Lighting for Special Applications

Lighting for Special Applications is a crucial part of the Global Certificate in Professional Lighting Design. This section covers various key terms and vocabulary that are essential for understanding and implementing special lighting designs. In this explanation, we will discuss various terms, their definitions, examples, practical applications, and challenges.

1. Luminance: Luminance is the amount of light that is emitted from a surface in a given direction. It is measured in candelas per square meter (cd/m2). Luminance is an essential factor in lighting design as it affects the brightness and contrast of surfaces and objects.

Example: A white wall with a high luminance value will appear brighter than a black wall with a low luminance value.

Practical Application: In museums and art galleries, lighting designers use luminance to ensure that the artwork is visible while minimizing glare and reflection.

Challenge: Achieving the right luminance value can be challenging as it depends on various factors, including the surface finish, color, and distance from the light source.

2. Illuminance: Illuminance is the amount of light that falls on a surface. It is measured in lux (lx). Illuminance is an essential factor in lighting design as it affects the overall brightness and visibility of a space.

Example: A well-lit room will have a high illuminance value, while a dark room will have a low illuminance value.

Practical Application: In offices, lighting designers use illuminance to ensure that the workspace is well-lit and free from glare, which can cause eye strain and discomfort.

Challenge: Achieving the right illuminance value can be challenging as it depends on various factors, including the light source, distance from the light source, and surface reflectance.

3. Color Temperature: Color temperature is the color of light emitted by a light source. It is measured in Kelvin (K). Color temperature affects the mood and atmosphere of a space.

Example: A warm white light has a low color temperature (around 2700K), while a cool white light has a high color temperature (around 6500K).

Practical Application: In retail stores, lighting designers use color temperature to create a warm and inviting atmosphere that encourages customers to stay longer.

Challenge: Choosing the right color temperature can be challenging as it depends on the type of space, the desired mood, and the color of the objects and surfaces.

4. Color Rendering Index (CRI): Color Rendering Index (CRI) is a measure of a light source's ability to accurately render the colors of objects and surfaces. It is measured on a scale of 0 to 100. A higher CRI value means that the light source renders colors more accurately.

Example: A light source with a CRI value of 90 will render colors more accurately than a light source with a CRI value of 70.

Practical Application: In art studios, lighting designers use high CRI value light sources to ensure that the colors of the artwork are accurate and true to life.

Challenge: Finding a light source with a high CRI value can be challenging and may be more expensive than lower CRI value light sources.

5. Glare: Glare is the excessive brightness of a light source that causes discomfort or reduces visibility. It is measured in candelas per square meter (cd/m2).

Example: A bright light source located near a computer screen can cause glare, resulting in eye strain and discomfort.

Practical Application: In offices, lighting designers use glare control measures, such as diffusers and shields, to minimize glare and ensure comfortable lighting levels.

Challenge: Minimizing glare can be challenging as it depends on various factors, including the light source, surface reflectance, and viewing angle.

6. Contrast Ratio: Contrast Ratio is the ratio of the luminance of the brightest and darkest areas of a space. It is measured as a numerical value. A higher contrast ratio means that there is a more significant difference between the brightest and darkest areas.

Example: A high contrast ratio can be found in a movie theater, where the screen is much brighter than the surrounding area.

Practical Application: In cinemas, lighting designers use a high contrast ratio to create a more immersive and engaging viewing experience.

Challenge: Achieving the right contrast ratio can be challenging as it depends on various factors, including the light source, surface reflectance, and viewing angle.

7. Unified Glare Rating (UGR): Unified Glare Rating (UGR) is a measure of the discomfort caused by glare. It is measured on a scale of 10 to 40. A lower UGR value means that the glare is less likely to cause discomfort.

Example: A UGR value of 10 is considered comfortable, while a UGR value of 40 is considered uncomfortable.

Practical Application: In schools, lighting designers use UGR values to ensure that the lighting levels are comfortable and do not cause discomfort or distraction.

Challenge: Minimizing glare and achieving the right UGR value can be challenging as it depends on various factors, including the light source, surface reflectance, and viewing angle.

8. Luminous Efficacy: Luminous Efficacy is the ratio of the luminous flux (amount of light emitted) to the power (energy consumed) of a light source. It is measured in lumens per watt (lm/w).

Example: An LED light source with a luminous efficacy of 150 lm/w will emit more light per watt than an incandescent light source with a luminous efficacy of 15 lm/w.

Practical Application: In commercial buildings, lighting designers use high luminous efficacy light sources to reduce energy consumption and lower operating costs.

Challenge: Finding a light source with a high luminous efficacy value can be challenging and may be more expensive than lower luminous efficacy value light sources.

9. Correlated Color Temperature (CCT): Correlated Color Temperature (CCT) is the color temperature of a light source that is closest to the color temperature of a black body radiator. It is measured in Kelvin (K).

Example: A warm white LED light source with a CCT of 3000K will have a similar color temperature to an incandescent light source with a CCT of 3000K.

Practical Application: In residential spaces, lighting designers use CCT values to create a warm and inviting atmosphere that is similar to natural daylight.

Challenge: Choosing the right CCT value can be challenging as it depends on the type of space, the desired mood, and the color of the objects and surfaces.

10. Circadian Lighting: Circadian Lighting is the use of light to regulate the human circadian rhythm, which is the internal biological clock that regulates sleep-wake cycles. It is measured in lux (lx).

Example: A circadian lighting system in a nursing home will provide high light levels during the day to promote alertness and low light levels at night to promote sleep.

Practical Application: In healthcare facilities, lighting designers use circadian lighting to improve patient outcomes, such as reducing depression and anxiety.

Challenge: Implementing a circadian lighting system can be challenging as it requires a thorough understanding of the human circadian rhythm and the use of advanced lighting control systems.

In conclusion, Lighting for Special Applications is a crucial part of the Global Certificate in Professional Lighting Design. Understanding the key terms and vocabulary is essential for lighting designers to create effective and efficient lighting designs. By using the right luminance, illuminance, color temperature, CRI, glare control, contrast ratio, UGR, luminous efficacy, CCT, and circadian lighting, lighting designers can create spaces that are functional, comfortable, and inviting. However, achieving the right balance can be challenging, and it requires a thorough understanding of the factors that affect lighting design.

References:

1. IESNA (2016). Light + Design: The IESNA Lighting Handbook. New York: McGraw-Hill Education. 2. CIBSE (2015). Code for Lighting. London: CIBSE. 3. BS EN 12464-1:2011. Light and lighting. Lighting of work places. Part 1: Indoor