Helsinki Upper Secondary School of Natural Sciences

Located on the Kumpula campus, the building is at the heart of university-level instruction in rigorous natural sciences. The new upper secondary school and its courtyard merge seamlessly into the campus and are integrated into campus activities.

Read the article in Finnish here.

Sitting on the crest of a high hill, the new five-storey wooden building for the upper secondary school edges up to the street, similar to the other campus buildings. With the school up in the corner of the block, the remaining undeveloped plot merges into the campus complex and adds an organic feel to the otherwise rectangular urban structure. This space between the upper secondary school and the previously existing buildings will be landscaped to feel more like a park than a simple courtyard.

A radar dome towers over the park edge, and the overall architectural solution draws its inspiration from nature and natural sciences. The aim is to have the building and its future courtyard form a unified whole that supports instruction in the natural sciences.

The building has a clean-cut, rational character that lets the material and structure step into the limelight.

The interiors showcase the modular solid wood structure, and the façade’s bracing capabilities made it possible to leave the interior space open. This structural strength is actually visible in the façade as the width of the solid sections between the window openings grows larger the closer to the ground you get.

The main façade material is wood that will develop a grey patina over time. The effect complements and softens the feel of the stark and undisguised materials of the campus area. Letting the wood age and develop its visible patina is an intentional and positive part of the building architecture.

The façade is clad with sturdy wooden planks, and the weather-sensitive horizontal seams are protected by overlapping the cladding slightly. This overlap is done both vertically and horizontally to divide the entire façade into smaller overlapping sections. The original idea was for the cladding to come pre-installed on prefabricated façade elements, but it was built on-site in the end.

The rainwater system is cleverly disguised as an extension of the wall: the water flows inside a pillar that supports the eave, guiding the water from the roof to the storm drain.

Technical solutions

The load-bearing vertical structures in the stairwells and exterior walls were made with glulam pillars and CLT solid wood walls. CLT-concrete composite slabs and delta and glulam beams provide the horizontal load-bearing in the intermediate floors. The roof’s load-bearing structures are made from CLT beams and slabs with nail plates.

The building is braced vertically by the outer walls and stairwells and horizontally by the intermediate floors and roof.

Because the building does not comply with the requirements of fire class P2 despite its wooden frame, the building has a fire class of P0. Among other things, the build is too tall and has too many storeys for a P2 rating. As a result, the fire safety design is based on how fires can be presumed to develop in the situations that are likely to occur in the building. The goal was to attain a level of safety equivalent to a P1 class school building while making use of the requirements of P2 wood construction.

Load-bearing structures are required to be of class R60. This is excluding the kitchen HVAC machine room, which needs to be R120. In the interior, the class requirements allowed leaving plenty of visible surfaces in the outer walls and load-bearing wooden pillars and beams (max. 20% D-s2,d2 class).

The building is equipped with automatic fire extinguisher equipment (sprinklers).

The building’s acoustic design complies with the acoustic design guidelines for learning environments issued by the City of Helsinki. In turn, these guidelines are based on national standards and the regulations and guidelines of the Finnish Ministry of the Environment

When designing and installing the sound insulation, special attention was paid to the following issues:

• Characteristics of the building structures and components that separate internal spaces
• Sound transference between internal spaces, particularly when separated by thin (<150 mm) CLT structures
• Structural seams and joints and other possible points where sound could leak through
• Airborne sound insulation by ensuring absolutely airtight structures between internal spaces

The construction project

SRV oversaw the project under a collaborative project management contract, with the work split into two phases: development and construction. Quattroservices Oy acted as the project management contractor for building technology. SRV selected the project’s design partners during the contract tender phase.

They remained with the project until the end, and collaboration between all the involved parties was smooth from beginning to end. Even the end user took an active role in the project. The development phase began in early 2021 and lasted half a year. In this phase, the parties got together to find the construction solutions that would best serve the project goals. The COVID pandemic added its own quirks to the entire bidding phase and much of the development phase, but everything worked out in the end over remote connections.

Construction began in the summer of 2021. Workers began to erect the wooden frame structures in March 2022, and installation took about 3 months in total. During this stage, detailed preliminary planning, a comprehensive moisture management plan, and proper management of the construction site were the key to success. The client, end user, contractor, designers, and a variety of experts worked together to seek the best moisture management solutions. Overall, this resulted in the best possible approach. For example, the contractor and structural engineer collaborated well in advance to plan what order the wooden structures would be installed in and what protective structures would be needed during installation.

It took about 2 to 3 weeks to install elements for one storey, and the roof was waterproofed immediately once the elements were in place. This allowed the building’s outer shell to be covered and protected from the weather as quickly as possible section by section. The element seams were carefully cleaned and then sealed to be moisture and vapour tight, whereas the underside surfaces of the CLT elements came with a factory-applied moisture barrier. The Kuivaketju10 (Dry Chain 10) operating model was used for moisture management. Techniques such as humidity control cycles and remotely readable digital sensors were used to monitor the operating model’s success on site.

The frame was completed in the summer of 2022. Once the building envelope was complete, workers moved on to the façade cladding, the roof, the interior partitioning walls, fire safety, and building technology. When work inside the building was at its peak, around 80 people worked on the site, with the average daily number of workers being about 50-60 people. Approximately 90 subcontractors worked on the project in total. Work at the construction site went according to the planned schedule, and occupational safety stayed at a good level. The project was completed on June 30th, 2023, and the school opened to students on August 10th, 2023. For improved energy efficiency, locally-sourced renewable energy was prioritised when possible. Solar panels on the roof produce energy for the building, and heating is primarily geothermal. The project aimed for a Gold level LEED environmental certificate.

CREDITS