This however, does not address the issue of the UK's existing commercial real estate stock which does not reflect high specification "green" projects.

If occupiers will pay a premium for the most "green" buildings, will they expect discounts for taking on more inefficient buildings, especially in view of rising energy costs? If so, will landlords seek to retrofit energy efficiency measures on old stock?

There has been pressure on the Government to help kick start sustainability within the commercial real estate sector by introducing incentives such as Stamp Duty Land Tax relief for green projects. Any incentives that the Government can introduce to mitigate costs would be welcomed by the industry.

The difficulty is ensuring that incentives result in completion, and that there is subsequent monitoring of green buildings when there is no industry consensus on how this should be approached.

It is unfortunate that the pressure on developers to deliver "green" buildings has arrived at a time when the market is ill equipped to soak up the cost. However, this does not mean that it can be ignored.

The commercial real-estate market must adapt to deliver sustainability at a realistic cost.

Simon Sherwood is a partner at Beachcroft, Leeds.