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Conference Call

The new national conference centre  at Spencer Dock is set to be one to be Ireland's first Very Good BREEAM-rated buildings. Colin Leopold finds out the  difference a tiny  city-centre site and nine and a half tonnes of  steel make.

There has been quite the rush to secure bookings for Ireland's new convention centre when it opens in Spencer Dock next year. It's interesting to think what the European Union of Geriatric Medicine will make of the tipped glass drum frontage which cut a jaw-dropping profile in the winter sun last month when they arrive for the first official conference not long
after the grand opening. No doubt it will still be a talking point even then but the truth is the already iconic building on Dublin's quays masks a complex structure which had its fair share of challenges to overcome in the early stages of construction.

Although it's already been given the nod, unofficially, for its Very Good BREEAM rating one of the first in Ireland, the project team for the Convention Centre Dublin (CCD) is probably more relieved that it as maintained its schedule and got to four levels in a restricted footprint enclosed by an office block, a canal, the Liffey and live Luas works to the rear. Transport and logistics were initially one of the main challenges, bringing steel on site in particular, says Donal McCarthy at Construction Management Partnership (CMPL), a joint venture between Sisk and Treasury Holdings. "It's  become less and less of an issue now with the heavy construction excavation, concrete works, steel, facades and the  drum at the front - out of the way," he says. With four tower cranes and, a number of mobile cranes in operation at the same time, keeping the heavy contractors fed with materials was a constant challenge. Access to the site was also key. A ramp to the rear, at the north end of the site, had to be moved as the slabs for  the basement were completed. "The logistics isn't a risk to us anymore whereas we would have considered it a risk up to maybe a couple of months ago. The weather was key," he says. "If you've got a crane down for two or three days then you've got a backlog of guys waiting and your sequence gets broken down. It's a constant management issue but we maintained our programme."  Most conference centres around the world, typically located just outside the centre of a city, have the advantage of a large footprint and build out exhibition hall next to auditorium. The brief for the CCD forced a new approach - building up. From the basement level there are two levels of car parking, a 45m x 60m exhibition hall at ground level, a 35m x 47m exhibition hall at first floor level and a 2000 seat auditorium positioned on top with public access from three separate levels. "The complex structure was primarily to overcome the tight footprint," says McCarthy. "It had to be a structural steel build because of what the brief required within the footprint we had. The exhibition  hall needed to be located on the ground floor because of access requirements and that was a requirement of the brief. So after that the auditorium ends up on level-three and obviously with an auditorium we have to have clear, spans and clear views from every seat. Those were the two main drivers on the complexity of the structure." The steel nine and a half tonnes to be exact begins at basement level, with two levels of car parking based around a standard 7.5m grid pattern. Above this, at ground level and upwards the structure takes on its architecturally driven and more challenging form.

Steel erection began on the south side of the site and has since progressed, in six phases, steadily northwards away from the two southern cores. The structural stability for the building comes from two southern re cores, the steel sway frame action of two mam frames and also braced frames. The re cores also contain the main stairwells which provide important access during construction. The steel frame then needed to accommodate all of the building's M&E services whilst staying within the architectural constraints and the OPW brief. Before construction began the site mainly consisted of former railway sidings and warehouses which once served the adjacent port. Initial work on this brownfield site involved clearing the ground and demolishing existing structures. The site was then excavated to a depth of 7.5m, and piled, with the two southern concrete cores then constructed in readiness for steelwork erection which started in late 2007. But designing and constructing a building with three large open areas, all on rop of one another, required considerable interaction between the team members.

The complex structural steel design model designed by O'Connor Sutton Cronin took nine months to develop. From this model the project was priced by Fisher Engineering. Following this, further development of the model (a joint effort between O'Connor Sutton Cronin and Fisher Engineering) took a further period of nine months. As a design or and build government contract, there are a number of third parties involved, says McCarthy. Once it's complete in 2010, main client Spencer Dock Development Company, under a public private partnership, will operate and maintain the NCC for a period of 25 years, after which the facility will revert ro the State.

Jacobs Engineering are the technical representatives  for the OPW and Arup are the technical representatives for the funders and the banks. "All the finishes and design goes through the OPW - we would have regular monthly meetings with them. However it's not an approval process, they simply acknowledge it. It's our responsibility to make sure we're OPW brief complaint."

CMPL also had to ensure they were BREEAM compliant at  all stages  throughout the build. This had an impact not just on the U-values and airtightness but also on the CO2 emissions
from the transport of materials and the amount of green space around rhe building.  There are a number of standard schemes  under which certain building types can be assessed - offices, schools, retail  and court buildings, for example. Where a non-domestic building cannot be assessed under one of these schemes it can be assessed under the Bespoke BREEAM scheme. Bespoke BREEAM is part of the BREEAM family of environmental assessment methods, a voluntary scheme that aims to quantify and reduce the environmental burdens of buildings by rewarding those designs that take positive steps to minimise their environmental impacts. White Young Green was the consultant for BREEAM certification. "The CCD score currently stands at 59% however we hope to further improve on that score on completion of an ecological rcporr which is currently being compiled," says CMPL building services engineer Marie Byrne. "An automatic lighting management and control system was specified to provide flexibility, cost and energy efficiency and maximise the use of daylight within the building. We also salvaged 15,000m2 - nearly 20% — of gravel from the original excavation for reuse on rhe site." High scoring was also secured for warerless urinals and district heating capability as well as the high level of carbon neutral cement that formed one of the largest pours in Irish history. 70% of the concrete is ground granulated blast furnace slag which comes from rhe steel making process. The total concrete used has been 30,000m3 with 21,000m3 recycled.   The build is currently at the internal fit-out stage. Not surprisingly for a convention centre with flexible use requirements, the brief here is relatively straightforward - the focus is on the services, lighting and air-conditioning rather than the high-end finishes. Architecturally one of the most noticeable features of the build is the 37m spanning glass dome which juts out onto the quays, offering views right across Dublin from the breakout space on each level. For this temporary towers were built and ringbeams were installed pretty much from the bottom up. "Each ringbeam would have come in three pieces, but they got smaller as you went up to the top.

They glazed in the middle and then pretty much  from the top down and then the gutters came in after that." A staggering 475 pieces of glass were used in total.  Something for those conference delegates to dwell on during their first break out session perhaps.

Main client: Spencer Dock Devetpment Company
Architect: Kevin Roche                                                                                                      

Structural engineer: O'Conor Sutton Cronin                                                                    

Main contractor: Construction Management:  Partnership (A JV between Treasury Holdings and John Sisk &  Sons)                                                                                          

Steelwork contractor: Fisher Engineering Steel tonnage: 9,600 tonnes                            

Overall project value: €215 million