By Lisa Nguyen, BSCS Candidate, Georgia State University

Executive Summary

Overview

Light ARchitect is a lighting simulation app created by Cooper Lighting Solutions for use by its agents, architects, specifiers, and any other customers who are involved with lighting design:

• The app enables users to create and visualize lighting designs instantly for exterior projects of virtually any size, from small parking lots to complex sports fields.
  
  
• A built-in customized catalog helps users find the right fixture.
  
  
• The application is accessible across platform at any time, uses colorful intuitive visuals and tools, and integrates Google Maps to further amplify the visualization of the outcome.
  
  
• The app can also be used to collaborate remotely with stakeholders.
  

Several customer case studies available on the Cooper Lighting Solutions website demonstrate the application’s integral role in creating faster, more efficient lighting layouts and in helping to close sales.

Photometric calculations are a cornerstone capability that contributes to Light ARchitect’s success. Colorful heatmaps enrich photometric calculation results and simplify decisions with a single glance.

With such a convenient and beneficial tool, the question arises: How definitively accurate is Light ARchitect’s photometric calculations algorithm compared to the standardized tools used in the lighting industry?

Prior to this data collection and analysis, no studies had been conducted targeting this topic.

Methodology

For data collection, the comparison is between Light ARchitect and Light Analyst’s software Luxiflux.

Luxiflux software is very similar to Light ARchitect; photometric calculations assume surfaces are flat, and access to Cooper Lighting Solutions fixture IES files are hassle-free.

• One fixture configuration type was manipulated and observed at a time while preserving the Light ARchitect default fixture settings in both software.
  
  
• Required calculation boundary parameters in Luxiflux were changed to match Light ARchitect.
  
  
• Photometric calculation results for both software were recorded then compared using the percentage difference of Light ARchitect to Luxiflux.

Key Findings

• Light ARchitect photometric calculations algorithm compared to Luxiflux on average differs less than 5% across every calculation type where fixture configurations pertain to mounting height, vertical tilt, arm length, color, and multiple heads configurations.
  
  
• For optics configuration, the algorithm on average differs less than 3% for average illuminance and average/min illuminance, and less than 10% difference for max illuminance and max/min illuminance.

Recommendations

• Light ARchitect photometric calculations algorithm is reliably accurate to one industry-standard tool.
  
  
• The application is completely free, provides both visually appealing and functional services, and proves its significant impact via customer case studies.
  
  
• I recommend the application to any user, regardless of expertise, who wishes to design a lighting layout.

Methodology and Results

Tools Used in Data Collection

Tools used in this study include Light ARchitect Satellite View on the browser, accessed at LightARchitectApp.com, and Light Analyst’s Luxiflux accessed through Cooper Lighting Solutions’ publicly available IES repository.

Luxiflux was chosen as the basis for comparison for several reasons:

• The software is reputable. It’s created and supported by Light Analysts, creators of industry standard, illumination engineering software, including AGI32.
  
  
• The software offers nearly identical customizable configurations as Light ARchitect. Its photometric calculations assume surfaces are flat just as Light ARchitect does.

Collection Method

• Photometric calculations of the observing manipulated variable were completed on Light ARchitect first and recorded.
  
  
• Then, Luxiflux was used, with fixture configurations set to match the fixture configurations used with Light ARchitect.
  
  
• Locked fixture settings in Light ARchitect that were not visible in the user interface included light loss factor (0.864) and max to min footcandle ration (capped at 10 to 1 footcandle).
  
  
• In the calculation screen of Luxiflux, two photometric values (min and max to min ratio) calculated from Light ARchitect were input into Luxiflux’s mandatory calculation boundary parameters.
  
  
• The average parameter in Luxiflux was untouched.
  
  
• Photometric calculation results from Luxiflux were recorded.
  
  
• The average illuminance, max illuminance, average to min illuminance, and max to min illuminance were compared using signed percent difference (Light ARchitect to Luxiflux) to show direction.
  
  
• For the overall averaged result of each configuration type, the absolute value of each percent difference was summed, then averaged for each photometric calculation type per data table. (Table graphics found below.)
  
  
• When adding a new fixture to Light ARchitect, the default values for fixture configurations were based on the default settings:
  • Mounting height: 30 ft
  • Vertical Tilt: 0 degrees
  • Arm Length: 1ft
  • Number of heads: single head

The choice of fixtures for this study was based on several factors.

Optics/Multiple Heads: Gan Galleon was chosen as it contains the most diverse IES files and the most diverse optics. This fixture is ideal for checking most optics in single and multiheaded scenarios.

Mounting Height/Vertical Tilt/Arm Length/Color: Fixtures were chosen based on popularity – the four used most often in successful layouts were selected. To further diversify the data, the two most popular optics types were used by all four fixtures that were chosen.

IES Files: The type of IES file chosen was based on the proximity to 20,000 lumens for each fixture. And 3000K color was selected as it is the most available fixture color across all fixtures.

Results

Overall, Light ARchitect photometric calculations algorithm undercalculated or overcalculated values by less than 5 percent for mounting height, vertical tilt, arm length, color, and multiple fixture heads across each configuration.

The algorithm undercalculated or overcalculated optics by less than 3% for average illuminance and average to min illuminance. The difference is shared across all optics.

The gap is widened to 10% when calculating max illuminance and max to min illuminance. The 10% difference is not equally shared across all optics; optics with excessively skewed shapes, such as SLL starting from the source, result in the largest difference while other optics, such as 5MQ and T2, share the same percent difference as the other photometric values.

If excessively skewed optics were ignored (SLL, SLLHS, SLR and SLRHS) then the average percent difference improves to 5%. This percentage is significantly more relevant to users as the aforementioned optics are rarely used. In contrast, the other 24 optics serve general purposes and have greater usage.

Discussion and Recommendations

Lighting designs created in the free application can be expected to reliably reflect photometric values to one industry-standard tool. The calculated values can be trusted as a project springboard to fulfill any regional standards particular layouts may require. Furthermore, Light ARchitect’s user-friendly design empowers all users, regardless of expertise, to create lighting layouts. The intuitive heatmaps simplify decisions to a single glance. To use the tool, minimal effort is required; the need for extra training is nullified.

Now, with tangible evidence regarding the accuracy of photometric calculations, I confidently recommend using the application for kickstarting outdoor lighting projects.