The design for the new Civic Offices for Cork City is the product of a ‘Design and Build’ competition set by Cork City Council. The building provides 9,200m² of office space, together with 140 car park spaces.
The site was a surface car park located to the rear of the existing 1930s City Hall located on the edge of Cork city centre. It is bounded by a fire station and multi-storey car park to the south, the City Hall to the north, and two busy roads to east and west.
The three facades of the existing City Hall provide independent access to a variety of civic functions: a concert hall accessed through the north façade of the existing building facing the River Lee, a Lecture Hall accessed from the east, and the Council Chamber entered from the west. Strategically, the building creates a new administrative entrance for the council to the south, ‘revealing’ the ‘back-stage’ elevation as the new, fourth facade to visiting public.
The project is structured around two dramatic spaces: a top-lit Civic Hall and a narrow Stair Hall, formed between the existing classical façade of the City Hall and the new building.
The building form is composite, consisting of masonry and glass-and-steel volumes. The solid, ‘masonry’ block is conceived of as a carved volume, eroded in response to the adjacent City Hall and city edge condition. It ‘clasps’ the projecting backstage of the City Hall, forming a link with the existing structure. It also fulfils the function of a ‘service block’, containing the principle services for both the existing City Hall and the glass volume – lifts, plant, canteen, staff resource centre, Comms room.
The crystalline volume of glass and steel is designed for maximum flexibility and contains office space. It is linked to the service block by bridges for circulation, great ‘chimneys’ for ventilation, and deep fins to control light.
This volume is wrapped in a double façade which modifies light and air for the internal environment. The outer screen is constructed of a fine lattice of galvanized steel flats suspended from great, galvanized steel trusses cantilevered from the roof slab. Glass sheets are fritted with a solar control pattern and clamped by galvanized steel beads to form a light, elegant façade to the city. This translucent addition to the city is conceived of as a lantern – a visible expression of the ethos of openness, transparency, and accountability of the City Council.
Environment and Sustainability
The form of the building is the product of a holistic environmental strategy which integrates the latest technology to create a good working environment. Office floor plates are naturally ventilated. The Civic Hall acts as a return plenum for adjacent office buildings while fresh air, collected at roof level using rotating wind cowls, is supplied through large ‘chimneys’ in the roof and walls of the Civic Hall to the floor plenum of offices.
Free heating and cooling are provided using ground water pumped through pipes embedded in exposed concrete soffits. These soffits are tilted towards floor-to-ceiling glazing to maximise daylight penetration, creating dynamic working spaces.
A double-façade consisting of angled leafs of fritted glass set within a galvanized steel lattice is designed as a buffer from wind and city noise allowing perimeter windows to be opened in the most inclement conditions. Gaps between vertical leafs allow sufficient cool air to enter in summer while in winter, the galvanized steel double facade generates a microclimate, allowing staff to open perimeter windows during the coldest months.
The outer glazed screen of the galvanized steel façade is patterned with 10mm x 200mm solid fritted rectangles set 1mm apart and graded vertically from dense grid to open. This generates sufficient shade to reduce solar gain and gives shade to work spaces while maximising daylight.
Structure of the facade
The precise setting-out of the hanging steel plates that support the outer leafs of glazing was critical to the successful installation of the double facade.
100 x 20 galvanized steel plates at 1200 centres are suspended from a single fixing point consisting of a single bolt fixed through an un-slotted hole. The location of this suspension point involved the designing of a series of areas of adjustment to accommodate building tolerances.
Primary Structure: 305 x 305 galvanized steel (UC) at 7.2 meter ctrs is shimmed vertically (A) and adjusted through slotted holes horizontally to align beams (B).
Secondary Structure: 1.4M high truss fabricated from 100 x 100 galvanized steel SHS spans 7.2 meters between columns. Adjustment vertically is accommodated with slotted holes and when correctly positioned, permanently shimmed off the beam (C). Lateral adjustment is via spacers between a vertical stanchion (not shown) and truss (D).
Fixing: Twinned 200 x 100 x 12 steel connector plates are welded to truss at 1.2 ctrs. Suspended 100 x 20 galvanized steel hangers are slotted between connectors. +/- 4mm horizontal tolerance is given between connector and plate (E). No vertical tolerance is given to lower fixing as this is the principle support point for the outer facade.
Images © Dennis Gilbert
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