A Hint of Gizeh in Lennestadt

Anyone travelling to Gizeh will – not surprisingly – see pyramids. But when travelling to Lennestadt, Germany, in the Sauerland region, nobody would expect it and is therefore truly impressed when they are standing in front of the pyramids. The energetic concept is just as surprising.

The Sauerland pyramids in Lennestadt are situated on a mountain overlooking the town of Meggen and can be seen from afar. It is a place of wonder and amazement, which is accessible to the public, starting in 2010. The area has been named the Galileo Park and exhibitions and presentations are already taking place there. The company RAYONEX is based in three of the seven pyramids.

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“It is not a place for simple, shallow-minded entertainment. It is in fact a place full of sophisticated attractions, intended to awaken the interest in new topics and encourage the mind to reflect on certain aspects,” according to Wolfgang Schmidt, constructor of the pyramids and company owner of RAYONEX and the bore rig manufacturer TRACTO-TECHNIK.

The pyramids are subject to an innovative energy concept. With this in mind, a decision was already made to apply geothermal energy for heating and cooling in the first pyramid, which was built in 2005. One of the reasons for this was the fact that gas was not available in this region at the time and therefore the only alternative would have been oil, but this option was not wanted under any circumstances.

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Additionally TRACTO-TECHNIK had the necessary bore-know-how, so the decision to go for geothermal energy was made very quickly.

To be able to heat the 1,300-m² offices and production areas of the Rayonex pyramids, a total of 15 flat, inclined bores, each of 50 m length (total 900 m) were placed into the mountain using HDD technology and later they were equipped with twin U-sondes. The heating load is 32.6 kW. The heating is direct, which means without the use of heat exchangers by circulating the sole volume from the pyramids into the mountain and vice-versa. As the area is situated on the filled ground of a disused mining site, a special focus during the bore process was set on boring through water leading horizons, as much as possible. This was intended to increase the high extracting and regeneration performance.

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Another bore method was applied to heat and cool the other pyramids. A total of nine vertical bores, each more than 99 m (total of 881 m) were carried out with the vertical bore rig Geodrill 20 V from TRACTO-TECHNIK. After completion, these bores were also equipped with twin U-sondes (diameter 32 mm). A 25 percent monoethyleneglycole mixture was used as the heat transfer medium. To be able to dimension the earth sonde field, the distribution of the sondes was calculated in advance using the “earth energy designer” software. The heating and cooling of the pyramids is steered from the energy supply station, the so-called “energy temple.” The 63 kW heating pump installed here provides a pleasant climate in all the pyramids.

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In the Galileo park, not only the buildings are heated and cooled, but also the 200-m² pond. In this case, the innovative GRD technology was applied. A shaft was installed on the pond’s island, from where 10 bores up to 50-m depths were produced radially. (diameter 114 mm). The compact bore rig only required a small setup surface and hardly causes any surface damage. The bore rig has a great advantage when renewing heating systems in old buildings. Also a study carried out at Siegen University has shown that radial bores are especially energy efficient and only cause minimum running costs.

Water was used as a heat transfer medium inside the coaxial sondes. This is called direct heating and cooling, without adding a heating pump to the whole circuit. The geothermal heating and cooling load is 15 kW.

Furthermore, an animal enclosure, where currently four coatis are living as “watchers” over the pyramids, was connected via a 8 kW air-water heating pump to the ground heater. The Sauerland pyramids are therefore operated with horizontal, vertical and radially installed geothermal sondes, as well as with an air-water heating pump. The following table gives an overview of the size, power and costs of the single sonde fields and the air-water costs.

Sonde field

Area to be heated

Heat or cooling load




Oil only heating

Gas only heating

Power heating and cooling WP


Horizontal bores RAYONEX pyramids

1300 m².

32,6 kW


7500 €

8670 €

3100 €


Vertical bores Galileo-Park pyramids

1400 m²

63 kW


6900 €

7950 €

4290 €


GRD Slanted bore technology Pond set-up

200 m²

15 kW


3500 €

3950 €

450 €


Air – Water WP Animal enclosure

130 m²

8 kW


2250 €

2600 €

850 €

This article was submitted by TRACTO-TECHNIK, which is based in Lennestadt, Germany.

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