{"id":5407,"date":"2026-09-29T10:02:00","date_gmt":"2026-09-29T08:02:00","guid":{"rendered":"https:\/\/ghetool.eu\/?post_type=course&#038;p=5407"},"modified":"2026-10-05T16:33:41","modified_gmt":"2026-10-05T14:33:41","slug":"interference","status":"publish","type":"course","link":"https:\/\/ghetool.eu\/fr_fr\/course\/interference\/","title":{"rendered":"Interf\u00e9rence"},"content":{"rendered":"\n<p class=\"wp-block-paragraph\">When you are designing borefields, the implicit assumption is always that your project is insolated and that the ground temperature is not influenced by any neighbouring system. While this can be true in some cases, in others the so-called thermal interference between different geothermal systems can be quite significant. In this chapter the concept of interference will be discussed, together with some calculation methods and how GHEtool Cloud can be used to quantify it.<\/p>\n\n\n\n\n\n\n\n\n\n\n\n<iframe title=\"Chapitre 8.2 : Interf\u00e9rence\" width=\"800\" height=\"450\" src=\"https:\/\/www.youtube.com\/embed\/k5ntZGEMQ78?feature=oembed\" frameborder=\"0\" allow=\"accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share\" referrerpolicy=\"strict-origin-when-cross-origin\" allowfullscreen><\/iframe>\n\n\n\n\n\n\n\n<h2 class=\"wp-block-heading\">What is interference?<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">A geothermal borefield is a ground heat exchanger and thereby influences the ground temperature directly. In winter, heat is extracted and the ground cools down, whereas in summer the ground is heated up again. The difference between the heat extraction and injection is the imbalance, which causes the ground temperature to drift over the years. However, this temperature drift does not stop at the edge of the borefield or the property, but travels through the ground and can easily be seen at 50 to 100 m depending on the ground properties.<\/p>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-large\"><img fetchpriority=\"high\" decoding=\"async\" width=\"940\" height=\"662\" src=\"https:\/\/ghetool.eu\/wp-content\/uploads\/2026\/09\/Interference-1.svg\" alt=\"Graphical representation of the thermal interference between different neighbouring geothermal borefields.\" class=\"wp-image-5410\"\/><figcaption class=\"wp-element-caption\">Graphical representation of the thermal interference between different neighbouring geothermal borefields.<\/figcaption><\/figure>\n<\/div>\n\n\n<p class=\"wp-block-paragraph\">In the illustration above, a new project is being considered between four already existing geothermal systems. Typically, the required design information for this project (building demand, type of fluid, ground properties etc.) is entered in GHEtool to find the required borehole depth (<a href=\"https:\/\/ghetool.eu\/course\/calculate-required-borehole-depth\">Part 7.2<\/a>) or borefield size (<a href=\"https:\/\/ghetool.eu\/course\/calculate-required-borefield-size-and-depth\/\">Part 7.3<\/a>) where the fluid temperatures stay within the predefined limit.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">This approach silently assumes that the new geothermal borefield is insulated from the environment and that the surrounding ground is only influenced by itself and not by another neighbouring system. However, in the case above, it is clear that the project falls within the influence of both bottom systems, which will cool down our borefield as well over the years.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">This implies that, when these neighbouring systems are not accounted for in our design, our minimum (or maximum) fluid temperatures will be different from the ones intended in the design. To overcome this issue, it is important to consider the thermal influence when designing a geothermal project.<\/p>\n\n\n\n<div class=\"note\"><p>With ground-source heat pumps gaining more and more interest, some countries started developing legislation to tackle this interference problem. Most notably, in the Netherlands, the maximum interference there can be on a single system is -1.5\u00b0C. When the interference is more than this, the design should be altered to make sure that the final fluid temperatures stay above -3\u00b0C borefield inlet temperature including interference.<\/p><p>In Switzerland, the SIA standard goes one step further and requires the borefield designer to consider future geothermal systems in the neighbourhood. When the imbalance is too big, regeneration of the borefield is proposed as a solution.<\/p> <p>The interference calculation in GHEtool Cloud is in line with the legislation in these countries.<\/p><\/div>\n\n\n\n<h2 class=\"wp-block-heading\">Model interference<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">There are different ways to model thermal interference, but most often either the infinite line source (ILS) or finite line source (FLS) solution is used, which is also used to calculate the g-functions of each borefield (see <a href=\"https:\/\/ghetool.eu\/course\/long-term-effects-g-functions\/\">Part 2.3<\/a>). Both approaches are implemented in GHEtool Cloud and are explained below, first for the case of the interaction between single boreholes and afterwards for the interaction between two different borefields with multiple boreholes.<\/p>\n\n\n\n<h4 class=\"wp-block-heading\">Infinite line source<\/h4>\n\n\n\n<p class=\"wp-block-paragraph\">The infinite line source model assumes that the borehole is an infinitely long line, which is a reasonable assumption for deep boreholes and for neighbouring systems that are sufficiently far apart. The main advantage of working with this infinite line is that it reduces the three-dimensional heat diffusion problem to a reasonably simple 1D problem, since there are no axial effects along the borehole and the heat transfer is symmetrical as shown below.<\/p>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-medium\"><img decoding=\"async\" width=\"293\" height=\"300\" src=\"https:\/\/ghetool.eu\/wp-content\/uploads\/2025\/09\/Infinite-line-source-model-293x300.png\" alt=\"Infinite line source model.\" class=\"wp-image-4245\" srcset=\"https:\/\/ghetool.eu\/wp-content\/uploads\/2025\/09\/Infinite-line-source-model-293x300.png 293w, https:\/\/ghetool.eu\/wp-content\/uploads\/2025\/09\/Infinite-line-source-model-1000x1024.png 1000w, https:\/\/ghetool.eu\/wp-content\/uploads\/2025\/09\/Infinite-line-source-model-768x787.png 768w, https:\/\/ghetool.eu\/wp-content\/uploads\/2025\/09\/Infinite-line-source-model-12x12.png 12w, https:\/\/ghetool.eu\/wp-content\/uploads\/2025\/09\/Infinite-line-source-model.png 1184w\" sizes=\"(max-width: 293px) 100vw, 293px\" \/><figcaption class=\"wp-element-caption\">2D representation of the infinite line source model.<\/figcaption><\/figure>\n<\/div>\n\n\n<p class=\"wp-block-paragraph\">The temperature effect at a distance $r$ from the borehole and at a time $t$ can be expressed as:<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">$$\\Delta T(r,t) = \\frac{\\dot{q}}{4\\pi k_s}\\cdot E_i \\left(\\frac{r^2c_v}{4k_s t} \\right)$$<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">where:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>$r$ is the distance from the emitting borehole in (m)<\/li>\n\n\n\n<li>$t$ is the time in (s)<\/li>\n\n\n\n<li>$\\dot{q}$ is the average specific heat extraction caused by the imbalance in (W\/m)<\/li>\n\n\n\n<li>$E_i$ is the exponential integral function<\/li>\n\n\n\n<li>$k_s$ is the ground thermal conductivity in (W\/(mK))<\/li>\n\n\n\n<li>$c_v$ is the volumetric heat capacity of the ground in (J\/(m\u00b3K))<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">Based on the equation above, it is clear that thermal interference decreases quickly with increasing distance and that the effect increases over time.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Finite line source<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">The finite line source (FLS), as the name suggests, takes into account the actual depth of the borehole and is therefore better suited for accurate calculations of thermal interference when boreholes are close to each other or have significantly different depths. This is because now the problem stays three-dimensional and the heat transfer across the borehole length can be considered more accurately leading to smaller interferences.<\/p>\n\n\n\n<div class=\"advanced\">The mathematics behind the finite line source is far more complex and is governed by the equation below. For further information, the reader is referred to the scientific literature on the topic, such as Cimmino and Bernier (2014).\n\n$$\\Delta T_{1\\rightarrow2}=\\frac{q_1}{2\\pi\\lambda}\\cdot\\frac{1}{2H_2}\\int\\limits_{\\frac{1}{\\sqrt{\\frac{4\\lambda}{V}t}}}^\\infty e^{-d^{2}_{12} s^2}\\left(I_{real}(s)+I_{imag}(s) \\right)ds$$<\/div>\n\n\n\n<p class=\"wp-block-paragraph\">The difference between the two models can be clearly illustrated with the following example. Imagine two boreholes, one 100 m deep and the other 150 m deep, each with a specific heat extraction of 10 W\/m. Using the ILS assumption, the thermal interference from borehole 1 to borehole 2 is the same as the interference from borehole 2 to borehole 1, since their specific heat extractions are identical.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">With the finite line source, the result is different. In this case the interference from the longer borehole to the shorter one is greater than the other way round. This is because the shallower borehole impacts the ground up to a depth of 100 m leaving 50 m of the other borehole less impacted, leading to an overall lower interference in that case.<\/p>\n\n\n\n<div class=\"advanced\">The purely mathematical explanation of the different insights and differences between the interference methods is beyond the scope of this course. The reader is referred to the work of Peere and Cimmino (2026) for more background information.<\/div>\n\n\n\n<h3 class=\"wp-block-heading\">Interference between two borefields<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">The models above describe the thermal interference between two single boreholes, so these methods should be extended to work with the interference between a borehole and a borefield or two borefields. Imagine, for example, the case below of a residential project consisting of three apartment buildings, each with its own collective borefield. Since the borefields are quite close together, it should be clear that they should have a significant impact on each other.<\/p>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-full\"><img decoding=\"async\" width=\"498\" height=\"364\" src=\"https:\/\/ghetool.eu\/wp-content\/uploads\/2026\/03\/Project.png\" alt=\"Residential projects with three separate borefields.\" class=\"wp-image-4852\" srcset=\"https:\/\/ghetool.eu\/wp-content\/uploads\/2026\/03\/Project.png 498w, https:\/\/ghetool.eu\/wp-content\/uploads\/2026\/03\/Project-300x219.png 300w, https:\/\/ghetool.eu\/wp-content\/uploads\/2026\/03\/Project-16x12.png 16w\" sizes=\"(max-width: 498px) 100vw, 498px\" \/><figcaption class=\"wp-element-caption\">Residential projects with three separate borefields.<\/figcaption><\/figure>\n<\/div>\n\n\n<div class=\"note\"><p>According to the research of Groenholland (2020), borefields up to six boreholes can be represented by a single borehole located at the geometric centre of the borefield. This fictitious borehole will take care of the entire heat transfer of the borefield and should have a borehole depth that is the average of all the borehole depths in the field.<\/p><p>This simplification is also implemented in GHEtool Cloud. By setting the (x,y) coordinate to the geometric centre and the <strong>borehole length<\/strong> to a multiple of the <strong>borehole depth<\/strong>, the software will calculate using this assumption.<\/p><\/div>\n\n\n\n<h4 class=\"wp-block-heading\">Equal energy exchange<\/h4>\n\n\n\n<p class=\"wp-block-paragraph\">One initial thought might be to distribute the total imbalance of the system over the different boreholes in the field. That way, we know what the specific heat exchange of each borehole will be, and we can simply work with the borehole-to-borehole interference methods from before and sum the results of the different boreholes afterwards. However, this assumes that all the boreholes in the borefield have the same contribution to the heat transfer, which is not the case. Therefore, a more accurate model is implemented in GHEtool.<\/p>\n\n\n\n<h4 class=\"wp-block-heading\">Different borehole contributions<\/h4>\n\n\n\n<p class=\"wp-block-paragraph\">Not every borehole in the borefield has the same contribution to the heat transfer of the entire field. Imagine a square borefield of 10&#215;10 boreholes below. It should be clear that the boreholes at the edge exchange more energy with the environment than the ones trapped in the middle. This implies that, when considering the thermal interference between pairs of boreholes, this difference should be accounted for.<\/p>\n\n\n\n<div class=\"caution\">This also illustrates why it is not a good idea to distribute the imbalance equally across all boreholes, since you are overestimating the contribution of the inner boreholes and underestimating the outer ones. Since the outer boreholes are closer to your neighbouring systems, assuming an equal distribution of the imbalance can lead to a significant underestimation of the interference for bigger borefields.<\/div>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"700\" height=\"600\" src=\"https:\/\/ghetool.eu\/wp-content\/uploads\/2026\/09\/Figure_1.png\" alt=\"Contributions of the different boreholes to the overall heat transfer of the borefield.\" class=\"wp-image-5413\" srcset=\"https:\/\/ghetool.eu\/wp-content\/uploads\/2026\/09\/Figure_1.png 700w, https:\/\/ghetool.eu\/wp-content\/uploads\/2026\/09\/Figure_1-300x257.png 300w, https:\/\/ghetool.eu\/wp-content\/uploads\/2026\/09\/Figure_1-14x12.png 14w\" sizes=\"(max-width: 700px) 100vw, 700px\" \/><figcaption class=\"wp-element-caption\">Contributions of the different boreholes to the overall heat transfer of the borefield.<\/figcaption><\/figure>\n<\/div>\n\n\n<p class=\"wp-block-paragraph\">Therefore, in order to calculate the final borefield-to-borefield interference, a new four-step approach is used:<\/p>\n\n\n\n<ol class=\"wp-block-list\">\n<li>Calculate the g-function of each borefield. (This step is identical to every borefield simulation.)<\/li>\n\n\n\n<li>Calculate the contribution of each borehole to the collective heat transfer.<\/li>\n\n\n\n<li>Distribute the imbalance between the different boreholes, weighted by each contribution.<\/li>\n\n\n\n<li>Calculate the interference between the borefields, based on the weighted sum of all their borehole-to-borehole interactions.<\/li>\n<\/ol>\n\n\n\n<div class=\"advanced\"><p>Another way of visualising the different contributions in the borefield is by looking at the normalised heat extraction (or equivalent heat injection) rate for the different boreholes. This is shown below.<\/p><figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"768\" src=\"https:\/\/ghetool.eu\/wp-content\/uploads\/2026\/09\/Heat-extraction-10x10-1-1024x768.png\" alt=\"Normalised heat extraction rate for different boreholes in the 10x10 borefield.\" class=\"wp-image-5414\" srcset=\"https:\/\/ghetool.eu\/wp-content\/uploads\/2026\/09\/Heat-extraction-10x10-1-1024x768.png 1024w, https:\/\/ghetool.eu\/wp-content\/uploads\/2026\/09\/Heat-extraction-10x10-1-300x225.png 300w, https:\/\/ghetool.eu\/wp-content\/uploads\/2026\/09\/Heat-extraction-10x10-1-768x576.png 768w, https:\/\/ghetool.eu\/wp-content\/uploads\/2026\/09\/Heat-extraction-10x10-1-1536x1152.png 1536w, https:\/\/ghetool.eu\/wp-content\/uploads\/2026\/09\/Heat-extraction-10x10-1-2048x1536.png 2048w, https:\/\/ghetool.eu\/wp-content\/uploads\/2026\/09\/Heat-extraction-10x10-1-16x12.png 16w\" sizes=\"(max-width: 1024px) 100vw, 1024px\" \/><figcaption class=\"wp-element-caption\">Normalised heat extraction rate for different boreholes in the 10&#215;10 borefield.<\/figcaption><\/figure><p>Here, it is clearly visible that the boreholes closer to the edge of the borefield have a higher contribution to the heat transfer than the inner ones. It is also clear that the heat transfer is greater towards the top and the bottom of the borefield. This is exactly the effect of using the more accurate FLS assumption.<\/p><p>The graph above was created using the uniform borehole wall temperature assumption. For more information, the reader is referred to Peere and Cimmino (2026).<\/p><\/div>\n\n\n\n<p class=\"wp-block-paragraph\">Let us now consider how the interference can be calculated in GHEtool Cloud.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Interference in GHEtool<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">Below, the different input parameters for the interference calculation are discussed.<\/p>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"286\" src=\"https:\/\/ghetool.eu\/wp-content\/uploads\/2026\/09\/Printscreen-1024x286.png\" alt=\"Print screen of the general settings of the interference calculation.\" class=\"wp-image-5415\" srcset=\"https:\/\/ghetool.eu\/wp-content\/uploads\/2026\/09\/Printscreen-1024x286.png 1024w, https:\/\/ghetool.eu\/wp-content\/uploads\/2026\/09\/Printscreen-300x84.png 300w, https:\/\/ghetool.eu\/wp-content\/uploads\/2026\/09\/Printscreen-765x214.png 765w, https:\/\/ghetool.eu\/wp-content\/uploads\/2026\/09\/Printscreen-18x5.png 18w, https:\/\/ghetool.eu\/wp-content\/uploads\/2026\/09\/Printscreen.png 1470w\" sizes=\"(max-width: 1024px) 100vw, 1024px\" \/><figcaption class=\"wp-element-caption\">Print screen of the general settings of the interference calculation.<\/figcaption><\/figure>\n<\/div>\n\n\n<p class=\"wp-block-paragraph\">In the figure above, the general settings for the interference calculation are given. The parameters asked (like the thermal conductivity, simulation period and volumetric ground heat capacity) are required by the line source models to calculate the ground thermal interaction.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">The maximum allowed interference is not directly used in the calculations, but it helps as a visual guideline. All values lower than the one shown here will be shown as red in the results.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">For the interference regulation, there are two options: the generic one (which holds for all countries) and one for the Netherlands. This is because in the Netherlands, not the seasonal performance factor (SPF) of heating and cooling is used, but they use the SPF of the entire system and the SPF for cooling. All other regions simply work with the SCOP for heating, domestic hot water and the SEER for cooling.<\/p>\n\n\n\n<div class=\"note\">The SPF of the entire system is defined as: $$SPF_{system}=\\frac{Q_{heating}+Q_{dhw}+Q_{cooling}}{Q_{heating}\/SCOP_{heating}+Q_{dhw}\/SCOP_{dhw}+Q_{cooling}\/SEER}$$Although both the legislation for the Netherlands and the generic one yield the same result, they differ in the reporting.<\/div>\n\n\n\n<p class=\"wp-block-paragraph\">When a contour plot is selected in the &#8216;General&#8217; tab, the reference coordinate can be set by clicking on &#8216;set map&#8217;.<\/p>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"271\" src=\"https:\/\/ghetool.eu\/wp-content\/uploads\/2026\/09\/Printscreen-2-1024x271.png\" alt=\"Print screen for all the systems in the interference calculation.\" class=\"wp-image-5416\" srcset=\"https:\/\/ghetool.eu\/wp-content\/uploads\/2026\/09\/Printscreen-2-1024x271.png 1024w, https:\/\/ghetool.eu\/wp-content\/uploads\/2026\/09\/Printscreen-2-300x79.png 300w, https:\/\/ghetool.eu\/wp-content\/uploads\/2026\/09\/Printscreen-2-767x203.png 767w, https:\/\/ghetool.eu\/wp-content\/uploads\/2026\/09\/Printscreen-2-18x5.png 18w, https:\/\/ghetool.eu\/wp-content\/uploads\/2026\/09\/Printscreen-2.png 1473w\" sizes=\"(max-width: 1024px) 100vw, 1024px\" \/><figcaption class=\"wp-element-caption\">Print screen for all the systems in the interference calculation.<\/figcaption><\/figure>\n<\/div>\n\n\n<p class=\"wp-block-paragraph\">Next, all the different systems for the interference calculation should be entered. This can be done by either adding a system, where you have the option to add borefields one by one or to link another scenario, whereby all the information from the other scenario is automatically linked. This last option has the advantage that, when your design changes, the interference calculation is automatically changed as well, minimising the risk of working with outdated data.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">When you want to calculate the interference for a whole neighbourhood for example, it is easier to import all the systems directly via a *.csv file. There are no limits to the number of systems you can import that way. For the people from the Netherlands, there is the option to import systems directly from the <a href=\"https:\/\/wkotool.nl\" target=\"_blank\" rel=\"noopener\">WKOtool<\/a>.<\/p>\n\n\n\n<div class=\"note\"><p>GHEtool is directly linked to WKOtool and thereby always contains the most recent boreholes. If you enter an address in the tool or select a location on the map, all the boreholes in a radius of 120 m are selected (in blue) as well as all larger (&gt;70 kW) geothermal systems in a radius of 350 m (in orange). When there are open systems nearby, a warning will be prompted.<\/p><figure class=\"wp-block-image aligncenter size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"787\" height=\"764\" src=\"https:\/\/ghetool.eu\/wp-content\/uploads\/2026\/09\/WKOtool.png\" alt=\"\" class=\"wp-image-5417\" srcset=\"https:\/\/ghetool.eu\/wp-content\/uploads\/2026\/09\/WKOtool.png 787w, https:\/\/ghetool.eu\/wp-content\/uploads\/2026\/09\/WKOtool-300x291.png 300w, https:\/\/ghetool.eu\/wp-content\/uploads\/2026\/09\/WKOtool-12x12.png 12w, https:\/\/ghetool.eu\/wp-content\/uploads\/2026\/09\/WKOtool-767x745.png 767w\" sizes=\"(max-width: 787px) 100vw, 787px\" \/><figcaption class=\"wp-element-caption\">Print screen from the data import from the WKOtool.<\/figcaption><\/figure><p>GHEtool can automatically import all of the recent systems from the WKOtool, but older ones can sometimes cause problems. This is because, previously, only the geometric centre was entered in the WKOtool, and when there are more than 6 boreholes in the borefield, this cannot be used for the interference calculation. In that case, you need to contact the local authorities to get the real borehole coordinates to perform the simulation.<\/p><p>For newer systems, all individual boreholes are put into the WKOtool, so they can be imported as such.<\/p><p>Be aware that not all information from the WKOtool is correct and that you should always double-check the imported results for mistakes (for example an unrealistically low heating\/cooling demand).<\/p><\/div>\n\n\n\n<h2 class=\"wp-block-heading\">Example<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">To illustrate the power of the interference module, two different cases will be studied: one with three apartment buildings on the same project field and one neighbourhood with 20 individual houses.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Three neighbouring apartment buildings<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">The first case where the interference is important is that of the three apartment buildings close to each other. Their three borefields are again shown below.<\/p>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-full\"><img decoding=\"async\" width=\"498\" height=\"364\" src=\"https:\/\/ghetool.eu\/wp-content\/uploads\/2026\/03\/Project.png\" alt=\"Residential projects with three separate borefields.\" class=\"wp-image-4852\" srcset=\"https:\/\/ghetool.eu\/wp-content\/uploads\/2026\/03\/Project.png 498w, https:\/\/ghetool.eu\/wp-content\/uploads\/2026\/03\/Project-300x219.png 300w, https:\/\/ghetool.eu\/wp-content\/uploads\/2026\/03\/Project-16x12.png 16w\" sizes=\"(max-width: 498px) 100vw, 498px\" \/><figcaption class=\"wp-element-caption\">Residential projects with three separate borefields.<\/figcaption><\/figure>\n<\/div>\n\n\n<p class=\"wp-block-paragraph\">The way to approach this problem is by creating a separate scenario per building\/borefield in GHEtool and sizing the borefield in this scenario as you would do otherwise. Afterwards, you create a <strong>new scenario<\/strong> specifically for the interference calculation where you link the different scenarios together like shown below.<\/p>\n\n\n\n<div class=\"caution\">When you want to combine different scenarios into one interference calculation it is important that your borefield is entered with the coordinates directly. This means that the standard configurations (like the rectangle etc.) cannot directly be used, but they should be converted to coordinates first, as discussed in <a href=\"https:\/\/ghetool.eu\/course\/working-with-borehole-coordinates\/\">Part 5.3<\/a>.<\/div>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"342\" src=\"https:\/\/ghetool.eu\/wp-content\/uploads\/2026\/09\/Print-screen-three-buildings-1024x342.png\" alt=\"\" class=\"wp-image-5418\" srcset=\"https:\/\/ghetool.eu\/wp-content\/uploads\/2026\/09\/Print-screen-three-buildings-1024x342.png 1024w, https:\/\/ghetool.eu\/wp-content\/uploads\/2026\/09\/Print-screen-three-buildings-18x6.png 18w, https:\/\/ghetool.eu\/wp-content\/uploads\/2026\/09\/Print-screen-three-buildings-767x256.png 767w, https:\/\/ghetool.eu\/wp-content\/uploads\/2026\/09\/Print-screen-three-buildings-300x100.png 300w, https:\/\/ghetool.eu\/wp-content\/uploads\/2026\/09\/Print-screen-three-buildings.png 1471w\" sizes=\"(max-width: 1024px) 100vw, 1024px\" \/><figcaption class=\"wp-element-caption\">Print screen of the three different buildings linked in the interference calculation.<\/figcaption><\/figure>\n<\/div>\n\n\n<div class=\"note\">When scenarios are linked in the interference calculation, all the values (like heating, cooling etc.) are left blank since they are dynamically coupled. If you change something in the respective scenario, it will be changed here in the back-end as well.<\/div>\n\n\n\n<p class=\"wp-block-paragraph\">Looking at the results, it is clear from the contour plot that there is a significant interference between the different systems after 25 years.<\/p>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"586\" src=\"https:\/\/ghetool.eu\/wp-content\/uploads\/2026\/09\/Interference-three-buildings-1024x586.png\" alt=\"Contour plot showing the temperature distribution in the ground after 25 years.\" class=\"wp-image-5419\" srcset=\"https:\/\/ghetool.eu\/wp-content\/uploads\/2026\/09\/Interference-three-buildings-1024x586.png 1024w, https:\/\/ghetool.eu\/wp-content\/uploads\/2026\/09\/Interference-three-buildings-300x172.png 300w, https:\/\/ghetool.eu\/wp-content\/uploads\/2026\/09\/Interference-three-buildings-767x439.png 767w, https:\/\/ghetool.eu\/wp-content\/uploads\/2026\/09\/Interference-three-buildings-18x10.png 18w, https:\/\/ghetool.eu\/wp-content\/uploads\/2026\/09\/Interference-three-buildings.png 1136w\" sizes=\"(max-width: 1024px) 100vw, 1024px\" \/><figcaption class=\"wp-element-caption\">Contour plot showing the temperature distribution in the ground after 25 years.<\/figcaption><\/figure>\n<\/div>\n\n\n<p class=\"wp-block-paragraph\">When the figure above is compared to the image after only 2 years, it is indeed clear that the interference is something that is important for the long-term operation of the borefield. In this short time window, no interference is visible between the different systems.<\/p>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"586\" src=\"https:\/\/ghetool.eu\/wp-content\/uploads\/2026\/09\/Interference-three-buildings-2-years-1024x586.png\" alt=\"Contour plot showing the temperature distribution in the ground after 2 years.\" class=\"wp-image-5420\" srcset=\"https:\/\/ghetool.eu\/wp-content\/uploads\/2026\/09\/Interference-three-buildings-2-years-1024x586.png 1024w, https:\/\/ghetool.eu\/wp-content\/uploads\/2026\/09\/Interference-three-buildings-2-years-300x172.png 300w, https:\/\/ghetool.eu\/wp-content\/uploads\/2026\/09\/Interference-three-buildings-2-years-767x439.png 767w, https:\/\/ghetool.eu\/wp-content\/uploads\/2026\/09\/Interference-three-buildings-2-years-18x10.png 18w, https:\/\/ghetool.eu\/wp-content\/uploads\/2026\/09\/Interference-three-buildings-2-years.png 1136w\" sizes=\"(max-width: 1024px) 100vw, 1024px\" \/><figcaption class=\"wp-element-caption\">Contour plot showing the temperature distribution in the ground after 2 years.<\/figcaption><\/figure>\n<\/div>\n\n\n<p class=\"wp-block-paragraph\">In the table, the interference between the three different systems is quantified. Here, system 1 (our first borefield for building A) receives -0.36\u00b0C of interference from the second borefield and -0.44\u00b0C of interference from the third system. Therefore, after 25 years, our first borefield will be 0.8\u00b0C lower than originally designed for.<\/p>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"253\" src=\"https:\/\/ghetool.eu\/wp-content\/uploads\/2026\/09\/Total-interference-1024x253.png\" alt=\"Interference values for the three different systems.\" class=\"wp-image-5421\" srcset=\"https:\/\/ghetool.eu\/wp-content\/uploads\/2026\/09\/Total-interference-1024x253.png 1024w, https:\/\/ghetool.eu\/wp-content\/uploads\/2026\/09\/Total-interference-300x74.png 300w, https:\/\/ghetool.eu\/wp-content\/uploads\/2026\/09\/Total-interference-766x189.png 766w, https:\/\/ghetool.eu\/wp-content\/uploads\/2026\/09\/Total-interference-18x4.png 18w, https:\/\/ghetool.eu\/wp-content\/uploads\/2026\/09\/Total-interference.png 1438w\" sizes=\"(max-width: 1024px) 100vw, 1024px\" \/><figcaption class=\"wp-element-caption\">Interference values for the three different systems.<\/figcaption><\/figure>\n<\/div>\n\n\n<p class=\"wp-block-paragraph\">If you want to make sure your fluid temperatures stay within the limits, you now need to go back to the different borefields and add the interference to the minimum allowed fluid temperature. So, in our case, all borefields were designed with a minimum inlet fluid temperature of 0\u00b0C; now it should be at least 0.8\u00b0C, 0.54\u00b0C and 0.59\u00b0C to account for the long-term temperature drift due to the imbalance.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">This implies that our first borefield should have 36 boreholes instead of 32, the second one 24 instead of 22, and building C should have a borefield with 24 boreholes instead of 22 as well. The resulting temperature profile of building A, after the correction for the interference, is shown below.<\/p>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"361\" src=\"https:\/\/ghetool.eu\/wp-content\/uploads\/2026\/09\/Temperature-profile-of-building-A-1-1024x361.png\" alt=\"Temperature profile of the borefield of building A with 0.8\u00b0C as a minimum limit to account for the interference.\" class=\"wp-image-5423\" srcset=\"https:\/\/ghetool.eu\/wp-content\/uploads\/2026\/09\/Temperature-profile-of-building-A-1-1024x361.png 1024w, https:\/\/ghetool.eu\/wp-content\/uploads\/2026\/09\/Temperature-profile-of-building-A-1-767x270.png 767w, https:\/\/ghetool.eu\/wp-content\/uploads\/2026\/09\/Temperature-profile-of-building-A-1-300x106.png 300w, https:\/\/ghetool.eu\/wp-content\/uploads\/2026\/09\/Temperature-profile-of-building-A-1-18x6.png 18w, https:\/\/ghetool.eu\/wp-content\/uploads\/2026\/09\/Temperature-profile-of-building-A-1.png 1420w\" sizes=\"(max-width: 1024px) 100vw, 1024px\" \/><figcaption class=\"wp-element-caption\">Temperature profile of the borefield of building A with 0.8\u00b0C as a minimum limit to account for the interference.<\/figcaption><\/figure>\n<\/div>\n\n\n<p class=\"wp-block-paragraph\">Afterwards, the interference can be recalculated, showing that now the temperature effect of the interference is less than the safety margin that was added to the designs, so one can be sure that the temperature limits will be fine.<\/p>\n\n\n\n<div class=\"hint\"><p>Designing with interference is therefore always a three-step approach.<\/p><ol> <li>The individual borefields are designed to be within the specified fluid temperature limits.<p><\/p><\/li> <li>The interference between the different borefields is calculated.<\/li> <li>Add the interference to the minimum fluid threshold (or the maximum, in case of a positive interference) and change your design accordingly.<\/li> <\/ol><p>Optionally, you can iterate the process above to find an even more optimal solution, but typically, one iteration is enough.<\/p><\/div>\n\n\n\n<h3 class=\"wp-block-heading\">Neighbourhood with 20 houses<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Another case consists of the construction of a new neighbourhood with 20 houses with individual geothermal boreholes. Although it is possible to enter each system as its own scenario in GHEtool and link them as such to the interference calculation, this can be quite time-consuming to set up.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Therefore, there is the option to import the scenarios directly from a CSV file into GHEtool. This file (an example can be downloaded at the end of this chapter) should contain the following columns:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>New\/existing system<\/li>\n\n\n\n<li>Name of the system<\/li>\n\n\n\n<li>X-coordinate of the borehole<\/li>\n\n\n\n<li>Y-coordinate of the borehole<\/li>\n\n\n\n<li>Total system length<\/li>\n\n\n\n<li>Borehole depth<\/li>\n\n\n\n<li>Heating demand<\/li>\n\n\n\n<li>Cooling demand<\/li>\n\n\n\n<li>SCOP heating<\/li>\n\n\n\n<li>SEER cooling<\/li>\n\n\n\n<li>DHW demand<\/li>\n\n\n\n<li>SCOP DHW<\/li>\n<\/ul>\n\n\n\n<div class=\"note\">When a certain system has multiple boreholes, you just create another line with a different (x,y) coordinate and other borehole length\/depth and keep everything else (name, efficiencies etc.) the same. That way, GHEtool will see them as different boreholes linked to the same system.<\/div>\n\n\n\n<div class=\"note\">For the case in the Netherlands, no DHW demand and efficiency is required. Besides that, the SCOP heating becomes the SPF of the entire system and the SEER the SPF for cooling.<\/div>\n\n\n\n<p class=\"wp-block-paragraph\">In the video below, the thermal interference between the different systems is shown for year one to year 25. Here, it is visible how the interference plays out over the years growing into one region of thermal interference of -0.2\u00b0C after 25 years. The situation after 25 years is shown at the end.<\/p>\n\n\n\n<figure class=\"wp-block-video aligncenter\"><video height=\"594\" style=\"aspect-ratio: 1098 \/ 594;\" width=\"1098\" controls src=\"https:\/\/ghetool.eu\/wp-content\/uploads\/2026\/09\/Video.mp4\"><\/video><figcaption class=\"wp-element-caption\">Interference over a period of 25 years.<\/figcaption><\/figure>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"586\" src=\"https:\/\/ghetool.eu\/wp-content\/uploads\/2026\/09\/Neighbourhood-1024x586.png\" alt=\"Interference between the 20 different systems are 25 years.\" class=\"wp-image-5425\" srcset=\"https:\/\/ghetool.eu\/wp-content\/uploads\/2026\/09\/Neighbourhood-1024x586.png 1024w, https:\/\/ghetool.eu\/wp-content\/uploads\/2026\/09\/Neighbourhood-300x172.png 300w, https:\/\/ghetool.eu\/wp-content\/uploads\/2026\/09\/Neighbourhood-18x10.png 18w, https:\/\/ghetool.eu\/wp-content\/uploads\/2026\/09\/Neighbourhood-767x439.png 767w, https:\/\/ghetool.eu\/wp-content\/uploads\/2026\/09\/Neighbourhood.png 1136w\" sizes=\"(max-width: 1024px) 100vw, 1024px\" \/><figcaption class=\"wp-element-caption\">Interference between the 20 different systems are 25 years.<\/figcaption><\/figure>\n<\/div>\n\n\n<h2 class=\"wp-block-heading\">Conclusion<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">In this chapter, the concept of thermal interference between neighbouring systems is explained. Just like different boreholes in the same borefield influence each other, so do boreholes of different systems have a mutual interference.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Two methods for the interference calculation were discussed: the infinite line source and the finite line source, where the first one is the fastest one and accurate for deep boreholes that are spaced relatively far apart, while the second one is the most accurate overall due to the three-dimensional approach of the heat transfer. It was also discussed how these methods to model the interference between two boreholes can be extended to model the interference between different borefields.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">It was shown that a borefield design with interference included consists of a stepwise approach where first the borefield is sized in isolation, after which the interference is calculated. As a third step, the interference is added to the temperature thresholds of the borefield so the new design still stands after the interference is considered.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">This interference effect is hence really important when designing a group of individual systems. In the next chapter, the concept of simultaneity will be discussed, which plays a role in the collective geothermal solution.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">References<\/h2>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Groenholland. (2020). <em>ITGBES, InterferentieTool Gesloten BodemEnergieSystemen<\/em>. Rapport GHNL 180760. Groenholland Geo-energiesystemen. Amsterdam. Online <a href=\"https:\/\/www.sikb.nl\/doc\/GHNL_180760_Aanvullende_rapportage_2020.pdf\" target=\"_blank\" rel=\"noopener\">here<\/a> [last visited: 17-09-2026]<\/li>\n\n\n\n<li>Peere, W., Cimmino, M. (2026). Thermal Interference Between Shallow Geothermal Borefields: A Comparison of Analytical Methods. <em>In proceedings of Der Geothermiekongress (DGK)<\/em>, 20-22 October, Postdam, Germany.<\/li>\n\n\n\n<li>Legislation in The Netherlands:&nbsp;<a href=\"https:\/\/www.sikb.nl\/doc\/BRL11000\/Protocol_11001_v3_1_20211102.pdf\" target=\"_blank\" rel=\"noopener\">BRL11000 Protocol 11001<\/a>&nbsp;(page 61-62)<\/li>\n\n\n\n<li>Legislation in Switzerland: SIA 384\/6 \u00a73.1.1.2<\/li>\n\n\n\n<li>Cimmino, M., Bernier, M. (2014). A semi-analytical method to generate g-functions for geothermal bore fields. <em>International Journal of Heat and Mass Transfer<\/em>, 70, 641-650.<\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\">Questions<\/h2>\n\n\n\n<div class=\"question\" data-chapter=\"2\">After the increase of the borefield sizes in the first case, why is it that the interference becomes less?<\/div>\n\n\n\n<div class=\"question\" data-chapter=\"2\">What would be the effect on the design if the three hydraulically separated boreholes in the first case were combined into one borefield? You can assume the boreholes stay in their place, but they will now be hydraulically connected as in the case of a 5th-generation district heating and cooling grid.<\/div>\n\n\n\n<div class=\"question\" data-chapter=\"2\">Run the interference calculation for the neighbourhood again, but now with only one borehole per system located at the geometric centre of the field. You can download the CSV file for this below.<\/div>\n\n\n\n<div class=\"question\" data-chapter=\"2\">What would change if, instead of using the finite line source, the infinite line source was used to model the interference? Do this for the first and the second case.<\/div>\n\n\n\n<h2 class=\"wp-block-heading\">Download<\/h2>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Download GHEtool simulation from this chapter&nbsp;<a href=\"https:\/\/ghetool.eu\/wp-content\/uploads\/course\/resources\/Course%208.2\/Course%208.2.pdf\">here<\/a>.<\/li>\n\n\n\n<li>Download the list of the 20 geothermal systems <a href=\"https:\/\/ghetool.eu\/wp-content\/uploads\/course\/resources\/Course%208.2\/Interference%20all%20boreholes.csv\">here<\/a>.<\/li>\n\n\n\n<li>Download the list of the 20 geothermal systems with the geometric centre <a href=\"https:\/\/ghetool.eu\/wp-content\/uploads\/course\/resources\/Course%208.2\/Interference%20geometric%20center.csv\">here<\/a>.<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\"><\/p>\n","protected":false},"excerpt":{"rendered":"<p>Lors de la conception d'un champ de forages, on part du principe que la temp\u00e9rature du sol n'est influenc\u00e9e par aucun syst\u00e8me voisin. Cependant, cette interf\u00e9rence thermique entre diff\u00e9rents champs de forages peut \u00eatre importante ; c'est pourquoi ce chapitre y est consacr\u00e9.<\/p>","protected":false},"template":"","section":[123],"chapter":[146],"authors":[39],"class_list":["post-5407","course","type-course","status-publish","hentry","section-chapter-2","chapter-part-8","authors-wouter-peere"],"_links":{"self":[{"href":"https:\/\/ghetool.eu\/fr_fr\/wp-json\/wp\/v2\/course\/5407","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/ghetool.eu\/fr_fr\/wp-json\/wp\/v2\/course"}],"about":[{"href":"https:\/\/ghetool.eu\/fr_fr\/wp-json\/wp\/v2\/types\/course"}],"wp:attachment":[{"href":"https:\/\/ghetool.eu\/fr_fr\/wp-json\/wp\/v2\/media?parent=5407"}],"wp:term":[{"taxonomy":"section","embeddable":true,"href":"https:\/\/ghetool.eu\/fr_fr\/wp-json\/wp\/v2\/section?post=5407"},{"taxonomy":"chapter","embeddable":true,"href":"https:\/\/ghetool.eu\/fr_fr\/wp-json\/wp\/v2\/chapter?post=5407"},{"taxonomy":"authors","embeddable":true,"href":"https:\/\/ghetool.eu\/fr_fr\/wp-json\/wp\/v2\/authors?post=5407"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}