Despite spending £90,000 on an efficient new heating system at Bute House in Edinburgh, Alex Salmond's utility bill has rocketed since he came to power in 2007.
The charges, which include gas and electricity bills for the 18th-century building, went from £77,000 in 2007/08 to an average of almost £100,000 for the past two years.
Taxpayers already spend £70,000 a year to lease the property from the National Trust.
The Conservatives said it was time to stop funding the First Minister's "lavish lifestyle" from the public purse and condemned spending on what they called "festooneries" at Bute House.
Taxpayers paid for the £30,000 living-flame gas fires to be installed.
A further £60,000 was spent on a new boiler system for in Charlotte Square. Historic Scotland, which took over responsibility for the property's upkeep in May 2012, was
asked under the Freedom of Information Act to give details of spending on maintenance. After not responding for three months, officials revealed that £30,229 was spent two years ago on "living-gas flame fires and incidental work". Around the same time, £58,777 was spent on a new boiler system.
Living-flame fires imitate coal or wood burning fires with gas flames set amid replica logs or coals.
The investment appears to have failed to keep costs under control.
Scottish Conservative MSP Alex Johnstone said: "A number of challenges are facing the public purse, which is why it should not be funding festooneries for the First Minister."
Green MSP Alison Johnstone, said: "It's ironic the public purse absorbs the rising fuel bill of Bute House while thousands of Scots on low incomes struggle to meet their heating costs.
"It would be useful to know what sort of energy efficiency measures are available to Bute House and if they have all been taken up."
The First Minister's spokesman declined to comment and referred inquiries to Historic Scotland.
A spokeswoman for the agency said: "Bute House is a working property and as such is used to showcase Scotland on a regular basis. Following expert advice, essential work was carried out due to the condition of the boiler and the opportunity was also taken to install a more energy efficient unit at that time."