FALSE! LEDs do produce heat, despite what some LED companies might claim. In fact, they can generate as much heat as other types of lighting such as high-pressure sodium (HPS), metal halide (MH), incandescent, or even a space heater of the same wattage. Even if LED lights were 100% efficient at converting electricity to light, they would still produce heat. Let's explore why.
Why LEDs Produce Heat
There are three main reasons why LED lights generate heat:
Imperfections in the Crystal Structure
LEDs produce heat due to slight imperfections in their crystal structure. When electricity passes through the diode, some of it doesn't get converted into light and instead turns into heat.
Internal Reflection
Another cause of heat production in LEDs is internal reflection within the diode. For highly efficient LEDs, about 80% of the electricity is converted into light, but only around 60% of that light actually exits the diode. The remaining light that doesn't escape gets re-absorbed by the diode and converted into heat.
Read more: 8 Best Light Stands in 2024 (For Studio amp; Outdoor Shoots)
Light Absorption
LED lights also produce heat through light absorption. As the light leaves the LEDs and interacts with objects in the grow space, it eventually gets absorbed and converted into heat. In a closed system where none of the light exits the grow space, almost all of it will ultimately turn into heat.
According to the Law of Conservation of Energy, energy cannot be created or destroyed, only transformed. So, when light is absorbed by objects in the grow room, it either gets converted into chemical energy stored by the plants or it turns into heat.
Debunking the Myth
Where does the myth that LEDs don't produce heat come from? Here are three reasons why people believe this misconception:
Less Infrared Radiation: LEDs direct far less infrared radiation at plants compared to HID lighting. High-pressure sodium (HPS) or metal halide (MH) lights operate at much higher temperatures, leading to more infrared radiation. In contrast, LEDs operate at lower temperatures, resulting in significantly less infrared radiation directed towards plants.
Higher Efficiency: LEDs are more efficient than other types of lighting, requiring fewer watts to produce the same amount of light. Since fewer watts are used, less total heat is produced in the grow space.
Better Light Utilization: The light produced by LED grow lights is more efficiently used by plants, meaning they require less of it. With the double efficiency of LEDs producing more light per watt and more light being photosynthesized, it is common for people to replace a 1000w HPS with a 600w LED grow light, resulting in 40% less heat in the grow space.
Ideal Temperature for Growing Plants Indoors with LED Grow Lights
The ideal temperature for growing plants indoors with LED grow lights depends on various factors such as the type of plants, the use of supplemental CO2, and the stage of plant development. Generally, for flowering or generative growth, it's recommended to have a daytime ambient air temperature around 83-85°F (28-29.5°C). The nighttime temperature should be about 10 degrees lower than the daytime temperature.
Read more: Why Are My LED Christmas Lights Dim? Let's Find Out!
Calculating Grow Light Heat Production
Calculating the amount of heat produced by a grow light is straightforward. You take the total wattage used (wall plug wattage) and multiply it by 3.41 to get the total BTUs (British thermal units) produced per hour. This applies to all types of lighting, including LED, HPS, MH, and others.
Example: 400w * 3.41 = 1364 BTUs/hr
Managing Indoor Grow Room Heat
While the heat generated by one or two LED grow lights is manageable, it's essential to have proper air circulation and ventilation in your grow room. Without adequate ventilation, several issues can arise, such as dust settling on plants and reducing their photosynthetic efficiency, increased humidity leading to decreased transpiration and mold growth, and lower levels of carbon dioxide affecting photosynthesis. Ventilation, circulation, and filtration are recommended to reduce smells, dust, and the exchange of pathogens.
Read more: Do LED Lights Get Hot? Everything You Should Know
Frequently Asked Questions
Q: Do LED grow lights produce more heat than other types of lighting?
A: LED grow lights can produce as much heat as high-pressure sodium (HPS), metal halide (MH), or incandescent lighting of the same wattage.
Q: Why do some people believe that LEDs don't produce heat?
A: LEDs are often perceived as not producing heat because they direct less infrared radiation at plants, operate at lower temperatures, and are more efficient, resulting in less total heat in the grow space.
Q: What is the ideal temperature for indoor plants grown with LED grow lights?
A: The recommended daytime ambient air temperature is around 83-85°F (28-29.5°C) for flowering or generative growth. The nighttime temperature should be approximately 10 degrees lower.
Q: How can I manage heat in my indoor grow room?
A: Proper air circulation, ventilation, and filtration are essential for managing heat in your grow room. These measures help prevent issues such as reduced photosynthetic efficiency, increased humidity, and decreased carbon dioxide levels.
