The comments came as prime minister Gordon Brown unleashed a £910m package to help borrowers cope with increasing energy prices.
Woolas is reported as saying: “People who want to invest in their homes have got an asset to borrow against.
“Loft insulations are expected to save homeowners up to £250 a year, which means the speedy repayment of any loan.
“The difficulty with the credit crunch is you can only get 75% of a mortgage.
“If you are an existing householder it is easier to borrow against this energy efficiency initiative because the pay-back period is so good.”