Cooling and heating for the new Festhalle in Bern
First recooling unit is placed on the prepared concrete strips.
A new Festhalle for Bern
What was built as a temporary structure in 1948 has been replaced 75 years later by a modern, new building that was inaugurated at the end of April 2025 as part of the BEA Bern Spring Fair. Covering an area of 9,400 m², the modern building houses two event halls for fairs, conferences, exhibitions and cultural and sporting events, as well as a spacious foyer. The multi-purpose ‘Stage’ hall is as big as two ice hockey pitches and holds up to 9,000 people. The smaller ‘Cube’ event hall provides space for around 2,400 people. At full capacity, there is an enormous amount of waste heat, up to 1,000 kW, that must be safely discharged, especially in summer.
Cooling and heating from a single machine
A custom CTA cooling/heating unit provides reliable air-conditioning all year round. In summer, it works as a chiller to cool the rooms; in winter, it works as an air/water heat pump to provide heat—or a combination of both, as required. The unit can be continually adjusted thanks to a frequency inverter. This means that, in each mode of operation, only the required amount of cooling or heat is produced. The cooling/heating unit has a cooling output of around 1,150 kW and, when operating as an air/water heat pump, produces around 820 kW of heat. It features two compressors as well as two cooling circuits, and its redundant operation offers increased operational safety. The system is controlled by a project-specific programmable logic controller (PLC) integrated into the higher-level control system.
Summer mode principle diagram
Defrosting with no loss of performance
Recooler defrosting is also controlled via this project-specific PLC. In winter, ice forms on the recoolers, decreasing system efficiency. As a result, the recoolers have to be defrosted on a regular basis. Each recooler is defrosted individually, in sequence, so there are three recoolers in operation at all times, meaning no performance is lost.
Meticulously planned installation
Because the new Festhalle does not have a technical centre, the entire heating and cooling system, including hydraulics, proudly weighing in at 18.7 tonnes, is built into the unit. In view of the compact size—the unit is only 13.6 metres long, 2.4 metres wide and 3 metres tall—placing the components and routing the hydraulic lines was an exciting challenge for CTA's engineers. The unit was produced in two separate blocks at the plant in Münsingen, transported to Bern, and assembled on the roof of the Festhalle. Its transportation and installation were meticulously planned, as they had to fit in with the tight construction schedule for the new Festhalle, and the installation date was already set nine months in advance. The lorries carrying the CTA unit and the four recoolers arrived on site exactly on time, and powerful cranes lifted all the components onto the roof of the Festhalle.
The cooling/heating unit CTAexklusiv
1,150 kW cooling capacity / 820 kW heating capacity
Custom-made CTAexklusiv
Zwei Kältekreisläufe mit je einem Schraubenverdichter
Continuous regulation
Natural refrigerant propane R-290
Prefabricated and delivered in two compact sections
The fight against ‘electricity pollution’
As part of the Festhalle project, special attention had to be paid to ensuring a ‘clean’ mains grid. This is because, during fairs and concerts, so-called harmonic oscillations in the mains grid can damage sensitive devices and machines, and lead to power cuts. Chillers regulated using standard frequency inverters can cause such harmonic oscillations. For this reason, a special frequency inverter was installed in the CTA cooling/heating unit; these components are rarely used in such systems. It ensures that the cooling/heating unit generates only low harmonic oscillations in the AC grid.
Natural refrigerant
Propane (R-290), an environmentally friendly refrigerant, is used in the Festhalle Bern. Each of the two cooling circuits requires only 63 kg of refrigerant. This low filling volume and an established safety concept ensure safe operation, even though propane is highly flammable. All refrigerant is contained within the roof unit and is therefore out of the way of public areas. Should any refrigerant unexpectedly leak, detectors will record this and the system will switch off below the explosion limit. An internal ventilator draws fresh air in and releases the air-gas mixture, which is harmless to people and the environment, into the open air.
Regionally anchored
«The fact that everyone involved was from the region and therefore close to the project was valuable for the very constructive and good cooperation.»
In safe hands
CTA service technicians maintain the installed systems at regular intervals to ensure they will continue to operate without issues over the long term. CTA offers its customers a diverse service package: Customers can choose the service that best suits their needs, from standard to flat-rate maintenance to the CTAprotect all-round no-hassle package with a warranty extension of up to 15 years.
Contributors
Planning: Amstein + Walthert AG
Main contractor: HRS Real Estate AG
Chiller and system supplier: CTA AG
