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IPG Wohlrab, Landeck & Cie.

IPG Wohlrab, Landeck & Cie. counts on Polysun: A reliable overview of all variants at all times for geothermal concepts:

Pictures: ©IPG Wohlrab, Landeck & Cie.

A new construction project is closely linked to the approval of subsidies. Why simulation software is indispensable in conjunction with the use of geothermal energy.

The engineering planning company (IPG) Wohlrab, Landeck & Cie. creates “building concepts for the future”. IPG provides all HOAI services for new buildings, conversions, modernizations, maintenance and repairs, from basic evaluation to project supervision and support. The engineers always pursue one goal: to harmonize quality, sustainability and economic efficiency – which is sometimes not trivial to achieve.

This is particularly true when it comes to sustainable construction. It is virtually impossible to imagine new construction without it, but the investments required for this have reached horrendous heights. Quite apart from the fact that there is a lack of companies that can implement such solutions in a timely manner. In addition, although subsidies are available, the suitability of the construction project must be proven in great detail in order to receive them. In short: IPG relies on Polysun to achieve a result that is pleasing and reliable for all sides. In this way, the company provides valid information and protects clients from unpleasant surprises.

The challenge
The simulation focused on the construction of a new neighborhood and, in concrete terms, the construction of three apartment buildings as the first construction phase. These are to be supplied with renewable energy in order to qualify for subsidies – an essential prerequisite for the project. To this end, preliminary geological investigations were carried out in which geothermal probes were favored for the houses to cover the heating load. A cold local heating network was then to be realized from these probes. In detail: The planned geothermal probes serve as a central heat source with a respective drilling depth of 99 meters, the maximum permissible depth.

The distance between the probes was to be seven meters and the three buildings were to be supplied via a central local heating network at a low temperature level (cold local heating). In addition, the installation of decentralized heat pumps in the individual buildings was planned for space heating by means of underfloor heating and for domestic hot water heating as a fresh water station. “A particular challenge in this planning was that the space for the individual probes was limited from the outset. We always had to take this into account, so that this simulation primarily had the character of a well-founded feasibility study with very different variants,” says Adrian Gebhard, an engineer working for IPG.

After the first test drillings were carried out in close cooperation with the geological teams, the engineer simulated the first variants with Polysun. In the course of this work, Adrian Gebhard quickly realized “that the planned 20 probes would not be enough to fully cover the annual heating energy requirement.” This first preliminary variant immediately gave rise to another important question: how can the annual heating energy requirement for all three buildings still be covered? The following is also important when using probes: if they are laid tightly, the ground gradually cools down over the years. This cooling can be counteracted by regenerating the ground in the summer months with the heat generated by the active cooling of the associated buildings. This was taken into account in the further simulation. The higher the number of probes, the more intensive the regeneration effort must be, which in turn is reflected in the costs.

“We were able to run through countless variants with Polysun, so that we had concrete clarity very early on about what was possible and what was not for this new construction project. This was an indispensable decision-making aid, especially in view of the tight requirements regarding subsidies. This would not have been possible without the simulation,” says expert Gebhard, describing the result.

For example, the regeneration of the probes using a solar thermal system in the form of vacuum tubes was investigated. However, the simulation quickly showed that the costs would exceed the budget. Another variant – flat-plate collectors instead of vacuum tubes – was also outside the possible cost framework.

The yield of the geothermal probes is very limited due to the official regulations on the maximum permissible heat extraction rate. Supplying the property exclusively via just 20 geothermal probes without additional regeneration of the probe field is just as impossible as regeneration via passive cooling alone.

Project cornerstones

At a glance

  • Engineering planning company (IPG) Wohlrab, Landeck & Cie
  • Sector: Service provider (general planner)
  • Location: Aschersleben, Saxony-Anhalt

The challenges

  • Validated proof of funding essential for new construction project
  • Geothermal probes planned – but quantity limited
  • Project requires a reliable range of variants as a feasibility study


Polysun Designer

Result with software Polysun

  • Realization of a wide range of options with reliable information
  • Always keeping an eye on both the cost framework and the planning alternatives
  • Clear proof of feasibility in each case


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