The stylish renovation of the historic courtyard of a valuable property over 180 years old and its covering into an urban space with a glass roof supported by organic shapes and processed in a state-of-the-art manner based on 3D modeling brought Pohjoisesplanadi 37 the Steel Structure of the Year 2025 award.
Pohjoisesplanadi 37 is a building of cultural and historical significance, which is part of the Esplanadi-Bulevardi cultural environment in the centre of Helsinki, designated by the Finnish National Board of Antiquities as a nationally valuable built cultural environment. The renovation, designed by JKMM Architects, in which the historic courtyard of the over 180-year-old valuable property was covered into a cozy interior space with an organically shaped glass roof supported by graceful steel structures, brought Pohjoisesplanadi 37 the Steel Structure of the Year 2025 award.
The award was announced in Helsinki on November 6.11th at the Steel Structure Day.
The Jardin courtyard, covered with a glass roof, creating an interesting new urban space in the Gaselli block, opened to the public at the beginning of July. The oldest part of the building, a two-story Empire building, was designed by Carl Ludvig Engel son Carl Alexander Engel, and the historical layers of the currently seven-story office and retail building create a fine dialogue and contrast with the graceful and organically shaped glass roof supported by a steel structure designed by JKMM.
The Steel Structure of the Year was selected by an award jury chaired by architect SAFA. Thomas KivinenThe award jury was impressed by the insightful steel structure solutions used to cover the building's courtyard.
“The new addition forms a valuable temporal layer to an already complex building complex. The structure improves both the functionality and aesthetics of the building, and its complex organic geometry creates a strong contrast with the architecture of the old building. The concept solves the challenge posed by the meandering boundaries of the old courtyard in terms of both geometry and structural functionality by acting as an organic form-giver. The design language based on the aesthetic contrast between new and old, as well as the passage to the courtyard, reward the visitor with a structural and aesthetic spectacle,” summarizes Tuomas Kivinen of Kivinen Rusanen Arkkitehdit Oy, who received the Steel Structure of the Year Award in 2024 for the Vuosaari Bioheating Plant.
"The surface treatment and coloring are warm and valuable, and the color scheme combines seamlessly with the warm tones of old buildings. The structure resembles natural structures and even creates an image of biomimetic design. The whole is innovative and meets the requirements of sustainable development, as the use of steel and optimization of the structure are at their peak," Tuomas Kivinen continues about the award criteria.
In connection with the high-quality renovation, significant changes were made to the lower floors, which will mainly house restaurant operations and retail space. The transformation of the courtyard in the middle of the building is very important. The former
The parking area has been transformed into a warm interior space under a sculptural glass roof. Supported by four large steel lattice pillars inspired by natural forms, the glass roof creates a light counterbalance to the solid stone walls.
Careful renovation and extension work improved the functionality and attractiveness of the valuable building in a prime location.
From the beginning of the project, it was known that this was a geometrically challenging project, where the implementation of the geometry, the number of unique parts, the amount of machining, and the experimental nature of the implementation required an advanced approach to design. In addition, old-fashioned modeling programs were not able to provide the geometric accuracy or flexibility in workflows required by the project, so the steel frame and glass supports of the project were implemented using computational design methods based on the Rhino program.
All of the project's manufacturing files, assembly and installation documents were also created mainly programmatically.
Ramboll designed the frame manufacturing and installation in close collaboration with experts from Teräselement, the company that contracted for the glass roof and steel structure. The design also included developing various solutions for the dimensionally accurate implementation of the structure. 3D files were created for all rods and installation supports, which in turn were used to create CAM files for the laser cutter.
The design and machining of the parts of the aluminum glass support system mounted on the steel frame were also modeled programmatically. In collaboration with Teräselement, auxiliary tools were developed for the assembly of the frame, which could be designed cost-effectively thanks to computational design methods. This also allowed the required 3D lattice shape to be formed from the rods with great precision.
The installation blocks were pre-assembled in a steel workshop and transported to the construction site in blocks. For the assembly of the vertical blocks extending into the ground, templates were developed, in which holes and rod marks were made with a laser cutter to enable precise assembly. For site installation, the frame also had site coordinate points, which were used to ensure the positioning of the blocks during installation.
The Steel Structure of the Year 2025 award for Pohjoisesplanadi 37 will be:
Tilaaja: Spring
Architectural design: JKMM Architects
Design of steel structures: Ramboll Finland Oy
Main implementer: Construction Office O. Hämäläinen Ltd.
Steel structure contractor: Steel Element Ltd.
The Steel Structure of the Year is selected from projects that have been proposed for the Steel Structure Association to be awarded. The proposals that have advanced to the final competition have been assessed by an independent jury, chaired this year by architect Tuomas Kivinen, from Kivinen Rusanen Arkkitehdit Oy. Kivinen Rusanen Arkkitehdit was responsible for the architectural design of the Vuosaari bio-heating plant, which won the Steel Structure of the Year 2024 award. The other members of the jury this year are Tommi Luukkonen (RIA), Janne Tähtikunnas (RIL), Tapio Kivistö (Construction magazine), Ahti Rantonen (AFRY/TRY), Juuso Pajukko (SAFA) and Timo Koivisto (TRY, secretary).
Honorable Mention for Oulu's Hartaansilta Bridge
The jury of the Steel Structure of the Year competition also decided to give an honorable mention to the Hartaan Bridge connecting Tuira and Hietasaari in Oulu. The double-span (85 + 85 meters) steel arch bridge, which combines walking and cycling, connects the opposite shores of the area, preserving the natural values of the place.
The bridge deck and the light traffic route running on it curves subtly in an S-shape, offering varying views, and the arch of the bridge forms a gate-like motif between Hartaanranta and Vaakunakylä.
“The landmark in its place acts as a symbol of the new city district, offering city residents the opportunity to observe their surroundings and enjoy the river scenery. Special attention has been paid to the sensitivity of the area's natural environment in the design process. Form and structure combine into a seamless whole; the bridge's design language emphasizes the structural operating principle, while the whole represents a high level of sculptural quality. Creative design solutions ensure that the structure does not dominate the landscape excessively. The infrastructure supports the city's goals of making the new city district visible and enables the smooth flow of light traffic. The bridge meets international standards as a light traffic structure,” the award jury explains the honorary mention given to the Hartaan Bridge.
The following will be awarded with an honorary mention from the Oulu Bridge of Honour:
Subscriber: the city of Oulu
Architectural design: Ylitys Oy and Maanlumo Oy
Structural design: Pontek Ltd.
Main contractor: YIT Infra Ltd.
Steel structures: Steel Group Ostrobothnia Oy
More information
Timo Koivisto
CEO, Steel Construction Association
timo.koivisto@rt.fi +358 50 408 1163Rakennustuoteollisuus RTT ry, Teräsrakennyhdistys ry