Ireland House, Tokyo

Competition Entry : 3000m² Embassy building

The House of Ireland has been conceived as contemporary townhouse in the tradition of Irish Georgian architecture adapted to the context and climate of Tokyo. The building is set back from the edge of the site creating an “area” that provides a separation of the ground floor accommodation from the street as well as providing light to the lower-ground floor. The street frontage is a transparent façade allowing passers-by to see into the reception and to the exhibition spaces whilst maintaining a security separation thanks to the setback. The entrance is accessed via a small bridge across the sunken area and accesses directly to the reception.

The movement of people through the Yotsuya Station Front Park continues on through the building to the private green garden to the rear of the site. The ground floor of the House of Ireland is largely transparent so that the people of Tokyo can see into the reception, library, and exhibition spaces, and sculpture terrace and out to the garden beyond. In this way the landscapes and vegetation of Ireland and Japan are horizontally linked through the ground floor. The consular section of the embassy is located to the left of the reception area and this suite functions independently within the House of Ireland with the consular staff office at the rear of the suite linked vertically to the embassy offices and shared staff facilities above.

A Vertical Community. The section has been developed around a central hall that extends vertically between the representational hub on the lower-ground floor and the office accommodation above. This is the central space of the building where the different parts of the community come together and from which they can be seen. Visitors pass along a gallery through this space and then descend a helical staircase to the hub below. On their way they can see down into a central performance area or look out to an outdoor sculpture terrace. At the end of the gallery they look over a garden in the depth of the site. This space will be filled with Irish specimen trees and plants. As a shaded grove in the heart of Tokyo it will allow visitors to experience a scent of Ireland when they visit the house and will visually draw them into the building from the street.

The programme of principal accommodation has been stacked with public and semi-public accommodation on the ground and lower-ground floors, and office accommodation on the first and second floors. The state agencies are housed in the front part of the building facing the street while the embassy occupies the rear facing onto the garden. This allows the embassy offices to connect vertically down to the consular office on ground-floor, and up to the official state residence on the third floor. The ambassador’s residence is conceived as a two-storey house sitting above these with the official accommodation on the third floor and a private family apartment on the fourth floor. As both of these suites are set back from the northern edge of the building, they each enjoy dedicated outdoor roof terraces and gardens that provide shade during the heat of a Tokyo summer.

Structural System. The structure has a concrete frame and cores that are expressed within the building, with infill sections of hybrid timber and concrete construction set into the frame. Gravity loads applied to the floors are resisted by the exposed concrete flat slab which spans between columns which have been inset from the façade line to achieve a glazed façade with unhindered external views. An alternative structural system considered by the team consists of a wood-concrete composite floor slab supported by Glulam secondary beams and Glulam columns.

The lateral load resisting system consists of two internal concrete cores designed to act together to resist wind and seismic loads via cantilever action from the foundations which will be designed to resist the resulting overturning moments. The proposed architectural concept consciously incorporates an efficient structural solution resulting in an elegant design solution. From a structural perspective, the rectilinear cores are ideally positioned within the floorplate and the corewalls are aligned from foundation to roof level avoiding the need for costly and structurally complex transfer structures.

Material Expression. The building envelope is largely glazed with a transparent façade at ground floor to provide visibility from the street, and a second skin of glass wrapping the office accommodation at first and second floors. This skin contains strips of photovoltaic cells on the east, south and west elevations that harness the rays of the sun to generate electricity. The photovoltaic cells are encapsulated in the glass in a striped pattern which creates vertical banding on the elevation and reduces the transparency from outside while still giving views out to the park and garden.

The ambassador’s residence has glazed walls with bronze mesh encapsulated in the glass giving an opaque appearance from the outside when viewed from the park, while still allowing views out. Areas of transparent glass face onto the private roof terraces to connect inside and outside and give a sense of spatial expansion.

The concrete frame structure is expressed internally with high ground-granulated blast-furnace slag (GGBS) content to minimise environmental impact. This whitens the concrete and it can be sand-blasted or polished and then sealed to a high finish. Infill mass-timber is used as much as possible to further optimise sustainability. Ceilings and other linings are in Irish oak and feature elements such as staircases and the reception desk are in bronzed steel. A slatted oak ceiling allows air to circulate freely to the structural soffit so that the thermal mass of the entire structure is engaged in the environmental strategy.

The fixed and loose furniture within the House of Ireland will provide an opportunity to showcase the excellence of Ireland’s culture of craft and making, as well as art and design. It is envisaged that special pieces of furniture and screens would be commissioned from makers along with special artworks.