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The importance of efficacy


Noun formal

the ability to produce a desired or intended result.

How is efficacy used in lighting?

In terms of lighting, efficacy can be measured by the number of lumens produced per watt of energy used (lm/W). A light engine with a higher efficacy will take less energy to produce the same number of lumens as a light engine with a lower efficacy.

Why is it important?

A light engine with a high efficacy will be able to produce more lumens per watt of energy used. This means that light engines with a higher efficacy are more efficient and are cheaper to run than a light engine with a lower efficacy with the same lumen output. Therefore, efficacy can be very important with luminaires which are run for long periods of time (such as street lighting) or for customers who are looking to reduce their energy costs.

How is efficacy achieved?

In a light engine, a higher efficacy is achieved by effective thermal management of the LED(s). Contrary to popular belief, LEDs do get hot and get less efficient the hotter they get. There are several ways in which we can look at cooling down these LEDs. Firstly, the choice of material for the PCB and dielectric is key for efficient thermal transfer. For example, an aluminium backed PCB will have a better level of thermal transfer then an FR4 board, and therefore will have a higher efficacy. These effects can be improved by making sure the PCB contains adequate copper flooding, correct solder mask to complement the desired optical output and the correct thermal solder paste and processing parameters to remove micro air voids. To increase efficacy, you can also look at other factors, such as optimising how the light engine is connected to its heatsink (via phase change material or thermal pad) and selecting more efficient LEDs to achieve the desired output.

How does efficacy apply to the Pro-LED Linear series?

When searching for a standard Zhaga format light engine, one would typically find efficacy values between 160-170 lm/W. The Pro-LED Linear series offers an efficacy of 171-210 lm/W across three variations; Standard, High Performance and Premium. This means that the Pro-LED series can offer a light engine that is both in your price range, while providing you a much more efficient and energy saving product. If you can’t find a product to meet you desired output however, at Universal Science we utilise our 15-year long experience in the thermal management and lighting industry to work closely with our customers to design and produce bespoke light engines to fit our clients needs. Our experienced technical team can help you choose the most efficient LEDs and design PCBs with any efficacy value to suit your needs. We also have close ties with many optic manufactures, allowing us to help you increase your Luminaires efficacy even further.

How can I find out more?
The data sheets for our Pro-LED Linear series can be found here.

If you would like to discuss bespoke light engines or thermal products, please contact us at:


01908 222211