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Horticutral Lighting
As we all know, LED lighting performance is affected by heat. It is claimed that LEDs has a wide range of suitable temperature from -30 °C to 60 °C and the optimal temperature for LED lighting is 25 °C. High ambient temperature will degrade the efficacy of LED lighting performance, resulting lower power conversion from electricity to light. If high ambient temperature weaken the performance of LEDs, what about the low temperature? Would the performance of LED lighting improved by colder temperature? We would like to take a look at the LED lighting performance in cold weather.
There are two main considerations of the performance of LED lights in cold weather - the capacity to start properly and operate stably. Generally speaking, cold weather refers to colder temperature. Rain, ice and snow are also happened in cold weather. To figure out whether LED lights perform well in cold weather, we have to know how LEDs work and the relationship between temperature and LED lights performance.
How LED work
A LED (Light-emitting Diode) is a semiconductor device that emits light with current flows. A die is the active area of LED. Plastic or ceramic housing encase one or many dies. When LED is forward-biased, electrons are able to recombine within the electron holes, releasing energy in the form of photons. This effect is called electroluminescence. The core of a LED is the wafer composed of P-type semiconductor and N-type semiconductor, with a transition layer between them called PN junction. In the PN junction of some semiconductor materials, the injected minority carriers compound with the majority carries will release the excess energy in the form of light. Therefore, LED is able to convert electrical energy directly into light energy. The color of the light is related to the energy required for electrons released. The more energy released, the shorter the wavelength of light emitted.
How cold weather affects LEDs performance
LEDs start up normally in cold weather
The capacity to start lighting in cold weather is important for some areas. A LED is a semiconductor without insulator or conductor, which means free electrons in a negatively charged component transfer to holes in positively charged components with the help of electrical energy. Light is emitted when the forward activity happens. LEDs are warmed up by the current flowing through them. Since LED reply on electronic driver rather than heat to turn on, LEDs are able to starting up in cold weather. Moreover, electronic drivers can be used from even in -30 °C. Therefore, LED lights can perform well in cold weather.
Lumen output does not affected by cold weather
Vary from conventional lighting methods, LED lights create less heat. Junction point temperature and ambient temperature are therefore lower than conventional lights. Lower junction and ambient temperature promote current conducting. Then lumen output is improved due to less stress on driver. As a result, cold weather will not affect the performance of LED lights in common conditions.
The following graph shows the relationship between junction temperature and relative luminous flux of a LED fixture. As it shown in the graph, there is a steady decrease of relative luminous flux with the increase of junction temperature. In other words, colder temperature will not decay LED lighting performance.
Considerations of LED lighting performance in cold weather
Except for LEDs, lighting performance in cold weather is also affected by materials, sealing and electrical equipment of LED fixtures.
Materials of LED fixtures
LED lighting performance is threaten by the cold weather as most material of LED fixtures are greatly impacted by low temperature and water. Thus, the material of LED fixtures is critical for LED lighting performance.
The components of LED fixtures should be made of high quality material. For example, the glass is supposed to be breakable glass, allowing the LED fixture to withstand sudden temperature changes. Metal, aluminium, carbon steels and plastic are widely used as the major material of LED fixtures. They may being more brittle and decay due to the low temperature. Manufactures use enclosure housing to protect the materials from impact of low temperature. Waterproof and corrosion resistance are also important for the materials of LED fixtures.
Sealing of LED fixtures
Sealing should also be taken into account for the lighting performance in cold weather. Seals are need to be poured and set at the temperature over 0 °C. It meas it is difficult to seal in cold weather with the temperature lower than 0 °C. Low temperature may cause the distortion of LED fixture components, making the interior component suffer the risk of exposure.
Additionally, field-installation are hard to achieve proper installations of seals due to the low temperature. To solve the problem, parts of LED fixtures are factory-sealed in advanced, reducing the need to seal in cold temperature condition. Factory-sealed increase the safety of electrical part of fixtures and make it easier for installation.
Electrical equipment of LED fixtures
Wire and cable are the electric equipment to transfer electricity to LEDs for lighting. Because LED do not create much heat, snow and ice may cover the LED fixtures in cold weather and cause serious problems with lighting performance.
Except for snow and ice, LED fixtures are also faced with the risk of rain. Factors that are mentioned previously have significant influence on wire and cable. Cables are recommended to be stored at temperature over 10 °C before installing. The heavy stress and low temperature of snow, ice and rain damage the insulation on wire and cable, blocking the electricity transmission possibly. In consequence, installation of cables should be slowly and carefully.
Conclusion
LED Lights can perform well in cold weather. Since LEDs do not need heat but electricity to turn on, they function normally in cold weather. Furthermore, lumen output of LEDs does not affected by cold weather. LEDs create less heat than conventional lighting. Cold weather releases the stress on drive and then improve the lumen output generally.
However, Lighting performance of LED lights is not only related with LEDs, but also the material, sealing and electrical equipment of LED fixtures. Cold weather greatly impacts the performance of them. Material may be more brittle due the cold weather, while it is hard to seal in cold weather. Electrical equipment, such as wire and cable, are more likely to damaged due to the cold weather. Choose the LED fixtures that are typically designed for cold areas will yield twice the result with half the effort. AGC provides LED lighting solutions for cold storage.
