The new town hall and public plaza in Tallinn, the beautifully preserved capital of Estonia, are to be placed right between the medieval city walls and the open waters of the Gulf of Finland. After winning an international design competition, BIG architects approached Ramboll to provide the complete engineering services.
Realising complex designs through computer modeling techniques
The design of the building is based on the idea of two-way transparency, which is a prerequisite for participatory democracy. Panoramic windows allow the citizens to see their city at work, and the public servants will be able to look out on their city and its citizens. The town hall consists of a series of boxes appearing to float above the ground. Underneath the buildings there is a public recreational area for citizens to use. The southernmost box is much taller than the rest and echoes the form of the classic gothic town hall spire, thus reflecting Tallinn’s architectural and civic history. Using industry leading computer modeling techniques, we have been able to efficiently and economically model the structure in close collaboration with the architects.
Achieving strict energy consumption targets
The city authorities have set very strict energy consumption targets for the building. The Ramboll design team was asked to ensure that the building meets passive house levels of energy performance – a real challenge when the design of the building has substantial amounts of glazing.
To help achieve the required annual energy consumption target, we have introduced features such as double skin façades and automatic roller blind systems to reduce cooling demands. Water evaporation is used for cooling and the natural low ambient temperatures of Tallinn during summer are used to condition the building. By eliminating refrigeration energy, this enables our design to focus further on enhancing the thermal insulation and achieving low heating demand.
As lighting typically accounts for the majority of the energy consumption in office environments, an intelligent lighting control system linked to an automatic blind system and daylight control enables significant reductions in energy usage.