Investigating the Unexpected Color Change in LED Lighting
Introduction
As an Executive Lighting Designer and Team Leader at Meinhardt Light Studio with experience in overseeing lighting installations for more than 100 projects, I've encountered a wide range of challenges. However, a recent office building project in Southeast Asia presented a unique and perplexing issue. While the fa?ade lighting, incorporating a DMX control system, was executed flawlessly, the interior lighting, specifically in the main lobby and corridors, exhibited a gradual and unexplained shift in color temperature.
The Problem
The office building's main lobby was initially illuminated with 4000K (cool white) LED lights controlled by a DALI dimming system. A month after installation, the light intensity noticeably decreased, and the color temperature shifted to warm white. Despite thorough checks of the dimming system and initial lux meter readings matching calculations, the issue persisted.
Investigation Process
To investigate the reduced lighting intensity, we scrutinized the dimming system. Each light was individually tested for dimming capabilities, and the control signals appeared normal.
To address the color shift, we coordinated with the supplier and installation team to examine the remaining uninstalled lights. These lights displayed the expected bright, cool white color when tested.
Given the height of the ceiling (6 meters), we requested the contractor to set up scaffolding to allow for a direct comparison of the "cool white" and "warm white" lights. Both lights exhibited identical physical characteristics and labeling, clearly indicating a 4000K color temperature. However, upon testing, one light emitted a warm white hue. To understand this discrepancy, we proceeded to disassemble the light's reflector.
Findings and Solution
Upon dismantling the light, we discovered that the adhesive securing the lens to the honeycomb structure was burnt, melted, and discolored to a yellow hue. This degradation of the adhesive had altered the light's spectrum, causing the shift from cool white to warm white.
After discovering the issue, we contacted the supplier, providing evidence of the defective lights. The supplier promptly replaced all affected lights with a new batch featuring a mechanical honeycomb lock, eliminating the adhesive-related problem.
Conclusion
This case highlights the critical importance of comprehensive testing and analysis during the lighting design and installation process. While the initial performance of the lighting system was as expected, a subtle and insidious issue emerged over time. By meticulously investigating the problem from multiple angles, we were able to identify and address the root cause, ensuring the successful restoration of the intended lighting ambiance.
Key Takeaways:
This project serves as a valuable learning experience and underscores the importance of a proactive and problem-solving approach to address unexpected challenges in the lighting industry.