Help


click here for Calculator Video Tutorial


Accessing the Calculator

To get to the calculator, select from the categories on the left of the Home page until the last remaining category is replaced by a list of luminaries that meet your criteria.

Click on the desired lumainaire, or check the box next to multiple items and press the 'Calculate selected items' button.


Using the Calculator

The calculator needs Flash to run.


When the calculator opens, click on the tabs on the left to open that section. Typically for first time visits, go through the input sections top to bottom. Once familiar with the operation, you can skip many of the input items and get results in seconds.

The calculator will compute instantly when it has enough input.

Each input section is shown below.


The drop down menu in the Luminaire section allows you to make instant comparisons between luminaires if you selected multiple items (see above, 'Accessing the Calculator'). Use the dropdown menu to select one of the loaded luminares. Light Loss factor is a fraction (between 0 and 1) that describes how luminare output decreases with time.


Enter your room dimensions in the Geometry section. It will highlight the graphic model when you hover over the input cells to make the dimensions clear.


Reflectances are expressed in percent. If your surfaces have lower reflectance (dark colours, matte finish) you will need more luminaires to achieve the same light ouput. The Coefficient of Utilization (CU) and effective cavity reflectances are computed and displayed.


Specify– enter a desired average illuminance level, number of luminaires or lighting power density. For example, if your input is illuminance the calculator will suggest how many luminaires to use and display the resulting LPD. Options include the ability to compute based on minumums, maximums and target.


The Advanced Layout section provides constraints on luminaire position by Rows & Columns, Spacing, Wall Spacing, Ceiling Grid or Continuous rows or columns.

Select the checkbox to override the calculation default and enter the desired setting for that parameter.

The spacing criteria is the maximum distance you can have between luminaires and still maintain a uniform illuminance on the work plane. If the numbers are red, you have exceeded the spacing criteria and you will not have uniform illuminance. Solutions include using a wider beam angle, increasing average illuminance or increasing mounting height.


The Advanced Luminaire information is automatically derived from the photometric files. We recommend you don’t override the defaults. However, it allows some simple prorating for the calculations based on Lamp Lumens and Luminaire Wattage.


Click the Preview button and complete user fields such as Project title and Description. In some browsers you may have to use the Scroll Page buttons.