Human-Centric Lighting Made Simple with Automation

Enhance the occupant experience with automated lighting and shading
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Sponsored by Lutron Electronics Co., Inc.
By Kathy Price-Robinson

Learning Objectives:

  1. Identify the key elements of human-centric lighting.
  2. Explain why human-centric lighting is important to occupant well-being.
  3. Appraise lighting fixtures for their ability to meet quality elements of human-centric lighting.
  4. Specify the control narrative/intent for a human-centric lighting design.

Credits:

HSW
1 AIA LU/HSW
IDCEC
1 IDCEC CEU/HSW
ICC
0.1 ICC CEU
IACET
0.1 IACET CEU*
AIBD
1 AIBD P-CE
AAA
AAA 1 Structured Learning Hour
AANB
This course can be self-reported to the AANB, as per their CE Guidelines
AAPEI
AAPEI 1 Structured Learning Hour
MAA
MAA 1 Structured Learning Hour
NLAA
This course can be self-reported to the NLAA.
NSAA
This course can be self-reported to the NSAA
NWTAA
NWTAA 1 Structured Learning Hour
OAA
OAA 1 Learning Hour
SAA
SAA 1 Hour of Core Learning
 
This course can be self-reported to the AIBC, as per their CE Guidelines.
As an IACET Accredited Provider, BNP Media offers IACET CEUs for its learning events that comply with the ANSI/IACET Continuing Education and Training Standard.
This course is approved as a Structured Course
This course can be self-reported to the AANB, as per their CE Guidelines
Approved for structured learning
Approved for Core Learning
This course can be self-reported to the NLAA
Course may qualify for Learning Hours with NWTAA
Course eligible for OAA Learning Hours
This course is approved as a core course
This course can be self-reported for Learning Units to the Architectural Institute of British Columbia
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Photo: Connie Zhou

Automated lighting and shading create a human-centric lighting experience for the occupants’ well-being.

EVOLUTION OF THE LIGHTING EXPERIENCE

Before the invention of electric lights, gas lamps, and candles, humans lived and worked under the natural rhythms of daylight. Daylight is a dynamic light source that changes daily (dark/light), seasonally (sunrise/sunset times), and within the day due to weather changes. This dynamic nature of daylight creates visual interest through color temperature, distribution, and brightness changes.

Firelight is the next natural light source in the evolution of lighting. This light source was not controlled until humans learned how to create and harness fire. It is a dynamic light source that moves, emits various warm tones, and provides a relaxing environment.

In the evolution of lighting, we will skip past many human-made light sources (candles, gas lights, carbon arc lamps, etc.) and go directly to one of the most beloved light sources, the incandescent lamp. This was the first standardized electric light source that allowed easy lighting control in homes or buildings with a simple switch.

Originally, lights could only be switched on or off, but eventually, dimming became an option. With dimming, people could warm dim the light, a natural feature of how the light is created (heating the tungsten filament). The incandescent lamp is capable of ultra-low light levels. Eventually, lighting needed to be more efficient because most of the energy from an incandescent lamp was output as heat rather than light.

The fluorescent lamp came in various form factors throughout its history. While this light source significantly improved energy efficiency, the light had many drawbacks. First, people often disliked the color quality of the light. The lamp startup was frequently slow, meaning it took a while for the light to get to full brightness (especially true in compact fluorescents). Finally, while the light sources could eventually be dimmed, fluorescent lamps did not warm dim, a key feature of the incandescent light. Nevertheless, the market shifted to fluorescent lighting due to energy savings, which was heavily marketed for its benefits, but many customers remained dissatisfied with the results.

The initial LEDs offered more significant energy savings than fluorescent lighting. These lamps did not suffer from slow startup, reaching full brightness immediately.

The challenges were color quality and dimming. The inability to warm dim persisted in the evolution from fluorescent to LEDs. Homeowners would unscrew an incandescent or compact fluorescent lamp (CFL) and install an LED lamp on a dimmer, but the lamp would not operate as preferred─leading to flicker, drop out, and other challenges. As a result, standards have developed to aid in compatibility.

Today, the LED is the most prominent light source. It is more energy efficient than its predecessors, has better color quality, and more desirable features. LEDs can warm and dim, just like incandescent lights. Dimming is much easier today than it was a decade ago. Some of these light sources even add features such as tunable white or full color control (to be discussed later).

Daylight Intensity and Variability

Let’s look at typical light levels of interior and exterior environments to illustrate the variability in daylight conditions. Most recommended interior light levels are between 10 and 50 footcandles, while exterior daylight conditions vary between 500 and 10,000 footcandles.

This range of daylight conditions makes it particularly difficult to use passive (fixed) shading (i.e., overhangs, permanent glass tint, fixed louvers, light shelves, etc.) and have high performance throughout the day. An active, dynamic system is the only way to maximize daylight throughout the day/week/month/year. Designers can optimize natural light for a point on the scale of conditions but not for the entire scale.

Correlated Color Temperature (CCT)

Correlated Color Temperature (CCT) measures how warm or cool a light source appears. The higher the number, the cooler the light appears. Lower numbers indicate a warmer appearance.

The unit of measure for CCT is Kelvin (Kelvin is an absolute measurement, and not “degrees Kelvin”), as it is actually a description of the temperature that a black body emitter would have to be heated to glow a specific color (an example is iron heated by a blacksmith, or the tungsten filament of an incandescent bulb). Because of this relationship, the black body curve refers to the range of reds, oranges, and whites made when heating the black body emitter (e.g. the tungsten filament incandescent) to different temperatures (e.g. dimmed level).

While it is somewhat counter-intuitive that the higher Kelvin number is a cooler temperature, think of an incandescent lamp. As more power flows through it, it is at a higher temperature, and its color is cooler. As it dims down, lowering its temperature, the light gets warmer in appearance. For reference of this scale, an incandescent lamp will usually range from about 1600K to 3000K from low end to high end.

 

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Originally published in November 2024

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