The Jungfraujoch is one of the biggest tourist attractions in Switzerland, as is the ice palace. Every hour, up to 500 people visit the 1,000-square metre ice grotto. Each person visiting the cave “leaves behind” a heat input of around 100 watts. If 500 people are inside the ice palace, they heat the hall from within with a whopping 50 kW. From the outside, global warming is causing additional problems for the ice palace. Without active cooling, it would start to melt.