Smart profiles for the SmartCity

Graz will soon be home to the “SmartCity,” an inner-city district based on a sustainable concept. This includes a primary school, completed in 2019, as part of the innovative SmartCity school campus.

The city of Graz in Austria is growing, but space is relatively limited. Therefore, city administration is pursuing the strategy of densifying well developed urban areas. Thanks to pioneering energy and traffic concepts, energy-efficient, resource-conserving and low-emission districts are to be created. The first district of the SmartCity is currently under way at the former industrial sites on Waagner-Biro-Strasse. Based on smart criteria, residential and commercial buildings are planned as well as a school campus in two stages of construction: The Leopoldinum Primary School, and in a second phase, a new middle school.

Compact and child-friendly

As for the design of the Leopoldinum Primary School, city administration opted for the draft by architect Alexa Zahn. Her monolithic construction made of concrete and steel was completed in autumn of 2019. Unplastered, grey, curtain-wall precast concrete components featuring three different surface textures dominate its solid character.

The Vienna-based architect aimed to create a timeless piece of architecture that would appeal to children. The competition was carried out in 2015 and presented quite the challenge. Besides the general specifications to create a sustainable building, the construction had to be four stories tall with a minimal base. The panel of judges were particularly taken by one aspect of architect Zahn's winning proposal: her suggestion to realise the school’s main entrance as a courtyard protected from the weather.

To this end she set the bottom two floors of the building block facing the street back by around 20 m, with the upper two floors extending over this space. On the back side of the building facing the west, she gave the building a soft boundary characterised by numerous staggered building sections. There are several roof terraces here, providing direct access to the outdoors from the upper floors.

High flexibility

The architect emphasises the high flexibility of her concept as an essential quality of the design. Consequently, she had the building structure of the SmartCity Primary School not constructed with load-bearing walls, but as a concrete skeleton structure with round columns made of spun concrete. In her tender, the architect already named portal doors from Forster Profilsysteme AG as a primary product. She is convinced by their high security and the slender steel profiles that feature enhanced stability even in large dimensions.

The building is also equipped with ten EI30 class (EI230C) fire protection doors from the forster fuego light system, a forster fuego light EI30 fire protection sliding door, as well as 12 additional portals in forster presto E30. Spanning several floors, the fire sections create an open atmosphere and transparency between the individual areas. Glazings in the gymnasium area that protect against falling are also forster presto solutions.

Pearlescent effect on exterior

The outside exclusively features forster unico doors with triple glazing. The windows and doors on the side of the ground floor facing the sun are also fitted with solar control glazing. The six double-leaf exterior doors had to meet escape route requirements and were equipped with integrated door closers or horizontal panic bars.

To counteract a potentially austere appearance due to the use of anthracite-coloured precast concrete components, the architect worked with offset reveals and windows. Some of these windows have parapets, while others feature glass spanning all the way to the floor. Alexa Zahn also opted for an unusual colour scheme for the windows and doorframes, selecting a pearlescent paint. Applied as a powder coating, its colour shifts subtly from silver to brass depending on the light.

Large widths

The forster unico profile series is not only suitable for realising thermally insulated tubular frame doors, but also for entire facades. As a construction material, steel can achieve large widths and heights with extremely slender cross-sections. The main entrance to the primary school opens onto a two-storey foyer with a wide, pedestal staircase on the side that can be used as a public gallery and invites people to linger during breaks. On the left, the staircase is rounded off by a glass facade made of steel profiles. Unlike in classic facade construction, there is no support structure carrying an embedded window system; this would have made the visible profiling too dominant. Instead, the architect chose a version with self-supporting forster unico steel profiles up to 6 m in length. The glazing could thus be mounted right to the supporting structure of the fixed glazing, impressing with its slim profiling.

All-round solution

Steel profiles offer numerous finishing options: In front of the large pedestal staircase in the ground floor foyer, a concrete partition wall zones off a teaching kitchen for all-day care. The wall features a fire-proof round window with a diameter of 1,230 mm. A 30 mm thick Pilkington Pyrostop pane is inserted in a round forster fuego light profile with edge dimensions of 50 × 65 mm. The weld on the profile joint is so clean that the material seam is invisible. Seamless profile joints is a key quality feature of tubular frame doors and windows made of steel. While other materials are machined with bevels and the profiles are wedged, steel allows for clean welding and grinding of the transitions. This gives door and window frames a monolithic quality, emphasising the appearance of the overall building.

Outlook

After completion of the primary school in 2019, the second phase of the SmartCity school campus, with a middle school, is now on the agenda. Once this second phase is completed, construction will begin on the weather-protected courtyard mentioned above, which helped convince the judges of the architect’s design. Meanwhile the connection point where the associated two-storey building bridge will be attached to the primary school is already visible: it’s the only solid exterior plaster surface on the current building.

Graz, Austria

Fire-resistant doors forster fuego light EI30 | Fire-resistant sliding door forster fuego light EI30

Portals forster presto E30 | Glazings forster presto (in the sports hall area)

Exterior doors forster unico

Architect: Alexa Zahn, Vienna

Fabricator: Allmetall, Klagenfurt

Further information: www.smartcitygraz.at