A frugal place to unwind

17.09.2015
In the Goona mountain restaurant you can relax at the fire­side after a day on the slopes. Still, it is worth to give a second thought at how the energy consumed up in the mountains has been generated. (Photo: Fortner ­Speichertechnik)
In the Goona mountain restaurant you can relax at the fire­side after a day on the slopes. Still, it is worth to give a second thought at how the energy consumed up in the mountains has been generated. (Photo: Fortner ­Speichertechnik)

The mountain restaurant Goona needs to draw 450 kWh of energy every day to supply its guests with good food in a cosy dining room. To cover that demand, it taps into three environment-friendly sources: the power of the sun, the fire of a wood-burning stove, and the waste heat from a refrigeration system. The three complement each other perfectly.

The mountain restaurant Goona paints a vivid picture in figures of its daily energy consumption. Dining room, kitchen, cold storage and sanitary facilities need as much energy as it takes to cook 2,750 servings of noodles, transport 86 skiers a day on a ski lift, or wax 1,833 pairs of skis. But the best part is that the restaurant, which is nestled directly beside the summit station of the Palüd cable car in the Brand skiing region of the Austrian federal state of Vorarlberg, generates all of its energy from ­renewable sources.

On the south side of the building, solar collectors with a surface area of 23.8 m² provide hot water. Above the solar collectors are 70 m² of hybrid collectors that supply both power and solar heat. Another 35 m² of solar hybrids occupy the east facade of the building. In the dining room a 31 kW water-fed wood stove can be stoked up. The stove can pump 25 kW of heat into the heating circuit through a heat ex­changer. A refrigeration system and a 46 kW hot ­water heat pump complement the energy supply for the ski lodge on its 1,600 m high perch.

More energy than needed

Together, the various systems can produce more energy than the restaurant consumes in the winter season. “With the wood stove, the Goona is fully auto­nomous in the winter season,” says Werner ­Neuhauser, Sales Manager of the Austrian company Forstner Speichertechnik, which provided the heat storage and recovery system. The amount of wood burned can be adapted to the daily conditions

as needed. The solar thermal system delivers 62,773 kWh of heat yield per year, says Neuhauser, and the heat recovery system adds a further 32,265 kWh. The heat pump contributes 6,980 kWh and the wood stove 27,750 kWh. The lodge is also aiming at energy independence for the summer season.

When skiers enjoy the sun terrace in fine weather, the ­solar energy system also reaches its highpoint. (Photo: Fortner ­Speichertechnik)

It all comes together in the stratified tank

As skiers wend their way to the various lift stations of the Brandnertal ski area, the alpine heat generators feed their energy into an array of tanks. Depending on the temperature, the solar and hybrid collectors feed their heat either directly to a 1,500 l stratified combi-tank or one of two 4,160 l buffer storage tanks. The excess heat from the wood stove and the ­refrigeration system can be transferred from the ­combi-storage tank into the big tanks for later use. A bus controller connects all the parts of the system to ensure that everything flows properly and the various components work together.

On the slopes, the lift moves skiers to their destinations on the mountain. At the Goona, the combi-tank distributes the hot water to the kitchen sinks, the lavatories and the rooms. The ventilation system, a high-temperature heating system in the restaurant and kitchen as well as under floor heating in the ­restaurant, the kitchen and in the basement are all supplied separately from the buffer tank. The water-water heat pump plays a special part in the system. It can raise the energy from the buffer tank to the required temperature and transfer it to the central heating unit. It taps into the temperature level of the large buffer tanks that is in the range of the return-line temperature of the heating system, some 25 ° C, which is no longer usable. In this manner, the storage tanks can be cooled down to 6 °C, leaving another 19 K to be used.

Lounge and sun terrace provide energy

Ecology and sustainability are guiding principles for the energy supply in the mountain lodge, but they ­also come into play in other aspects of the building. Designers have used wood to make the building’s ­superstructure from a renewable raw material. The optimally insulated building is thus fitted with a wooden cladding that harmonises with its surroundings. Inside, the wood creates a cosy atmosphere. The wood stove in the dining room not only creates luxurious warmth, but its open hearth makes the lounge, with its comfortable chairs, a comfortable space. The stove thus offers a triple benefit: it creates atmosphere, warms the guests, and reheats the ­combi-tank.

When the weather is fine in the mountains, the Goona welcomes guests in greater numbers. The more guests come, the more energy consumption ­rises. The amount of sunshine and increased need for hot water thus rise in tandem. This is a good precondition for using the solar radiation in collectors. When the restaurant guests enjoy the warming rays and the panoramic views from the 500 m² sun terrace, the ­Solator collectors provided by Austrian company C. Bösch are hard at work, delivering high-temperature heat to the storage tanks.

The hot-water heat pump feeds its energy, like the other heat sources, into a combi-tank. (Photo: Fortner ­Speichertechnik)

Refrigeration system provides heat

A bit less spirited, but no less useful, the Solator hybrid collectors also integrated into the facade of the terrace do their part as well. The waste heat from the solar cells with their low temperatures can be used ­either directly for the floor heating system or as a source of energy for the heat pump. Hybrid collectors are considered an innovative way of boosting the efficiency of conventional photovoltaic modules because they recover heat that normally goes unused. As temperatures rise, the output of solar modules declines. Hybrid collectors use this heat, thus cooling the cells. Solator does this with a heat-transfer fluid flowing through flat metal tubes mounted on the back of the photovoltaic modules.

In addition, the hybrid collectors make it possible to use a heat pump, since bore holes for ground-source heat pumps are prohibited in the mountains. “And for an air heat pump, it is just too cold at this ­elevation in the winter,” says the Forstner employee Neuhauser. The photovoltaic part of the hybrid collectors also provides more power than is needed to ­operate the heat pump, which means that there is enough solar power left over to drive a refrigeration system.

The system draws heat out of the refrigerated goods. To avoid simply discharging the heat into the environment, where it serves no purpose and is lost, Forstner has developed the Frionic heat recovery system. On its way to an external condenser, the refrigerant in the cooling system flows first through a special 560 l heat storage tank, where it is condensed in a separate refrigerant exchanger, heating up the contents of the tank. The Frionic tank is connected to the central combi-tank. The concept has been well received. The Skiarea Test team, which has been evaluating ski resorts around the world for more than 18 years, selected the Goona as the most popular mountain restaurant of winter 2013/14.

Joachim Berner