Valsana’s game changing ice battery

For more than ten years, the Tschuggen Collection has been actively committed to preserving the natural environment. To date, the Collection has reduced its total fossil fuel consumption by almost 90%. In addition, 100% of the electricity used is eco-certified. A particular milestone in this commitment is the Valsana Hotel in Arosa.

Since its construction in 2017, the entire hotel complex – including the adjoining shops and residential building – has operated at 1,800 metres above sea level without the use of fossil or other fuels. At the heart of the complex is its pioneering ice battery.

What makes looking after the ice battery so demanding?

A large part of my work involves monitoring the heat recovery systems and the ice battery. Several different technical systems work together throughout the hotel, so it is important to monitor the individual components continuously and keep optimising them.

Where does the recovered heat come from?

There are many sources of heat within the hotel that we can make use of. A large proportion of the waste heat is recovered from waste water. This comes, for example, from the showers, spa, laundry and kitchen, and has an average temperature of around 15 to 22°C. After the heat has been recovered, the temperature of the waste water can fall to as low as 4°C before it flows into the sewage system.

The supermarket on the ground floor also operates numerous refrigerators and refrigerated display cabinets. In addition, the refrigeration systems in the hotel kitchen generate waste heat. This energy is also fed into the ice battery.

In summer, the system can also be used to cool parts of the hotel, including the restaurant and kitchen, helping to create a comfortable indoor climate.

How does the ice battery work?

All the heat required for the three buildings is generated using the hotel’s own waste heat and geothermal probes. This energy is fed into a large latent heat storage unit – the ice battery. The heat pumps draw their energy directly from this storage unit, which can be thought of as a large water tank.

The tank holds 860,000 litres of water. Inside it are more than 400 metres of pipework, around 1.5 metres high, through which a water-glycol mixture flows. These pipes are connected to the heat pump circuit.

When the heat pumps extract large amounts of energy, the water surrounding the pipes can freeze, forming a block of ice. To thaw the ice again, waste heat from the heat recovery systems is fed back into the water tank. If more waste heat is available than energy is being extracted, the ice melts and the water can warm to as much as 15°C. This heat can then be used again.

Could the same principle be used in everyday life?

In principle, yes. If we all had an ice battery in the basement, although that is still very much a vision for the future, we could reuse some of the heat generated in our everyday lives. Washing, cooking and showering all produce heat that would otherwise often go unused.

What is the most exciting part of your job?

For me, the most exciting part is continuously monitoring and improving the system. Even with such a complex system, there are always opportunities for further optimisation. We are constantly asking ourselves: Where can we recover more heat? How can we use the available energy even more efficiently? It is very rewarding to see how these improvements can continuously enhance the building’s energy performance.

What kind of interest does the system attract?

There is something special about working with a system like this. Comparable solutions are still not very widespread, and that is something we are proud of.

Universities and companies regularly visit us to learn more about the system and how it works. We are delighted by the level of interest and are always happy to share our experience and knowledge. For example, I have already been in contact with a member of staff from the castle of the Prince of Liechtenstein, as well as with the Arosa Academy.