Event Centre Satama Arena

Kotka’s new Event Centre Satama Arena is in Kantasatama harbour on the outskirts of the city centre. The harbour was built 150 years ago to serve the wood processing industry, and the event centre’s bold yet understated architecture pays homage to the tall wooden ships and sails of that era while making a nod to the more streamlined metal halls of recent times.

Read the article in Finnish here.

Event Centre Satama’s lobby is open to the public. This seamlessly connects the building to its surroundings, while the added shelter makes it easier for visitors to make active use of the outdoor spaces. The lobby also ties the block’s buildings together, providing access to the university of applied sciences that is currently under construction next door. Event Centre Satama also includes a restaurant, meeting rooms, and event halls that can be used by all the buildings in the block. Together, the buildings form an inspiring complex with multiple uses.

When viewed from a distance, the lobby’s welcoming warm wooden panelling is hidden under the building’s zinc shell, but gradually becomes more visible to visitors as they approach. The gently curved ceiling is made from curved glulam beams that literally hang from the structures much like the split hem of a large tent. The shape of the arch is optimised for the tension in this structure: the beams are as narrow as possible, which saves wood and therefore makes both environmental and financial sense. The actual arena is a vast, rectangular hall with excellent sound insulation. The feel of the space can be modified as needed with partition walls, curtains, lighting, and collapsible stands. Wooden slats on the walls play a role in the acoustics by spreading sound evenly to listeners, and they also visualise the possible placements of the stands. They are a testament to the impressive versatility of the space, convertible from intimate 20 person meetings to large concerts with standing audiences of up to 3,200 people. The support facilities surround the hall on three sides: the kitchen, energy centre, and loading and storage spaces are located on the ground floor, and the meeting rooms, offices, and dressing rooms are upstairs. Windows and openings are shielded by open “fins” in the zinc façades, providing privacy and shade from the sun – and an exciting surface that changes in appearance as the viewer walks by.

When choosing materials, the team focused on a low carbon footprint, longevity, easy maintenance, and recyclability. The design optimises the materials used in the structures: the roof trusses and truss pillars supporting the hall’s suspended ceiling are made of steel since they will be under the heaviest stress, the foundations and the kitchen are concrete for maximum fire endurance, and the remaining structures are built from solid wood elements. The lobby surfaces are solid wood, and the intermediate floors and roof structures are built from prefabricated wooden elements. A total of approximately 1,400 cubic meters of wood has gone into the load-bearing structures. They bind an estimated 970 tons more carbon dioxide than was generated during their production. The construction plan was optimised to ease installation of the elements and to manage the amount of work required. The foundations, subfloor, and stairwells are a combination of cast-in-situ concrete and prefabricated concrete elements. The building’s outer shell is made entirely of recyclable, massive zinc that has already developed a natural patina on its surface. Design and construction of the event centre are in accordance with BREEAM guidelines and aim for a BREEAM certification level of Very Good. In addition, the entire Kantasatama area is aiming for the BREEAM Communities certificate for sustainable community planning.

Technical solutions

Event Centre Satama’s most distinctive parts are the lobby with its arched ceiling and the flat-roofed rectangular hall. According to the permit, the complex is a two-storey wooden building with fire class P0. This classification is based on exit time simulations. Based on its intended purpose, Event Centre Satama is classified as a building meant for gatherings ranging from concerts and sports events to congresses and trade fairs. This means the wooden wall and ceiling surfaces in the building’s main rooms need to meet the requirements of class C-s2, d1. The building is equipped with an automatic fire extinguishing system.

In the building’s interior, various solid wood surfaces have been left visible on load-bearing elements and intermediate floor slabs, and the décor includes wooden interior panelling and trim. These choices were made for their structural, architectural, and acoustic merits. The lobby acoustics are based on a slatted ceiling that is backed by acoustic wool indoors and plywood outdoors. Apart from the acoustic felt cladding on the wall facing the neighbouring university of applied sciences, all the lobby’s walls have hard wood panelling or glass surfaces. The arena hall has plenty of sound damping surfaces, and the sound-reflecting and partitioning slats are only used in the lower part of the hall and solely up to listener height.

When it comes to its structure, the building’s most unique aspect is the suspended wooden ceiling in the lobby. Spanning 33 metres, the glulam arches are held in place solely by tension. Along the outer wall, they are attached to the ground by means of steel diagonal pillars and drawbars anchored to the rock. On the crest of the ceiling, the wooden arches connect to the hall’s steel roof trusses and to the steel truss structure within the wall between the lobby and hall. The latter is anchored to the rock, whereas the hall ceiling needs less anchoring thanks to its light weight.

The construction project

Event Centre Satama had the misfortune of starting out in tough times. Planning and early construction were hampered by the Covid-19 pandemic, more precisely the production problems and the sharp rise in raw material costs that followed. Due to the atypically elevated risk of cost overruns, the tendering round produced no bids, and the only choice was to continue through negotiations.

With the building permit already in hand, all the parties in the negotiated cooperative project management contract got together in the spring of 2021 to develop the project plan and to find the most feasible solutions. For example, the original plan for a wire-suspended lobby ceiling was replaced with a functional wooden solution that retained the same free-hanging shape. To shorten construction time, much of the load-bearing and bracing was built from prefabricated steel lattice structures instead of the original plans for casting them of concrete on site. Structures and construction phases were optimised to make it possible to build without weather protection despite the extensive wooden structures. The development phase can be deemed a success: the technical quality and architecture of the building has not changed in essence, but the selected solutions are more affordable and easier to install.

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