Passive cooling of high output LEDs in living walls

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Living walls are vertical surfaces carefully designed to support a range of living plants that improve aesthetics and air quality within buildings, and are being increasingly adopted by architects and building owners. Living walls require supplemental lighting to provide the plants with sufficient light in order to survive and thrive. LEDs are often the most appropriate light source for living walls. LED technology is improving rapidly, and each new generation of LED produces greater amounts of light, increasing the options of the living wall lighting designer. However, the latest LEDs produce more heat as well as light, and lighting systems must be carefully designed to ensure that heat will be safely removed from the LED itself to prevent overheating that reduces LED performance and life. It is important to note that living walls lighting must not only provide appropriate lighting for both plant maintenance and viewing, but the system itself must be architectural appropriate and blend seamlessly into the architecture of the installation location. Nedlaw Living Walls and the University of Guelph plan to investigate potential methods of cooling higher performance LEDs, with a focus on determining configurations of LEDs and associated heat sink materials that will continue to allow passive cooling of the lighting system. This project will also investigate the limits of passive cooling of LEDs in a living wall lighting context, to identify if there is a point at which it will be necessary to switch to active cooling (e.g. water circulation, fans) as future generations of LEDs continue to produce more and more heat, but need to be maintained at similar temperatures to current LEDs. The researchers conduct experiments on lighting modules using themocouples, helium bubble flow visualization and infrared cameras, and simulations of current and future systems using computational fluid dynamics software. The results of this research will give Nedlaw Living Walls important quantitative information about temperatures and heat transfer within current lighting system designs, and provide guidance for planning future generations of living wall lighting systems, while also identifying areas for future in-depth research.