Dublin recladding project symbolises Irish recovery

But construction came to an abrupt halt in 2009 as the bank, which was heavily exposed to property lending, ran into financial issues and was eventually nationalised by the Irish government. Since then, the building has stood derelict – a symbol of both the bank’s collapse and the stalled construction industry.

Now, after six years of inactivity, as the country’s construction sector moves into recovery, work has finally begun to complete the building, albeit for a new client. Multidisciplinary consultant Aecom, along with local architecture practice Henry J Lyons, has taken on the challenge of creating a new skin to enclose the concrete skeleton that has been left exposed since the banking crisis began. Aecom was employed directly by the bank’s new owner, the Central Bank of Ireland, as facade and structural engineer.

Will MacDonald, regional director at Aecom, explains: “They had a building that needed a facade, so they employed us to work with the lead architect to design the facade. It’s unusual for us to be employed directly by the client, but it’s an ideal situation, as you are in direct contact with the developer.”

MacDonald has a keen sense of the project’s importance to the city, both as an engineering feat in itself and in removing the city’s concrete albatross. He describes the old building as a monument to the bad times: “There is bad feeling towards Anglo Irish, as a lot of people lost money when it collapsed.”

The site was originally owned by Zoe Developments, a company of failed tycoon Liam Carroll, that had planned for Anglo Irish to be the anchor tenant of a new financial district. After parts of his group of companies went into liquidation, ownership of the property passed to Ireland’s National Asset Management Agency (NAMA). The site was eventually sold to the Central Bank for a reported knock-down price of €8m in 2012.

John Mulcahy, former head of asset management at NAMA, has been quoted as saying it was essential that the site be redeveloped: “It was like a burnt-out tank on the road to Kuwait – a symbol of our failure,” he famously told the International Corporate Restructuring Summit in 2013.

As the site became an embodiment of the banking collapse, NAMA was keen for it to be quickly redeveloped.

“We sold the old Anglo headquarters to the Central Bank on the basis that every film crew that came to Dublin wanted to shoot the Anglo building,” Mulcahy added.

The abandoned skeleton of the building stood exposed to the elements for six years. Photo: William murphy

The Central Bank of Ireland, the country’s financial services regulator, wanted a new building to rationalise its operations and signal a fresh page after criticism for its role in the Irish financial crisis. The 22,500 sq m office block will allow it to bring its 1,400 staff, currently housed in six locations around the city, under one roof in the new North Wall Quay – at a reported cost of €140m (£98.5m).

Although the bank bought the site at a greatly reduced price – MacDonald estimates the site’s current value is around €40m – it came with one obvious complication: the skeleton of the incomplete building. It was one of two eight-storey blocks planned for the site as part of a cluster of five buildings designed by Traynor O’Toole Architects for Carroll’s Zoe Developments and its successor, Danninger.

Demolition of the structure, which had been exposed to the elements for the past six years, followed by a rebuild based on a new design would have perhaps been the simplest and cheapest option. But as the Central Bank wanted to complete the project as quickly as possible, the decision was made to work with, and build on, the existing frame.

“Programme was key,” says MacDonald. “Demolition would have meant going back to planning for approval, then tendering to demolish before starting the rebuilding process. Speed was the biggest issue, so they decided to keep the existing frame.”

The original scheme was relatively far progressed: the building’s reinforced concrete frame was nearly completed, and a large proportion of the Metallbau facade already fabricated and awaiting shipping in a warehouse in Germany. However, as both the bank and Danninger, acting as developer/contractor, had been liquidated, the construction documents and drawings of the building were not available, so the design work had to start from scratch.

The anodised aluminium veil is made up of 40 differently shaped triangles and will be fixed to the existing fittings.

Coastway Surveys was employed to carry out a 3D laser scan survey of the unfinished concrete frame and produce an as-built 3D Revit model of the project.

Although Aecom was initially concerned that the frame might be too weather-worn to progress, the base turned out to be structurally sound.

“We undertook a survey of the entire building to identify what work was still needed and were surprised at the condition the structure was in,” says MacDonald.

Based on this survey, Aecom presented the bank with four facade options, three of which were variations on a standard glazed box, similar to Anglo Irish’s original scheme. The fourth was in two parts: glazed internal curtain walling wrapped in a perforated aluminium veil. To Aecom’s surprise, it was this fourth option that the bank settled on.

“Out of the four designs, in our opinion, this was the wacky one. We were surprised they chose it,” MacDonald recalls.

He believes the combination of the glazing with a veil provides the bank with a building that is both transparent and economical. The inner curtain wall has been designed based on a 1.5 metre wide module, to correspond with the original design’s dimensions and make use of the facade brackets that are already installed.

“We didn’t initially want to use the existing brackets, as they had been exposed to the elements for so long, but we had them surveyed and tested. They have been 100% proof loaded, so we can proceed with them with confidence,” explains MacDonald. “I spoke to other consultants who said they would replace all the fixtures as a matter of principle. However, this could have created other concerns. To replace, we would have had to drill new holes for all the fittings, opening up the concrete and, without detailed drawings, there is the potential of hitting a lot of the rebar [reinforcing steel].”

High-performance design

The double-glazed modules play a key role in the building’s environmental and security strategies. The outer pane is made of 13.5mm heat-strengthened laminated glass with a high-performance coating that is extremely hard to crack – one of many measures required to meet the bank’s high security conditions.

Behind this outer pane is a 15mm argon gas-filled void and an inner pane of 10mm clear toughened glass. This high energy-performance glazing helps to give the building a rating of A2 – the second highest on Ireland’s Building Energy Rating scale – and a BREEAM “excellent” score.

Each glazing module contains integrated vents as part of the mixed-mode ventilation system. Visible on the exterior as a strip of louvres, the mechanical system allows building users to control the flow of natural air into the office.

Standard unitised modules, made by Dublin’s Architectural Aluminium, are used on most of the envelope, but customised units have been designed using Autodesk Revit (version 2015) to wrap around a kink that animates the facade.

John Hallahan, managing director of Architectural Aluminium, explains: “We designed some new profiles to supplement our existing unitised curtain walling system. These had to be independently tested in the UK to verify the weathertightness and performance.”

The subcontractor has tested the system with full-scale test modules already installed on site, and is currently fabricating the facade modules.

The installation of the facade adds another complication. Normally, mini-cranes would be set on the floor slabs for this, but as the loadings of these slabs are not known, a tower crane will be needed.

“Usually, around 10% of the tower crane’s operational time is used for the facade installation, but here it will be more likely to be around 90%,” says MacDonald. The impact of this is greatly reduced as, of course, the frame is already complete. So the facade can be installed in a vertical sequence – the contractor can work up each face of the building, rather than in horizontal layers.

The five-month facade installation is now under way. Dublin-based Walls Construction won the European Union-compliant tender in April, beating Sisk, Bennett Construction, BAM Ireland, John Paul Construction and PJ Hegarty & Sons.

Surrounding the glazed cladding, Walls will be installing an anodised aluminium veil composed of 3 metre-wide triangular elements – the sail-like forms acknowledge the maritime setting. Because of the building’s irregular shape, the geometry for these elements is extremely complex and requires 40 differently shaped triangles.

Along with creating an architectural presence for the new headquarters, the veil also has an environmental role, as the mesh reduces solar heat gain. This allows for glazing with a higher level of light transmission, achieving environmental targets without the tinted glass that would have been necessary if the building were exposed to direct sunlight.

Between the glazing envelope and the veil is a 780mm void – the minimum amount of space required by the rope access teams to clean the glazing.

The bank headquarters that began in 2006 is on its way to completion, albeit with a new design and for a different financial institution. By the end of the year, the building should be fully enclosed, erasing the incomplete skeleton from Dublin’s skyline. Interior fit-out will follow before occupation in late 2016.

The golden colour of the new building may be a cliché, as well controversial, yet it may be a welcome signal that prosperity, for both the financial and construction sectors, has returned to Ireland.