"I have been in property all my working life," the prosperous-looking man yawned languorously.

"For 30 years, I have heard minister after minister declaim that government needs to set an example, demanding only the best in energy performance from the buildings it occupies."

He leaned forward, with a conspiratorial wink. "But we know it's only words. In the end, they never deliver. Which is why my gas-guzzling buildings still get let to 'em. Daft thing is, if they ever did only require the best, they would transform energy standards in the entire commercial sector overnight."

The public sector is the most valued tenant of the lot. Not because it pays the rent much quicker than other people. But because, unlike the private sector, it never goes broke. Eventually, that rent does get paid.

This unique factor puts the public sector in a very strong bargaining position. If it only realised it. Any energy standard it required would swiftly become the industry norm: nobody wants to rule out letting to the most preferred tenants.

Instead the rhetoric continues, about the need only to occupy the "top quartile" energy performing buildings. And precious little is done to ensure that the words are put into action.

Last year, the government's own Sustainable Development Commission (SDC) became the latest in a long line of official organisations to examine how effectively the government is being in cutting the fuel bills of the buildings it occupies.

After all, not only has that pledge about only occupying "top quartile" buildings appeared in every energy efficiency policy statement this century. So also has the pledge to reduce fuel bills by 20 per cent.

The SDC's conclusions excoriated the government. It prompted a formal inquiry from the powerful House of Commons environmental audit committee, which is holding public hearings over the present month on the topic. From the tone of the initial exchanges, you do not have to be Nostradamus to forecast what conclusions their final report may reach.

It seems that however high-flown the rhetoric about only occupying buildings with low energy running costs, actual practice during lease negotiations still concentrates upon the location, and then the initial square footage cost.

But seldom what the actual running costs will be. Nor that within a few years, the extra fuel costs of an energy inefficient building will easily outweigh any savings made per square foot occupied.

Three years ago, Anne Snelgrove was elected for the first time as Labour MP for Swindon South. Unless you are a constituent, the chances are you will never have heard of her before.

She has never publicly made a fuss querying a policy she has to defend; she has certainly never voted against the government. She is a Parliamentary Private Secretary, an unpaid aide to the Transport Secretary Ruth Kelly.

Each year, there is a Parliamentary ballot open to all non-ministers. The handful whose names are drawn can introduce a Parliamentary Bill on a topic that interests them.

Over the past 12 years, there have been no less than seven successful Bills on energy efficiency, a signal that at least our elected representatives want to see rhetoric turned into action.

Most Private Members Bills fail. Either because government opposes them. Or because some powerful external lobby does. It is a complex and fraught exercise getting own-initiative Bills onto the statute book.

This year the senior Conservative MP Michael Fallon finally won government support for his Planning & Energy Bill.

This permits local authorities to require developers to build to energy standards higher than the minimum under Building Regulations, and to source at least 10 per cent of a development's fuel from local renewable sources. Measures that ministers have long endorsed in speeches and policy documents. But not necessarily being followed through on the ground.

Anne Snelgrove also came up trumps in the annual Ballot. She decided that her Bill would simply require central government and its agencies only to enter into leases for those buildings which were in that top quartile in terms of energy performance. Just as all those government speeches and policy papers had stated.

She published her Bill in draft form. And waited to hear which Minister would respond. Nobody was quite sure whether this was an issue for Communities & Local Government: they look after buildings.

Or the Business Department (BERR) which handles energy policy. Or the Treasury: because they oversee the office of Government Commerce. Or DEFRA, who are responsible for ecological issues.

Yes, government was in favour, she was finally told: how could they not be? But could she alter the phrase "top quartile", because even though it was government policy, it was so difficult to measure?

But then, what about re-negotiations of leases for already occupied premises? Many of these would be sub-standard. Would government and its agencies have to leave in consequence?

As this would be just the moment to demand energy improvements, that point remains for negotiation. As does another proposal that perhaps such stringent standards should only apply to government commissioned, as opposed to leased, buildings: a very tiny minority.

These and other "clarifications" remain to be sorted out, if not at the Second Reading debate on May 16, then hopefully in subsequent committee.
I mentioned these caveats to my lifetime property man acquaintance. He smiled ever so benignly. And shrugged: "Carry on watering this Bill down, it's back to business-as-usual. Told you, all just fine words".

For once, let him be wrong.
• Andrew Warren is Director, Association for the Conservation of Energy.