It is a building, an installation, a memory of hard times in Connemara and an object lesson in how perceptions can be turned around. The Irish entry at the Venice Architecture Biennale, entitled the Transformation of an Institution, carries a far more powerful charge than most of the offerings on display from around the world.

On paper it does not look much — a single-project national exhibition in a year when most participating countries crammed as many architects and projects as possible into their showpiece pavilions as the biennale celebrates its 20th birthday. After all, it has become the most prestigious public exhibition of contemporary architecture in the world.

But Ireland, which has never had a permanent home at this Venetian arts enclave, has turned this apparent deficiency to advantage. Its single design is ripe with meaning, adroitly displayed as an independent work of architecture in its own right. It also occupies a prominent position befitting its status — difficult to achieve in this jostling kasbah.

Ireland’s commissioner happens to be Shane O’Toole, Culture Ireland’s architecture correspondent, which is why I am writing this rather than him. It was made clear that if I didn’t like O’Toole’s efforts I would be free to smite him round the head with a gondola oar. No need, I’m pleased to say. The Irish pavilion has a rare clarity and poetry.

O’Toole knew exactly the project and the architects to embody the stated theme of the biennale — Metamorphosis. The evolving labour of love that is the Letterfrack Furniture College in Connemara, designed by architects Sheila O’Donnell and John Tuomey, is a transformation on a number of levels. In Venice they have transmuted it once more, into a vessel of metaphor. It is made not only as a response to the theme, but as a physical response to the ancient naval buildings in which this part of the exhibition takes place. The moment you encounter it, you know it is right.

It is not just a matter of physically changing and adding to an existing complex of buildings in a remarkable landscape, as the architects have done over the last 10 years. It is also about moral cleansing. Letterfrack Furniture College is a thriving independent organisation, but was once the Christian Brothers’ institution, St Joseph’s industrial school.

The brothers’ regime there lasted from 1888 to 1973. Later, instances of harsh abuses of the children emerged, so Letterfrack holds dark memories.

The rural development organisation known as Connemara West finally took over the buildings and later O’Donnell and Tuomey were commissioned to improve and extend what was by then earmarked as a furniture college. Today Letterfrack is working so well the college is oversubscribed. The recently constructed, largely asymmetrical timber workshop buildings are inspired by the area’s rugged landscape and wind-sculpted trees, drawing the old, transformed buildings into a new campus.

That, in a nutshell, is the history of Letterfrack. However, the Irish pavilion does more than tell the simple story. It uses the narrative as a way to investigate the notion of architectural metamorphosis and redemption, and it does so by means of powerful installation pieces.

A large and noble-looking space in the building known as the Artiglierie (a natural hiatus in the long trudge through the international architecture exhibition laid out in Venice’s stupendous Arsenale buildings) has given Ireland its most prominent biennale location yet. That would count for nothing if the content was insufficient. However, O’Donnell and Tuomey — formidable architectural theorists as well as hands-on designers — have taken the opportunity to represent the project in architectural as much as narrative form.

The first move was probably the hardest. While not wanting to clutter the room, they had to make the interventions sufficiently powerful to stop people in their tracks. The installation is both derived from and a commentary on Letterfrack and its history. There is a thoroughly accessible explanatory display. There is also mystery.

Three big objects and two small ones define the space. All are in timber. The dominant one, called Open Frame, is derived from the timber-framed structure of Letterfrack’s machine-hall workshops. Dynamically angled, it carries information on three levels. A high-tier panorama which catches your eye the moment you enter the room provides the landscape setting. On the other side an eye-level monochrome picture frieze is partnered by desk-height display cases which tell the story in words, pictures and objects.

The second big object is the “Scary House”. This is a work of architecture in its own right — but skewed architecture. The house could also be a chapel or from some angles a boat or lobster pot. It is a structure within a structure, and the two parts are at odds, fighting one another but held firmly together, or indeed supporting each other. The building is also a kind of landscape, since in part it has a sandy, beach-like floor, an oblique commentary on the history of Letterfrack, vernacular architecture and the topography of the region.