The Layers of Light

Ambient, Task, and Accent

Field and Supply 2016

A Makers' Market in Upstate New York

Why LED is the Way to Be

Lighting Measurement, Color Rendering, and Correlated Color Temperature

October 07, 2016

Why LED is the Way to Be

Lighting Measurement, Color Rendering, and Correlated Color Temperature

October 07, 2016

In our post, Exposed-Filament & Edison-Style Bulbs: Turn of the Century Lighting, we discussed the long road to the incandescent light bulb and the electrical system that allows everyone to have light at home. In that post, we also paused to admire the aesthetic beauty of these bulbs and the warm light they cast off, noting their comeback and the objections to their widespread use.

We love incandescent bulbs. We love their warm light; we love their ability to render color; we love their familiarity. But we're a company that looks to the future and loves to make use of emerging technologies and techniques. There has been a whole heck of a lot of emerging tech in the world of lighting over the three decades we've been in this game.

Just think back to 2000-2001 for a moment. What were cellphones like? Did anything have a touch screen? Did anyone ever utter the phrase, "social media?"

That same accelerated technological growth has occurred in some other fields. Lighting has been one of them. 

While light-emitting diode (LED) technology has been the clear leader in terms of energy conservation and duration before replacement, there have been aspects about it that have not made it ideal for home use, from an aesthetic standpoint. 

That has changed. To assist you in making informed decisions, this post briefly familiarizes you with the facts about light as it stands today. How we measure it. How we rate it. What factors to consider in choosing light sources. Let's get started.

Design: Stacey Blake | Fleming by HVL with LED behind milk-glass diffusers

Lighting Measurement Terms

Used to be a time when you were talking about indoor light, the only unit of measurement you needed to reference was “watts.” Ah, but those were simpler days. The term “watts” refers not to anything intrinsic to light itself, but to the amount of electricity consumed in generating it. One could safely assume that with more electrical energy going to a bulb, more light would radiate.

With so many other options in lighting today, the lexicon used to measure and describe it has widened. The most essential term to know is "lumens," a unit of measurement for light itself, not the electricity used to produce it. “Lumens” refers to the amount of light emitted. 

Where you used to look for watts, now you look for lumens. A “Lighting Facts” label in accordance with the U.S. Department of Energy will break the information down to lumens, watts, and “lumens per watt” (lm/W). This last measurement shows you how energy-efficient a light source is by demonstrating how much electrical energy (watts) is being used to provide how much light (lumens).

For example, if a 60-watt incandescent bulb produces 800 lumens, and a new LED bulb produces 840 lumens on 9 watts, earning a “lumens-per-watt” efficacy score of 93, that LED bulb is conserving a lot of energy and putting out slightly more light than the 60-watt traditional bulb. And that's not getting into the fact that the LED bulb is going to last around 20 years, while the incandescent will need to be replaced in a year.

Design: Michelle Gage | Julien wall sconce by HVL

Bulbs, Color, and Current Technology

Advances in lighting technology have made it useful to have some understanding of the science of color. Particularly relevant are two scales used to measure aspects of light: Correlated Color Temperature and Color Rendering Index. These two scales indicate how a certain light source feels and brings out colors. When exploring LED and other options, understanding these tools helps you to get light most conducive to your needs and preferences.

Color Temperature

A spectrum for Correlated Color Temperature (CCT) indicates the color and warmth of light. The temperature is measured in Kelvins (named after this righteous dude, who was so cool he got to call himself Lord Kelvin, even though his name was William Thomson). The CCT spectrum runs from 0K to 7000K, but it's really the span from 2700K to 6500K that assists in assessing electric light sources. Toward the lower end (2700K) warm white moves through bright white all the way to daylight on the higher end (>6500K). Somewhat confusingly, “warm” refers to the lower temperatures and “cool” refers to the higher ones. That’s because these value distinctions refer to the felt experience of the light. Proceeding along this arc, “warm” color temperatures encapsulate light that appears orange and yellow, while “cool” covers white and eventually blue.

“Warmer” light is more desirable in relaxing settings, such as living rooms, bedrooms, and dining areas, while “cooler” light is more useful in places like the bathroom, the kitchen, and the laundry room, where tasks require us to see—and see color—as best as possible. Which leads us to the Color Rendering Index.

Color Rendering Index

The CRI, or Color Rendering Index, is a tool devised by the International Commission on Illumination (or CIE, an acronym derived from its French name, Commission internationale de l'éclairage) to measure how accurately a given light source renders the colors of objects it illuminates. The standard against which these light sources are judged is natural daylight itself. Traditional incandescent light comes the closest to daylight in rendering colors. However, light-emitting diode (LED) technology and other applications have quickly made large leaps in this regard. The index runs along a scale of 1-100, with 1 being abysmal and 100 being life-like. Think of it like a score on a test—the closer to 100, the better.  

Homeowner: Tasha Agruso of Kaleidoscope Living | The Astoria chandelier by HVL is LED-driven

Bulb Types

At Hudson Valley Lighting, we appoint a variety of bulb types and light sources for our fixtures, including G9 Xenon incandescent bi-pin bulbs (not discussed in this post). It's fair to say, though, that exposed-filament incandescent bulbs and innovative LED  options are the types we favor. This is especially true now, as we move forward. We've been making some LED fixtures for a while, but they're beginning to account for more of our offering, such as in our Fall Collection 2016, where they account for nearly a quarter.


Home has a signature hue, distinguished from enervating public spaces by its inviting warmth, which envelops us each evening upon our return. Using a carbon or tungsten filament in a glass vacuum, the traditional bulb is available in a variety of shapes and degrees of transparency. It provides a yellow-orange light which is comforting, and it yields accurate colors from everything it illuminates. Fashion has brought the Edison-style bulb back into demand. Many of our fixtures are fitted with some variety of incandescent bulb, often for aesthetic reasons. They are easily replaced.


Now, there are smart and sophisticated ways to use these energy-saving, long-lasting options. Exposed-filament bulbs in the Edison style are available in LED form, and we specify these for some fixtures.

(We also have a sister company, CSL [Creative Systems Lighting], that does a lot of work with LED in the tape light, recessed light, warm dim downlights, and other pragmatic applications.)

It’s the G9 LED bulb that warms the cockles of our lighting designers’ and engineers’ hearts, though. Why? Using only 3 watts of electrical energy, it produces 280 lumens of light, at a color temperature of 3000K—roughly the same as an ordinary bulb! At the same time, it has a Color Rendering Index (CRI) score of 80. It ain’t daylight or incandescent, but it’s close. To top it all off, it’s dimmable, which, as discussed in this guide, is essential to a good lighting plan. Its one drawback is that it’s not pretty to look at. Rather, it resembles nothing so much as an extruded tooth. But you never see it. We obscure the light source by placing it behind opaque or acid-etched shades. The light is pleasantly diffused through the glass shade and is especially useful in kitchen, bath, and laundry settings.  

Homeowner: Ali Hynek | Boca wall sconce by HVL

Bulb Law

A few years ago, the United States Federal Government passed legislation designed to gradually phase out energy-wasting incandescent bulbs. When people discuss traditional light bulbs as wasting energy, what they mean is that much of the electrical energy going to power the bulb is being converted into heat. This is why a traditional bulb can be quite hot to the touch. In addition to the desired light it provides, it creates an unwanted side-product: heat. Sometimes, more energy is going into heat than light.

There’s a lot of confusion about the legislation passed and what it means for the average consumer. Simply put, the bulb ban prevents the production in America of incandescent bulbs from 40 watts-100 watts, with some exceptions (e.g., vintage throwback bulbs which constitute some of a fixture's aesthetic worth). Existing bulbs may still be sold and new bulbs that provide the same amount of light but with less expenditure of heat and energy can still be produced and sold here. We do not specify bulbs that cannot be replaced for any of our fixtures. Depending on the fixture, replacements are available either through the lighting showroom you purchased it from, the average hardware store, or directly through us. Please see our Bulb Legislation page for more information.  

There. That ends today's class. Are there any questions?

Austin + Alex of Homme Boys using one-light LED Tafts in a flush mount capacity along with Salem sconces to assist in lighting this beautiful dark hallway.