Dynamic & Diffuse Light leverages varying intensities of light and shadow that change over time to create conditions that occur in nature.

THE EXPERIENCE
A space with a good Dynamic & Diffuse Light condition conveys expressions of time and movement to evoke feelings of drama and intrigue, buffered with a sense of calm.

ROOTS OF THE PATTERN
Lighting design has long been used to set the mood for a space, and different lighting conditions elicit differing psychological responses. The impact of daylight on performance, mood and well-being has been studied for many years, in a variety of environments.
Early research showed that productivity is higher in well daylighted work places, and sales are higher in daylit stores, and that children performed better in daylighted classrooms with views – the research focus was on lighting strategy and task performance and less on human biology. For instance, quality daylighting has been reported to induce more positive moods and significant less dental decay among students attending schools with quality daylight than students attending schools with average light conditions (Nicklas & Bailey, 1996).

Recent research has focused more heavily on illuminance fluctuation and visual comfort, human factors and perception of light, and impacts of lighting on the circadian system functioning. Sunlight changes color from yellow in the morning, to blue at midday, and red in the afternoon/evening; the human body responds to this daylight color transition. The response is apparent in body temperature, heart rate, and circadian functioning. Higher content of blue light (similar to skylight) produces serotonin; whereas, an absence of blue light (which occurs at night), produces melatonin. The balance of serotonin and melatonin can be linked to sleep quality, mood, alertness, depression, breast cancer and other health conditions (Kandel et al., 2013).

WORKING WITH THE PATTERN
The objective of the Dynamic & Diffuse Light pattern is twofold: to provide users with lighting options that stimulate the eye and hold attention in a manner that engenders a positive psychological or physiological response, and to help maintain circadian system functioning. The goal should not be to create uniform distribution of light through a (boring) space, nor should there be extreme differences (i.e., glare discomfort).

The human eye and the processing of light and images within the brain are adaptable over a broad range of conditions, although there are limitations. For example, when the lighting difference between adjoining sources or surfaces has a brightness or luminance ratio of greater than forty-to-one, glare may occur, which diminishes visual comfort (Clanton, 2014). For work areas, luminance ratios between task and immediate surround should not exceed 10 to one. So while dramatic lighting differences may be great for some religious, socialization and circulation spaces, they are not a good idea on work surfaces.

Diffuse lighting on vertical and ceiling surfaces provides a calm backdrop to the visual scene. Accent lighting and other layering of light sources creates interest and depth, while task or personalized lighting provides localized flexibility in intensity and direction. These layers help create a pleasing visual environment (Clanton, 2014).
Movement of light and shadows along a surface can attract our attention. For example, the dappled light under the canopy of an aspen tree, or the reflections of rippling water on a wall. These patterns tend to be fractals, and the brain is attuned to moving fractals.
Just as variations in lighted surfaces are important for interpreting surfaces, conducting a variety of tasks, and safe navigation, circadian lighting is important for supporting biological health, so leveraging opportunities for illuminance fluctuation, light distribution and light color variability that stimulate the human eye without causing discomfort will improve the quality of the user experience.

Design considerations for establishing a balance between dynamic and diffused lighting conditions:
• Dynamic lighting conditions can help transition between indoor and outdoor spaces.
• Drastically dynamic lighting conditions, such as with sustained movement, changing colors, direct sunlight penetration and high contrasts, may not be appropriate for spaces where directed attention activities are performed.
• Circadian lighting will be especially important in spaces the people occupy for extended periods of time.

A prime example of a Dynamic & Diffuse Light condition is at the Yale British Art Museum, designed by Louis Kahn. Despite the building’s stark exterior, the diversity of interior spaces and differing orientations of windows, clerestories, skylights, and a large central atrium allows for light to penetrate at variable levels of diffusion to create an enhanced visitor experience, while upholding indoor environmental conditions necessary for displaying fine art.

EXAMPLES
Naturally Occurring
• Daylight from multiple angles
• Direct sunlight
• Diurnal and seasonal light
• Firelight
• Moonlight and star light
• Bioluminescence Simulated or Constructed
• Multiple low glare electric light sources
• Illuminance
• Light distribution
• Ambient diffuse lighting on walls and ceiling
• Day light preserving window treatments
• Task and personal lighting
• Accent lighting
• Personal user dimming controls
• Circadian color reference (white light during the day and lack of blue light at night
• Color tuning lighting that produces white light during the day, and minimizes blue light at night

Author of «14 patterns of biophilic design / improving health & well-being in the built environment» – Terrapin Bright Green, LLC.
About author:
Terrapin Bright Green is an environmental consulting and strategic planning firm committed to improving the human environment through high performance development, policy, and related research, in order to elevate conversations and help clients break new ground in thinking creatively about environmental opportunities.