Within a research project that started in 2005, four case studies for medium sized companies located around Kassel (Germany) were carried out to analyse the suitability of implementing solar heating systems for process heat generation. Specific and overall heat consumption and temperature ranges were estimated or measured and transient needs of the heat supply systems were analysed, with focus on existing stores and hydraulics, used fluids (e. g. steam cycles) and possibilities for heat recovery installations [7]. The Hutt brewery in Kassel is one of the investigated companies. It was founded in the 1750’s and has a current staff of about 60 employees today. The brewery produces approximately 80,000 hl of beer per year and has an annual final energy consumption of 6.5 GWh. More than 80% of the energy is supplied by natural gas and used to provide process heat, hot water and space heating. All heat consumers are connected to a steam network that is fed by a boiler (P = 2.6 MW*). The production process is operated in one shift on five days per week. During summer, the amount of produced beer increases by a factor of 1.3 compared to the winter period. Based on their production capacity, technical installations and energy consumption, the Hutt brewery is a representative example for a typical SME in the brewing sector. The continuous development over the last decades with structural alterations and technological changes led to a non-optimised combination of production sites, installations and energy supply. Thus, energy efficiency measures of different complexity can be realised within several sections of the production process.

Independent from the specific characteristic of a brewery, the production of beer can be divided into three parts: brewing, fermentation/storage and filling of bottles, kegs or cans. Figure 1 shows the simplified scheme of the production process at the Hutt brewery. In the beginning, the wort is produced within the brewhouse by mashing, lautering and boiling. After cooling the wort, it is stored in the fermenting cellar. Once fermented, the beer is filled into bottles and kegs. Within the production process, the brewhouse has a share of 40..50% of the overall heat consumption. The bottle and keg filling hall, with the bottle washing machine as biggest consumer, requires about 20..30% of total heat demand [8]. Besides a small amount of hot water for filtration, there is no significant heat demand within the process step fermentation and storage. However, this part is characterised by high electricity demand for cooling.