PAR, which stands for Parabolic Aluminized Reflector, bulbs produce about four times the concentrated light intensity of general service A shape bulbs and are ideal for recessed and track lighting. Like all light bulbs, the numbered value (i.e. PAR 20 and PAR 30) represents the diameter of the bulb in 1⁄8 of an inch. Therefore, a PAR 38 would be 4.75 inches in diameter. LED PAR light bulbs provide a directional output and exceptional beam profile characteristics while using only a fraction of power.
Lumens
With new light bulbs, shopping by lumens is more important than shopping by watts when choosing which energy-efficient bulb to purchase. While wattage measures the amount of energy required to light products, lumens measure the amount of light produced. This means that the more lumens the product has, the brighter the light source is. Instead of buying products based on how much energy they consume (watts), consumers should consider how much light they give us (lumens).
Wattage
Wattage is the measure of the bulb's energy consumption - not how much light it puts out. Energy-efficient bulbs use fewer watts to give off the same amount of brightness (lumens). Because of this, LEDs (which have typically low wattages when compared with lumens) not only help reduce energy usage but also lower electric bills.
Color Temperature
Color temperature refers to the color appearance of the light that comes from a light source. It's an important performance characteristic to asses when evaluating bulbs because the color temperature creates the mood of the space you are lighting and can thus influence buying behavior or work performance. The apparent color of a light source is measured in Kelvin. The higher the Kelvin temperature, the whiter the light.
Dimmable
Dimming LED bulbs gives you the same kind of flexibility and control you can expect from your incandescent bulbs. With so many improvements to this technology, it has become easier to find an appropriate energy-efficient replacement to work with your dimming system. You will save more energy and find a large reduction in your electrical bill while still getting the amount of light that you need with dimmable LEDs. Customers also use these dimmers for track lighting--where desirable ambient light levels are needed but where a dimmed light setting is also desirable.
Beam Spread
PAR lamps contain engineered surfaces that control the beam of light to a precise angle. There are seven different classifications of these angles. Very Narrow Spot is at 15 degrees or less and casts an intense, focused beam. Narrow Spot is at 16 to 30 degrees and casts a slightly less focused beam. Spot is at 31 to 60 degrees and casts a medium-sized beam. Narrow Flood is at 61 to 90 degrees. Flood is at 91 to 120 degrees and casts a wide beam. Wide Flood is at 121 to 160 degrees and casts a dispersed beam to cover a large area. Very Wide Flood is over 160 degrees and casts an extremely wide beam.
Energy Star Rated
Products with Energy Star labels meet the energy efficiency requirements set forth in ENERGY STAR product specifications. Some guidelines include contributing significant energy savings nationwide, delivering the features and performance demanded by consumers (in addition to increased energy efficiency), and energy consumption and performance being measured and verified with testing.