Guide to Lighting + Lamping: Color Temperature, Color Rendering and Lumens
Sourcing lighting for your project isn’t just about aesthetic, though we know that’s the fun part. Lighting has a host of other considerations, like Kelvin Color Temperature, CRI, lumens and others that you’ll want to understand when specifying everything from functional recessed lights to a show-stopping chandelier. Here are the basics to understanding the most common specs in lighting and lamping.
Kelvin Color Temperature
What it is: The measurement used to describe the appearance of the light put out by a particular bulb. The higher the Kelvin (measured by K), the whiter the light.
What to look for: In residential applications, Kelvin color temperatures typically begin around 2700K for warm, incandescent light and go up to 3500K, which is close to that of a fluorescent light (for reference, a candle is just under 2000K at 1,900 Kelvin). Color temperatures of more than 3500K are usually reserved for commercial (4000K), hospital (5000K and up is a very bright white) or other utility applications where ultra-bright light is needed (direct sunlight is 4,700K so imagine how bright a 5,700K bulb would seem). For turning night into day with flood lights, consider 6,000K to 7,000 Kelvin.
CRI (Color Rendering Index)
What it is: A measurement of how light will affect the appearance of color, as compared to a natural light source. The higher the CRI, the closer to “true” color you will have in that light.
What to look for: An excellent CRI is 90 and above, meaning lights and bulbs with a CRI of 90+ will produce a more accurate color rendering of the objects that are lit by it. Consider the kitchen, for example—an excellent CRI for the lights in this room will ensure food is presented in its most natural (and likely appetizing) color.
What it is: A measurement of how bright a bulb or light is. The higher the lumens, the brighter the light. This was traditionally measured by watts, but lumens is now the standard of communicating the brightness of a bulb or integrated lamp.
What to look for: The lumens will be provided by any bulb or light fixture on the packaging or product description. In terms of how many lumens you’ll need—it depends on the space. Light intensity is measured in “foot candles” per square foot. A good rule of thumb is to aim for a certain amount of lumens per square foot for the “general lighting” layer of your lighting plan:
Note, this guide is for general lighting in a room—you may look for more lumens in these spaces to provide focused task lighting to certain areas like countertops, desks, etc. For commercial applications like restaurant lighting, hotel lighting, retail lighting and more, see below:
|Restaurant Lighting||15 lumens per square foot|
|Retail Lighting||30 lumens per square foot|
|Hotel Lobby Lighting||50-60 lumens per square foot|
|Office Building Lighting||40-50 lumens per square foot|
|Office Hallway Lighting||20 lumens per square foot|
|Restaurant Kitchen Lighting (general)||30-40 lumens per square foot|
|Restaurant Kitchen Lighting (task)||70-80 lumens per square foot|
|Commercial Space Lighting||70-80 lumens per square foot|
More and light fixtures now come with integrated LEDs, which means the lighting is built right into the fixture and no bulbs are required. These fixtures should provide you with all of the lamping stats—color temperature, CRI, lumens—upfront since there is no alternative lamping. For fixtures where you will provide the bulbs separately, you’ll want to find these stats on the bulbs themselves.
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