basic lighting and acoustics

7/26/2019 Basic Lighting and Acoustics

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XIII. BASIC LIGHTING

ACOUMODULE 32 – BA

MODULE 33 – BAS



MODULE 32 –

BASIC LIGHTING

LIGHTING CONCEPTS

LIGHTING SOURCES



LIGHT AND LIGHTING

LIGHT• Visible light (commonly referred to simply

as light) is electromagnetic radiation thatis visible to the human eye, and isresponsible for the sense of sight.

LIGHTING

• Lighting or illumination is the deliberateuse of light to achieve a practical oraesthetic effect.

• Lighting includes the use of both artificiallight sources like lamps and light fixtures,as well as natural illumination bycapturing daylight.

BASIC TYPES OF LIGHTINSOURCES

• NATURAL LIGHTING

• Daylighting (using window

light shelves) is sometimesmain source of light duringbuildings.

• This can save energy in plaartificial lighting, which repmajor component of energconsumption in buildings.

• ARTIFICIAL LIGHTING• Generated by converting v

of energies into light.

• HEAT

• CHEMICALS

• ELECTRICTY



TYPES OF ARTIFICIAL LIGHTING SOURCES

• Incandescent Lamps

• R and PAR

• Tungsten - Halogen

Filament Lamps

• Fluorescent Lamps

• Energy Savings Lamps

• Neon Vapor Lamps

• PL lamps

Gaseous Discharge Lamps

• Mercury Vapor Lamps

• Metal Halide Lamps

• High Pressure Sodium Lamps

High-Intensity Discharge Lamps

• Retrofit LED Fixtures

• LED Strip Lights

• LED Standalone Systems

LED Lamps



CLASSIFICATIONS OF LUMINAIRES

1. Indirect

• 90% to 100% of the light output is directed towards theceiling and upper walls of the room.

2. Semi-indirect

• 60% to 90% of the light is directed upwards; 40% to 10%downwards.

3. General diffuse or direct-indirect

• provides approximately equal distribution of light upwards

and downwards.

4. Semi-direct

• 60% to 90% of light is directed downwards; while 40% to 10%is directed upwards.

5. Direct

• 90% - 100% of the light output is directed downwards



TYPES OF NON-DIRECT LIGHTING

Cove Lighting a system where light sources areshielded by a ledge to distribute light upwards

over the ceiling and upper wall. It is a form ofindirect lighting.

Valance Lighting a system where light sources areshielded by a panel parallel to the wall usuallyacross the top of a window. This provides light

both upwards and downwards over the wall.

Cornice Lighting a system where light sources areshielded by a panel parallel to the wall andattached to the ceiling to distribute lightdownwards over the wall. This is considered asdirect lighting.



General Lighting

Localized Lighting

Accent Lighting T Y P E S O F L I G H T I N

G

C O N F I G U

R A T I O N M E T

H O D S



FACTORS FOR DESIRABLE SEEING CONDITIONS

Intensity of Illumination

• intensity of light required will depend upon the tasks involved asfollows

•a) for casual work, as in conferencing, interviewing and inactivefiling – 10 to 30 fc

•b) for moderate work, as in intermittent filing and generalclerical work – 30 to 50 fc

•c) for prolonged work, as in active filing, index referencing andmail sorting – 50 to 100 fc

•d) for precision work, as in accounting, auditing, tabulating,bookkeeping, business machine operation, reading poorreproductions and rough layout drafting – 100 to 150 fc

• for fine precision work, as in cartography, designing and detaildrafting – 150 to 200 fc

Quality of Light

•Uniformity

• freedom from variations of illumination in a room or space.Absolute uniformity signifies same intensity throughout and it isnot always practicable to attain. A deviation of 25% from theaverage intensity cannot be detected by the eye, and isconsidered an acceptable maximum.

Quality of Light

•Diffusion

• refers to the number of directions and illuminating rays proceed. Good diffusi

falls upon a matte or satin surface fromthus eliminating shadows and streaks oresults from illumination from one direvisual confusion because of distorted h

•Absence of Glare

•Glare is defined as the effect of brightnwhich causes annoyance or discomfortinterferes with seeing. When the glare in the field of vision, it is known as “dirglare”. When glare is caused by the ref

a viewed surface, it is known as “reflecglare”.

•Color of Light

•depends upon the type of lamp chosenprovide yellow light; although there aredepending upon the color of their glasshave the greatest variety of colors rangbluish white and even pinkish white. Cenhance certain qualities. For example

used to enhance food in restaurants.



UNITS IN LIGHTING

• Unit of luminous intensity of a light source in a specific direction. Also called candle.

Technically, the radiation intensity in a perpendicular direction of a surface of 1/600000 square meblack body at the temperature of solidification platinum under a pressure of 101,325 newtons permetre.

Candela (cd)

• Unit of light intensity, measured in lumens per square foot. The brightness of one candle at a distafoot. Approximately 10.7639 lux.

Footcandle (fc or ftc)

• Unit of light flow or luminous flux. The output of artificial lights can be measured in lumens.

Lumen (lm)

• Unit of illumination equal to one lumen per square metre. The metric equivalent of foot-candles (equals 0.0929 footcandles). Also called metre-candle.

Lux (lx)



MODULE 32 –

BASIC ACOUSTICSTHE NATURE OF SOUND

ARCHITECTURAL ACOUSTICS



DEFINITIONS OF SOUND

Physical wave in an elastic medium, usually air

The sensation stimulated in the organs of hearing bymechanical radiant energy transmitted as longitudinalpressure waves through the air or other medium

A vibration in an elastic medium such as air, water, mostbuilding materials, and the earth

Physically, sound is a rapid fluctuation of air pressure



ARCHITECTURAL ACOUSTIC

ACOUSTICS: branch of physics concerned withsound deals with the production, control,transmission, reception, and effects of sound

Three Elements of Acoustics

• Sound Source ( e.g. human speech, HVAC equipment)

• Transmission Path (e.g. air, earth, building materials)

• Receiver (e.g. humans, animals, sensitive medicalequipment)



ARCHITECTURAL ACOUSTICS

• The science of sound phenomena in buildings, dealingwith the production, transmission, and absorption ofsound.

• The art and science of designing a room or buildingwhich insures both comfort and communication, andprovides special features as the purpose and use of thestructure requires

Definition

• Planning to isolate noise sources from quiet areas(Noise Control)

• Improvement of sound conditions in a room (SpaceAcoustics)

• Structural precautions to reduce noise penetrations(Structure-borne sound control)

3 Aspects of Acoustical Design in Buildings



PROPERTIES OF SOUND

WAVELENGTH

• the distance a soundwave travels during eachcomplete cycle ofvibration (λ).

AMPLITUDE

• the strength or power ofa wave signal. The"height" of a wave whenviewed as a graph.

FREQU

• the numdisplaceoscillatioparticle second.



PROPERTIES OF SOUND



PROPERTIES OF SOUND

• the rate at which sound energy is being transmitted,measured at any point in the medium

INTENSITY

• the fluctuation in the atmospheric pressure caused

by the vibration of air particles due to a sound wave.

SOUND PRESSURE

(Watts)

• the subjective attribute of an auditory sensationLOUDNESS (Phon)

• the number of displacements or oscillations that aparticle undergoes in 1 second.FREQUENCY (Hertz)

• the attribute of an auditory system which enables usto pinpoint sounds on a scale (high-low frequency)

PITCH

• a steady periodic sound; a sensation having pitchTONE

• combination of the number, prominence, pitch, andintensity of the overtones

TIMBRE



PROPERTIES OF SOUND

• minimum intensity

that is capable ofevoking an auditorysensation in the ear

Threshold

ofAudibility

• minimum soundpressure level whichstimulates the ear to apoint which is painful

Thresholdof Pain



SPACE ACOUSTICS -

BEHAVIOUR OF SOUND ON A

MEDIUM

1. INCIDENTOR DIRECT

SOUND

2. REFLECTEDSOUND

3. ABSORBEDSOUND

4. DIFFUSEDSOUND

5.DIFFRACTED

SOUND

6.TRANSMITTED

SOUND



O S



ACOUSTICAL

DEFECTS

ECHO

• Sound waves which have been reflected to a listener

with sufficient magnitude and time delay

SOUND SHADOW

• Occurs when an area does not receive an adequateamount of direct sound

FLUTTER ECHO

• A rapid succession of noticeable small echoes

DISTORTION

• An undesirable change in the quality of musical sound

SOUND CONCENTRATION

• Sound reflections from concave surfaces concentratingon a single area

ROOM RESONANCE

• sounds within a narrow band of frequencies tend tosound louder than other frequencies

CREEP

• Sounds creeping along large concave surfaces



FIN

basic lighting and acoustics

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