Farmleigh has been used to accommodate foreign dignitaries for just 24 nights during the past two years, according to the Office of Public Works.
One of the main reasons the Government gave for the purchase of the mansion in 2001 was the need to have suitable State accommodation for foreign guests.
"This is going to be really a considerable benefit to the State in the years ahead," the Taoiseach, Mr Ahern, said on the day the purchase was announced. "It will be used for State occasions and State visits - we've not had a residence where foreign dignitaries or heads of state have stayed, and we've been unique in the wrong direction in that regard."
According to OPW figures, Farmleigh has been used for overnight accommodation by foreign visitors for only 24 of 766 nights since it was opened - after refurbishment - in July 2001. The former Guinness family mansion, which was bought for €29 million and refurbished at a cost of €23 million, cost almost €2.5 million to run last year.
The Department of Foreign Affairs said that the figure of 24 nights' usage did not reflect the property's full use, since it also hosted foreign and state meetings throughout the year. It added that Farmleigh will be the venue for many meetings when Ireland takes presidency of the European Council next year. An OPW spokeswoman said the house is in a "constant state of readiness" for foreign guests, and used on an almost daily basis for hosting events.
At the time of the purchase the Government also said the building would be used for cultural events. This year, a series of free outdoor events, including concerts, resulted in a huge response from the public, with over 320,000 applications for tickets.It has also been used for a number of cabinet meetings and an Inter-Governmental conference on the North.
This year, Farmleigh hosted what appear to be its most satisfied guests - at least if length of stay is anything to go by. The king and queen of Malaysia visited in June and stayed four nights, the longest that any overseas guests stayed.
In June 2002 visits by the Presidents of Latvia, Slovenia and Nigeria meant the house was occupied for a total of five nights that month. But almost a full year passed before any other foreign guests slept in Farmleigh, despite visits to Ireland by, among others, the Danish, Slovenian and Romanian Prime Ministers.