The oldest brewery in the world, the Bayerische Staatsbrauerei Weihenstephan, is gradually investing in the modernization of its brewery on Weihenstephaner Berg in Freising. Most recently, a new brewing cellar was inaugurated after just 1 ½ years of construction.

For the construction of this combined cellar, the company relied on the experts from Kiefer Klimatechnik, who specialize in plant construction in the beverage industry, among other things. For this reason, the Kiefer experts were also involved in the construction of the new brewery cellar at the Weihenstephan brewery. The task was to check the planning, technical boundary conditions and interfaces and to ensure installation, commissioning, maintenance and inspection. There were high demands in terms of hygiene, room humidity and design, as the new brewery cellar will be used for events, customer visits and tastings, among other things.

“Oldest brewery in the world” and ‘oldest still existing brewery in the world’ - the Weihenstephan brewery is rightly proud of its proven tradition and especially of its different types of beer. To ensure that the 1000-year-old art of brewing continues to be successful in the future, the company has drawn up a master plan in collaboration with the Weihenstephan Technical Office, which is now being gradually implemented. In addition to a new logistics center, a new dealcoholization plant and a new filtration system, a new brewing cellar has now also been built. The reasons for this were manifold: due to the increasing demand for bottom-fermented beers such as Helles, Pils or Festbier, especially in summer, the previous cellar had reached its capacity limit. This is because these specialties require lower temperatures and longer fermentation and storage times. As a brewery originally specializing in top-fermented wheat beer, the old tanks were not designed for this, neither in terms of volume nor economically. The relocation of the new logistics center freed up space so that the new cellar could be built directly onto the existing historic buildings.

In July 2024, the brewery celebrated the opening of the new combi cellar. There is now space for a total of 24 beer tanks, of which three small and four large pressure tanks, four combination tanks and one spent yeast tank were installed in the first expansion stage. This will allow the company to react very flexibly to the demand for top and bottom-fermented beers in future. The project was preceded by an extensive one-year planning phase. This was because special requirements had to be taken into account, especially for the air conditioning technology. A beer cellar is a highly sensitive production area in terms of hygiene, with clear specifications regarding temperature, humidity and maximum carbon dioxide levels, hygiene and room air flow. For example, all built-in parts had to be made of stainless steel in order to withstand regular cleaning with acids and alkalis as well as corrosion. In addition to hygiene, heat and moisture dissipation are particularly important. For this, the technical management of the Weihenstephan brewery called in experienced experts in ventilation technology. Kiefer Klimatechnik GmbH from Stuttgart has been planning and implementing modern ventilation and air conditioning systems for over 140 years, specializing in the beverage industry and breweries in particular.

In addition to numerous successful projects at other renowned breweries, Kiefer also impressed with an earlier contract at the Weihenstephan brewery. The Stuttgart-based company successfully took on the planning and implementation of a sorption dehumidification system for an existing storage cellar. “For the new combi-cellar, it was necessary to check the planning, technical boundary conditions and interfaces as well as to ensure installation, commissioning, maintenance and inspection,” reports Thomas Sigle, Head of Plant Construction at Kiefer Klimatechnik. He was responsible for coordinating with the architects and technical management in advance, carried out the inspection and coordinated the subsequent implementation. Various specifications had to be observed during planning: Compliance with a specific humidity window - i.e. a maximum of 70 % relative humidity in the room - had to be ensured in conjunction with the expected surface temperatures of room enclosure surfaces such as the floor, ceiling, walls and parts of the brewing system. “As some of the media pipes with associated installation parts have surface temperatures below 0°C, the amount of condensate on these installations should be largely reduced. One of the ways we achieved this was by distributing the air evenly throughout the room,” continues Sigle.

It was also necessary to limit the relative humidity in the room to prevent mold growth. To achieve this, the dew point temperature had to be limited on the cold building surfaces. Due to partially wet floor surfaces in the basement rooms and the infiltration of outside air with high absolute humidity, dehumidification is therefore a particularly important point. This is ensured by introducing dehumidified outside air. Dehumidification takes place both in the central ventilation unit at high outside air humidities through condensation in the heat recovery unit and in the air cooler of the subsequent after-treatment unit. This allows supply air humidities of 6.1 g/kg to be achieved, corresponding to a dew point temperature of 6.5°C. If operating experience shows that further dehumidification is required, sorption elements can be retrofitted. This allows absolute supply air humidities of 1.8 g/kg corresponding to a dew point of -3°C to be achieved. In addition, the tanks and the system technology are so intelligently piped that leakage of the beer and subsequent splashing is largely avoided.

As carbon dioxide is heavier than air and can easily accumulate in closed rooms or lower-lying areas such as cellars, such an accumulation or even a discharge into other rooms must always be avoided. Even in such cases, the outside air to be supplied is dehumidified and the carbon dioxide produced during fermentation is extracted. In the event of an accident, the outside air flows in directly via the multi-leaf damper integrated in the outer wall.

The brewery often hosts events, guided tours, celebrations and visits from tourists and customers. As beer can also be tapped directly in the new cellar, the room needed to be appropriately illuminated with LED show lighting if required. For this reason, high demands were placed on the design of the system planning and the interior design. For example, the ventilation components had to be visually integrated in such a way that they blended into the room in a visually appealing way. Sigle adds: “That's why we designed the wall-mounted CO2 detection devices and the stainless steel fresh air flow units in close consultation with the architect.”

The fact that the new combi cellar is also ideally suited for large celebrations, as desired, was demonstrated at the inauguration: “Everyone involved in the project was delighted and very satisfied with the result,” says Sigle. This means that beer can continue to be brewed in Weihenstephan at the highest technical level - ideally for another 1000 years.