How Are Leds So Energy Efficient?
LEDs (light-emitting diodes) have become the most energy efficient lighting technology widely available today. But LED lights were not an overnight success story. The development of LED technology has taken place over many decades.
The first LED was created in 1927 by Oleg Losev, a Russian scientist who reported on the creation of a new electrical source of light in a Russian journal. However, practical applications were limited for several decades https://en.wikipedia.org/wiki/Light-emitting_diode. It wasn’t until 1962 that LEDs became commercially viable as electronic components, initially emitting low-intensity infrared light. Over many iterative improvements, LEDs grew increasingly efficient and bright enough for lighting applications.
The first high-brightness blue LED was invented in the 1990s, opening the door to white light LEDs. After decades of progress, LED lighting became a truly mainstream lighting option in the 2000s. Today, LED bulbs are up to ten times more energy efficient than traditional incandescent bulbs and last 25 times longer. Let’s explore what makes them so efficient.
How LEDs Work
LED stands for “light emitting diode.” LEDs are semiconductors that emit light through a process called electroluminescence. When voltage is applied to the semiconductor material, electrons can recombine with electron holes, releasing energy in the form of photons or light particles. The color of the emitted light depends on the semiconductor’s material composition and structure.
LEDs contain p-n junctions made of different semiconductor materials. When voltage is applied across the p-n junction, electrons are able to recombine with holes at the junction, causing the release of energy as photons. The wavelength or color of the emitted light depends on the semiconductor materials used. LEDs can be fabricated to emit various colors from red to blue by using differing semiconductor materials.
The development of high-efficiency blue LEDs enabled white light LEDs through phosphor conversion. A yellow phosphor coating on blue LEDs absorbs some of the blue light and re-emits it as yellow, combining to appear white. Adjusting the phosphor composition and ratio of blue light converted allows tuning of the light’s color temperature.
LED Advantages
LED lighting offers several key advantages compared to traditional lighting like incandescent and fluorescent bulbs, making LEDs an appealing option for many applications. One major advantage of LEDs is their extremely long lifespan and durability. Whereas an incandescent bulb may last for 750-1000 hours and a compact fluorescent bulb may last for 6000-15,000 hours, LED bulbs can have a lifespan well over 50,000 hours (Source). The longevity of LED lights is a huge benefit, saving on maintenance and replacement costs over time.
LEDs are also much more energy efficient than traditional lighting. They consume up to 90% less energy compared to incandescent bulbs as they require less wattage to produce the same amount of light output (Source). This efficiency translates into direct energy and cost savings. Furthermore, LEDs give off very little heat, reducing demands on HVAC systems.
The durable nature of LED lighting also provides advantages. LEDs contain no filaments or glass components that can break from impacts. They are highly resistant to external damage from vibrations, shock, and weather. LEDs can even operate well in cold temperatures unlike fluorescent lighting (Source).
Finally, LED lighting provides advantages through design flexibility. The small size of LEDs allows for lighting innovations and customization of light fixtures and lamps. LEDs can also produce a wide range of light colors opening up options for lighting that suits the application.
Energy Efficiency Explained
One of the main reasons LEDs are so energy efficient is they waste much less energy as heat. Traditional incandescent bulbs convert about 10% of their energy to light and around 90% is wasted as heat. Compare that with LEDs which convert over 80% of their energy input into visible light, with only about 20% lost as heat. So LEDs generate very little heat compared to most other types of lighting (Energy.gov, 2022).
Another reason LEDs are so efficient is they emit directional light, focusing their illumination where it’s required. Some LED bulbs utilize light diffusing technology to appear omnidirectional like incandescent bulbs. But inherently LEDs emit light in a specific direction, so almost all of the light shines exactly where it’s intended with minimal losses or wasted peripheral illumination. This precise directional lighting allows LEDs to consume much less power than omnidirectional light sources to achieve the same luminous efficacy in the desired location (Sustainability Vic, 2022).
LED Driver Circuitry
One key reason LEDs are so energy efficient is their use of constant current driver circuits. Unlike incandescent bulbs which run on a constant voltage, LEDs require a constant, stable current to operate properly. Running LEDs on a fluctuating current can cause uneven brightness and premature failure.
LED driver circuits work by regulating the current to the LED, rather than regulating the voltage like a conventional power supply. They employ control circuitry and components like resistors to maintain a steady current even as the input voltage varies or the LED heats up and changes resistance.
This constant current is typically set to just below the maximum current rating for the LED to prevent overdriving it. Sophisticated LED drivers even allow adjusting light levels by changing the current. The end result is an efficient and reliable energy delivery to the LED.
Thermal Management
One of the keys to the energy efficiency of LEDs is how they manage heat dissipation. Unlike incandescent bulbs that emit a lot of infrared radiation and high temperatures, LEDs operate at much cooler temperatures.
LEDs are semiconductor devices that are very sensitive to heat. Too much heat reduces light output, shifts the color spectrum, and shortens the lifespan of the LED. Effective thermal management is critical.
LED bulbs and fixtures utilize metal heat sinks to draw heat away from the LED junction and dissipate it. The large surface area of the heat sink allows for heat to efficiently transfer to the surrounding air. The shape and design of the heat sink can be optimized for maximum heat dissipation.
PCB boards are designed to conduct heat to the heat sink as well. High thermal conductivity materials like ceramics and copper are used. Fans are sometimes used in high power LED fixtures to improve airflow and cooling.
Proper thermal design keeps the LED junction below critical temperature thresholds, enabling high efficiency, consistent light quality, and long operating life.
Light Output
One of the key advantages of LED lighting is the high light output or lumens produced per watt of electricity. This source states that LED technology typically produces 75-110 lumens per watt. In comparison, incandescent bulbs only produce 10-18 lumens per watt. So for the same amount of energy consumed, LEDs produce 4-10 times more light output.
To understand the difference, a 60W incandescent bulb produces around 800 lumens. Whereas a comparable 9W LED bulb produces the same 800 lumens. This is because the LED produces over 90 lumens per watt, versus only 13 lumens per watt for the incandescent. According to this comparison, a 250W incandescent bulb outputs 14,000 lumens, whereas an LED bulb consuming just 30W can produce the same 14,000 lumens.
The bottom line is that for the same light output in lumens, LED bulbs consume far less energy in watts. This drastic difference in efficiency leads to significant energy savings over the lifetime of LED products.
Price Considerations
While LED bulbs are more expensive upfront compared to incandescent bulbs, they provide significant long-term cost savings that make the higher initial price worthwhile. An LED bulb can cost $2-$10 whereas an equivalent incandescent is only $1-$2. However, incandescents burn out after 750-1000 hours whereas LEDs can last 25,000-50,000 hours, meaning you need to replace incandescents much more frequently [1]. When you calculate lifetime costs, LEDs are a clear winner.
For example, replacing a 60W incandescent that’s on for 3 hrs/day with a similarly bright 9W LED, the incandescent lasts 1 year and the LED over 6 years. The incandescent costs $1.50 each time it’s replaced, so 6 replacements over 6 years totals $9. The LED costs $5 upfront and then just $5 over 6 years. That’s an 84% cost savings by switching to LED [2]. While more expensive upfront, LEDs pay for themselves over time through drastically reduced energy and replacement costs.
New Applications
LED lighting is being adopted for a variety of new applications beyond traditional lighting. Some key emerging uses include horticulture, healthcare facilities, and digital displays.
In horticulture, LED grow lights are becoming popular for indoor plant cultivation. LEDs allow growers to customize the light spectrum for optimal plant growth and development. Compared to traditional lighting like high pressure sodium lamps, LEDs run cooler, last longer, and allow more targeted light delivery (1).
In healthcare, LED lighting is being installed in hospitals and medical facilities. LEDs have anti-bacterial properties, do not emit UV radiation, and provide quality illumination for healthcare tasks. Tunable white LEDs also allow staff to adjust light color to suit different purposes (2).
For digital displays and signage, ultra-bright LEDs allow for crisp, vibrant video walls and screens. Outdoor LED displays are extremely durable and visible. From stadium jumbotrons to Times Square billboards, high-power LEDs make modern display technology possible.
With their versatility, efficiency and customizability, LEDs are enabling innovations across many new applications beyond general illumination.
The Future of LEDs
The future of LED lighting looks very promising. According to the U.S. Department of Energy, LEDs are expected to be used in most lighting applications by 2035 due to their superior efficiency and lifespan compared to traditional lighting like incandescent and fluorescent bulbs.[1] There are several key developments happening with LED technology:
Increasing Efficiency
Researchers continue to find ways to make LEDs even more energy efficient while maintaining or increasing light output. For example, a new thin-film LED technology developed at the University of Houston could double efficiency compared to current LEDs.[2] Higher efficiency means lower energy use and costs for lighting.
Smart Lighting
With the growth of smart home technology and IoT devices, smart LED lighting is becoming more popular. These connected LED systems can be remotely controlled, scheduled, dimmed, and programmed with different color and warmth settings. This allows customization and automation for different needs and situations.[3]
Human-Centric Lighting
There is increased focus on human-centric or circadian lighting – LED systems designed to support human health, sleep, alertness etc. by aligning color temperature and intensity with natural daylight cycles. Such solutions can benefit learning, productivity, healthcare, and more.[4]
In summary, the future of LED lighting includes even greater energy savings, intelligent controls, and lighting tailored for human biology and well-being. The technology will continue evolving to meet diverse lighting needs while reducing energy consumption.
[1] https://www.energy.gov/sites/default/files/2019/04/f61/whats-next_ei_april2019.pdf
[2] https://www.sanforce-tech.com/what-does-future-of-ed-lighting-technology-look-like/
[3] https://www.energyfocus.com/the-future-of-led-lighting/
[4] https://www.sanforce-tech.com/what-does-future-of-ed-lighting-technology-look-like/
