The current climate debate has given extra impetus to the use of ground heat because it makes particularly sustainable heating and cooling possible for large and small energy consumers. The concept is simple – the deeper the borehole, the higher the temperature. However, the forces acting on the probe also increase with depth. With its «hipress» borehole heat exchanger, Jansen AG has developed an innovative system solution capable of operating at up to 500 metres below ground. The probe, which was launched on the market in 2018, has already become a firm fixture in the industry and 
proven successful in various projects. These include, for example, an apartment building that called for a heat pump solution with borehole heat exchangers requiring 
the minimum area for installation and offering operating cost savings. 

This reference project confirmed the system’s ease of installation and operating cost savings

Deeper borehole heat exchangers are necessary where a high energy demand has to be covered and there is relatively little available space. This is the situation, for example, when refurbishing the heating systems of large residential  developments. A case in point was the reference project «Chemin des Grottes» in Fribourg, the capital of the canton of the same name in western Switzerland. 

A heat pump solution using borehole heat exchangers was required for an ageing apartment building with an attached low-rise multi-storey residential block. The only area accessible by normal plant and machinery stood between the apartment building and an access road, but it was not much bigger than the length of two drilling machines. Various options were investigated, and a number of different ground loop technologies compared. The final choice fell upon the JANSEN hipress, the variant with the special 42 x 3.5 mm heat exchanger pipes, due to its ease of installation and excellent reliability. The design was based on three 300 metre probes. On the tightest of sites, contractor Broder AG drilled the three heat exchanger boreholes with a diameter of just less than 130 mm to the specified 300 metre depth. The borehole heat exchangers were lowered to the bottom of the holes using hydraulically braked reels.