Lumen method

Lumen method determines the average light levels in large open areas. The lumen
method in lighting design is a simplified method to calculate the light level in a
room. The method is a series of calculations that uses horizontal illuminance
criteria to establish a uniform luminaire layout in a space. In its simplest form, the
lumen method is merely the total number of lumens available in a room divided
by the area of the room.
1Fc= 1 lumen/ 1 sq.ft
Illuminance = Lumens x area
By calculating average value of illuminance levels:
1. The average value of Lumens distributed evenly over surface.
2. It can be used for simple and large surfaces and in open areas with simple
layout
3. It is based on the unit definition of a ‘Foot-candle’.
For solving problems lighting, one needs:
1. To determine how much light is needed then how many fixtures are
needed.
2. Determine area receiving light (usually task surface, floor or work plane)
The desired illuminance (in foot-candles):
1. Lumens needed = area of space (in sq.ft) x illuminance (in FC).
2. No: of fixture needed = lumens needed/ lumens per fixture.
The two safety factors make the lumen method procedure more accurate:
1. COEFFICIENT OF UTILIZATION FACTOR: Defined as “the ratio of total
lumens received on the working plane to the total lumens emitted by the
light source. It shows how well the considered surface is receiving light. It
depends on the geometry of the room and orientation of the
fixture.Example: Direct fixture- 85% (0.85), Indirect fixture- 50% (0.5),
Accent or spot fixture- 95% (0.95), Ambient and wash fixture- 75% (0.75).
 2. FACTOR EFFECTING UTILIZATION FACTOR: Type of light, light fitting, Color
surface of walls and ceiling, mounting height of lamps, Area to be
illuminated Its value lies between 0.4 and 0.6 for direct fittings it varies
from 0.1 to 0.35 for indirect fittings.
3. LIGHT LOSS FACTOR: It accounts for Depreciation of lighting system over
the time. We generally make assumption of 85% (0.85).
So, these factors impact on the predicted effect of light solution. Now the lumen
method equation is: Lumens needed= area of space x illuminance/ (CU x LLF)
CU= Coefficient of utilization factor
LLF= Light Loss factor

Point Calculation Method

The Point Calculation is used for calculating the light intensity as it is affected by
distance (light spreads out) using candela values. A method to calculate the
horizontal illuminance on a work plane within a space, as well as its uniformity.
Only the direct illumination from the luminaires to the work plane is taken into
account. It is generally used for situations involving a specific surface lighted from
a specific distance by a directional or accent fixture.

Illuminance = candela value of fixture / distance squared

E = CD / D square.
The distance unit is in foot so distance squared is in ft square.
Estimate location of lighting equipment, Light density = Candle power = Candela,
Candela information given by Manufacturer, Center Bean Candle Power – CBCP –
center of a directional light, Illuminance = Candela value ÷ Distance (squared) (in
feet), E = CD ÷ D square
The first method for lighting design which is Lumen method is used to calculate
average illuminance for places having uniform lighting distribution, but this
method, for example, can’t answer the following questions:
What is the illuminance on a wall display from a spotlight aimed at the display?
How much light is striking a point on the façade of a building or in a parking lot
from a floodlight?
The only way for getting answers for above questions is by applying point to point
method for lighting design.
Three Factors must be considered for applying the Point-by-point method:
1. Luminous intensity,
2. Distance,
3. Orientation of the surface.

Outdoor lighting & it's importance

Outdoor lighting refers to landscape lighting or garden lighting, the use of outdoor
illumination of private gardens and public landscapes. It is for enhancing outdoor
spaces and purposes of safety, nighttime aesthetics, accessibility, security,
recreation and sports uses etc. The purpose of the outdoor lighting is to increase
the efficacy of human activities during the time when it is dark and to make
production, transportation, construction, city beautification, etc. in the outdoor
areas efficient, safe, secure and comfortable.
Exterior lighting is important equally as the interior lighting. It should be properly
and functional, to provide relaxing atmosphere and at the same time safety and
fun. The lighting has big impact too the whole look of your garden and patio and
thats why you need to pay attention where will you set the lights and what kind of
lighting you will use to light up your yard. Nowadays, there are so many functional
lighting ideas, you just need to find the right one that will be suitable to your
exterior.

1. Beauty: Outdoor lighting can be used to create ambiance on patios and

decks while making the exterior of a home look more aesthetic and
attractive from the sidewalk. It adds an extra elegance to the outdoor
space.
 2. Safety: By illuminating pathways you can rest assure at your next party.
Outdoor lighting can help the homeowners and guests find their footing.
3. Security: Security is another important factor for using outdoor lights. By
illuminating entryways, dark walkways and garages, homeowners can help
deter potential intruders.

Clerestory window
A clerestory window is a large window or series of small windows along the top of
a structure's wall, usually at or near the roof line. Clerestory windows are a type
of glass window placement found in both residential and commercial
construction. A clerestory wall often rises above adjoining roofs. Two alternatives
to standard windows are clerestory windows – those high-up windows that sit
between two levels of external roofing – and skylights. They both have their uses
in passive solar design, though you have to be careful with their effects on light
and heating. Because they are placed high up compared to other windows,
clerestories can deliver sunlight far deeper into a living space than normal vertical
glazing. Their main function is twofold: they deliver extra daylighting and they
provide a method of heating thermal mass in north walls which would normally
be in shade. To maximize the effect of clerestory windows, they should be located
facing thermal mass walls, at a distance of between 1 and 1.5 times the target
wall height. So, for a 12-foot wall, the clerestories should be 12-18 feet away.
Clerestory windows have many benefits:
 They allow a lot more light into the building, while reducing glare and improving
privacy.
 They increase solar gain in the living space and particularly in thermal mass
placed on the north side of the home.
 They are a great choice if the bottom-Storey windows are obstructed by trees,
neighboring homes or other structures.
 They add to the overall aesthetic of the home.

Monitor lighting
Monitor lighting can be used to reduce glare, heat gains, and protect internal
spaces from direct sunlight, by providing an opaque roof and overhang above the
glazing. Heat gains can be reduced by tilting roof lights towards the North in order
to utilize diffuse north lighting. Adding daylighting and ventilation through roof
monitors is a strategy with growing popularity and potential. Common sense
might lead us to believe that penetrating the roof with monitors could
compromise a building’s insulation and thermal performance. However, with the
availability of advanced products, such as glazing, suspended film and high-
performance sealants, well-designed and constructed rooftop penetrations can
successfully lower energy costs and improve occupant comfort and health. Roof
monitors are vertical fenestrations built into raised structures atop the roof. If the
monitors are operational, they contribute exponential building-performance
enhancements beyond the other penetration types, including stack-effect
ventilation. Roof monitors has many functions: natural daylighting, ventilation,
passive heating and cooling, glare reduction and structural support for rooftop
solar-power systems. Roof monitors help disperse natural daylight more evenly
and completely throughout a room than windows on the side of a building. When
paired with thermal mass, such as concrete or water, vertical glazing on the roof
helps capture heat from the sun to offset the building’s heating load. Glare
presents a big problem for worker productivity in buildings; careful design of roof
monitors and ceiling systems can help distribute the light and reduce contrast
glare. Finally, monitors can be topped with angled roofing that matches the
optimal sun exposure angle for solar panels mounted atop.

WORKING OF LED
Electroluminescence is an optical phenomenon and electrical phenomenon in
which a material emits light in response to the passage of an electric current or to
a strong electric field. The Light-emitting diode is a two-lead semiconductor light
source The lighting emitting diode is a p-n junction diode. It is a specially doped
diode and made up of a special type of semiconductors. When the light emits in
the forward biased, then it is called a light-emitting diode. The light-emitting
diode simply, we know as a diode. When the diode is forward biased, then the
electrons & holes are moving fast across the junction and they are combined
constantly, removing one another out. Soon after the electrons are moving from
the n-type to the p-type silicon, it combines with the holes, then it disappears.
Hence it makes the complete atom & more stable and it gives the little burst of
energy in the form of a tiny packet or photon of light. This is also called as working
of LED

Emerging Trends In LED

LED light fixtures are the new technology trends in the lighting industry. It has
many advantages from environmental health to your own health. These lights
are energy-efficient and they consume less electricity which eventually results
in the reduction of energy bills. Moreover, they impart less heat that helps in
reducing the carbon dioxide produced by the lights.
1. Built-in Lights: This is the new lighting trend by LED technology. That’s
because LED lights don’t require frequent replacements. Today,
manufacturers are fittings lights inside the walls and ceiling to make them
look as much as possible seamless. The builders are creating the designs
which are integrated with the lighting fixtures.
2. Connectivity: The more use of the LED lighting technology in the
mainstream, the connectivity has improved a lot. The dimmers and sensors
are part of the lighting industry for ages now, but with the advanced digital
connectivity, this trend of controlling has become an important part of the
lighting industry.
3. LiFi: The term Li-Fi stands for ‘Light Fidelity’. It is a technology for wireless
communication using LED lights to transmit data between devices. Li-Fi
comprises of multiple LED lights that form the basis of the wireless
network. It is like Wi-Fi, except that it uses light spectrum and is 1000 times
faster. Li-Fi allows data to be transmitted by modulating the intensity of
light from an LED source which is then received by a photo-sensitive
detector. Once received, this light signal is then demodulated into
electronic form. LED lights can be switched on and off at a fast rate which is
not perceptible to the human eye, making wireless communication
possible. It is set to transform our shops, museums and indoor spaces into
 efficient places where data can be transformed using the available lighting
sources.

FIBRE OPTIC LIGHTING

Optical fiber can be used for transmitting light from a source to a remote location
for illumination as well as communications. In fact, fibers are made to not only
transmit light but to glow along the fiber itself, so it resembles a neon light tube.
It is comprised of a core and cladding coating that trap light, allowing light to
travel long distances. The applications for fiber optic lighting are many, generally
based on utilizing the special attributes of the fiber as well as its unique
characteristics. Some of the important special types of applications than others.
Heat-Free Lighting: Since the light source is remote, the fiber transmits the light
but isolates the heat from the light source from the illumination point, an
important consideration for lighting delicate objects, such as in museum displays,
that could be damaged by heat or intense light.
Since the fiber is nonconductive the power for the light source can be placed in a
safe location electrical safety can be achieved for underwater lighting such as
used in swimming pools and fountains or illumination in hazardous atmospheres
can be done safely with fiber optic lighting.
Precise Spotlighting: Optical fiber can be combined with lenses to provide
carefully focused light on extremely small spots, popular for museum exhibits and
jewelry displays, or simply light a specified area precisely.
Optical fiber makes light much more durable. Optical fiber, either plastic or glass,
is both strong and flexible, much more durable than fragile light bulbs.
The Look of Neon: Fiber that emits light along its length, generally called edge-
emitting fiber, has the look of neon tubes for decorative lighting and signs.
Vary the Color: By using colored filters with white light sources, fiber optic lighting
can have many different colors and by automating the filters, vary colors in any
preprogrammed sequence.
Simpler Installation: Fiber optic lighting does not require installing electrical
cables to the light locator and then installing bulky light fixtures with one or more
bulbs on location. Instead, a fiber is installed to the location and fixed in place,
perhaps with a small focusing lens fixture, a much simpler process. Often several
fibers can use a single light source, simplifying installation even more.
Easy Maintenance: Lighting in hard to access areas like high ceilings or small
spaces can make changing light sources difficult. With fiber, the source can be in
an easily accessible location and the fiber in any remote place. Changing the
source is no longer a problem.

DAYLIGHT FACTOR
The daylight factor (DF) is a very common and easy to use measure for the
subjective daylight quality in a room. It describes the ratio of outside illuminance
over inside illuminance, expressed in per cent. The higher the DF, the more
natural light is available in the room. The Ein illuminance can be considered as the
sum of three different illuminances:
1. the direct illuminance if the sky is visible from the considered point (Ed)
2. the illuminance due to the reflex ions on the outside environment (Eer)
3. the illuminance due to the reflex ions on the inside surfaces (Eir)
It is expressed as such: DF= SC + ERC + IRC (for clear sly), DC=direct component,
ERC=externally reflected component, IRC=internally reflected component

DF = 100 x Ein/ Eext

Ein=inside illuminance at a fixed point, Eext=outside horizontal illuminance under
an overcast (CIE sky) or uniform sky.
A daylight factor can be measured for a specific point or expressed as an average.
The latter is the arithmetic mean of the sum of point measurements taken at a
height of 0.85 m in a grid covering the whole floor area of the room. Different
countries have different regulations and may require the use of point or average
measurements.

Advantages of daylight:
1. Human performance is improved under daylighting
2. Delivers abundant, high-quality lighting that is required by many activities.
3. Colors are rendered accurately
 4. Natural light improves morale and productivity
5. Lower risks of accidents and errors
6. Natural ventilation is facilitated
7. Reduced operation and maintenance costs
8. Demand savings during daytime peaks.
9. It can improve the quality of light in a space.
Daylighting, with proper electric lighting controls, can result in significant energy
savings by reducing electric lighting loads and associated cooling loads. In
addition, with proper solar control, solar gains during cooling load periods can be
mitigated and solar gains during heating load periods can be utilized, reducing the
energy requirements of both cooling and heating a space.
The overall objective of daylighting is to minimize the amount of artificial light and
reduce electricity costs, but it can also lower HVAC costs as well. Electrical lighting
produces a lot of heat, whereas, if properly controlled, natural lighting generates
hardly any heat at all. People have a natural attraction and need for daylight.
Studies suggest that daylighting has a direct impact on well-being, productivity
and overall sense of satisfaction. Even retail stores have seen the environmental
and monetary benefits of daylighting for both employees and consumers. In an
experiment, stores that included skylights over certain departments found that
overall sales per square foot were higher in the departments lit by natural light.

Landscape Lighting
Landscape lighting has excessive potential to enhance the landscape and provides
many benefits for both residential and commercial applications. Landscape
lighting can provide safety, security, ambiance, aesthetics, mood and drama to
the outdoor area. It is limited only to the designer's imagination; the practical
functions and various mood effects of landscape lighting are endless. The
entrance should be well lit for safety purpose. Doorways: A wall fixture is the
obvious solution by a doorway for new construction. Concealing the light source
particularly in the case of on an existing building where concealing cable may be
difficult. Garage and Driveway: Avoid glare to the driver pathway. Well-lit
pathways: Used primarily for safety to highlight sidewalks, drives, or any path to
ensure safe pedestrian passage at night. Installed low to the ground, path lights
literally light the way for safety and security. Ideally, we should choose a path
light that is covered on the top so that the light will spread evenly along the
ground, rather than create a glare. Paths and Steps: Designed to provide
orientation and special care should be given to illuminating steps and level
changes and make user feel safe and comfortable. Underwater lighting: It
highlights plants inside water & captures light to show off depth or imaginative
design. It also increases attractiveness and safety in dark. Cascading fountains and
falls reflect light in their movement adding a visual perspective to the sound of
rippling or spraying water.
Landscape lighting enhance plants, flowers, shrubs, and trees. Small spotlights
and well lights are common for landscape lighting as they do not compete with
plants for attention. Landscape lights can also be used to highlight architectural
features like columns and most landscape lights can be used in both capacities.

luminous intensity-The luminous intensity (candelas) is the strength (intensity) of

the light produced in a specific direction. It is Luminous Flux in a certain direction,
radiated per unit of solid angle & its unit is candela. The luminous intensity of any
light source is compiled graphically into diagrams known as candela or
candlepower distribution curves. Polar and Cartesian graphs are used within the
lighting industry for this purpose. Distance- Distance between a surface and the
source affects the illuminance (luminous flux per unit of area) striking that
surface. Surface of a given area that is closer to the source captures a larger
portion of the flux in the cone than a surface of the same given area that is
further away. Considering the luminous intensity as the luminous flux (lumens)
leaving a source in a cone traveling in a specific direction, as the area increases
the illuminance decreases while the luminous flux remains the same. Inverse
Square Law- It states that the cross-sectional area of the cone increases with the
square of the distance from the source. Therefore, the illuminance on this surface
varies inversely with the square of the distance from the source. Orientation of
the Surface- Surface orientation is included in the Inverse Square Law by adding a
cos θ term: E = I/ d2 cos θ. where θ is the angle between the light ray coming
from the source to the point, and a line that is perpendicular (normal) to the
plane or surface on which the illuminance is being measured or calculated.