It is Lumens not WattsOver many generations of use, a definition formed that equated watts to light output. Wattage was used when deciding on the lamp you wanted. If you wanted a lower light level, you selected a 40-watt bulb. If you needed it brighter, you selected a 100-watt bulb. Watts are only a measure of how much electricity the lamp takes to operate. While this was never the correct interpretation of the brightness of a lamp, it is an easy correlation that the public understood and it never went further than that. As with any old technology, we must throw away that old way of thinking. The correct way to know how bright a lamp is related to the “LUMEN OUTPUT” of the bulb.
Color TemperatureBut lumens alone won’t give you the comfortable light that you want. You must also understand “Color Temperature and the Color Rendering Index.” Color temperature describes the warmth or coolness of a light source and that itself can be confusing. To help understand color temperature – also known as “Kelvin Temperature” – here is a simple analogy. A “black body radiator” like the material tungsten is heated. As the black body radiator increases in temperature, the color of that radiator changes in unison. This is where much of the confusion begins and here is why. The HIGHER color temperature (3500-5500k) in lighting is called “COOL” white, while the LOWER color temperature (2200 – 3000k) is called “WARM” white.
Color Rendering IndexThe Color Rating Index (CRI) measures how a light shows the true color of what is in its cast. The higher the CRI of an LED, the truer your item color will be under that light. Think how the appearance of clothing and food will look. It is not necessary to have high CRI lamps in every spot in the home – think of applications such as bathrooms, kitchens, closets, art studios. The higher the CRI number, the more accurately the color of the illuminated object appears.
Dimming LED LightingWhen LED first hit, the scene dimming the lamp was not an available option, limiting where the lamp could be used. Then LEDs became dimmable and, while the brightness of the lamp decreased, the color of the lamp did not change to the yellower light we wanted to set the mood. There are now LED lamps that have a feature that recreates the gradual decrease of lumens and increases the warm ambient tones wanted in the home.
Why Won’t My Dimmer Work with LED Lighting?Another important piece about dimming LED lighting is the compatibility of the dimmer to the light source. The truth is that the old dimmer that has been in the home for some time won’t work with LED. At one time the only way to know for sure if a dimmer worked with an LED was to test it. As the popularity of the LED increased, manufacturers included a list of approved dimmers and this is the easiest way to determine if everything is well-matched. A common problem that happens when old dimmers are in place is that LED lamps do not turn off completely. They continue to glow. There are new dimmers in the market place referred to as 0-10v. These dimmers consider the lower voltage use of LED lamps and help to reduce visible flicker.
It’s On the LabelAll this new information is a lot to remember when you just want to replace a burned-out bulb. In 2008, the Department of Energy began a program to “promote accurate and consistent” performance claims. The result is the “Lighting Facts” label. The labels can vary in the information they have on them;
- Lumens indicate light output.
- Lumens per watt (lm/W) indicates efficiency.
- Watts indicate the energy required to light the product.
- Correlated Color Temperature (CCT) indicates light color.
- Color Rendering Index (CRI) indicates the effect of the lamp’s light on the color appearance of objects.
- LED Lumen Maintenance (optional)
- Warranty (optional)
With all the LED energy-efficient choices available for use by homeowners, facility managers and their municipal applications, there is no reason to put off saving today. If you haven’t switched out your old lighting for LED, now might be the time.