## In a glance

This calculation module calculates district heating potential within the selected region using 2 threshold values: 1) Minimum heat demand in each hectare, 2) Minimum heat demand in a DH area. Areas within the selected region, which fulfill these conditions are returned as DH areas. Furthermore, the heat demand in these regions are return in form of indicators as DH potential.

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## Introduction

The heat demand plays an important role in the determination of potential district heating (DH) areas. For example, the implementation of district heating in areas with low heat demand is not economically viable. On the other hand, defining any area with high heat demand density as a potential DH area can also be inaccurate. A high heat demand density in an area could be due to the presence of a few consumers with a very high heat demand within that area. On the contrary, a low average heat demand density could be a sign of zones with a very low heat demand within the selected area. The aim of the calculation module "CM - DISTRICT HEATING POTENTIAL AREA: USER-DEFINED THRESHOLD" is to provide a reasonable balance between heat demand density in an area and its constituting zones.

The "CM - DISTRICT HEATING POTENTIAL AREA: USER-DEFINED THRESHOLD" determines the DH areas and their corresponding DH potential based on heat demand densities. The heat demand densities are obtained from an input GIS layer. The Hotmaps toolbox and database provides a default heat density map that can be used in this calculation module. The Hotmaps heat density map is in raster format and has a resolution of one hectare and Coordinate Reference System (CRS) of "ETRS89 / LAEA Europe - EPSG 3035". The cells in the map show the heat densities in MWh/ha. Besides this default map also maps generated by the user can be uploaded to the toolbox and used in this CM.

As output, one GIS layer, three indicators and two diagrams are presented. These outputs are explained in detail in the section Sample Run. The output layer demonstrates the potential DH areas. By clicking on each area on the map, a window pops up and the DH potential corresponding to that area is shown. Within the INDICATORS / GRAPHICS windows in the RESULTS section of the toolbox, relevant indicators and charts regarding DH potential within the selected zone and potentials in sub-zones are illustrated.

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## Inputs and outputs

The input parameters and layers, as well as output layers and parameters, are as follows.

Input layers and parameters are:

• Minimum heat demand in each hectare [MWh/ha]: a value between 0 and 1000
• Minimum heat demand in a DH area [GWh/year]: a value between 0 and 500
• Heat density map: a default map is provided in the toolbox; own uploaded maps can also be used in the CM
• in raster format (*.tif)
• with 1-hectare resolution
• demand densities in MWh/ha

Output layers and parameters are:

• DH areas in raster and shapefile formats
• DH potential in each DH area GWh/year
• Total heat demand in GWh within the selected zone
• Total district heating potential in GWh within the selected zone
• Potential share of district heating from total demand in selected zone

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## Method

The potential for DH in a specific region can be defined by the overall heat demand and its spatial allocation. In the Hotmaps toolbox, the heat demand is represented in the form of a raster map. In order to properly define potential DH areas, both the heat demand in each cell and also in an area should reach a certain level. As a starting point, the Hotmaps toolbox suggests default values for these two parameters. However, depending on the distribution of heat demand and also the local conditions, the Hotmaps user can modify these values.

The determination of DH areas is done in two steps:

In the first step, all the cells with heat demand below the input parameter "Minimum heat demand in hectare" are filtered. By eliminating these cells from the map, we obtain groups of cells that are attached to each other. Each set of these attached cells constitute small zones that here, are referred to as “coherent areas”. In the second steps, the total heat demand in each coherent area is calculated. For each coherent area, if the total heat demand is higher than the input parameter "Minimum heat demand in a DH area", it is considered as a potential DH area.

Finally, for the DH areas, the potential is calculated and presented in the form of a GIS layer, which can be seen in the toolbox.

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## GitHub repository of this calculation module

Here you get the bleeding-edge development for this calculation module.

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## Sample run

Here, the calculation module is run for the case study of Aalborg in Denmark.

• First, use the "Go To Place" bar to navigate to Aalborg and select the city.

• Follow the steps as shown in the figure below:

• Click on the "Layers" button to open the "Layers" window:
• Click on the "CALCULATION MODULES" tab.
• Click on the "CM-DISTRICT HEATING POTENTIAL AREAS: USER-DEFINED THRESHOLDS" button.
• Now, the calculation module "CM-DISTRICT HEATING POTENTIAL AREAS: USER-DEFINED THRESHOLDS" opens and is ready to run.

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### Test Run 1: default input values

The default input values show the general conditions under which an area can be considered as a potential DH area. These values should be regarded as starting point only. You may need to set values below or above the default values in the toolbox considering additional local conditions. Therefore, the user should adapt these values to find the best combination of thresholds for his or her case study.

To run the calculation module, follow the next steps:

• Assign a name to the run session (optional - here, we chose "Test Run 1") and set the input parameters (here, default values were used).

• Press the button "RUN CM" on the bottom left.
• Wait until the process is finished.

Note: If you wish to change your input parameters, you can press "STOP CM", modify your input parameters and re-run the CM

• As output, indicators and diagrams are shown in the "RESULTS" section on the right side of the toolbox. The indicators show:
• the total heat demand in GWh within the selected zone,
• total DH potential in GWh within the selected zone,
• the share of DH potential from the total demand, which is obtained by division of DH potential by total heat demand in the region.

Additionally, also two diagrams are generated. The first shows the DH potential in each DH area. The corresponding labels can be found on the map, too. The second diagram illustrates the total DH potential in comparison with the total heat demand in the selected area.

• Also a new layer is added to the canvas showing DH areas. This layer is added to the list of layers under the category "Calculation module" in the very bottom of the layers section. The run session name distinguishes the outputs of this run from other ones.

Following these steps you will get an impression of the input values and potential DH areas.

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### Test Run 2: modified input values

Depending on your experience and local knowledge, you may increase or decrease the input values to obtain better results. In the case of Aalborg, for instance, you may know that the heat demand in outer city areas is relatively close to the central part of the city and DH system is also feasible in those areas. Therefore, you may decide to reduce the minimum heat demand in cells that are part of a DH area; however, to guarantee enough heat demand, you may increase the minimum heat demand in a DH area. Here you re-run the calculation modules with new input parameters.

• Assign a name to the run session (optional - here, we chose "Test Run 2") and set the input parameters (250 MWh/ha for min. heat demand in hectare and 35 GWh/year for the minimum demand in DH area).

• Press the button "RUN CM" on the bottom left.
• Wait until the process is finished.
• As output, indicators and diagrams are shown in the "RESULTS" section on the right side of the toolbox. The indicators show:
• the total heat demand in GWh within the selected zone,
• total DH potential in GWh within the selected zone,
• the share of DH potential from total demand, which is obtained by division of DH potential by total heat demand in the region.

Additionally, also two diagrams are generated. The first one shows the DH potential in each DH area. The corresponding labels can be found on the map, too. The second diagram illustrates the total DH potential in comparison with the total heat demand in the selected area.

• Also a new layer is added to the canvas showing DH areas. This layer is added to the list of layers under the "Calculation module" category. The run session name distinguishes the outputs of this run from other ones.

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## How to cite

Mostafa Fallahnejad, in Hotmaps-Wiki, CM-District-heating-potential-areas: user-defined-thresholds (April 2019)

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## Authors and reviewers

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