Green Lighting for Northern Virginia and the DC Metro Area

The term “green” is used to describe everything today. There are green cars, towels, cleaning products, strollers, etc. It seems that the advertising agencies in America have decided the number one way to sell their products is to market them as green. I am sure I am not the only one that believes that this term is being overused for marketing purposes today. But despite the marketing push for everything “green”, the lighting industry has been making huge strides for a long time in making light bulbs that are long lasting and extremely energy efficient.
Whenever this topic is brought up the first question that is asked is, “when are LEDs (Light-Emitting-Diode) going to be ready?” We will discuss LED in our blog, but for this particular post we will simply look at which light sources are currently giving us the best Lumen per watt output.

A lumen is a measurement of reflective light off of a surface. This is the measurement in which all light sources are rated and we will look at a measurable comparison between different sources.

Incandescent = 8 lumens/watt
Quartz = 16 lumens/watts
Fluorescent = 40-80 lumens/watt
Induction Fluorescent = 80 lumens/watt
Mecury = 30-40 lumens/watt
High Pressure Sodium = 120 lumens/watt
Metal Halide = 60-80 lumens/watt
Ceramic Metal Halide = 80-110 lumens/watt
LED = 30-80 lumens/watt

Incandescent bulbs are the least energy efficient light sources available. In 2012 they will become illegal to sell in the US. Although I do not personally agree that it is the government’s job to tell us which light bulb we should use, due to technological advances the incandescent bulb will become a thing of the past.

The light source with the greatest lumen to watt output is the high pressure sodium. These are the orange lights used most frequently for street lighting. In Europe they use low pressure sodium lights that have a 240 lumen/watt ratio, but when they were introduced in the US, people revolted because the color was so bad. Sodium lights are useful due to their longevity and efficiency, but due to the poor coloring it is limited in its applications.

The three most promising light sources out there are the Induction Fluorescent, LEDs, and Ceramic Metal Halide.

The induction fluorescent has a good lumen/watt ratio, good color, and can last up to 100,000 hours. You will begin to see this light source used in commercial applications such as wall packs and parking lot lights. It gives a great linear light output, but is not designed to go long distances, such as up lighting a building.

The LED is the light source that is getting all the attention right now. It has the most potential of any light source. Some of the claims are slightly exaggerated right now about performance. You may hear some say that these light sources will give out a lot of light, use almost no energy, and last 1,000,000 hours. Currently the lumens/watt ratio is between 30-80. The CRI (color rendering index) rating is only around 80. That is a fair rating, but not up to par with other light sources available. As the drivers (power supply) improve and the color improves, this will become a light source that is used in many applications. Our company currently uses LEDs for certain applications and will use more as the technological advances improve.

The Ceramic Metal Halide is a light source that is not getting a lot of attention right now, but it will. This is not the standard metal halide that we see all over the place. This source of light has increased the lumens/watt ratio to rival the Sodium lights. It has a 15,000-18,000 life span, and it has a very high CRI rating at 90-96. They have also done away with the lumen maintenance problems associated with metal halides. Lumen maintenance depreciation becomes obvious in metal halides because you can see the bulb change color.

At Outdoor Lighting Perspectives of Northern Virginia we do things a little different than most other exterior lighting contractors. We pick out the right light source for the application, then build the fixture around the light source. After all, we want our central focus to be on the effect of the light fixture. There is much more to come as we compare the CRI of each light source, the lumen maintenance, and how much energy one can save by using these green light sources.