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Ecotect Tutorial : Calculate Artificial Lighting using Analysis Grid


This tutorial explains how to calculate and display artificial lighting levels using the analysis grid in an Ecotect model.


You will need about 10 minutes to complete this tutorial.

Training and Accreditation

Successfully completing this tutorial fulfills one of the practical skills required for completing Level 1 of the Artificial Lighting training module.

Resources Required

To complete this tutorial, download and open the file located under the Attachments section at the end of this tutorial.


  1. The Ecotect file contains a simple thermal model consisting of a single zone, some light objects and the analysis grid turned on and sized accordingly. The analysis grid has been set up at 700mm above floor level, being the typical desk height at which you might measure lighting levels, say in an office environment.
    You need at least one zone, one light and the analysis grid turned on in order to perform the analysis.
    You need at least one zone, one light and the analysis grid turned on in order to perform the analysis.
  2. Start the calculation wizard by selecting the Calculate»Lighting Analysis... menu item. Select the Overall Daylight and Electric Light Levels radio option, and then click Next.
  3. The next wizard screen allows you to choose whether points or an analysis grid is used for the calculation. Select the Over the Analysis Grid radio option, press F2 to go back to the model to make any adjustments if necessary (F2 to return to the wizard), and then click Next.
  4. Specify how precise you would like Ecotect to be with its calculations. Usually, the default setting of High is suitable for most calculations, however this can be varied using the slider. Naturally, the greater the precision, the longer the calculation processing time required.
  5. Even though you are analysing artificial lighting levels, it is still necessary to specify the Design Sky Illuminance in your model. This allows you to compare electric lighting levels to those provided by daylight either together or in isolation. If you are unsure of how to calculate or adjust these settings, accept the default selections offered by Ecotect, and then click Next.
  6. You can specify room based settings on the next wizard screen. These only relate to the calculation of daylight factors, and so do not affect the results for artifical lighting. Leave these settings as they are, and then click Next.
  7. The final wizard screen presents a summary of all of the settings you have selected. Make any adjustments, if necessary, and then click Ok to commence the lighting analysis.
  8. Ecotect takes a few moments to calculate the lighting levels based on the settings you have specified in the wizard. However, you will need to check that Ecotect is actually displaying the values you are interested in examining. Go to the Analysis Grid control panel, and under the Grid Data & Scale section, choose from one of the following five options :
    • Daylight Factor - the percentage of light available to interior spaces based upon the selected Design Sky Illuminance level.
    • Daylighting Levels - amount of available daylight measured in Lux (being lumens per square metre).
    • Electric Light Levels - amount of light available from artificial sources, measured in Lux.
    • Overall Light Levels - includes both daylight and artificial lighting to determine overall light levels in Lux.
    • Illumination Vector - indicates the dominant general direction from which the available light emanates at each point of the analysis grid.
  9. The analysis grid allows for a greater number of options for how the data is displayed within the 3D editor and Visualise windows. Experiment with the Analysis Grid and Visualise control panels to explore the different possibilities available.

This image was created using different options under the Analysis Grid and Visualise control panels.
This image was created using different options under the Analysis Grid and Visualise control panels.


  • Ecotect uses the Point-By-Point method for determining artificial light levels within an enclosure. This simply calculates the sum of contributions from all light sources actually visible from each measurement point. The contribution of diffuse light is not calculated in this method. Thus, the lighting levels produced using this algorithm are to be used only as a guide during initial decision-making as they provide a relative scale from which to measure the effects of different model changes.
  • If necessary, Ecotect can export your model to Radiance for a more comprehensive lighting analysis.
Artificial Lighting
Ecotect Tutorial : Calculate Artificial Lighting using Points


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Calculate Artificial Lighting using Analysis Grid

comment posted by MLH :: 11 April 2008 - 1:21pm

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