Futuristic windows at the new Holyrood building do not let enough light into MSPs' offices, it has been claimed.
There have been complaints over the design
Some MSPs have said that the gloom is so bad they will have to keep their office lights on all day.
Tory member Brian Monteith said the latest problem was "a serious embarrassment" for parliament bosses.
Holyrood Progress Group member Jamie Stone rejected the claims. "There is no reason for our Conservative colleagues to be in the dark," he said.
The ongoing Fraser Inquiry is currently examining the spiralling costs for completing the unique design by the late Catalan architect Enric Miralles.
Tory MSP Lord James Douglas-Hamilton said Snr Miralles had failed to take account of the Scottish climate.
He said: "I suspect the architect, being Spanish, was used to tremendous
amounts of sunlight.
"In Spanish architecture, the shade is very much to be welcomed against the
ferocity of the sun.
"But being quite a way further north, we regard sunlight in a slightly
The strangely-shaped windows were inspired by Sir Henry Raeburn's painting of
the Reverend Robert Walker skating. Some are also covered with oak lattices.
The windows are also designed to allow MSPs to sit inside them while they are
Green MSP Robin Harper said the design was also at odds with the parliament's
claims to be environmentally-friendly.
He said: "I think our chances of getting any sunlight into our offices are
about one hour a day.
"We are going to have to burn more electricity than we otherwise would.
"We will have to use the lowest energy bulbs possible."
But Mr Stone, a Liberal Democrat MSP, rejected the claims.
He said: "Natural light comes into the MSP offices from both the east and west sides of the building."