Lighting and Acoustics Notes

Lighting

• Radiant Energy: Lighting is radiant energy that radiates equally in all directions.
• Intensity Diminishes: As light spreads from its source, its intensity diminishes according to the square of the distance.
• Absorption and Reflection: Objects can absorb or reflect light.
• Sustainable Design: Modern lighting considers sustainable design.
• Light Reveals: Shape, color, and texture of objects.

Factors Affecting Visual Field of Light

1. Brightness
2. Contrast
3. Glare
4. Diffusion
5. Color

Brightness

• Contrast in brightness aids perception of shape and form.
• Brightness = Illumination x Reflectance

Contrast

• Task Area Brightness: Surrounding area should range from 1/3 to 5 times the brightness of the task area.
• Brightness Ratio: The maximum recommended brightness ratio between the visual task area and its immediate background is 3:1.
• High background brightness helps in delineating shape and outline.
• Increased surface brightness aids in discriminating surface detail.

Glare

• Human eyes can adapt to different lighting levels between tasked surface and its background.
• Eyes respond to a minimum brightness ratio of 2:1 and a maximum of 100:1 or more, but only for a limited time.
• Eyes cannot immediately respond to extreme changes in lighting levels.
• Direct glare is often a problem with bare LEDs exceeding the maximum acceptable luminance.

Indirect Glare

• Caused by a tasked or viewing surface reflecting light from a light source into the viewer's eyes (veiling reflection).
• Solution: Increase ambient lighting and use low-brightness lighting fixtures.

Types of Glare

• Direct Glare: Caused by the brightness of light sources within the normal field of vision; the brighter the light source, the greater the glare potential.
  • Solutions:
    1. Locate sources of brightness out of the direct line of vision.
    2. Use properly shielded or baffled lighting fixtures.
    3. Raise the background brightness of the light sources and reduce brightness ratio.

Diffusion

• Diffused Lighting: Broad sources of light produce diffused lighting, minimizing contrast and shadows.
• Directional Lighting: Enhances the modeling of form and texture.

Color

• Color Temperature: Measured in Kelvin; refers to the appearance of the light source when lighted.
• Lower Temperature: The lower the color temperature, the warmer the light appears.
• Important quality of light is its color and how it affects the coloration of objects and surfaces.

Daylighting

• Sunlight Direction: Considers sunlight coming in from different directions.
• Window Sizes: The bigger the windows, the more light will enter.
• Direct Sunlight: Emphasizes hot bright colors.
• Skylight: More diffused and enhances cool colors.
• The ceiling and rear wall of a room are generally more effective than the side walls or the floor in reflecting and distributing daylight.

Glare with Daylighting

• Glare is caused by excessive contrast between the brightness of a window opening and the darker wall surfaces or cast shadows adjacent to it.
• Eyes adjust to the brightest light, reducing the ability to discern less brightly lit areas.
• High window openings allow daylight to pass through the interior space and help prevent glare.
• Windows set flush in a wall or ceiling accentuate contrast between bright exterior and darker interior surfaces.
• Windows on the edge or corner of a wall maximize light entering the window.
• Light Shelf: An exterior horizontal construction located below the head of the window opening and typically just above eye level.
• Skylights: Flat, dome, and tubular skylights.

Lighting Principles

• Poorly placed lighting contributes to distracting visual clutter.
• Organized lighting patterns emphasize architectural features and provide cues to the use and orientation of space.
• Lighting layout drawings coordinate lighting fixture locations with other ceiling elements.

Lighting Effects

• Effectively guide the viewer's eyes to direct areas or points of interest.
• Warn against potential or harmful areas.
• Provide illumination to spaces.
• Brightness Balance Strategies:
  1. Light opposite walls of a space.
  2. Mix wall washers on one wall with non-uniform lighting on the other.
  3. Balance perimeter illumination of a space with its center.
  4. Lighting horizontal surfaces emphasizes detail, people, and movement and de-emphasizes the architecture.
  5. Illuminate vertical and overhead surfaces to emphasize architectural form.

Integrated Lights

• Manufacturers develop ways to integrate lights into architectural surfaces.
  1. Illumination of floors
  2. Wayfinding signs
  3. Ceiling applications that provide surface lights
  4. Prefabricated sheet metal panels with built-in LEDs for walls

Lighting Design Guidelines

• Use available watts to supply light when and where needed; limit unwanted light.
• Integrate and control daylight in the space.
• Choose light sources carefully and locate them with discretion.
• Control lighting with dimmers, timers, and occupancy sensors.

Illuminance

• Measure of incident light on a surface.
• Considerations: Orientation and visual task.
  1. Illuminance levels are very important.
  2. Vary with task.
  3. Higher levels required for tasks that are small or have very low contrast.

Lamps

• Electric light sources used in lighting fixtures.
• Quality of light differs according to the specific type of lamp used.
• Light is further modified by the housing and any reflector, lens, or baffle.

Color Rendering Index (CRI)

• A measure of a lamp's ability to render color accurately when compared with a reference light source of similar color temperature.
• Manufacturers are working to improve the CRI of all light sources.
• Spectrometer is another tool to measure light output and other rendering abilities.
• Ranges from low quality to excellent.

LED (Light Emitting Diodes)

• Radiates very little heat and is highly energy-efficient.
• Long life, typically ten years.
• High-power white LEDs are used for illumination.
• Characteristics:
  • Insensitive to vibration and temperature shock
  • Shock-resistant
  • Contains no mercury
  • Designed to use less energy and have lower watts rating
• A 25-28 watt LED has a 2600 lm rating, equivalent to 150 watts incandescent.
• Watts are a measure of energy used, not used to measure brightness of LED
• 6-9 watts of LED = 50 watts of incandescent bulb

Discharged Lamps

• Produced light by the discharge of electricity between electrodes in a gas-filled glass enclosure.
• Common type is fluorescent lamp.

Fluorescent Lamps

• Are low-intensity discharged lamps that produce light by generating an electric arc that passes through the mercury vapor sealed within their tubes.
• Contain mercury and require special handling for recycling.

Compact Fluorescent Lamp

• More efficient and have a longer life than incandescent lamps.
• Requires a ballast to regulate electric current through the lamp.
• Available Colors:
  • Warm white
  • Cool white
  • Sunlight
  • Cool daylight
  • Skywhite
• CRI rating is 50-95; color temperature 2700-8000K.

High-Intensity Discharge Lamps (HID)

• Produces light by passing an electrical current through gas or vapor under high pressure.
• For industrial, commercial, roadway, and security lighting.

High-Pressure Sodium Lamps (HPS)

• Have higher purchase costs, lower light efficiency.

Metal Halide Lamps

• Used for high ceilings where lamps are left for extended periods; have excellent color.

Incandescent Lamps

• Have shorter lifespans.
• Contain metal filaments that are heated within a glass enclosure until they glow.
• Are available from 6-1500 watts and low efficacy rating from 4 to 24.5 lumens per watt only.
• Only 12 percent of power is used in lighting, while the remaining is given off as heat.

Tungsten Lamps

• Tungsten or halogen lamps are incandescent lamps.
• Designed for more precise beam control and higher efficacy, energy savings where focused lights are needed.
• Requires a step-down transformer to lower the power to 12V.
• Dimming requires the use of a magnetic transformer specially designed for use with low lighting components.

Light Fixtures

• Electrical lighting device containing one or more light sources and all accessory components required for its operation.

Linear vs. Volumetric Sources

• Linear Sources:
  • Can be used to give direction, emphasize the edges of planes, or outline an area.
  • A parallel series of linear sources can form a plane of illumination effective for the general diffused lighting of an area.
• Volumetric Sources:
  • Are point sources expanded by the use of translucent materials into spheres, globes, or other 3-dimensional forms.

Types of Light Fixtures

The three most common forms of architectural lighting are cove, soffit and valance; all three are integrated into the room's structure.

• Architectural: Cove, soffit, and valance; commonly used as ambient lighting.
  • Cove Lighting: Located in a ledge, shelf, or recess high up on a wall, and the light is bounced toward the ceiling or upper wall.
  • Soffit Lighting: Located in a soffit or cornice near the ceiling, and the light radiates downward, washing the wall with light.
  • Valance Lighting: Located in a wood, metal, or glass valance mounted above a window or high on the wall, and the light bounces both upward and downward.
    The technique of bouncing light off walls and ceilings is known as indirect lighting, which is favored by many lighting professionals because indirect lighting minimizes shadows and glare.
• Recessed: Installed above the ceiling, this type of lighting has an opening that is flush with the ceiling.
  • Requires at least 6 inches of clearance above the ceiling, and insulation is essential.
  • Sends a relatively narrow band of light in one direction; can be used to provide ambient, task, or accent lighting.
• Track: Mounted or suspended from the ceiling, track lighting consists of a linear housing containing several heads that can be positioned anywhere along a track; the direction of the heads is adjustable also.
  • Often used for task or accent lighting.
• Undercabinet: Mounted under kitchen cabinets, this type of lighting can be linear or a single puck-shaped fixture.
  • Extremely popular as task lighting in a kitchen.
• Pendants: Suspended from the ceiling, a pendant light directs its light down, typically over a table or kitchen island.
  • Enhances the decorative style of a room; can provide ambient or task lighting.
• Chandeliers. Suspended from the ceiling, chandeliers direct their light
  upward, typically over a table. They can enhance the decorative style of a
  room. Chandeliers provide ambient lighting.
• Ceiling. This type of fixture is mounted directly to the ceiling and has a
  glass or plastic shade concealing the light bulb. Ceiling fixtures have
  been common in homes for nearly a hundred years, often providing all
  the ambient light in a room.
• Wall Sconces: Surface-mounted to the wall, sconces can direct light upwards or downwards.
  • Wall sconces provide ambient or task lighting.
• Desk, Floor & Table Lamps. Made in a wide range of sizes and styles,
  lamps are extremely versatile and portable sources of light in a room.
  *Reflectors control the distribution of
  the light emitted by a lamp.
  *Ridged baffles reduce the brightness
  of a light source at the aperture of the
  housing.
  *Baffles, such as louvers and eggcrates,
  redirect the emitted light and/or shield
  the light source from view at certain
  angles.
  *Surface-mounted
  mandatest surface-mounted fixtures. The ADA mandates that surface-mounted fixtures that are between 2'3"
  and 6'8" above the floor should not extend more than 4" into the space."

Track Mounted Lighting

• Functions through a continuous track or rail system, commonly mounted on the ceiling or wall.
• Suitable for most residential spaces and are often used alongside other lighting options.

Mounting Styles

• Recessed
• Semirecessed
• Surface-mounted
• Track-mounted
• Pendant-mounted

Types of Lighting

• Ambient or general lighting.
• Accent lighting.
• Task lighting.

Components of Lighting Design

• Line
• Point
• Plane
• Sparkle
• Volume

Principles of Lighting Design

• Manipulates the fundamental elements and quality of ambient and focal lighting as well as sparkle.

  • Ambient lighting provides general and shadowless light.
  • Focal lighting offers a contrast in brightness that is directive and creates a sense of depth.
  • Sparkle includes highlights and scintillating sequences.

• Ambient Lighting: provides the overall illumination for a room. It's designed to createcreate
  a uniform light level throughout the space, allowing people
  to move around comfortably and easily see each other.

  • Provides a general level of illumination.
  • Creates a comfortable and uniform light level throughout the room.

• Is appropriate for frequently configured areas or spaces where the location of task varies

  • The addition of direct and indirect sources of light to ambient lighting makes it more efficient and condusive to further the clearness of a certain space

• Focal Lighting: creates brighter
  areas within the ambient light
  level of a space through the use
  of task lighting and accent
  lighitong

• Task Lighting: illuminates specific areas of space for the performance of the visual task or activities.
  Light source is placed near to the
  tasked areas.

Accent Lighting

• A form of focal lighting that creates a focal point or rhythmic patterns of light and dark within a space.
• Highlights objects, creates focal points, adds depth and dimension, and improves ambiance.

Sparkle Lighting:

• Often produce little ambient light - they are all about sparkle.
• Lighting can bring out the highlights in the objects that it shines on or introduce sparkle through the brilliance of the fixture itself.

Measuring Light

• Major consideration in lighting design is energy conservation.
• Considerations Include:
  1. Space appearance
  2. Glare
  3. Daylighting
  4. Color and luminance of finishes
  5. Light distribution, etc.

Light Measurement Parameters

• Luminous Intensity (Candela): Measures the amount of light emitted in a specific direction.
• Luminous Flux (Lumens): Measures the total amount of light emitted by a source.
• Illuminance (Lux or Footcandles): Measures the amount of light falling on a surface.
• Luminance (Candelas per Square Meter or Nits): Measures the intensity of light reflected from a surface.
• Color Temperature (Kelvin): Describes the color appearance of light.

Instruments Used

*Light Meters (Lux Meters):

*Photometers:

*Spectrometers:

*Colorimeters:

Photometric Data Considered

• Luminous Intensity Distribution Curve (LIDC)

Direct vs Concentrating

• Direct light travels in a straight line from a source to a target, while concentrating light uses optical elements to gather and focus light from a wider area onto a smaller one.

Direct vs Spread

• Direct light is concentrated on a specific area or object, creating a definedbeam of light. Examples: Task lighting, spotlights, floodlights, and sunlight are examples of direct
  light.

Spread light is dispersed over a wider area, creating a softer and more uniformillumination. Examples: Diffused light sources, lamps with diffused shades, and indirect lighting systems are
examples of spread light.

Luminous Intensity Distribution Curve (LIDC)

• Represents the light pattern produced by a lamp or light fixture.
• The coefficient of utilization indicates the efficiency of a light source.
• The Light Loss Factor (LLF) reflects the decreased in luminous output that occurs over the operating life of a lamp.

Acoustics

• Deals with the production, control, transmission, reception, and effects of sound.
• Sound occurs when energy is transmitted as pressure waves through the air and another medium.
• Sound wave travels outward spherically from its source until it encounters an obstacle.
• Sound, when it strikes an object, is either absorbed, reflected, or a combination of the two.

Sound in a Room

• Hearing sound directly from its source and then from a series of reflections of that sound creates reflective sound.
• Continuous presence of reflective sound can cause echo, flutter, or reverberation problems.

Acoustics Considerations

• Requirements for sound, reverberation time, and resonance vary with activity and sound types.
• Designers must choose materials that suit the purpose of the area.

Reverberation

• Refers to the persistence of sound within a space, caused by multiple reflections of the sound after its source has stopped.
• Altering a space's orientation or adjusting the proportion of reflective and absorbent material can aid sound clarity.

Parameters

• Decibels (dB) is a unit expressing relative pressure or intensity of sound on a uniform scale.
• Equal Loudness Contour: Represents the sound pressure level at which sounds of different frequencies are judged to be equally loud.
• Sone: A unit for measuring the apparent loudness of a sound.

Isolating Sound

• Noise: Unwanted, annoying, or discordant sound.
• Strategies to control external noise:
  1. Isolate the noise from its source.
  2. Locate noise areas as far away as possible from quiet areas.
  3. Reduce the transmission of sound from one space to another.
• Sound can be transmitted through air and solid materials of a building's structure.

Strategies to Isolate Sound

• Use quiet mechanical equipment system.
• Use resilient mounting and flexible connections.
• Isolate equipment vibration from the building structure.
• Eliminate flanking paths along interconnecting ductwork or piping.

Noise Reduction

*Any finish or object in a space can absorb, block or transmit sound.

Important to Note : 1) Materials that address noise reduction 2)Acoustics control. Quieter HVAC Systems

Noise Reduction Depends On

• Transmission loss through the wall, floor, and ceiling construction.
• Absorptive qualities of the receiving space.
• The level of masking or background sound.
• Create zones for activities according to sound level.

Transmission Loss

• A measure of performance in preventing the transmission of airborne sound.

TL Rating Enhancement Factors

• Mass: The heavier and denser the body, the greater resistance to sound transmission.
• Separation into Thin Layers: Introducing airspaces into construction assembly disrupts the path of sound transmission.
  *Absorption : absorptive materials help dissipate sound in a room.

Discontinuous Construction

• Discontinuous construction breaks the continuity of the path through whi structure-borne sound can be transmitted.

• Installing a fiberglass blanket in between the two rows of

  studs increases the transmission loss.

*ounting the finish material on resilient channels perm
the surface to vibrate without transmitting noise to the supporting structure.
*Sound can be transmitted through any clear air path
e the tiniest cracks around doors, windows, and electricaloutlets. Careful sealing of these openings can preventairborne noise from entering a room.

Sound Absorption

• Absorptive materials can dissipate some of the incident sound energy and reduce the portion of sound transmitted.
• Helpful in spaces with distributed noise sources, such as offices, schools, and restaurants.

Sound in Offices

• Material choices and room typologies affect the sound of a space.
• Open-plan offices can have detrimental effects on acoustic privacy and speech intelligibility.
• Office cubicles often use acoustical material to absorb some of the sound.