"Interferentie Tool Gesloten Bodemenergiesystemen" - ITGBES.COM, the international version
ITGBES is a tool developed by Groenholland Geo-energiesystemen, originally to assess thermal interference between adjacent individual borehole heat exchangers. It has been in use since 2013 and in 2019 an automated version was developed and made available for free for the Dutch market.
The tool calculates the thermal interactions between borehole heat exchangers. This means the temperature effect on the position of another heat exchanger is calculated as function of annual energy exchange (kWh/year), length of the boreholes and distance between the boreholes The temperature effect on the borehole itself or fluid temperatures are not calculated
The simplified excel tool is based on correlations calculated with the accurate Finire Line Source (FLS) method. The correlations are validated with detailed models and accurate for distances over about 5 meters and a maximum six individual borehole heat exchangers per system. The correlations have been developed for a range of energy demand profiles and soil thermal conductivities.
ITGBES.COM as design aid
In many projects a design of the borehole heat exchanger system fo several (5 - 500) individual houses needs to be made. All these houses can have a different energy demand profile and different borehole heat exchanger layout. Common design tools however only allow design of collective borehole heat exchangers, with one overall energy demand profile, all boreholes of same depth and distance and often specified regular layouts.
Even worse: the boundary condition of equal flow temperatures to all boreholes does not apply, the flow temperature and loading of each borehole is determinded by that particular system. This also means that boreholes with a more central position have more interactions with neighbours than periferal boreholes.
Now, a designer can use ITGBES.COM to calculate the real temperature interactions between boreholes of different systems and use those to adjust the temperture-limit of the individual design (using standard design tools) of that system. In that way all systems in a cluster will get a different, but correct, length depending on their ownn characteristics and on the influence of all neighbouring systems.
Beyond ITGBES.COM : ITGBES-PRO
Due to the accuracy possible with the correlations in the simple excel tool there are a number of limitations. The most important limitation is that a maximum of 10 systems that can be processed. The underlying model (ITGBES-PRO) has the full accuracy of the Finite Line Source model and integrates with a detailed borehole thermal resistance model. With ITGBES-PRO therefore it is possible to:
- Do a fully integrated design of clusters of different borehole heat exchanger systems.
- Optimize energy use of a development by assigning energy budgets to each system,
even before energy demand profiles are known
