Borg (formerly known as Summerheat) develops underground heat storage technology. Water is heated in a high-quality underground vessel, to near the boiling point. When there is a heat demand, it can be drawn directly from this.

The first product will be applied in single-family homes. By storing heat, it becomes possible to match the heat demand to when the energy is available. When the barrel is very large, it is even possible to produce and store such an amount of hot water in the summer with solar collectors which can be used to heat a house all winter. On a smaller scale, shorter periods can be bridged, such as generating during the day and heating all day.

Borg fits in well with ifund’s focus area energy: local energy is generated, stored and used when necessary. The potential impact is particularly high: 40% of the energy consumption in the Netherlands results from our heat demand and 12% of the emissions come from residential heating. The transition to a gasless built environment is high on the agenda of the Dutch government, and with its innovation, Borg offers a solution that can contribute to this transition.

Ifund invested in Borg in 2019. We have played a direct role in the company’s inception as a financier and co-founder, with Stefan van Eijk – ifund’s fund manager – spending part of his time as interim CEO of Borg.