A closed loop heat pump will be integrated in the tunnel dryer at the production site of Wienerberger in Uttendorf, Austria. It is a continuous dryer, where the shaped clay products (green bricks) with a moisture content of around 30% are dried to 2-4%, which is the maximum moisture that is allowed in the firing process in the kiln. In the tunnel dryer, bricks are dried in a counter-current flow of air. Drying air is heated by heat exchanger surfaces, which are supplied with hot water from a heat recovery cycle and are located inside the tunnel. The heat pump will also use the heat recovery cycle as the heat source. The heat pump will provide hot water up to 160°C to heat the drying air. The hot air is fed into the outlet zone of the tunnel dryer, where the highest temperatures are required. The heat pump will act as a booster for the heat recovery cycle. The heating capacity of the demonstrator will be around 400 kW. Compared to the natural gas burner that is currently used, about 79% of the CO2 emissions and 84% of the end energy consumption can be avoided due to the heat pump.