Friday 9 October 2009

'Sky pod' would give Liberty Hall scheme wow factor second to none, say architects

LIBERTY HALL is to be replaced by a significantly taller building with a “sky pod” on top similar to the Gravity Bar at the Guinness Storehouse, to give visitors panoramic views over the city and Dublin Bay.

Siptu unveiled details of the proposed development yesterday at an annual conference marking the trade union’s centenary. The union pledged the new Liberty Hall would have a “wow factor” second to none in the capital.

Designed by Gilroy McMahon Architects, who were also responsible for Croke Park, the facilities would include a 300-seat theatre at lower ground level, a heritage centre illustrating Siptu’s history and 15 floors of open-plan office space.

The existing 17-storey building, which is 60m (197 feet) tall, would be replaced by a 20-storey tower rising to a height of 84m with a glass-fronted “sky lift” to take visitors to an enclosed observation terrace at the top.

Unlike the present tower, which has square floorplates, the new one would be trapezoid in shape. But the architects have sought to ensure that the relative proportions of its height and scale would yield a satisfactory “slenderness ratio”.

After carrying out shadow studies to measure the impact of the proposed tower on nearby buildings as well as extensive consultations with Dublin City Council’s planners, they even shaved 2m off every floor to produce a better result.

The “sky dome”, composed of two interlocking semi-circles, would have three levels, incorporating the observation terrace and Siptu heritage centre, space for temporary exhibitions and an outdoor cafe enclosed by a 5m glazed screen.

Des McMahon, of Gilroy McMahon Architects, said it was likely to attract 250,000 visitors annually, generating good revenue for Siptu. From the terrace, it would be possible to look down on the GPO in O’Connell Street and other historic buildings.

Another important element of the new Liberty Hall’s “engagement with the public” would be its generous double-height entrance area, stretching the full width of the building, including a podium adjoining the tower not unlike the present one.

The three-storey podium, set back from Eden Quay, would have a cafe, information desk, reception area and a large cut-out in the floor through which a curving staircase would lead down to the new theatre, all lit up at night.

Ground-floor level would be raised by almost a metre, to protect the building against future floods, with more space created outside on the constricted footpath at the corner of Beresford Place by cantilevering the tower over the lower three floors.

Access to the office floors would be via four lifts at the northeastern end of the tower, protected by turnstiles, and there is also provision for two staircases. The public “skylift” would be located on the western side, with views over the Liffey Quays.

One of the principal objectives, Mr McMahon said, is to create “an appropriate, energising and inspiring” workplace for Siptu’s staff, allowing them to interact in a way they cannot do with the present arrangement of “isolated” cellular offices.

These offices are laid out around a service core that takes up 40 per cent of the floorplate on every level, compared to 30 per cent for the much larger service core now proposed. “It’s totally impossible . . . really a white elephant,” Mr McMahon said. “The Eiffel Tower is as valuable today as it was 100 years ago, but Liberty Hall is not. It was a building of its day, not unique, except for its location and timing [it was completed in 1965] and a carbon disaster in terms of its use of energy.”

Dave Richards, who was involved in designing the new building, said it would be the first office block in Dublin to achieve an A3 energy rating, with less than half the carbon dioxide output of newly-constructed air-conditioned offices.

As a result of relying on partly-assisted natural ventilation as well as low-watt lighting, solar panels and a building energy management system, Siptu would be able to reduce its annual energy bill from €450,000 to just €220,000.

Mr McMahon said he was convinced that the new Liberty Hall, which would be much broader on Eden Quay yet appear quite similar when viewed from O’Connell Bridge, would quickly become a Dublin landmark.

Irish Times

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