The oldest of the buildings dates back to 1230, the newest was added in 1935. The most urgent problems concern the buildings' heating, ventilation, and lighting systems.

"The heating is what it is with old systems, it was built long ago, it can't be regulated, it's unstable. Parts of the building are too hot, and others too cold. Some people always have their windows open because it's too warm, while others are complaining about the cold," head of the economic department of the Riigikogu, Argo Koppel, told ERR.

The decision was made to overhaul the building. Yet the time when the works will start is still unclear, as planning the renovation touches on plenty of regulatory issues as Toompea Castle is under heritage protection, and the matter is accordingly delicate.

Koppel expects the planning, dealing with upcoming issues, and settling the financial points some four years, so works on the buildings are not likely to begin any sooner than that.

The Riigikogu and its offices will have to be moved to a provisional location for the time of the renovation, but at this point this is too far in the future still to be able to say where it would move, Koppel said.

The parliament's current use of floor space including offices covers about 15,000 square meters.