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QUANTITY OF LIGHT

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SPACE HEIGHT RATIO
QUALITY OF LIGHT

The light that we actually see, brightness can be measured as the light leaving a lamp, or the
light reflecting from an object's surface.
If not controlled, brightness can produce levels of glare that either impair or prevent a desired
task being performed. Glare can be described as direct or reflected glare, which can then result
in discomfort or disability.

• Direct glare comes straight from the light source.

• Reflected glare shows up on the task itself, such as a computer screen.

• Discomfort glare does not prevent seeing makes it uncomfortable.

• Disability glare prevents vision. A popular example is holding a glossy magazine at a certain
angle; a veiling reflection results, impairing our reading of the page.
 Methods of lighting

1.General/ Ambient Lighting

General lighting, also known as ambient lighting, is the primary source of illumination
in a space. Its purpose is to provide overall illumination evenly throughout the area,
ensuring visibility and creating a comfortable environment for various activities.
 Methods of lighting

1.General Lighting

Key characteristics of general lighting include:

• Uniform Distribution: General lighting fixtures are typically designed to distribute
light uniformly across a room or space, minimizing shadows and ensuring
consistent illumination levels.
• Low to Medium Intensity: The intensity of general lighting is moderate, providing
sufficient brightness for navigation and basic tasks without causing glare or
discomfort.
• Wide Coverage: General lighting fixtures such as ceiling-mounted or recessed lights
are positioned strategically to cover large areas efficiently.
• Versatility: This method is versatile and adaptable to different settings, including
residential homes, offices, classrooms, and public buildings.
• Examples: Fluorescent tubes, LED panels, recessed downlights, chandeliers, and
surface-mounted fixtures are commonly used for general lighting purposes.
 Methods of lighting

2.Local/ Task Lighting

Task lighting is focused illumination designed to enhance visibility and facilitate
specific activities or tasks. Unlike general lighting, which illuminates entire spaces, task
lighting is directed to particular areas where detailed work is performed.
 Methods of lighting

2.Task Lighting

Key features of task lighting include:

• Localized Illumination: Task lighting fixtures are positioned to provide
concentrated light directly onto work surfaces, such as desks, countertops, or
reading areas, improving visibility and reducing eye strain.
• Adjustability: Task lighting fixtures often have adjustable features, allowing users
to control the direction, intensity, and angle of light to suit their specific needs.
• Higher Intensity: Task lighting typically has a higher intensity than general lighting,
ensuring adequate brightness for detailed tasks without casting harsh shadows or
causing glare.
• Specialized Fixtures: Various fixtures are used for task lighting, including desk
lamps, under-cabinet lights, pendant lights, and track lighting, each tailored to
specific applications.
• Energy Efficiency: Task lighting systems can be energy-efficient, as they provide
targeted illumination where needed, minimizing unnecessary light spillage and
reducing overall energy consumption.
 Methods of lighting

3.Accent Lighting
Accent lighting is used primarily for decorative or architectural purposes, highlighting
specific features, objects, or areas within a space to create visual interest and
ambiance. It adds depth, texture, and drama to the environment, enhancing its overall
aesthetic appeal.
 Methods of lighting

3. Accent Lighting

Key aspects of accent lighting include:

• Emphasis on Highlights: Accent lighting fixtures are strategically positioned to
illuminate focal points, architectural elements, artwork, or decorative objects,
drawing attention to them and creating visual contrast.
• Higher Contrast: Accent lighting is often characterized by a higher contrast ratio
between light and shadow, creating dramatic effects and adding dimensionality to
the space.
• Flexible Design: Accent lighting allows for creative freedom in design, enabling
designers to experiment with different light sources, colors, intensities, and angles
to achieve desired visual effects.
• Layered Lighting: Accent lighting is frequently used in conjunction with general and
task lighting to create layered lighting schemes that enhance the overall
atmosphere and functionality of the space.
• Examples: Track lights, wall sconces, recessed spotlights, picture lights, and LED
strip lights are commonly employed for accent lighting purposes.
INCANDESCENT LIGHT

• Incandescent light bulb is just an electric

light used to generate light energy.
• Production of light takes place with a
tungsten filament heated by the electric
current passing through it.
• A quartz or glass bulb is used to protect
the filament from oxidation.
• Also, the bulb is filled with inert gas.

The below table shows a comparison between different light bulbs used commonly.
FLUORESCENT LIGHT

Fluorescent bulbs work through a process that

involves exciting gas molecules to produce
light.
1. Electricity Flow: When you turn on a
fluorescent bulb, electricity flows into the
bulb through a ballast. The ballast regulates
the flow of electricity to the bulb.
2. Excitation of Gas: Inside the bulb, there is a
small amount of mercury vapor and an
inert gas, usually argon. When electricity
flows through the tube, it ionizes the gas,
causing it to emit ultraviolet (UV) light.
3. Phosphor Coating: The inner surface of the
tube is coated with a phosphor powder.
When the UV light hits this phosphor
coating, it excites the phosphor atoms,
causing them to emit visible light.
FLUORESCENT LIGHT

PROS:
• Energy Efficiency: Fluorescent bulbs are more energy-efficient compared to traditional
incandescent bulbs. They produce more light while using less electricity, making them
cost-effective in the long run.
• Longevity: Fluorescent bulbs typically last much longer than incandescent bulbs. They
can last up to 10 times longer, reducing the frequency of bulb replacements.
• Brightness: Fluorescent bulbs produce bright, even lighting, making them suitable for
various indoor applications such as offices, schools, and homes.
• Color Temperature Options: Fluorescent bulbs come in a range of color
temperatures, from warm to cool, allowing users to select the type of light that best
suits their needs or preferences.

CONS:
• Contains mercury
• High initial cost
HIGH INTENSITY DISCHARGE LAMP

High-Intensity Discharge (HID) bulbs are a type

of electric gas-discharge lamp which produces
light by creating an electric arc between
tungsten electrodes.
1. Ignition: Initially, an electrical voltage is
applied across the electrodes. This
generates an arc between them, ionizing
the gas within the bulb.
2. Arc Formation: Once the gas is ionized, the
arc is sustained, creating a high-intensity
light.
3. Light Emission: The arc emits light by
exciting metallic salts or mercury vapor
present in the bulb, which then emit
photons, producing visible light.
4. Color Temperature: The color of light
produced depends on the composition of
the salts or gases inside the bulb.
HIGH INTENSITY DISCHARGE LAMP

Pros:

1. High Light Output: HID bulbs produce significantly more light compared to
traditional incandescent bulbs, making them suitable for large indoor or
outdoor spaces.
2. Efficiency: They are more efficient than incandescent bulbs, converting more
electrical energy into visible light, resulting in less energy wastage and lower
electricity bills.
3. Long Lifespan: HID bulbs have a longer lifespan compared to incandescent
bulbs, typically lasting around 10,000 to 20,000 hours, reducing the frequency
of replacements.
4. Brightness: HID bulbs produce bright, intense light, making them ideal for
outdoor lighting, such as streetlights, stadiums, and automotive headlights.
5. Colour Options: HID bulbs are available in various color temperatures, ranging
from warm white to cool white to daylight, providing flexibility in lighting
design.
HIGH INTENSITY DISCHARGE LAMP

Cons:

1. Warm-Up Time: HID bulbs require a short warm-up time to reach full
brightness, which can be a drawback in applications where instant
illumination is necessary.
2. Cost: Initial costs for HID bulbs and fixtures tend to be higher compared to
traditional incandescent bulbs. However, their longer lifespan and energy
efficiency can offset this initial investment over time.
3. Environmental Impact: HID bulbs contain materials such as mercury, which
can pose environmental hazards if not disposed of properly. Additionally, their
energy consumption contributes to greenhouse gas emissions.
LOW PRESSURE SODIUM LAMP

Low-pressure sodium (LPS) bulbs are a type of

gas-discharge lamp that produces light by
passing an electrical current through a tube
filled with low-pressure sodium vapor.
1. Gas Discharge: When electricity is passed
through the sodium vapor within the bulb,
it ionizes the gas, causing it to emit light.
2. Spectral Emission: Low-pressure sodium
bulbs emit light primarily at a wavelength
of 589.3 nanometers, which corresponds to
the yellow-orange region of the spectrum.
This makes them highly efficient for
producing monochromatic light.
3. Phosphor Coating (Optional): Some LPS
bulbs have a phosphor coating on the
inside of the tube, which broadens the
spectrum of emitted light, making it slightly
more acceptable for human vision.
LOW PRESSURE SODIUM LAMP

Pros:

1. High Efficiency: Low-pressure sodium bulbs are among the most efficient
sources of artificial light available, converting a high percentage of input
energy into visible light.
2. Long Lifespan: LPS bulbs have a longer lifespan compared to many other
types of lighting, which reduces the frequency of replacements and
maintenance.
3. Monochromatic Light: The monochromatic yellow-orange light emitted by
LPS bulbs is beneficial in certain applications where color rendering is not
critical, such as street lighting and security lighting.
4. Low Glare: The light from LPS bulbs produces very little glare, making them
suitable for areas where excessive glare could be a concern, such as
roadways.
LOW PRESSURE SODIUM LAMP

Cons:

1. Limited Color Rendering: The monochromatic light emitted by LPS bulbs can
distort colors, making them unsuitable for applications where accurate color
perception is necessary, such as in retail environments or for outdoor sports
lighting.
2. Slow Start-Up Time: LPS bulbs typically have a longer warm-up time
compared to other types of lighting, which may be a drawback in situations
where instant illumination is required.
3. Bulky Design: LPS bulbs tend to be larger and bulkier than some other types
of lighting, which may limit their suitability for certain fixtures or applications.
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