UMEP Manual/ Tutorials/SEBE
- 1 Introduction
- 2 Initial Practical steps
- 3 Steps
- 4 Preparing data for SEBE
- 5 Running the model
- 6 Irradiance on building envelopes (alternatively see the tips below – currrently better)
- 7 Solar Energy Potential
- 8 Covent Garden data set
- 9 Questions for you to explore with UMEP:SEBE
- 10 References
- 11 Tips
Lindberg et al.’s (2015) solar radiation model SEBE (Solar Energy on Building Envelopes) allows estimates of solar irradiance on ground surfaces, building roofs and walls. It uses a shadow casting algorithm with a digital surface model (DSM) and the solar position to generate pixel-level information of shadow or sunlit areas. The shadow casting algorithm (Ratti and Richens 1999) has been developed to incorporate walls (Lindberg et al. 2015). This is of interest for a broad range of applications, for example solar energy potential and thermal comfort.
SEBE is incorporated in UMEP(Urban Multi-scale Environmental Predictor), a plugin for QGIS. As SEBE was initially developed to estimate solar energy potential on building roofs, the Digital Surface Models (DSMs) used need to include roof structures, such as tilted roofs, chimneys etc. Methods to produce accurate ground and building DSMs for SEBE include the use of LiDAR technology and 3D roof structure objects in vector format.
In this exercise you will apply the model in Gothenburg, Sweden and Covent Garden, London to investigate solar energy potential, how it changes between buildings, with seasons, with the effects of vegetation etc.
Initial Practical steps
- Start the QGIS software
- Windows: If not visible on the desktop use the Start button to find the software (i.e. Find QGIS under your applications)
- Select QGIS 2.16.3 Desktop (or the latest version installed)
When you open it on the top toolbar you will see UMEP.
- If it UMEP not on our machine, download and install the UMEP plugin
- Read through the section in the online manual BEFORE using the model, so you are familiar with it’s operation and terminology used.
Data for Tutorial
To use SEBE the datasets are (for password access if not already provided)
|Image||Date Details||Download from|
|centre of Gothenburg, Sweden|
|London Covent Garden||data|
Variables included in the meteorological data file. No. indicates the column the file is in. Use indicates if it is R – required or O- optional (in this application) or N- Not used in this application. All columns must be present but can be filled with numbers to indicate they are not in use (e.g. -999).
Preparing data for SEBE
SEBE plugin: located at UMEP -> Processor -> Solar Energy -> Solar Energy on Building Envelopes (SEBE) in the menu bar.
Running the model
Now you have all data ready to run the model.
Irradiance on building envelopes (alternatively see the tips below – currrently better)
To determine the irradiance on building walls:
- Open the SunAnalyser located at UMEP -> Post-Processor -> Solar Radiation -> SEBE (Visualisation).
- This can be used to visualize the irradiance on both roofs and walls.
- Choose the input folder where you saved your result for one of the runs.
- Mark an area with the tool (Area of Visualisation) on the map canvas by click first once
- Drag to produce an area
- Click again to finish.
- Click Visualise. Now you should be able to see the results in 3D.
3D Visualisation for Mac currently not working properly
Use the Profile tool to see the range of values along a transect.
- Plugins > Profile tool > Terrain profile.
- Draw a line across the screen on the area of interest. Double click and you will see the profile drawn. Make certain you use the correct layer (see Tips).
- If this is not installed you will need to install it from official QGIS-plugin reporistory (Plugins > Manage and Install Plugins).
Solar Energy Potential
In order to obtain the solar energy potential for a specific building:
- The actual area of the roof needs to be considered.
- Determine the area of each pixel (AP ): e.g. 1 m2
- As some roofs are tilting the area may be larger for some pixels. The actual area (AA) can be computed from:
AA = AP/cos(Si) where the slope (Si) of the raster pixel should be in radians (1 deg = pi/180 rad).
Covent Garden data set
A second GIS data set is available for the Covent Garden area in London
- Close the Gothenburg data (it may be easiest to completely close QGIS and re-open).
- Download from 
- Add the Covent Garden data
- Extract the data to a directory
- Load the Raster data (DEM, DSM) files (as you did before)
- UMEP -> Processor -> Solar Radiation -> Daily Shadow pattern
- Allows you to calculate the shadows for a particular time of day and Day of Year.
Questions for you to explore with UMEP:SEBE
- Use the Gothenburg dataset consider the impact of vegetation.
- What are the main differences between the two model runs with respect to ground and roof surfaces?
- To what extent are the building roofs affected by vegetation?
- Consider the differences between London and Gothenburg. You can run the model for different times of the year by modifying the meteorological data so the file only has the period of interest.
- For Covent Garden, determine the solar energy potential for a specific building within the model domain. Work in groups to consider different areas. What would be the impact of having a smaller/larger area domain modelled for this building? Identify the possibilities of solar energy production for that building.
- A report might include a map showing where on the roof solar panels could be located and statistics on solar energy potential for the roofs on the chosen building.
- Statistics might include area (m2) that could be utilized and total potential solar energy.
- What are other factors you need to consider to improve the analysis?
- Goodwin NR, Coops NC, Tooke TR, Christen A, Voogt JA 2009: Characterizing urban surface cover and structure with airborne lidar technology. Can J Remote Sens 35:297–309
- Lindberg F, Jonsson P, Honjo T, Wästberg D 2015: Solar energy on building envelopes - 3D modelling in a 2D environment. Solar Energy. 115, 369–378
- Ratti CF, Richens P 1999: Urban texture analysis with image processing techniques Proc CAADFutures99, Atlanta, GA
Authors of this document: Lindberg and Grimmond (2015, 2016)
Contributors to the material covered
- University of Gothenburg: Fredrik Lindberg
- University of Reading: Sue Grimmond
- Background work also comes from: UK (Ratti & Richens 1999), Sweden (Lindberg et al. 2015), Canada (Goodwin et al. 2009)
Repository for UMEP
|Meteorological file in UMEP has a special format.||If you have data in another format there is a UMEP plugin that can convert your meteorological data into the UMEP format.
|Plugin to visualize data in 3D: called Qgis2Threejs.
|TIFF (TIF) and ASC are raster data file formats||In the left Hand Side there is a list of layers.
|You can save all of you work for different areas as a project – so you can return to it as whole.
||You can change the shading etc. on different layers.
|UMEP repository.||Other Getting Started Help|