Trying to comply with Part L is a costly game of guesswork.

Imagine you are a tailor charged with making a suit for a customer who refuses to offer himself up for measurement, cannot decide on the cloth and will not agree on a style. Furthermore, you must finish the suit by tomorrow morning or suffer a severe financial penalty.

Customers like that you could do without. Yet this is the situation we at McCarthy & Stone - along with most other housebuilders - have faced for several months as the ODPM has dithered over Part L of the Building Regulations.

The approved document has just been published, but we are still waiting for other key papers containing information critical to the design and specification of a new building just two weeks away from the 6 April implementation date.

Even building control officers are up in arms. They are so confused by the lack of information that they have co-signed a letter to their political overlords urging them to deliver the goods.

For reasons reeking of political gamesmanship, not only is John Prescott sticking rigidly to the April deadline, long before the industry is ready, but he has squeezed us at both ends of the implementation process by shortening the lead-in and transitionary periods.

It is, as the Home Builders Federation has said, simply unworkable. It has reached such a crucial point that the HBF is having to take the reins and push through its own technical guidelines ahead of the government's, hoping that they will agree.

Do they not realise we are often working two years in advance on a building’s design?

In practical terms we cannot stop work, so we're having to guess. It is impossible to price a building accurately or provide checklists to show that insulation standards have been met because we don't know what they are. If we get it wrong, it could cost many thousands of pounds.

On top of this, the new standard assessment procedure software used to calculate heat loss has only just been released, with the result that our staff will still be in training after 6 April, prior to sitting an examination for accreditation (which will not be available until May). Do they not realise we are often working two years in advance on the design of a new building?

Part L deals mostly with energy requirements that have been tightened up to meet new European Union standards. We have no quarrel with this in principle, especially here in the retirement sector where small heating bills are an important selling point. But I have a fundamental problem with being told how to do it.

Prescott brazenly admits he has defined standards at every level "rather than allowing builders to trade different kinds of improvements against each other". We are actually quite good at designing buildings, so why doesn't he simply set the energy performance requirements and let us decide how to achieve them, instead of the prescriptive approach that stifles our ability to juggle the options?

It's yet another example of the deputy prime minister's passion for micromanaging everyone and everything that crosses his ever-widening path. And look where it has left us.