co-lor tem-per-a-ture: noun The temperature at which a black body radiator emits radiation of the same color as a given object.
You may or may not be able to understand the definition of color temperature, but you know it when you see it. The two luminaires in this photo both have compact fluorescent lamps in them.
Saving energy = saving money = good.
Mismatched color temperatures = bad.
The one on the left is a cooler color temperature than the one on the right. A cooler color temperature has a higher number, measured in Kelvin, while a warmer color temperature has a lower number. These two are around 3000K and 2700K. When shopping for replacement lamps, make sure to get consistent color temperatures, and decide ahead of time whether you want a warm color like incandescent or a cooler, "whiter" light.
I was recently in one of those big box home stores helping my parents shop for things for the new house they are building. We looked at lights and ceiling fans. We checked out some electrical devices, outlets, and switches. We looked at carbon monoxide and smoke detectors - hard wired or battery powered? Dual technology or separate? We checked out some appliances. We walked all the way around the store looking for a public restroom... My point is that we were there for a while - 30 minutes or maybe an hour - when I noticed that someone in the lamp (light bulb) aisle was standing in the same place staring at the same lamps when arrived AND when we left.
It used to be so easy. The only question you had to answer when replacing a light bulb (lamp) was, "How many Watts?" But that was then. I'm here to save you a few minutes in the lamp aisle at the home store. Before your next trip, be armed with the answers to the following five questions:
1. How Bright?
Today we have to think in Lumens instead of Watts. An old 100 watt lamp produced about 1600 lumens. A 60 watt standard incandescent lamp is about 800 lumens, and 40 watt incandescent = about 450 lumens. Before you shop, know how bright you need the light to be - in lumens.
2. What Color?
Not all "white" light is the same color. For more on that topic, check out the pictures in this previous post. The point is that most of today's sources are available in different color temperatures. To most closely resemble incandescent light, select a warm hue, between 2500 and 2800 Kelvin.
3. Where Used?
This question really embodies lots of other questions. Is it in an enclosed fixture? Indoors or outside? In a transient space like a closet? Somewhere extremely hot or cold? Is it used to accent a piece of art, or does it need to be fairly shadow-free? Certain CFLs don't do well in winter temperatures, LEDs prefer the cold. Most LEDs aren't designed for fully enclosed fixtures. Many CFLs aren't either. CFLs generally take a little time to get fully bright, so they might not be the best choice for closets. LEDs tend to be very directional and better for accent lighting, but can be diffused for general lighting. CFLs are great for general shadowless illumination but are never very directional. Know where the new lamp will be used.
4. How Controlled?
Is the lamp you are replacing on a switch or a dimmer? If it is controlled with a dimmer, replacement options are more limited, and you should check dimmer compatibility before you purchase a replacement.
5. How Much Money?
Consider both initial cost and ongoing costs. To spend the least money today, buy an incandescent or halogen replacement lamp. In the long run, this choice will cost the most in energy and replacement lamps, even though the initial outlay is the smallest for this category. The middle of the road option is fluorescent. It will cost a little more today, but will last a little longer and save a little more energy than the traditional sources. Top of the line is LED. These still cost the most, but will provide the most light per watt and will last the longest...provided you buy a quality product and use it in an appropriate application.
If you head to your local light bulb store with the answers to these questions in mind, you should save yourself a few minutes. Maybe you'll even have enough time to browse the clearance aisle and get one of those inflatable snow globes at 75% off!
I’m Dreaming of an LED Christmas...
As a lighting designer, one of my favorite things about the holidays is the lighting. I love the soft flicker of candlelight, the twinkling tree lights, and a warm fire in the fireplace. It’s the time of year when most everyone dons their Santa/lighting designer cap and changes the lighting in their home for a month. Whether you string icicle lights around the roofline of your entire house or just wrap a strand of lights around a tree or wreath, you are being faced with this question: to LED or not to LED?
Five things to consider:
1. Initial Cost - These lights still cost more than standard incandescent holiday lights. However, from the looks of today’s store shelves, LED will be your only future option. You already have to search a little to find the standard incandescent lights.
2. Energy - Over their lifetime, these lights will pay you back what you spent and more on your electric bill. Here’s what the Department of Energy has to say about it. (Scroll to the bottom for the Holiday Lights section.) This is all theoretical, of course. Reliability is improving all the time, but my personal experience with LED holiday lights has been about a 30% early failure rate. Perhaps I’m just unlucky. The lights are guaranteed, but time is precious – especially during this season.
3. Color - As with all of the new technologies there are choices to be made about color. At least with Christmas lights we are used to thinking about color! Look at the samples before you make your selection. Some white lights are more blue in color while others look more yellow. Which look do you want? The icy wintry blue look or the warm glow of the yellowish lights?
4. Environment - To be environmentally responsible, don’t use any lights at all. To be both festive and environmentally responsible, just make sure you don’t add more lights since you’re saving energy with LEDs. Better yet, consider the solar LED products that are hitting the shelves today. You will still contribute to sky glow, but you won’t be consuming electricity with your light display.
5. Recycle! Remember – when you do toss out all of those old strands of lights - recycle them! In the St. Louis area, we are partnering with St. Louis Green to recycle 128,000 pounds of lights this year. That’s literally tons of waste that will be diverted from landfills. And hopefully every one of those strands will be replaced with a lower wattage, longer lasting option.
Tell us about your experience. Do your LED holiday lights work well? Have you noticed a difference in your electric bill? Have you had any luck with solar LEDs?
...May your days be merry... and bright!
Incandescent Replacement Lamps
There are three viable major categories of incandescent lamp replacements available today. Think of it like an election.
Consider all of the options and then make your selection - cast your vote. Sometimes, like in an election, you may have to pick the best of the worst...but you do have a choice, so your duty is to become informed about those options before making your selection.
This lamp type is most similar to incandescent in cost, color, physical appearance, light, dimming behavior,
technology...in nearly every way. Halogen is about 30% more efﬁcient than standard incandescent and lasts about
twice as long. The advantages and disadvantages almost perfectly align with advantages and disadvantages of incandescent lamps. They provide instant-on light. They are fully dimmable, The color rendering (CRI) is 100. With
incandescent or halogen, there are no color temperature options They do not require a ballast. They are mercury free,
TCLP and RoHS compliant. They are not sensitive to ambient temperature. They tend to be sensitive to vibration..
They produce heat when they operate. An A-lamp replacement will cost under $2 and will pay you back $3.08 in energy savings over its lifetime.
This lamp type is the one consumers are being told to use instead of incandescent. CFL is about 75% more efﬁcient
than incandescent and lasts about ten times as long. Their function is actually quite different than incandescent, but
they have been fairly common for ﬁfteen years now, so people have grown accustomed to their strengths and weaknesses. They aren’t exactly “instant-on”, but require a brief warm-up, so they are not the best option for very transient spaces or spaces controlled by occupancy sensors. They can be partially dimmable with the proper ballast, The color rendering (CRI) can be low - and that is one reason the CFL has gotten a bad reputation, but look for a CFL lamp with a CRI in the mid-80s for satisfactory color rendering.
Often I hear people say, “I just hate the color of ﬂuorescent light.” Fortunately, ﬂuorescent is available in a variety of colors. Be aware of that and be sure to get a color that you DO like. Once upon a time, lamps available in big box stores did not display the information needed to select the color. But now that is changing. Starting in 2011, the Federal Trade
Commission began requiring lamp packaging to bear a label like this:
Notice the section called "Light Appearance" which indicates how warm or cool the light looks. The warm colors more closely resemble incandescent.
This will be an even more useful tool when CRI is included, shown as “Color Accuracy” in the above DOE Lighting Facts label for LED. CFL lamps do require a ballast. They are not mercury free, but the small amount of mercury used in a high quality lamp can make it TCLP and RoHS compliant. They are sensitive to ambient temperature, and don’t operate as well in cold weather. However, there are lamp ballast combinations available that work well in temperatures down to -10 degrees F. Compared to incandescents, they are not particularly sensitive to vibration. However, if used in an application where they are turned on and off frequently (less than 3 hours per start) the lamp life will be signiﬁcantly shortened. A 100W A-lamp replacement will cost about $5 and will pay you back about $50 - $100 in energy savings over its lifetime!
While this replacement option is generally being written off by consumers as too expensive, it is an incredibly hot
item in the speciﬁcation market. LED is currently about 85% more efﬁcient than incandescent (and its efﬁcacy is still
improving because the technology is still young) and lasts about ﬁfty times as long. Unlike ﬂuorescents, they do provide instant-on light. They can be partially dimmable, typically down to 10% with the proper equipment coordination, The color rendering (CRI) is often similar to ﬂuorescent - but look for a CFL lamp with a CRI over 90 for very good color rendering. LED lamps require a driver, which is similar to a ballast. They are mercury free, and unlike all of the other lamps, they are virtually UV and IR free, so they will not fade fabrics or art. They are sensitive to high temperatures, but they love cold weather. Heat is their enemy, and the astute designer will look for good heat-sinking to ensure that LED junction temperature is maintained at its ideal level. They are not particularly sensitive to vibration. Some look yellow when they are not in use. Others are available in a more traditional looking white color. An A-lamp replacement will cost about $25 - $40 and will pay you back about $240 in energy savings over its lifetime!
This is an exciting time in the lighting industry, with the pace of change increasing exponentially! How can you possibly keep up with it all? My recommendation is to hire a lighting designer. It is my job to keep up with all of these changes, and it has been my privilege to share them with you! I believe that the importance of having a lighting designer on your projects will continue to increase as the technology changes, because lighting designers dedicate themselves to the art and technology of light, and can help you avoid the pitfalls of selecting the wrong technology or even the wrong version of the right technology.
Lisa J. Reed, lighting designer and Principal at Envision Lighting Design, LLC