The UCD Belfield Campus in south-east Dublin has a daytime population of about 20,000 students and 5,000 staff. At present there are on-campus student residences for approximately 2,500 students, and it is intended to increase this to 5,000 over the coming years. The residences are grouped into defined ‘student villages’, and this project is part of the developing Roebuck Village, centred on Roebuck Castle, an historic structure dating back to c. 1200, though largely rebuilt in the 19th Century.
This building is the second stage of Roebuck Village, the first stage being Roebuck Hall, completed by Kavanagh Tuite Architects in 2006. When design started on Roebuck Castle residence in 2008, in establishing the brief with UCD it was decided to raise the bar, and aim for an exemplary ‘green’ project. Passive House was subsequently adopted as the reference standard, and the project has attained Passive House Certification, as well as receiving the RIAI (Royal Institute of Architects of Ireland) 2011 Award for the “Best Sustainable Project of the Year”.
The typical floor plan, for “hall of residence” style accommodation, contains en-suite student rooms and kitchenette, living and study rooms on either side of a spine corridor, arranged in two ‘apartments’ on either side of a central lift and stair core.
This basic simple plan form is off-set and articulated around the central core, where at ground level the main entrance and cafeteria face onto a walkway through the building, providing a link with previous and future stages of the Roebuck student village. Secondary escape stairs at each end of the building are expressed, again articulating the simple compact building form. The roof-top plant room housing, containing the central plant (heat recovery ventilation, water storage tanks and other plant) is external to the insulated building volume, but is expressed as a vertical extension of the central lift and stair core.
The building is of GGBS concrete cross-wall, stair core and floor structure, with lightweight unitised metal framed external wall panels to all the student rooms. The unitised panels create an airtight façade (point fixed to the slab edges for minimum cold bridging), and together with wood-framed curtain wall façades to the three stair core volumes, provide large sealed elements that are then easily air-sealed to the basic concrete structure with EPDM membranes. This strategy largely ‘designed-out’ problems of air sealing the project.
The student rooms have passive house certified triple-glazed windows (U-value 0.8 W/m2K). They are openable, but have an interlock control, closing the local room heating circuit when the window is opened.
The corridors and stair cores are not heated, and are glazed with wood-framed, high-performance double-glazed curtain walls (U-value 1.2 W/m2K).
All concrete walls are insulated externally with 130mm foil-faced and taped PIR boards, and clad with the TrespaMeteon boards on Eurofoxrainscreen support system. This same cladding system runs over all the unitised light-weight wall panels, giving a uniform external appearance to all. The cladding has a limited number of earthy colours, relating to adjacent buildings and the natural context, helping to give the building an understandable and human scale.
The project makes extensive use of renewable or recycled materials, such as acetic-acid modified timber (Accoya), recycled sorghumstrand board (Kirei Board), water-based paints, linoleum floor finishes (Marmoleum), and GGBS (ground granulated blast furnace slag) cement based concrete.
Heat recovery ventilation is provided through two central roof top heat-wheel air handling units, and heating is provided from spare capacity in the adjacent Roebuck Hall condensing gas boilers, supplying mini-radiators in the student rooms.
Domestic hot water (the largest heat load in the building), is partially (33%) supplied by a drain-back flat-plate solar water heating system on the roof, coveringa local20% renewable energy requirement. Rainwater is harvested from the building roofs, and used for toilet flushing.
Post-completion commissioning and occupants’ reviews, monitoring of actual systems and comfort performance are essential for us to study and learn from the actual results, and to develop our skills and expertise going forward.
In line with this, UCD Energy Research Group, funded by SEAI (Sustainable Energy Authority of Ireland), has commenced a two year programme of monitoring and post occupancy evaluation of the building. A roof-top weather station provides full climatic data,andmonitoring equipment, installed in 16 student rooms in the building, provides data on indoor temperature, humidity and CO2levels, electrical use and lighting loads. It also records overall energy required for space heating and domestic hot water; heat flows from MHRV and solar collectors. The data will be analysed by UCDBuilding Environmental Lab to inform on actual savings from individual systems, provide data for further research in the application of the Passivhaus Standard in Ireland, and ensure that the students are residing in a comfortable and healthy environment.
We have reached a stage where both regulatory changes and rising operational energy costs are giving a major ‘push’ towards better, “greener” building design standards. Improved building materials, elements and systems, and developing professional knowledge and expertise combine to give a huge opportunity for skilled designers to create better buildings, better architecture: advanced environmental performance and efficiency, functional, well detailed, and good looking solutions.
This project demonstrates that fine architectural design can be achieved together with exemplary high-performance building construction. It is necessary however, from the conceptual design stage, to ‘design-in’ thermal performance, and to ‘design-out’ thermal bridging and air-tightness problems. This is both a challenge and an opportunity, with no more shortcuts (any more…) to success!