The new biology and chemistry block at Schubart Grammar School in Aalen – what better place for students and teachers to experience at first hand the interplay between construction excellence and science. Developed by Liebel Architekten BDA in collaboration with Transsolar, the science wing makes groundbreaking use of three environmentally friendly forms of energy: light, thermal energy, and geothermal energy. It’s a pleasant place to learn science. And now it proudly sports a DGNB Climate Positive award.

In the quiet town of Aalen, nestled in the rolling countryside of the Swabian Jura hills, stands Schubart Grammar School, an example to many with its perfectly appointed classrooms. Erected in 1912, the main school building was designed by none other than Paul Bonatz. It was one of the earliest projects worked on by the famous architect, who also designed the Main Station in Stuttgart and is still considered a trailblazer in the field of school architecture.

With its imposing stature, the listed building underwent extensive refurbishments in the 1980s. At the same time, the basement was expanded and now extends under the schoolyard which runs over its roof. From this area, sweeping open-air staircases lead over to the rest of the school grounds comprising a dining hall, a gym, a sports field and a special chemistry and biology block, which was completed in 2019. The integral air conditioning concept in the building was developed by Liebel with Transsolar, entirely in the spirit of the pioneering architecture embodied by Paul Bonatz more than 100 years ago – only this time the focus lies in sustainable construction.

A school campus with added benefits: the open area can be used by the local community outside school hours. © Liebel Architekten BDA

Carbon-neutral design from start to finish

The contract for designing the new science wing was awarded to Liebel, a local architecture firm, in 2017. Bernd Liebel and his team brought Transsolar, an climate engineer from Munic, on board. Their aspiration from the outset was to achieve a net zero energy building. Now, over a 12-month period the building generates at least as much energy as it requires. The official design aim was to consciously offer an alternative to the trend towards technology-driven buildings.

First, however, it was important to respect the historical significance of the old building next door. By paying close attention to existing contours, each individual building section within the school complex has been brought together in harmony to create a coherent ensemble of urban buildings. The new building even makes visual references to – and highlights – the ridges of nearby hills. The outdoor area on the grounds was also redesigned and is now a popular meeting place outside school hours.

Architecture hand in hand with a climate-control concept

Another of the aims of the architects was to embed as much of the new building as possible into the terrain of the school grounds. As well as ensuring the science wing would not overshadow the architectural significance of the Bonatz building, this also compensated for a natural protrusion in the ground. The result is a compact, hybrid wood and concrete building with expansive windows.

The distinctive saw-tooth roof was initially developed for practical reasons. A number of roof studies have shown that north-facing saw-tooth roofs maximise the amount of natural light in buildings. Increasing daylight in the building made it possible to cut lighting costs by around a half.

The relatively high proportion of concrete in the building prevents the interior from overheating, especially in the summer. In addition, wooden elements on the upper floor require less grey energy while the expansive concrete surfaces allow the building to store thermal energy. Even at the height of summer when outdoor temperatures can hit 40°C, the indoor temperature remains at around 25°C without any need for air conditioning. Instead, the rooms are cooled at night by automatically tilting windows with small motors and allowing air to swirl through the building at an angle.

The integral climate control concept combines local energy sources with solar systems at no additional cost. © Transsolar

Healthy indoor air thanks to geothermal heat

To maintain indoor air quality, the science block was fitted with a hybrid ventilation system. This opens and closes windows or propels air into the building through a 45-metre-long underground channel where air from the outside is cooled or preheated. The channel uses a slow fan to gently propel air into the classrooms without creating a draft. From there, air is distributed into other areas of the building. During breaks between lessons, the rooms are briefly ventilated again by opening the windows.

Exchanging energy between old and new

The ambitions of the team working on the project are reflected by an interesting formula they came up with for the building: 1 + 1 = 1. Their premise was that the old building and the new science block should not require any more energy than the existing building by itself. To do this, the two buildings exchange energy. An existing combined heat and power unit is sufficient for covering the low heating requirements of the new building, and any surplus energy supplied by the new photovoltaic system is forwarded to the old building and dining hall.

The numbers and feedback speak for themselves

Figures generated by monitoring systems show that the building outperforms estimated zero-energy standards. Taking all factors into account, under normal operation the science block even meets German energy-plus standards. In other words: it’s climate-positive.

Feedback from the schoolchildren and teachers is also highly positive. As future users of the building, they were involved in the project from the very beginning. As a result, they now know how to use the building properly, allowing the ventilation and energy concept to fulfil its maximum potential. Everyone has learned new things about the building over time and gained a better understanding of the opportunities offered by sustainable construction. As such, an educational goal has also been accomplished.

Naturally as owners of the building the local community has also benefited from the innovative architecture and climate concept. As well as paving the way in school buildings, the town of Aalen is also reducing its operating costs.

Bernd Liebel (Liebel Architekten BDA) and Wolfgang Steidle (Mayor of Aalen) being interviewed at the DGNB Sustainability Day on 1 July 2021. (Interview in german) © DGNB

Award-winning architecture hand in hand with an outstanding climate concept

The exemplary design and sustainability of the school extension has attracted a variety of prizes and honours. These include an award from the Federal Government for sustainable buildings, neighbourhoods and ecological innovation (Bundespreis Umwelt und Bauen), a DGNB Climate Positive Award and the Hugo Häring Award from the Association of German Architects (BDA).

The building also attracted a further award at the recent DGNB Sustainability Day, held this year on 1 July. The science block was named national winner of the Green Solutions Awards in the buildings category. The project is therefore an automatic finalist in the international contest, which was initiated by the social media platform Construction 21. The award ceremony will take place in November at COP26, the UN Climate Change Conference in Glasgow. We’ll be keeping our fingers crossed!

Winners of the German Green Solutions Awards 2020-2021 (left to right): Bernd Liebel (Liebel Architekten BDA), Wolfgang Steidle (Mayor of Aalen), Johannes Kreissig (Chief Executive Officer, DGNB) © DGNB

If you’re also intending to embark on the journey and planning a climate-positive project, DGNB offers a treasure trove of valuable information. For example, take a look at our DGNB Climate Positive award and also do order our publication Climate Positive: Now! for deeper information.