Civil servants covered up potential savings of £705m in order to help former housing minister John Healey justify scrapping proposed changes to Building Regulations that were designed to make existing homes more energy efficient

Last June, Healey removed the proposal, called “consequential improvements”, from the draft consultation on the 2010 revisions to Part L. The £705m estimate of potential savings to consumers and businesses was removed from the mandatory economic impact assessment which shows the financial impact of new regulations.

The Association for the Conservation of Energy said it was told by senior civil servants that Healey instructed them to strip out the savings in the public version of the document after the Cabinet had approved the original. The original document, gained under the Freedom of Information Act by the association, showed the potential savings were 2.3 times greater than the cost of energy efficiency improvements.

The changes would have required homeowners to make energy efficiency improvements to their existing property when adding an extension or converting a garage.

Healey justified removing the proposal on the grounds that consequential improvements would have cost homeowners too much.

Last June he told Building: “In my view, in the present economic downturn, the environmental case didn’t offset the cost and potential complexity in the proposals thus far outlined.”

When Healey was asked this week about removing the figures, he said that when the impact assessment was completed, that was the version published with the Part L consultation.

Andrew Warren, the director of the association, said: “In a sane world, we would be sending the bill for the benefits foregone to the former minister - whose determination to place personal prejudice before practical evidence is even now leading to more emissions and higher fuel bills.”