County of San Mateo RecycleWorks Facilities

San Mateo County Facilities
The recycling program for county employees


Understanding Lighting Choices
There are a variety of lamps available for different application needs, ranging from retail to warehouse, office or residential sites. Choosing the appropriate lamp for the task requires understanding what is available and how to pick amongst them. Fluorescent lamps and Compact Fluorescent Lamps (CFLs) are available in different color temperatures and color renditions. Color temperature refers to how we perceive the light emitted from a lamp while color rendition is how accurately the light makes objects appear (as compared to full daylight). These two figures allow us to know what type of lighting our eyes will perceive, and can help in lighting choices.

Color temperature is measured in degrees Kelvin (K). The following chart shows the color temperatures of different types of light.

Source: Media College

Typically businesses choose lighting in the range of 4,000 to 6,500 degrees K because it is brighter and easier on your eyes, making computer use more comfortable. This light is perceived as cool and bright, like sunlight at noon. The lower color temperatures are similar to light levels at sunrise or sunset.

Color rendition is important in determining what colors are accentuated. Color rendition is measured by a color rendition index (CRI). Lamps with a low CRI, like sodium vapor lamps (street or parking lot lights) render gray, which makes things look orange. Higher CRI lamps render blue, green and violet, which makes things appear white. Early fluorescent lamps had a relatively low CRI, causing people to look pale or ill in the light. Recent fluorescent lamps have a much higher CRI providing a brighter and better quality light.

For example at County Office Building 2 located at 555 County Center: The building contained first generation T8 lamps with a color temperature of 3500 degrees Kelvin. The County replaced the old diffusers and lenses with new ones utilizing 2nd generation 5000 Kelvin fluorescent T8 lamps and electronic low power ballasts. The 5000 kelvin lamps provide more lumens per watt than the 3500 kelvin lamps. Since a higher kelvin temperature lamp produces a whiter light, the new fixtures will take only 2 lamps instead of 3, saving over 1/3 of the electricity used to power the old 3 lamp fixtures.

Look For A Retrofit Near You!

Why use energy efficient lamps?
  1. Lower utility bills
    Using a more efficient lamp and ballast requires less electricity. This directly results in a lower utility bill. The retrofit at 555 County Center will yield an anticipated savings of almost 10% of electricity use.
  2. Better light level and color = better work place
    Lighting has an important impact on the physiology of human beings. Having a properly lit building with the correct color temperature and color rendition for the task being performed can provide numerous benefits for employees. For example, Computer Vision Syndrome (eye strain, headache and back pain) can be alleviated with correct lighting, decreasing employee sick time and improving morale.
  3. Environmental
    Through energy efficiency the amount of electricity needed is reduced. Energy is produced from a variety of sources, the majority in the United States coming from fossil fuels. Power plants that process the fossil fuels produce air pollution and greenhouse gases. Over the lifetime of a single T8 lamp one can save $70-80 in utility bills, over 500 kWh of electricity (the same amount delivered by burning 500 lbs of coal) and prevent the release of 500 lbs of carbon dioxide, a greenhouse gas, into the atmosphere. Collectively these savings add up and have significant environmental benefits.