LED lights have a high efficiency compared to conventional light sources. Nevertheless, some LED light sources become very warm in certain situations. GU10 lamps and recessed spotlights in particular often generate a lot of heat. Here you can find out why some LED lamps have a high heat output and what you have to pay attention to.
LED light heat generation
Compared to old incandescent and halogen lamps, the LED technology has become much more efficient. The old light sources could not be touched when switched on without burning. Due to the high efficiency of the LED lamps one could think that they hardly produce any waste heat. Unfortunately this is a dream come true, because even with current LED technology there is still a certain amount of waste heat.
Heat dissipation from incandescent lamps and LEDs
The heat development of LED lamps is significantly lower than that of old incandescent lamps. Incandescent lamps generate only about 5% light from the energy fed in, the remaining 95% is converted into heat. With current LED lamps, things look much better. Here about 40% of the used energy is converted into visible light and only 60% into heat.
The percentages show the difference in heat generation between the two lighting technologies. It becomes even clearer when comparing two lamps of the same brightness:
- 60W incandescent lamp with 730 lm
- 6W LED illuminant with 730 lm
The incandescent lamp converts 95% of the energy used into heat. The LED illuminant achieves an efficiency of 35% and converts 65% of the used energy into heat.
Incandescent lamp: 60W · 0.95 (95%) = 57W Heat output
LED: 6W · 0.65 (65%) = 3.9W Heat output
The heat loss of the incandescent lamp is almost 15 times as high as that of the LED.
Do LEDs generate infrared heat?
In the example above, the incandescent lamp generates 57W of heat loss. This is emitted into the environment in the form of invisible infrared radiation. This also causes the lamp glass to heat up to such an extent that you would burn yourself immediately if you touched it. LED lamps do not produce infrared radiation. Therefore you can also touch bright LED lamps without burning yourself. But where is the waste heat?
The 3.9W heat loss from the example is mainly generated in the light emitting diode and to a small extent in the LED driver. The LED is a semiconductor. Its heat loss is not radiated by itself, but must be dissipated via a suitable cooling solution. Otherwise the LED would die of heat. If the operating temperature is too high, the lifespan of the light source also decreases.
Also LED lights and illuminants have a certain heat development. However, this is much less than with the old light sources. In addition, the power loss is not radiated in the form of infrared heat, but must be dissipated from the lamp via a heat sink.
How big is the LED heat output?
LED lamps and illuminants can heat up differently. This mainly depends on the following points:
- Light output
The waste heat from low-power luminaires is usually so low that it can easily dissipate into the environment. Brighter lamps with a higher luminous flux naturally produce more power loss. A good integrated cooling of the LED is very important here. A high efficiency of the LED lamp ensures a good ratio between light output and power dissipation.
The size of the LED light source also has an indirect influence on heat generation. In small light sources there is less space for heat sinks, which is why they generally become warmer. The location where the lamp is installed determines how well the heat loss can be dissipated into the environment.
Retrofit vs LED luminaire
With the retrofit LED illuminants the old illuminants can be easily replaced. The larger the design, the easier it is to dissipate the heat loss. Heat generation is therefore very low with E27 lamps. On the other hand, retrofit lamps for G4 or G9 pin bases have a very small design. There is hardly any space left for an adequate heat sink.
Despite LED technology, some of these very small lamps therefore become very hot and there is a risk of burns when touching them. In contrast, the heat development is less problematic with native LED lights. Here the LEDs are integrated into the luminaire right from the start. The LED and the luminaire form a single unit, which allows a better cooling concept to be implemented.
IN practice small illuminants become warmer due to the poorer cooling possibilities.
Heat generation from LED spots and recessed spotlights
The heat generated by recessed LED spotlights or spots can become problematic under certain circumstances. Recessed spotlights, for example, are recessed into the ceiling and can primarily dissipate their waste heat downwards into the room. A good metal construction of the spotlight supports the heat dissipation.
In order to keep the heat development of the LED spotlights as low as possible, the number of spotlights can be increased and the power per spotlight reduced. Instead of 5 spots with 800 lumens each, 8 spots with 500 lumens each can be installed for the same brightness. This reduces heat generation in each individual spotlight.
In order to further reduce the heat output in the spotlight, 12V low-voltage spots can be used. These usually have a lower heat output than the 120V variants. In a low-voltage recessed spotlight, the only power loss occurs in the LED chip and in the driver. The heat loss of the power supply unit does not occur in the spotlight, but in the separate LED transformer.
By increasing the number of spots with a lower output, the heat loss per spot can be reduced. With low-voltage spotlights, the power supply losses can be transferred from the spotlight to the transformer.
Heat generation from GU10 lamps
LED GU10 lamps are a classic replacement solution for old GU10 halogen lamps. The heat generation depends strongly on the installation situation. If the GU10 LED is installed in a spotlight without lamp glass, the waste heat can easily be radiated to the surroundings. When the illuminant is used in a lamp glass or recessed spotlight, heat generation is usually much higher.
The use of 120V GU10 lamps with an integrated power supply tends to result in an even higher heat output. Particularly with suspended lamps, the heat loss can only be dissipated to the socket via the base. If the lampholder is in a recessed spotlight, the result is often a high operating temperature with reduced lifespan.
The heat development of GU10 LEDs with high light output and unfavorable installation situation can be problematic. Native LED spotlights are a good alternative due to the better cooling concept.
LED lamps without heat generation remain a dream 🙂 After all, the heat loss is very low compared to old light sources. The amount of heat generated depends greatly on where the lamp is installed. In order to further reduce heat dissipation, you should ensure that the LED lamp has a good degree of efficiency.