The council said the current single-glazed windows, of which there are 1,437, were fitted when the offices were built in the mid 1960s and have now deteriorated.
It comes at a time when the council has had to make big cutbacks to services due to budgetary restraints.
But Bucks County Council finance and resources cabinet member Peter Cartwright said: “Of course we’re in tough times but as a responsible owner of public buildings we need to ensure they’re properly maintained.
“We also have a duty as a responsible employer to maintain good working conditions and we have listened to feedback from our staff about the windows.”
The work, which will begin in February 2013 and is expected to last nine months, will introduce new windows with better thermal efficiency and reduced solar gain. It is hoped it will reduce energy costs by 15%.
And Mr Cartwright added: “This capital project ensures we have windows that meet modern energy efficiency requirements, and which will reduce the cost of heating and cleaning, while also improving working conditions.
“We have given the job to a local contractor, providing local work for local people. What’s more, our membership of a procurement group of local authorities means we’ll get a rebate on the cost.
“The sale of surplus county council-owned properties has allowed us to invest in these improvements, as well as investing in other properties, such as schools.”