The country's favourite new building was built for and funded by students.
About one fifth of the 12,500 people who voted in the Irish Architecture Awards picked the colourful 11,000sq metre student centre at University College Dublin (UCD).
Billed as UCD's epicentre of sport, social and academic life, it opened last June and was the first project on the campus to be funded entirely by students.
The Royal Institute of the Architects of Ireland (RIAI), which ran the competition, ruled out a hijacking of the competition by the student body, comparing it to last year's winner NUI Galway which won with nearly half the year's votes.
Eddie Conroy, chair of the judging panel, said the building demonstrates this dynamic piece of Irish architecture.
"The judges felt the use of colour, choice of materials and the simplicity of its layout contributed greatly to its ease of use to the students and staff of UCD as well as to members of the public, regardless of age, size, ability or disability," he said.
The best house in the country is Quarry House at Slievebawnogue in the Dublin mountains designed by Andrew Clancy Architect.
It is two dwellings for a brother and sister in a disused quarry built on uncertain ground conditions of discarded spoil, where the house acts as an inhabited bridge between natural and man-made outcrops.
The student centre, designed by Fitzgerald Kavanagh & Partners, beat off competition from contemplation space at the Mater hospital designed by Michael Goan and the Temple Bar umbrellas by Sean Harrington Architects in third place. The UCD building also came first in the best universal design category.