LED is passive or active cool

Cool LEDs! Why cooling light emitting diodes is so important

It's very simple: the better the thermal management of an LED lamp, the greater its light output and the longer its service life. Therefore, when using environmentally friendly semiconductor technology, adequate cooling is always important. Because LEDs only convert around 35 percent of electrical energy into visible light - the rest into heat. And this heat has to be dissipated via the circuit board and a heat sink in order to avoid exceeding the maximum permissible working temperature of LED chips over a longer period of time and the associated heat death. We therefore explain to you what you have to consider when buying and installing LED recessed lights.

Not to be seen in recessed downlights, but absolutely indispensable: the black cooling frame, which is absolutely necessary for LED lights to dissipate heat. Photos: Preacher

At least since the Europe-wide ban on incandescent lamps, LEDs have been on everyone's lips, because their advantages over well-known light sources are obvious: LEDs are significantly more energy-efficient, convince with their good light output, they are many times smaller and also more durable than conventional light sources. Provided that LEDs have a sufficiently large heat sink and are installed correctly.

Good thermal management prevents LEDs from heat loss

With passive cooling, the heat sinks of LED lamps and luminaires should always be large enough to be able to remove the heat generated by the LED modules after commissioning. Nevertheless, the space advantage that the small LEDs have over incandescent and energy-saving lamps must of course not be completely lost. This is precisely why the developers have switched to using so-called extruded heat sinks made of thermally conductive aluminum for recessed lights and downlights, in the form of a so-called cooling frame or with fins arranged in a star shape. This design increases the surface of the heat sink many times over, which in turn has a positive effect on the heat dissipation to the environment. In terms of weight, price and mechanical strength, the aluminum heat sink can hardly be surpassed and has therefore long been the standard in luminaire production. Alternatively, there are much more efficient, but at the same time much more expensive, heat sinks made of ceramic or copper. The customer is once again spoiled for choice, but in most cases opts for the aluminum variant because it offers the better price-performance ratio.

Active or passive cooling? That depends on the purpose

There are now many ways to integrate complete LED lights very discreetly into the heat sink and vice versa also heat sinks into the LED lights so that it is no longer visible. The shape and size of the heat sink depends not only on customer requirements, but also on the maximum LED chip temperature, the permissible weight of the luminaire and, last but not least, the available installation space. If the LED is even actively cooled - i.e. by an electric fan or the supply of cooling liquid - an even more compact design of the light source or the luminaire is possible. In contrast to passive cooling, active cooling by a fan is always accompanied by a sometimes clearly audible noise level, which can be perceived as annoying, especially when used in your own four walls. And: If the fan is defective, this will always have a negative effect on the LED light, which will quickly be damaged due to the lack of cooling and death from heat.

Cooling frame enables faster heat absorption and better heat distribution

There are also LED lights with a smaller heat sink for low installation heights. For example the model P.34.14 from Prediger.

With our Prediger downlights and recessed lights, we therefore rely on the much more reliable passive cooling with the help of a cylindrical aluminum body that completely encloses the cooling frame. This construction enables a much faster heat absorption and thus a better heat distribution, which in turn has an extremely positive effect on the light output and the service life of our LED lights. However, in order to still meet the different requirements, we have recently started offering our round downlights with a particularly flat LED module in addition to the standard version. The two Prediger lights P.34.13 and P.34.14, for example, are particularly suitable for ceilings with a low installation height. However, it is very important to always observe a few basic safety distances during installation. At the installation point, there should always be 3, rather 5 cm space above the heat sink. All around the luminaire as well, so that the heat can be dissipated properly, the LEDs function properly even during prolonged operation and thus achieve their average service life of 20,000 hours.

Timely planning of recessed lights is the be-all and end-all

Before installing the luminaire, the condition of the ceiling must be checked. Concrete ceilings are usually suitable for the installation of recessed lights without any problems, because the building material concrete is non-flammable and at the same time offers enough capacity to dissipate the heat of the LED module properly. If, on the other hand, there is insulation material in the false ceiling, this must be removed generously around the luminaire; a mounting pot for the luminaire is then also urgently required. Particular caution is of course also required with wooden ceilings. In order to be on the safe side, early and professional lighting planning for downlights is always recommended - if possible before construction, so that the required installation pots can be embedded in the ceiling. Retrofitting downlights is in principle possible in many cases, but it is much more planning-intensive and therefore always associated with avoidable additional costs.

Tip: If you need help with lighting planning, the Prediger lighting consultants will be happy to help and advise you.

When installing LED luminaires, there must be enough space in the ceiling, after all, the luminaire and driver emit a lot of heat when used for a long time. Graphic: preacher