Cost Update: Façades Glass façades are an increasingly popular solution to modern design needs, as well as promoting natural light and ventilation. Tomàs Kelly at Davis Langdon PKS and Duggan Systems in Limerick look at the current cost drivers The site for the new IT building at University College Cork lies to the north west of the main campus, located at the old greyhound racetrack in the south-west of Cork city. The area of the site is approximately 5.5 acres. A principle objective in the design of the building was the portrayal of a strong modern image of a progressive, growing, and top class university. The building expresses the modern, high-tech requirements of the brief such as the requirement for a flexible and adaptable building, easily accommodating change in response to the rapidly evolving nature of the computer science and microelectronics industries.

An early decision was taken to arrange the staff rooms: lecturers’ offices, postgraduate offices, professors’ offices etc. on the south side of the building to avail of the southerly aspect and views over the river and across to the campus itself. Student areas are arranged on the northern side of the site, along the Western Road. A central linear atrium separates the student areas into two zones. The atrium is used in this context as an organising element, providing a means of clearly orientating the building’s users. The atrium assists in natural ventilation of the student areas and provides space for exhibitions/displays in addition to its primary function as the main circulation route through the building for up to 3,000 occupants. The form of the building clearly expresses its internal function. The composition of the external façades to the north and south are punctuated by projecting glazed staircases located on the axis of the principle internal circulation routes. These elements also clearly express the modular nature of the design while containing the glass walls of offices and teaching laboratories. The east and west elevations consist of solid walls of natural coloured terracotta panels punctuated with areas of glazing. The solid elements protect the internal working environment from the harmful effects of the low east and west sun while the glazed areas allow light into the internal landscaped gardens and atrium. Brise-soleil are fitted to the south facades to allow the maximum amount of glass to be used in order to both optimise the view to the river and protect the occupants from excessive glare and solar heat gain. This specification for the façade sub-contract was of the “performance type” and was prepared to clearly indicate the performance requirements of the curtain walling system to be installed.

The façade package comprised curtain walling, terracotta rainscreen cladding, plantroom louvres, brise-soleil and the atrium rooflights and included all glazing, metal panels, and doors forming part of the external skin of the building. The façade sub-contractor was held responsible for the design, testing, fabrication, delivery to site and the installation of an air tight and water tight façade system. The curtain wall system was designed as a conventional stick system however the specification allowed for the substitution of a unitised bi-modular system as long as the critical profile dimensions and sightlines were substantially adhered to. Duggan Sytems tendered a unitised system which was very similar in appearance to the designed system and this system was accepted. A high performance glass was specified for the building due to the high extent of glazing being utilised on the north and south elevations. The north facing glass has a low-e coating to limit heat loss and the south facing façade has been provided with external brise-soleil to limit the amount of solar heat gain and glare. Cost Drivers The key selection criteria and their associated variants are all interrelated and in turn can impact considerably on cost, itself a key selection criteria. Architectural Intent Architectural intent in response to client brief represents the catalyst for any project. Creativity, raising the bar, exploring new technologies are all to be encouraged during initial design development. This creates an environment where new products and building techniques are identified for the benefit of the project. There is inevitably a commercial angle to every project and as such architectural intent and cost must align to ensure viability of the project. Achieving cost targets also envelops the other three criteria, as below. Performance The primary function of the building envelope is to protect building occupants from the elements, in no particular order; water tightness, minimal air leakage, solar gain and sun glare control. The base chassis system solution is driven in the first instance by the necessity to accommodate building idiosyncratic wind loads. The single largest performance driver and one which can effect cost and architectural intent is approved Part L of the Building Regulations, which links the performance of building envelope and services to reduce harmful CO2 emissions. Managing the fine balance of providing a building with suitable natural light whilst controlling solar gain and heat loss represents a significant challenge to the design team. Other key performance criteria includes acoustics, both reducing noise from outside to in and flanking, between floors and through framing profiles. Selection of building envelope systems and materials should also take cognisance of longevity of life whilst minimsing the amount of maintenance required. Glass cleaning and replacement strategies should be considered in tandem. Buildability Shape, repetition, access, skill base, programme; commercial viability of most buildings is influenced by efficient build programmes, which ensure that construction costs are kept to a minimum and enable the floor space to be sold or/and let at the earliest opportunity. In this regard the design of primary frame, building envelope, services and fit out must be commensurate with quick, safe and integrated installation methodologies, without compromising qualilty. Cost Material prices; all four criteria are interrelated, with 1-3 influencing cost. Cost has been listed at number four, as initial design aspirations can often misalign with client cost expectations. The design process and interaction between architect, client and other consultants must therefore enable all four criteria to align, to ensure viability of a scheme. COSTS The building envelope and in particular the glazing façade plays an important role in achieving the building aesthetic and sustainable goals. This database of information, combined with input from Duggan Systems, Limerick, has been used to generate the cost data below: Windows Aluminium double glazing: €450-€600 per m2 There are a wide range of window systems available from the Upvc, timber and dual timber/aluminium which are primarily used in residential to aluminium window systems used in non-residential projects. The choice of frame material along with the glass specification will obviously influence the cost. Curtain Walling Stick system: €550-€700 per m2    Unitised system: €700-€850 per m2 Curtain walling systems have a number of potential construction methodologies, including stick system, unitised systems and variants of these two. Unitised systems involve large panels and glazed elements being prefabricated off-site allowing them to be easily installed on site. The unitised systems do involve a premium on direct construction costs however they may well involve programme benefits which need to be considered on each project. Climate Wall €1,700-€1,900 per m2 A climate wall is a double skinned glazed façade with a void (usually 600 - 1400m wide) between the two skins. This void would contain a form of solar shading in the form of brise soleil or blinds. This shading would reflect a considerable portion of the solar gain during warm periods and the void can act as a flue to draw in cool air and exhaust hot air. Again it is a popular technology at present which allows the aesthetic to be maintained whilst contributinig to meeting the Part L regulations. Planar Structural Glazing €600-€1000 per m2 Frameless structural glass solutions have become increasingly popular in recent years as they help in achieving an aesthetic of clean lines and minimising obstructions to the view (frames) and helping to maximise daylight. The system is generally constructed with large structural glass units bolted together by means of stainless steel spiders and sometimes supported by glass fins which have a structural function. Ancillary Items Doors: single/double €1,500-€2,000 per door Horizontal aerofoil brise soleil €400-4500 Revolving door 2m diameter manual/automatic (cost per door) €25,000-€30,000 Rainscreen/terracotta/pelicolour cladding €350-€500 Actuators (cost per actuator excluding wiring) €500-€700 New IT Building, UCC Client: University College Cork Architect: Scott Tallon Walker Quantity Surveyor: Davis Langdon PKS Main contractor: Rohcon Ltd Structural Engineer: Arup Consulting Engineers Services Engineer: PM Group Façades Contractor: Duggan Systems Exclusions (to cost estimates) Structural Supports Preliminaries Attendances Actuators and electrical controls Main Contractors discount/profit