The report, which is based on more than 100 PFI projects, is the biggest survey of its type to be carried out in the UK.
A separate report by the NAO, due to be published today, is expected to back the £100m PFI redevelopment of the Treasury's headquarters. This report is also expected to praise the effectiveness of PFI as a procurement route.
The document is believed to focus on the financial side of the Treasury headquarters deal, which has had a troubled history.
The refurbishment was originally priced at £200m, and won by a Stanhope-led consortium in 1996. The deal later collapsed after wrangles over risk allocation.
She told business leaders in Birmingham that bonuses paid to contractors could be linked to examination results, and added that the modernisation of schools could not be achieved without the PFI.