When choosing light source for illumination at night, you might encounter parameters like wattage, lumens lux(foot-candels).
What do they mean?
Wattage measures power consumption; lumens measure brightness. Lux (foot-candles) indicates the brightness on the ground or surface of an object. It shows how bright we perceive the road/surface at night.
Many people still rely on wattage to determine how bright a light bulb will be, but that’s not the best approach anymore. With advanced LED lighting technology, it’s essential to focus on lumens for brightness and light efficiency(lumens per watt).
Key Takeaways
- Lumens indicate the brightness of a bulb, while wattage indicates energy use.
- Lux shows the light intensity on a certain ground area
- Understanding light output can help you find a better lighting solution for your solar street light projects.
Understanding Light Output: Lumens vs. Watts
The Basics of Lumens and Watts
Lumens are a measurement of the total amount of visible light emitted by a source. The higher the lumens, the brighter the light will be. On the other hand, watts measure the amount of energy a light bulb uses to produce that light. In traditional bulbs, higher wattage often means brighter light, but this is not true for modern energy-efficient bulbs, which adopt LED chips
For example:
- Incandescent bulbs: A 60-watt bulb produces about 800 lumens. Light efficiency is 800/60=13.34lumen/watt
- CFL bulbs: A 15-watt CFL can produce the same 800 lumens. Light efficiency is 800/15= 53.34lumen/watt
- LED bulbs: An LED bulb uses only about 10 watts for the same brightness. Light efficiency=800/10=80lumen/watt
However, 80 lumens/watt was obsolete data in 2009;
In 2024, LEDs can be as efficient as 200 lumens/watt. For example, the Philips LUXEON 3030 2D Mid Power LED, which Enkonn Solar chose as the light source for solar street lights, can reach 209 lumens/watt.
Lumens to Watts Conversion
“Lumens to watts conversion” refers to the relationship between the brightness you want and the energy you need to achieve that brightness.
For instance, a simple chart would look like this:
| Lumens (Brightness) | Watts (Energy Use) |
|---|---|
| 8000 | 40 |
| 12000 | 60 |
| 20000 | 100 |
Using these charts, you can determine which bulbs will meet your brightness needs efficiently.
Importance of Luminous Efficacy
Luminous efficacy measures how efficiently a light source converts energy into visible light. It is expressed in lumens per watt (lm/W). Higher luminous efficacy means more light for less energy.
Energy-efficient bulbs, like LEDs, have high efficacy ratings. For example, an LED might produce 200 lumens per watt, while traditional incandescent bulbs might only make about 10-17 lumens per watt.
Comparing Bulb Types: Efficiency and Output
Incandescent vs. LED vs. CFL vs. Halogen
- Incandescent bulbs are traditional and emit warm light (approx. 3000K). They use more energy, producing light with only about 10-17 lumens per watt.
- LED bulbs stand out as the most energy-efficient option, providing 200 lumens per watt, which is the newest data in 2024.
- CFL (Compact Fluorescent Lamps) are better than incandescent, averaging around 35 lumens per watt.
- Halogen bulbs are a type of incandescent that uses halogen gas, making them slightly more efficient than standard incandescent bulbs. They produce about 12-22 lumens per watt but still fall short compared to LEDs and CFLs.
Evaluating Bulb Efficiency and Lifespan
The efficiency of bulbs directly affects your energy costs. LED bulbs last between 15,000 to 50,000 hours and consume up to 80% less energy than incandescent bulbs. In contrast, incandescent bulbs only last about 1,000 hours. CFLs have a lifespan of around 7,000 to 15,000 hours and are also more efficient than incandescents. Halogen bulbs typically last 2,000 to 4,000 hours.
Impact of Bulb Type on Energy Consumption
Your choice of bulb significantly impacts your energy consumption. For example, a standard 100-watt incandescent bulb produces about 1,600 lumens, while an LED bulb delivering the same light output only uses about 8 watts. This significant reduction leads to lower energy bills. CFLs, while consuming around 23 watts for similar brightness, still outperform incandescents. Halogen bulbs, although slightly better than standard incandescents, still consume more energy than the energy-efficient options. Keeping wattage in mind helps you reduce costs and make environmentally conscious choices.
Light Quality Factors Beyond Brightness
When choosing lighting, it’s important to consider factors beyond just brightness. Light quality significantly affects mood and function in a space. Two key aspects to examine are color temperature and developments in LED technology.
Color Temperature and Ambiance
Color temperature is measured in Kelvin (K) and impacts how light feels in a room. The color temperature is determined by the color of light emitted when iron is heated to a specific temperature. For instance, when iron is heated to 3000K, it emits a yellowish color, and when it is heated to 6000K, it emits a white color. So, a bulb with a lower Kelvin rating (around 2700K-3000K) produces a warm, cozy glow ideal for living areas. This type of light can create a relaxing ambiance.
In contrast, higher Kelvin ratings (5000K-6500K) give off cooler, bluish light. This can enhance focus and alertness, making it suitable for workspaces.
LED Technology and Light Source Innovation
LED technology has been advancing rapidly. When we started our LED lighting business in 2007, the LED chips only produced 60-70 lumens per watt. However, by 2024, the light efficiency had increased to 210 lumens per watt. This significant increase in efficiency has led to a reduction in the cost of LED lighting products, making this new technology more affordable and accessible to a larger number of people.
Practical Guidance for Consumers
How to Choose the Right Lighting Solutions
When selecting lighting, focus on lumens rather than watts. For example, if you want a similar brightness to a traditional 60-watt incandescent bulb with 800 lumens output, look for an LED that provides around 800 lumens.
Calculating Cost Savings and Environmental Impact
Switching to LED lights results in significant energy savings. For instance, replacing a 60-watt incandescent bulb with a 4-watt LED can save you approximately $150 over its lifetime.
To understand your savings, remember the formula:
(Old Wattage – New Wattage) x Hours Used x Days Used x Cost per kWh = Total Savings.
This helps gauge the impact on your electricity bills. Additionally, using LED lights contributes to a positive environmental impact by using less energy and reducing your carbon footprint.
Understanding Lighting Labels and Energy Star
Always check lighting labels for information. Look for Energy Star certification, which indicates high efficiency and performance. These labels provide important details about lumens, wattage, and expected lifespan.
