The council wants to sell its seafront headquarters, King’s House, for housing and move more staff into a refurbished Hove Town Hall.
It also plans to let about a quarter of the town hall for commercial use and build a roof-top extension, adding a floor to the northern part of the building.
Premises used for social care in Buckingham Road would also be sold.
But questions about the future of the Citizens Advice Bureau – currently based in Hove Town Hall – are expected to be raised.
Brighton and Hove City Council said that the changes were “phase three” of its “Workstyles” project, aimed at making better and more efficient use of its property portfolio.
A report to a special meeting of the council’s Policy and Resources Committee next Thursday (12 September) sets out the case.
The council said: “King’s House could be sold in proposals to improve the way the council works while delivering big savings to invest in efficiency measures.
“Selling the building, valued at an estimated £9 million, would raise funds for better IT systems, energy efficiency and digital communication.
“It would also help reduce the authority’s property portfolio costs.
“The change is being proposed under phase three of the ‘Workstyles’ project that looks at modernising the council’s business.
“The authority aims to change the way it works to improve customer access and service delivery, make best use of office space, save money and cut its carbon footprint.”
Three options are being considered. The preferred option involves selling King’s House, a grade II listed building, to complete the work styles programme.
The council said: “It would include refurbishing outdated offices at Hove Town Hall to modern standards and equipping them with modern technology. Empty space in the building would become offices.
“Around a quarter of the building would also be released for commercial use which would generate further income for service improvements and smarter working methods.
“It is estimated the changes could save approximately £700,000 per year in running costs.
“If sold, King’s House is thought to be suitable for housing, subject to planning permission. It would include both private and social housing.
“Among benefits to the city would be an injection of almost £2 million of government New Homes Bonus funding over six years.”
Councillor Leo Littman, the ruling Green Party’s lead member for finance, said: “This proposal to move offices will help modernise the council and allow us to better serve the needs of the community.
“Combining this move with the more effective use of technology it will make possible will save money.
“Not only will this benefit the people of the city, it will also give our staff extra flexibility, allowing them to achieve a better work-life balance. It will also help to improve energy efficiency.”
New technology was installed at Bartholomew House in 2011 in phase one of the Workstyles programme.
About 500 staff were able to use the new technology work more flexibly across three of five floors in the refurbished building in Bartholomew Square, opposite Brighton Town Hall.
The ground floor was extended to create a customer service centre.
Phase two consisted of three major projects, involving 700 staff and the opening of a new customer service centre at Hove Town Hall in February this year.
The customer service centre brought together council staff and Sussex Police after the force closed the old police station in Holland Road. It was sold to the council for use as a school.
Another element of phase two involved bringing the vast majority of the Children and Families Service Team together on one site.
By basing them at the Moulsecoomb Hub, the council said that it had increased collaboration at modern facilities for staff and customers.
The rest of Bartholomew House has also been renovated.