Ecotect provides a number of different methodologies for calculating the daylight factor of a given space. This tutorial provides an introduction on how to perform and display a daylight factor calculation using the analysis grid.
You will need about 30 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 Daylight training module.
To complete this tutorial, download the DaylightExample.zip Ecotect file available in the File Attachments section of this tutorial. If you have previously completed the Daylight Factor Using Points tutorial, you may wish to have this model available for comparison purposes.
- Open the DaylightExample.eco file. The model consists of a single zone with three different shaped windows in one of the walls. Note, however, that the area of each window is the same.
The DaylightExample Ecotect model.
- Daylight factor calculations vary depending on the geographic location of your model. To set the location for your model, click on the Project tab to the left of the main window. In the Site Location section of the screen, choose your location by clicking on the Find button and searching for your city by name. Double-click the required city, and the latitude and longitude will be entered as the site location. Close the Location Tool window.
Select the geographic location for your model under the Project tab.
- We now need to configure the analysis grid for use in the daylight factor calculation. Click on the Analysis Grid tab to the right of the main work area to display the analysis grid control panel.
Click on the Analysis Grid Control Panel.
- The analysis grid settings may look a bit overwhelming at first, but there's actually only a few things you need to set before you can start using it. Start by click on the
button, which will turn on the analysis grid in your model.
Turn on the analysis grid.
- If your analysis grid is orientated vertically instead of horizontally, have a look under the Grid Position section of the control panel, and make sure that the axis value is set to XY. This should sort it out.
If your grid looks weird, check the Axis option is set to XY.
- We now need to adjust the analysis grid to suit our model, both in terms of size and grid divisions. To fit the analysis grid to the zone, select the floor plane of the zone. Then click on the Fit to Selected Objects button and select the Fit Grid in Current Axis (2D) sub-option. This should resize the analysis grid to correspond with the zone floor (Note: the analysis grid will be a bit smaller than the zone, for reasons only Andrew can explain).
Click on the Fit to Selected Objects button.The resized analysis grid.
- To set the vertical height of the analysis grid, go to the Grid Position section of the analysis grid control panel and set the offset value to 700. This sets the analysis grid at around desk height.
Set the grid offset to 700.
- To configure the number of divisions used for the analysis grid, click the
button. Set the number of cells as shown and click Ok (note that the Z number of cells doesn't really matter for this tutorial). The grid divisions in the model will update accordingly
Set the number of cells as shown.The analysis grid divisions updates accordingly.
- Now we can perform the daylight factor calculation. Go to the Calculate...' menu and select the Lighting Analysis item.
Select the Lighting Analysis item from the Calculate menu.
- The Lighting Analysis Wizard dialogue box appears on screen. As we haven't put any artificial lighting in our model, select the Natural Light Levels radio option and then click Next.
Select Natural Light Levels and click Next.
- The wizard now prompts you to specify where light values should be calculated. As we are using an analysis grid, select Over the Analysis Grid and click Next. Don't worry about the Use Full 3D Extents of Analysis Grid checkbox option.
Select Over the Analysis Grid and click Next.
- Now set the precision level for your daylight factor calculation. Naturally, the more precise the calculation, the longer Ecotect takes to complete the analysis. Click Next once you're done.
Set the precision level for the calculation.
- Set the Design Sky and Luminance Distribution for the calculation. Because you specified the geographic location at the beginning of the tutorial, the Design Sky should already be set. As for Luminance Distribution, this is generally left on Overcast Sky Condition, unless you have reason to believe Uniform Sky Condition is more appropriate (ie. for location near the equator). Click Next.
Set the Design Sky and Luminance Distribution.
- Now we specify the room-based settings. Select Average (x 0.90) window cleanliness, and check Calculate Room-Averaged Window Areas. Click Next.
Specify the room-based settings.
- We're almost there. The wizard will now display a summary of the settings you have selected. Make any adjustments if required, and then click Ok.
The wizard summarizes your calculation settings.
- Just before Ecotect starts the daylight factor calculation process, a dialogue box may prompt you to recalculate the inter-zonal adjacencies in your model. It's generally a good practice to do this, so click Ok.
This dialogue box may appear. Click Ok to recalculate interzonal adjacancies.
- Ecotect starts performing its calculations, and then displays the daylight factor values for the analysis grid you specified. A legend appears in the top right hand side of the main work area showing the range of values calculated.
Ecotect calculates and displays the daylight factor analysis grid.
- To change the attribute/units being measured, go to the Grid Date & Scale section of the control panel, and then select from the first pull-down menu. The analysis grid updates accordingly.
- If you change the minimum or maximum values for the analysis grid, be careful that this doesn't distort the representation of the grid data (ie. reducing the range to make the zone seem brighter).
- If you change the size and/or divisions of the analysis grid under Grid Management, you will have to perform the lighting analysis again.
- Even though the three windows have the same surface area, note how the different window proportions and heights impact on the penetration of daylight into the space.