DEPARTMENT of ARCHITECTURE I BRAC University LIGHTING DESIGN CONSIDERATIONS DEPARTMENT of ARCHITECTURE I BRAC University

Lighting Design “Design” is the science and art of making things useful to humankind. Lighting design is the application of lighting—including daylight when it is specifically used as a source of lighting—to human spaces. Like architecture, engineering and other design professions, lighting design relies on a combination of specific scientific principles, established standards and conventions, and a number of aesthetic, cultural and human factors applied in an artful manner. Lighting Design

Design Considerations FORMAT OF PRESENTATION Lighting Quantity Task Illuminance Lighting Quality Light Distribution, including: • Task and ambient lighting • Day lighting integration • Light pollution and light trespass Space and Workplace Considerations, including: • Flexibility • Appearance of the space and luminaires • Color appearance • Luminance of room surfaces • Direct glare • Reflective glare Lighting on People and Objects, including: • Modeling faces and objects • Surface characteristics • Points of interest Design Considerations Implementation Economic / Cost Consideration Energy / Sustainability FORMAT OF PRESENTATION

Design Consideration – 1. Lighting Quantity Task Illuminance Task Illuminance describes the amount of light falling on a surface. It has two components. Amount of Light – (based on usage or multiple usage of a space) After detailed study and research CODES – provides values & 2.If the surface is horizontal - horizontal illuminance if the surface is vertical - vertical illuminance Some tasks though are at an angle, such as reading a book in a hospital bed. Design Consideration – 1. Lighting Quantity

Design Consideration – 2. Lighting Quality Lighting profoundly affects many human reactions to the environment. These human reactions range from the obvious, such as the dramatic beauty of an illuminated landmark or the emotional response of a candlelight dinner, to subtle impacts on worker productivity in offices or sales in retail stores. Light Distribution, including: • Task and ambient lighting • Day lighting integration • Light pollution and light trespass Space and Workplace Considerations, including: • Flexibility • Appearance of the space and luminaries • Color appearance • Luminance of room surfaces • Direct glare • Reflective glare Lighting on People and Objects, including: • Modeling faces and objects • Surface characteristics • Points of interest • Sparkle Design Consideration – 2. Lighting Quality

Design Consideration – 2. Lighting Quality / Distribution Task and ambient lighting Task lighting systems independent from the space’s general lighting systems (serving specific task) are found in building types for instance, the display lighting in retail stores is a form of task lighting. Similarly, task lights are used in industrial manufacturing and assembly, health care, residential lighting, and many other interior lighting applications. Options include – indirect luminaries mounted atop cabinetry or workstations – Suspended luminaries – Recessed luminaries Ambient Lighting Task lights can’t light the balance of the room, and thus some other type of lighting system is needed to produce the ambient illumination in the room. Design Consideration – 2. Lighting Quality / Distribution

Design Consideration – 2. Lighting Quality / Distribution Task – Ambient Lighting produce energy savings in three ways: Locating the light source close to the task most efficiently produces the illumination levels needed for the task. Task illumination levels don’t have to be maintained uniformly through out the space, so ambient levels can be lower. Some occupants won’t use their task lights, and empty offices or workstations with absent occupants don’t have to be fully illuminated Design Consideration – 2. Lighting Quality / Distribution

Design Consideration – 2. Lighting Quality / Distribution Day lighting Integration Practice of using windows, skylights and other forms of fenestration to bring light into the interiors of buildings using various means. Incorporating day lighting in the lighting design can be done by: Proper control of the fenestration luminance Daylight sensing and compensation control systems which allow adjustments to electric electrical lighting system Glare controls should also be incorporated in the design New techniques for “piping” light into interior spaces can allow sunlight and daylight to furnish a higher percentage of illumination requirements and more uniform distribution Design Consideration – 2. Lighting Quality / Distribution

Design Consideration – 2. Lighting Quality / Distribution Light pollution In outdoor lighting, electric light may illuminate adjacent properties which become offensive if unwanted is known as light trespass. Electric lights emitting light upward o reflecting light upward cause a condition called light pollution which causes moisture and particles in the air to glow at night. Several steps to minimize light pollution & light trespass Use night lighting only when and where necessary Use the minimum amount of light needed rather than the maximum Use sources with cutoff optics that restrict light to the intend area of illumination Use more sources, each of lower wattage, to improve uniformity in the intended illumination area and minimize trespass into adjacent areas. Design Consideration – 2. Lighting Quality / Distribution

Design Consideration – 2. Lighting Quality / Space & Workplace Space and Workplace Considerations, including: • Flexibility • Appearance of the space and luminaries • Color appearance • Luminance of room surfaces • Direct glare • Reflective glare Design Consideration – 2. Lighting Quality / Space & Workplace

Design Consideration – 2. Lighting Quality / Space & Workplace • Flexibility Advance lighting designs should be flexible enough to ensure that: Lights operate where needed, and are off where not needed, as people move around within a space and use rooms in different ways. The lighting space system can be rapidly reconfigured to match a changed floor plan or accommodate a different space use, and still operate at maximum energy efficiency. The lighting system permits multiple uses and on-demand flexibility in multiple-use spaces such as conference rooms and modern A/V classrooms. Design Consideration – 2. Lighting Quality / Space & Workplace

Design Consideration – 2. Lighting Quality/ Space & Workplace Appearance & Space of luminaires Luminaries efficiency and the ability to use efficacious sources have become increasingly important criteria for selecting luminaries. Designer should find lighting systems that embody the project’s style or aesthetic but to do so using high-efficacy sources and efficient principles. For instance, choose luminaries that “hide” light source but avoid such as crystal chandeliers that require lamps with bare incandescent filaments. Design Consideration – 2. Lighting Quality/ Space & Workplace

Design Consideration – 2. Lighting Quality/ Space & Workplace The appearance of color both in terms of color rendition (CRI-Colour Rendering Index) Correlated colour Temperature (CCT) are important in the overall feeling of the space, and in some instances can have a dramatic effect on visual tasks. Design Consideration – 2. Lighting Quality/ Space & Workplace

Design Consideration – 2. Lighting Quality / Space & Workplace Color Rendering Index (CRI) describes how a light source makes the color of an object appear to human eyes and how well subtle variations in color shades are revealed. The CRI is a scale from 0 to 100 percent indicating how accurate a "given" light source is at rendering color when compared to a "reference" light source. The higher the CRI, the better the color rendering ability.  Halogen is considered the “reference” light source and has a CRI of 100. CRI of 100 in an LED source has not yet been developed.  CRI in the 90’s is possible but very expensive. Fluorescent lamp sources are considered very poor in CRI running in the low 70’s. A CRI index >80 is considered very good.  Design Consideration – 2. Lighting Quality / Space & Workplace

Design Consideration – 2. Lighting Quality / Space & Workplace Correlated Color Temperature For good visual comfort, light needs to have the right color and quality. Light can feel cool or warm. This is quantified by the "color temperature" and measured in degrees Kelvin. The higher the color temperature, the bluer the light is.  This may seem counter-intuitive, as we think of blue as a "cooler" color than red, but it comes from the physics of black body radiation.  People generally prefer bright light to be bluer, like daylight, while they prefer dim light to be yellow, like candlelight.   The color temperatures of daylight and various common light sources are below. Design Consideration – 2. Lighting Quality / Space & Workplace

Design Consideration – 2. Lighting Quality / Space & Workplace Luminance of room surfaces – Periodic trends in interior design introduce dark paints and finishes. These trends contribute to difficulty in producing energy-effective design by increasing lighting requirements to raise surface luminance into the comfortable range. Lighting designer should: Encourage the use of high diffuse reflectivity (light colored) surfaces and minimize the use of dark surfaces. Use computer modeling to ensure that the average room surface luminance is at least 10% of the task background. With indirect lighting systems, use computer calculations to check for uniformity and try to maintain 10:1 luminance ratio or better. Design Consideration – 2. Lighting Quality / Space & Workplace

Design Consideration – 2. Lighting Quality / Space & Workplace Direct Glare . Caused by a view of the light source, often with high contrast to the surroundings. Glare is associated not just with lamps, but also with daylight, especially when one is exposed to low angle, direct sunlight. Be concerned – more about the glare caused by lamps, lenses and other overly bright sources of manmade lights – less about glare of sunlight and small point sources – most concerned about sources of glares in relation to the stationary tasks when building occupants cannot easily relocate themselves or their tasks Design Consideration – 2. Lighting Quality / Space & Workplace

Design Consideration – 2. Lighting Quality / Space & Workplace Reflective Glare Have long been associated with gloss-coated paper, pencil paperwork and computer CRT (cathode ray tube) screen. Indirect lighting, by creating a diffuse and uniform illumination has been advocated as solution. Can create specular reflections that can cause glare reducing comfort or disabling the worker’s vision in particular areas. Reflective glare - when system has been optimized to reduce glare – then consider: modifying the task to eliminate remaining glare problem such as use of flat screen CRT or active matrix. Use of ink rather than pencil Use of matte-coated or uncoated paper rather than gloss coating paper. Changing finishes of polished floors or shiny conference room tables. Design Consideration – 2. Lighting Quality / Space & Workplace

Design Consideration – 2. Lighting Quality Lighting on People and Objects, including: • Modeling faces and objects • Surface characteristics • Points of interest Design Consideration – 2. Lighting Quality

Design Consideration – 2. Lighting Quality Modeling faces and objects In human vision, shadows and highlights enhance the perception of three dimensions. Both are the products of directional light sources. The sun and the moon produce well-defined shadows, and are considered dramatic and attractive light sources. Diffuse light, like the light from a cloudy sky, produces an even light that is relatively shadow-free. Once considered desirable, it is now realized that shadow-free light can fail to render changes in surfaces making a space or task less visible. To model a surface for better recognition of its shape and features, in general some percentage of directional light is considered important. Consider using a blend of direct and indirect lighting in most designs to provide a combination of comfort and modeling. To achieve a minimum modeling, a directional light for an object or area of interest should be at least 20-25% of the total illumination. Design Consideration – 2. Lighting Quality

Design Consideration – 2. Lighting Quality Surface Characteristics Lighting techniques that reveal architectural nuance like texture enhance visual perception have become more commonly requested by building owners and architects Design Consideration – 2. Lighting Quality

Design Consideration – 2. Lighting Quality Point of Interest In retail and museum lighting, designers use highlights of up to 10 times the ambient light level to draw attention to key display. Recognize that it’s wasteful to create lighting than is needed. Carefully select highlights, and use a minimum effective highlight level. Creating highlights in contrast to lower ambient illumination levels Creating highlights with efficient sources as close to the object or surface as possible. Small points of light from fiber optic sources or LEDs may offer efficient ways to create highlights or attract attention where specifically desired. Design Consideration – 2. Lighting Quality

Implementation Implementation Economic / Cost Consideration Energy / Sustainability Design Consideration – 3. Implementation

Design Consideration – 3.Implementation Energy Efficiency Energy-efficient lighting design focuses on ways to improve both the quality and efficiency of lighting. Match the amount and quality of light to the performed function. Install task lights where needed and reduce ambient light elsewhere. Use only energy-efficient lighting components, controls and systems. These include Fluorescent and LED lighting options. Maximize the use of daylighting. Daylighting is the use of windows and skylights to bring natural light into your home. Use of Daylight Energy Efficiency Incorporate proper lighting controls Infrared sensors †Motion sensors †Automatic timers †Dimmers …Replacement with energy efficient lamps CFLs and LEDs Design Consideration – 3.Implementation

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