Satavuo School in Laukaa has become the ecological centre of the entire village

Satavuo School in Laukaa serves as an example for Finnish wooden schools and ecological construction. The new school, which combines three village schools, has grown into a centre for the entire village and a beacon for an ecological lifestyle. Sweco was in charge of the school’s structural and building services engineering.

Implemented as a project management contract, Satavuo School became the most ecological school building in Finland upon completion. The cosy and healthy new school was made available to preliminary school, preschool and day care children from three villages in 2018. The school has gradually become the centre of the entire village, around which low-carbon housing and sustainable business is being planned.

“The school has been welcomed with open arms, and the occupants are particularly pleased with the building itself as well as the selected materials and technical solutions,” says Jukka Vähäsöyrinki, Development Engineer for the Municipality of Laukaa. “In addition to this, the building has become an ecological example in the region.”

Adaptability in practice

Sweco was in charge of the school’s structural and building services engineering. The open, well-lit and easily-modifiable spaces were constructed in a modular fashion. “This means that the school can adapt to a variety of uses over the coming decades, both in terms of teaching and other activities in the evenings,” says Heljo Hakulinen, Sweco’s design director for HVAC and automation technology.

The concept of adaptability has already been realised in practice. “We divided one space into two in a cost-efficient manner, which was possible thanks to careful planning in advance,” Vähäsöyrinki says. In the design phase, it was ensured that any modifications and adjustments to electrical, ventilation and structural engineering solutions could be easily implemented, in case of a need to divide spaces, for example. “The building will most certainly expand in the future, since the school’s capacity is already in full use.”

The school’s staff and pupils, village residents and municipal residents were listened to carefully in designing the school. One of the most important goals was to ensure that the premises were comfortable and healthy for all occupants. “This is why the ‘Terve talo’ criteria were used for moisture management, and the highest possible P1 category was applied to cleanliness control during construction,” Hakulinen says.

“Another goal was to utilise industrial wood construction as much as possible and design a versatile building that will stand the test of time for the next 100 years,” adds Jouko Rossi, Sweco’s department manager for structural engineering.

Energy calculation to compare CLT and log

Satavuo School was built from CLT Finland Oy’s (Hoisko) CLT solid wood, for which the raw material is PEFC-certified Finnish wood. However, the school was originally designed as a log building. Sweco’s experts conducted multiple energy and life-cycle calculations. “The first calculations on the optimal positioning of the ventilation machine rooms were already included in the building’s spatial model,” says Sweco project manager Juho Kääriäinen.

As the design process progressed, energy consumption calculations were also conducted to compare log and CLT. The variables were the exterior wall’s thermal transmittance (U value) and both wood materials with and without insulation. The comparison was used to put together a table that indicates the total energy consumption. “CLT elements turned out to be the superior choice in terms of life-cycle costs and energy efficiency,” Kääriäinen says. “Outdoor air leaks through the CLT wall are nearly non-existent.”

Seamless cooperation in structural and technical engineering

Many new solutions were created in order to make the solid wood work as the school’s load-bearing structure. For example, the exterior walls were implemented without separate pillars. “We compared the pros and cons of numerous alternative structural solutions,” Rossi says. Costs, functionality, buildability, carbon footprint and energy efficiency were the most important factors in terms of the final choice.

The process of combining innovative wood structures and technology requires seamless cooperation. “Wood is a sensitive material with less load-bearing capacity than concrete or steel. This is why we took the utmost care in going over the lead-throughs and technical rooms with the structural engineers,” Hakulinen says.

Interaction within the same company was easy. “We could react to changes quickly and provide the client with solutions that worked from the perspectives of both structural and building services engineering,” Hakulinen says. Information modelling was also used to fit the various technical categories together. “Building information modelling is also an important tool for energy calculation and carbon footprint simulation.”

A long-lived wooden school is a carbon sink in itself, and Satavuo School is also a low-energy building. 40% of the annual power consumption is generated by means of solar panels, and the school is heated with its own pellet power plant. “In addition to this, energy circulation is supported with a needs-based ventilation system with heat recovery,” Hakulinen says.

On 1 February 2021, Satavuo School received the OKKA Foundation’s sustainable development certificate.

“The school has been welcomed with open arms, and the occupants are particularly pleased with the building itself as well as the selected materials and technical solutions.” 

– Jukka Vähäsöyrinki, Municipality of Laukaa 

 

“We were able to divide one space into two classrooms cost-efficiently thanks to careful planning in advance. The building will most certainly expand in the future.” 

– Jukka Vähäsöyrinki, Municipality of Laukaa 

 

“The school can adapt to a variety of uses over the coming decades, both in terms of teaching and other activities in the evenings.” 

– Heljo Hakulinen, Sweco 

 

“This is why the ‘Terve Talo’ criteria were used for moisture management and the highest possible P1 category was applied to cleanliness control during construction.” 

– Heljo Hakulinen, Sweco 

 

“We compared the pros and cons of numerous alternative structural solutions. Costs, functionality, buildability, carbon footprint and energy efficiency were the most important factors in terms of the final choice.” 

– Jouko Rossi, Sweco 

 

“We could react to changes quickly and provide the client with solutions that worked from the perspectives of both structural and building services engineering.” 

– Heljo Hakulinen, Sweco