Wood construction enables sustainable municipal development
In a historic decision in 2018, the municipality of Tuusula committed to renewing most of its municipal network of services. This requires a number of new buildings to be built, including large campuses for up to 1,000 students. The target is to complete about one project per year. Measured by gross square metres, 60,000 m2 will be added to the municipal building stock. This is equal to a third of the current total. Like many other municipalities, Tuusula has had problems with indoor air in its buildings. A burning desire to resolve this issue and to provide safe and healthy facilities served as a background for the decision to renew the city’s buildings.
Text: Katerina Zaitseva
Read the article in Finnish here.
The municipal strategy calls for us to build a sustainable future in Tuusula and for us to promote the protection of the environment in all our operations. To ensure a sustainable future for the coming generations, we set out to renew the service network, boldly experimenting with new building materials that also result in lower emissions. The Martta Wendelin daycare centre was the first to be built under the new policy. Completed in August 2022, it was built with CLT elements. This daycare centre received the Nordic Swan ecolabel as a mark of the environmentally-friendly nature of the building over its entire life cycle, including everything from the construction phase to the recycling of materials.
The Monio upper secondary school and cultural centre will be the second site following this policy. It is being built as a hybrid structure with no less than 25 kilometres of logs, and will be finished in August 2023. The facades and the partition walls delimiting the high lobby space of this building are non-settling log. The wooden structures use Kerto-Ripa system elements for the intermediate floors and glulam for the vertical structures, stiffening diagonal beams, and the roof structures. The remaining structures are steel and concrete.
The initial projects in Tuusula’s new service network are ambitious even at a national level. The Martta Wendelin daycare centre is the largest solid wood daycare centre in Finland by cubic metre, while Monio is Finland’s first three-storey log school. The projects have also received accolades: the Martta Wendelin daycare centre was a 2022 Wood Award candidate and Monio was designated the 2022 work site of year by Rakennuslehti. The municipality of Tuusula also won the Pioneers in Public Wooden Construction award last year. We have successfully promoted wooden construction by trying new things boldly and without preconceptions
We used carbon footprint calculations to check the emissions generated by our service network buildings over their lifecycle. In particular, we have found that our wooden buildings are clear winners in terms of their carbon handprint, as the positive contributions to the environment are now called. The carbon handprints of wooden buildings can be up to 8 times larger than those of conventional buildings. Wooden buildings store carbon dioxide from the atmosphere as long as the wooden building is in use. Even after the building is demolished, the wood material can be recycled as building components and finally used for energy production.
The way o the pioneer isn’t always easy, and we have run into our share of challenges along the way. With the Martta Wendelin daycare centre, we faced our first challenges on the design table. Because of the requirements of the Nordic Swan ecolabel, the Siberian larch that was initially selected as the façade cladding material had to be replaced with larch grown in Finland. However, the Finnish larch turned out to be less durable. Running electrical cables through solid wood structures wasn’t quite as straightforward as we had thought either. When bids were solicited from contractors, we found that the split contract option we had chosen was not the best contract model for this kind of building. This led to very few bids, but we were still able to select partners in the end.
Looking back, we can say that a turnkey project would have been a better model for getting the work done. Under this model, the developer would have been responsible for the design as well, which would have spared us the challenges of coordinating design and construction. Because we required that shelter from the weather be put into place for construction, all CLT elements needed to be lifted into place under a large tent. All work took under this tent. Because of it, we had to cut down more trees than planned. Despite the challenges involved, we refuse to risk exposing our structures to moisture damage, which is why we will continue to follow this practice on our building sites in future as well.
A fixed-price contract was selected as the model for the Monio secondary high school and cultural centre. This made things a little easier compared to a split contract, which requires a lot of client resources. However, many of the choices made during design had to be changed during construction. For example, all the intermediate floors in the building were switched out from the initial design after the contract was signed. This required both the contractor and the client to be flexible and to collaborate effectively. Because the structures were unique, many of the fastener details for the log structures in Monio had to be made on site because they were not available in a prefabricated form.
On the whole, we found that these kind of wood construction projects demand extensive expertise and professional skills from designers, contractors, and the client. You need to carefully consider the contract model, whether the client’s resources and expertise are sufficient for the task at hand, and what the best approach is for ensuring proper competition. Because these structures are still somewhat unfamiliar, wood construction partners play a key role in public procurement. However, we have advanced with purpose towards our goals despite the challenges. We resolved the issues we encountered along the way by collaborating effectively with our partners and by drawing on the team spirit of our own organisation. We are proud to be able to declare that our wooden projects have become spectacular landmarks in Tuusula.
In itself, wood is by no means a new building material for us. Rantatie street in Tuusula has a rich selection of old wooden villas that were popular with the artist community at the turn of the 20th century. Examples include painter Pekka Halonen’s log-framed studio home and poet J. H. Erko’s log-framed Erkkola. These over hundred-year old wooden buildings are excellent carbon storehouses. We are going back to the roots of wooden construction because wood has already proved itself to be an excellent building material that is natural and simple. While wood is certainly combustible, it can also be made safe because there is a lot of knowledge about how wood behaves while burning. A wooden-framed house can withstand flames for a long time without collapsing because the carbonisation of the surfaces in a fire protects the structures from burning further. People also find wooden buildings to be very pleasant, and we are happy to continue to build such healthy and safe spaces from wood.
I hope we continue to see innovation from operators in the wood construction industry, to engage in a good dialogue, and to have the courage to try new things. Even though we already have a long history with wood construction, we are still at the cutting edge of new construction methods and are learning new things together. By selecting wood construction, the public sector can become a trend setter while simultaneously supporting the Finnish economy.
One or our great pleasures has been to see how the cosy Martta Wendelin daycare centre came to life last August as young and old users flowed into the wonderful facility we had worked so hard to design and build. Wood construction allowed us to create pieces of art and to keep Tuusula growing sustainably
WRITER OF THE ARTICLE Katerina Zaitseva, program manager, MSc Eng., Growth and environment, Tuusula municipality