The Faculty of Architecture and the Faculty of Engineering Science at Innsbruck University have since been upgraded. The Austrian Federal Property Association, Bundesimmobiliengesellschaft (BIG), initiated a two-tier European competition for their refurbishment in 2009. The locally-based architecture practice, ATP, was awarded first prize. During the design phase, BIG decided to use the upgrade of the Faculty of Engineering Science (accommodating civil, environmental and mechanical engineering students) as a pilot project for highly energy-efficient refurbishment. The aim was to reach the EnerPHit Standard developed by the Passive House Institute − a Passive House Standard for refurbishments with slightly lower requirements than those for new-builds.
A pair with different characters
The two departments are situated on diagonally opposite corners of the university campus’ central square. The only difference between the two buildings before the refurbishment was their height: the Faculty of Architecture was four storeys high and the Faculty of Engineering Science eight. Both buildings are adjoined by double-storey structures. In the case of the technical science department, these volumes accommodate mainly lecture halls; in the architectural department, the space is primarily filled with workstations and design studios.
Today the different character of the departments is visible from the exterior. The Faculty of Architecture has had its balconies marginally cut back and floor-to-ceiling high glazing installed at the outer edge. A second skin with maintenance balconies and frameless safety glass fins was added to the exterior. As a result, the useful floor area has increased by 180 square metres per storey. The exterior facade is designed mainly as protection from rain and sun. Despite its excellent ability to transmit light, the glass features a very low g-value that prevents overheating of the rooms in summer. The issue of glare protection is being addressed over the next few months by the addition of a screening system to the interior.
The facade of the technical science department varies greatly from the Faculty of Architecture in that the architects were eager to create a perfectly planar surface in which ribbon windows alternate with aluminium cladding. The balconies were removed, but the original window parapets made of insulated concrete sandwich panels were retained behind the facade cladding.
In the interior, both buildings display a similar structure. The main corridor wraps around a central core and full-height glass elements separate the offices and seminar rooms from the access zones. However, the working methods − and thus the layouts − of the two departments are fundamentally different. Whereas traditional one and two-person offices dominate the Faculty of Engineering Science, the generally far larger rooms in the Faculty of Architecture are characterised by a studio workshop atmosphere. Here the main features include industrial oak parquet flooring and white-painted concrete ceilings with visible service ducts, which are only partially concealed behind acoustic panels. The intention of the visible building services is to give future architects a better understanding of the technical principles of their study objects. In contrast, the ventilation ducts in the technical science department are hidden behind suspended ceilings; the electricity and data cables are incorporated in cable ducts alongside the facade. The floors are finished with rubber flooring that varies in colour in each storey.
The heating, ventilation and cooling systems in both buildings are very similar in terms of concept, however not in terms of detail. In winter and summer, a mechanical ventilation unit with heat recovery supplies the rooms with fresh air. An automatic nighttime ventilation system has been installed to cool the office and seminar rooms during the night. Whereas room-high ventilation flaps fulfil this purpose in the Faculty of Architecture, the system opens motorised window sashes in the Faculty of Engineering Science. Cooling coils have been incorporated in the ventilation units to cool the daytime supply air during hot summer spells. The cooling systems are fed by cold water sourced from a groundwater well, which is also intended to supply the sprinkler systems in the case of fire.
The energy for the heating of both department buildings is provided by the university’s district heating system. In the architecture department, the architects had full-height radiators installed along the facades, which at first glance resemble slender steel supports. In the case of the Engineering Science Department, the original radiators have been retained. However, every second radiator has been removed due to the significant reduction of the heat demand.
Small steps towards Passive House Standard
A number of small improvements have led to a far more ambitious energy standard of the Faculty of Engineering Science. The insulation of the facade and the roof was increased to 24 centimetres and quadruple-glazed windows (triple plus single glazing) were used in place of the originally planned double-glazed windows. Rather than insulating the basement ceiling, high-quality insulation was added to the perimeter of the building.
The windows have been designed to ensure effective cross ventilation, as well as sufficient protection from the sun even on windy days. The design team conceived an innovative top-hung window for this purpose. The solar protection blind is fitted between the triple glazing and an additional fourth pane on the outside, which acts mainly as a weather shield. In case of maintenance, the single-glazed element can be removed to reach the blind. Each of the four-part ribbon windows includes two fixed elements and two opening leaves. The latter open outwards providing a far larger opening, and thus a far greater air exchange than traditional bottom-hung tilt windows.
In order to ensure sufficient cross ventilation in the interior of the building, the partition walls had to be equipped with high-performance airflow openings. It is for this reason that the planners designed a complex sound-insulated construction above the doors. At first glance, these elements hardly differ from conventional transom windows.
