The abbreviation PAR stands for ‘Parabolic Aluminized Reflector’. These lights are used in a wide range of applications ranging from headlamps to recessed lights in commercial and residential buildings. Thanks to their design, PAR lights have mostly replaced ‘R’ lights (Reflector type lamps). PAR lights are installed inside PAR light cans. As the name indicates these lights have a parabolic reflector. A parabolic reflector coupled with a precision designed diffuser lens enables better control over light. PAR lights can have a light spread ranging from 18 to 100 degrees.
Par lights are quoted as PAR 20, PAR 64, etc. The number after PAR is the diameter of the light in eighths of an inch. Dividing the number after the abbreviation ‘PAR’ with the numeral ‘8’ gives the diameter of the light in inches. Thus, a PAR 64 light has a diameter of 8 inches while a PAR 30 light has a diameter of 3.75 inches. . If you are planning to replace one of your halogen or incandescent PAR lights with modern LED PAR lights you need to know the PAR number or its diameter to order the right size lamp for your recessed fixture.
What must one look for in a PAR light?
Par lights are often installed in recessed containers. They are therefore difficult to replace. When choosing a replacement lamp, look for one that has the maximum life. Incandescent bulbs are the worst and LEDs are by far the best.
| Lamp Type |
Expected Life |
| LED |
30,000-50,000 hrs |
| Incandescent |
1000 - 2000 hrs |
| Halogen Lights |
4000 - 5000 hrs |
The expected lamp life is statistically defined as the number of hours over which 50% of the lamps still remain in operation. The actual life of a lamp may be higher or lower depending on a variety of reasons. For example a lamp used in a farm setting will be affected by high relative humidity and high levels of ammonia in the air which in turn may lead to lower lamp life.
Low temperature operation is an important characteristic. Since PAR lights are often installed in recessed or covered cans high temperature can lead to premature bulb failure and in extreme cases may lead to accidental fires. Halogen bulbs in particular have a very high operating temperature and if inflammable packing material in the roof is too close to these bulbs the risk of fire is very real. LED lights produce very little heat compared to incandescent (one tenth), halogens or CFLs (half). Yet the heat that is generated must be conducted away to prolong the life of the bulb. While the LED is resistant to temperature the sophisticated electronics need protection. Good quality LED PAR lights therefore have a customized aluminum heat sink. Aluminum being a good conductor of heat quickly carries the heat away from the electronics and dissipates it safely instead of letting it build inside the can.
Quality of the Diffuser lens is critical in determining the light control achieved by any PAR light. A good quality diffuser lens reduces light wastage and spreads it in a highly controlled manner. Ultrasonically welded diffuser lenses further increase reliability and performance.
Energy consumption is a vital component of the total cost of any lamp. Compared to LEDs, halogen lights that are mostly used in recessed cans are energy hogs.
| Par Light |
LED |
Halogen |
| PAR 20 |
6 Watt |
50 Watt |
| PAR 30 |
9 Watt |
75 Watt |
| PAR 38 |
6 Watt |
60 Watt |
Overall savings from modern LED lights are expected to be in the region of 50 to 70 percent over the lifetime of the bulb. And this does not factor in the replacement costs. Factor those in and savings begin to touch the 100% mark. It therefore comes as no surprise that LED PAR lights are emerging as the number one choice for lighting engineers for a variety of applications.
| Characteristics |
Incandescent |
Halogen |
LED |
Comments |
| Color Rendering Index |
97 - 100 |
85 - 90 |
75 – 85 |
High CRI improves color perception. In most applications a CRI of 75 and above is sufficient |
| Color temperature (Kelvin) |
2500 - 3000 K |
3000 K |
A range of color temperatures ranging from warm white (3000 K) to cool white (4200 K). |
Color temperature can help you choose the right bulb that produces light you like best. LED's provide a wider choice of Color temperatures. |
| Luminous Efficiency (Lumens/ Watt) |
9- 15 |
13-30 |
100 Lumens / Watt and higher |
With new developments the luminous efficiency of LEDs are increasing regularly. Some experimental systems have an efficiency of 150 Lumens/ watt. |
| Lamp Life (Hours) |
1000 hours |
3000 hours |
50000 hours or more |
Long lamp life translates to low replacement and maintenance costs. If you use an electrician’s services to replace burnt out bulbs these costs can be prohibitive. |
| Lamp Configuration |
Point source of light |
Point source of light |
Multiple LEDs- hence multiple sources of light in a single bulb |
LEDs achieve better light distribution and low glare as the origin of light is spread over a larger area |
| Energy consumption (Watts) sample electricity consumption |
80- 100 Watts |
60 Watts |
6 Watts |
The use of reflectors and the bulb design enables the use of lower wattage halogen lamps as more light is available in the room from halogen and LED PAR lights. |
| Operating cost |
Highest |
High |
Lowest
|
|
A Note on Luminous Efficiency –
Luminous efficiency is the most common metric used to compare different light bulbs. It is important to keep a few things in mind. Reflector and lens quality can drastically impact the amount of light available from a bulb. The difference can be as high as 20%. Human eyes can adapt to a wide range of light levels and dimmable bulbs combined with good reflectors and lenses can enable you to achieve the same results with 40% fewer lumens! This is one of the reasons why CFLs are not the hot favorite for use in recessed can lights as a considerable portion of the light is wasted and is not available for lighting. Mercury contamination is of course the other problem holding CFLs back.
The preceding data demonstrate why LEDs make sense as PAR lights. For a detailed analysis of mercury emissions, energy consumption and cost of LED lights you can refer to the excellent resources in the “LED Education” section.