One in five South Australian schools will be upgraded under a huge government push to improve facilities in the state.

It is estimated that $690 million will be spent either upgrading or refurbishing a total of 91 primary and secondary schools across South Australia; an amount that represents the largest investment in public education in the state’s history. This new round of funding (which comes from the sale of the Lands Title Office, rather than the existing maintenance budget) will bring government spending on education to a total of $1 billion over the past four years.

Among cited concerns are old buildings and classrooms, some of which have been built using asbestos. These will be replaced with new designs, while other schools will be subject to more surface-level upgrades.

Funding will also be allocated to the construction of three new schools in Adelaide’s outer northern and southern suburbs, as well as within the CBD. According to the government, this will likely take place between 2018 and 2022.

Typically, each of the 91 schools targeted for upgrades will be allocated between $5 million and $10 million. Exceptions such as Seaton High School and Norwood Morialta High School, which require more extensive works due to the existence of old transportable buildings, will have up to $30 million spent on them.

“This is the largest investment in our public education system in our state’s history,” said SA premier Jay Weatherill in a statement on Monday.

“A world-class school system is an essential foundation for the next generation of South Australians.

“Schools that are better equipped, with increased capacity and superior facilities, will help to give our children a headstart.”