Lake water for luxury hotel
A world-class luxury hotel recently opened on top of Mount Bürgenberg in Switzerland: the new Bürgenstock Resort. Switzerland’s largest hotel facility is heated and cooled with energy from Lake Lucerne, with approximately 300 m3 of water per hour pumped up the mountain.
Tourism has a long tradition in the Lake Lucerne region of Central Switzerland. The first hotel was built on Mount Bürgenstock in 1873, and over the following decades the mountain became a destination for gastronomy and tourism. In its heyday from the nineteen-fifties to the ninteen-eighties, prominent figures from the world of politics, business and society discovered the Bürgenstock Resort for themselves. Ownership changed hands several times around the turn of the millennium, until in 2008 Katara Hospitality Switzerland AG, a subsidiary of the Qatar Investment Authority, took over the hotels and numerous other buildings. Led by Managing Director Bruno H. Schöpfer, the company planned and realized the new resort.
The new owners have invested nearly 550 million Swiss francs, creating a resort with four hotels ranging between three to five stars superior, a total of 383 rooms and suites and a 10,000 m2 alpine spa. The conference center offers 2,200 m2 of space for more than 800 guests, including 31 meeting rooms and a ballroom for 600. The resort also features two indoor tennis centers that can be converted into event venues for 500 guests each.
Eight restaurants, a 9-hole golf course, a funicular, a movie theater and various retail stores offer visitors, conference attendees and foreign guests ample opportunities to linger. Nearly 800 persons will one day work at the Bürgenstock Resort. The latest building, „Waldhotel Health & Medical Excellence“, was inaugurated in December 2017.
Energy from the lake
To ensure the energy supply can keep pace with the facility’s expansion and modernization, a new power station was built to serve as the heart of the resort. It combines nearly 130 years of tradition with the latest technology. Just as in 1888, the water from Lake Lucerne is captured outside the village of Kehrsiten and pumped up Mount Bürgenstock. Back then, this was done to supply drinking water; today it supplies energy to the resort. The basic concept is simple: Heat pumps extract the energy from the lake water, which is then used to heat the buildings.
New powerful pumps convey 78 liters of water per second up the mountain, an elevation difference of 500 meters. The old freshwater reservoir on top of Mount Bürgenberg is used as a storage basin; from there water is pumped into the power station. Heat pumps with 1.3 MW peak power heat the water in the system to 45 to 55°C, depending on the outside temperature. The water is then distributed to the various buildings and used either for direct heating or as a source of energy for the buildings’ heat pumps, which heat the domestic water to 65°C. There is a good reason for this two-stage system: If the water were transported at 65°C, the energy loss would be substantially higher than at 45 to 55°C, and the coefficient of performance (COP) of the heat pumps would be considerably lower. For cooling, the lake water is used directly. The water temperature 37 meters below the lake’s surface is a chilly 5 to 7 °C throughout the year, so the lake water covers 70 to 90 percent of the heating requirements and all of the cooling. The water used is redirected back into the lake. It flows through a turbine, which recovers some of the energy. This energy is then used to pump the water up the mountain.
Safety is no longer guaranteed if somewhere a gate valve is defective, a pipe bursts or excess pressure builds up. That’s why we constantly collect data at all the crucial locations.Thomas Guebey, overall head of Siemens projects at the Bürgenstock Resort
Comprehensive building automation
The power station is controlled using systems from Siemens. Thomas Guebey, head of the customer service team and overall head of Siemens projects at the Bürgenstock Resort, reports: “The project was enormous. The safety and security of people and assets topped the list of priorities, along with uninterruptible supply.” The water from the lake travels in a nearly closed system; water is removed only to irrigate the green areas. “Safety is no longer guaranteed if somewhere a gate valve is defective, a pipe bursts or excess pressure builds up. That’s why we constantly collect data at all the crucial locations.” This data is compiled and recorded by the Desigo CC building management platform. “If the values are not right, the Siemens system automatically switches off and notifies the personnel in charge,” explains Guebey.
But Desigo CC manages, monitors and visualizes not only the heating and cooling. “The ventilation equipment, sanitation systems, room automation and area security are integrated as well,” continues Guebey. Desigo CC receives error messages from the electrical systems and measurement data from the energy supply system, and issues high-level commands to the shading and lighting systems. Sinamics variable speed drives from Siemens contribute to demand-based and ecological operation of the building systems and, in conjunction with other disciplines, provide just the right amount of heating, cooling and ventilation. Thanks to the uniform system structure, the individual components are perfectly coordinated and easy and intuitive to operate via Desigo CC. Site security is provided by Siemens video surveillance systems. “Thanks to this single-source solution, the inventory of spare parts can be kept at a minimum,” states Guebey.
The power station has been in operation for nearly two years. The station’s dedicated building also houses the control center and the associated computer rooms. “Our initial experience has been excellent,” says Guebey. “Since the power station was commissioned in January 2016, the technical services team has needed to address only a few growing pains.” Most of them were false error messages from the controls or defective gate valves that needed replacing. Everything has run virtually error-free since February 2016. Now the buildings are being gradually hooked up. The power station has yet to be tested under a full load; even during the very cold January of 2017 it ran at only about one-fifth of maximum.
Picture credits: Bürgenstock Hotels AG; Siemens
Numerous Siemens products were installed for building management in the Bürgenstock Resort. In the 20 connected buildings, there are 60 control cabinets. Sinamics G120 variable speed drives provide for demand-based operation. Decentralized Desigo PX automation stations control the primary systems such as heating, cooling and ventilation; the room automation in the suites is operated through the Siemens Total Room Automation (TRA) solution.
The Desigo CC building management platform collects and visualizes data for the entire resort, forwards information on the state of the entire system and features intuitive operation. Desigo CC thus reduces the workload for the operators and provides critical information for making informed decisions regarding operation and optimization.
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