Page 78 - GRIHA Manual Volume II - Introduction to National Rating System
P. 78
70 GrIha Manual: Volume 2
The following is a description of some of the common outdoor lighting techniques.
1. Path lighting: It is specifically designed to light pathways and walkways to provide security and
visibility for walking. Usually, low-impact lights are used, which are either installed next to the
path facing down or buried in the path itself facing upwards.
2. Down lighting: This technique is used for lighting-specific activity areas. Light source is above
the object that is to be lighted like on a pole, building, wall or tree.
3. Uplighting: Uplighting is used to highlight interesting features like trees, fountains or sculptures.
It involves lighting objects by placing light source below them (like placed on a clamp on the
ground or buried in the ground).
4. Spread lighting: Spread lighting is used in creating evenly distributed low levels of circular light
patterns to illuminate wide areas of ground cover or landscaping.
5. Façade lighting: Façade lighting is used to accentuate building façades by placing light source
near the base and aiming it such that the façade is bathed with light.
6. Security lighting: Security lighting is used to illuminate those areas around the house that
have the potential of becoming a hiding place for intruders. This can be achieved by using a
combination of low-level lighting and down lighting or spot lighting.
Design recommendations
1. Standards: Exterior lighting requirements specified by the Energy Conservation Building Code
2007 of the Bureau of Energy Efficiency, Government of India, should be referred to while
designing outdoor lighting.
2. Uniform illumination: Exterior lighting design should be such that it provides uniform lighting
and avoids pockets of insufficient or excessive lighting.
3. Glare control: Glare is caused due to excessive luminance from unshielded light sources at the
eye level. Glare affects the visual performance as sudden change in the brightness of visual field
causes discomfort to the human eye. Therefore, glare problems should be limited to appropriate
locations, shielding and selection of fixtures.
4. Luminous efficacy: Efficiency of lamps is measured in terms of their luminous efficacy, which is
the ratio of luminous flux (lamp lumen output) to the power consumed by the lamp. It reflects
the energy conversion efficiency of a lamp for converting electricity to light form. By specifying
minimum allowable values of luminous efficacy of lamps, the total power consumption by
outdoor lamps can be optimized for required lumen output. Both these values are mentioned
on the lamp packaging/wrapper and can be calculated very simply.
5. Lighting power density (LPD): This term refers to the maximum lighting power required per unit
area of a building (watts per square metre or watts per square feet). LPD values should not
exceed the values specified by the Energy Conservation Building Code 2007.
Outdoor lighting sources
A few commonly used outdoor lighting sources are described below.
# Fluorescent lamps: Fluorescent lamps are gas discharge type of lamps and are very popular
nowadays as an alternative to incandescent lamps. Fluorescent lamps use electricity to excite the
low-pressure mercury vapours, and the ultraviolet energy produced by mercury atoms activates
the phosphorous to produce light. For proper operation, these lamps have inbuilt ballast for
regulating the flow of current through the lamp.
In fluorescent lamps, the quantity of light emitted and its colour is based on the composition
of phosphorous. Luminous efficacy of new generation fluorescent lamps ranges from 80–95
lumens/watt with an average life of up to 10 000 hours.
The following is a description of some of the common outdoor lighting techniques.
1. Path lighting: It is specifically designed to light pathways and walkways to provide security and
visibility for walking. Usually, low-impact lights are used, which are either installed next to the
path facing down or buried in the path itself facing upwards.
2. Down lighting: This technique is used for lighting-specific activity areas. Light source is above
the object that is to be lighted like on a pole, building, wall or tree.
3. Uplighting: Uplighting is used to highlight interesting features like trees, fountains or sculptures.
It involves lighting objects by placing light source below them (like placed on a clamp on the
ground or buried in the ground).
4. Spread lighting: Spread lighting is used in creating evenly distributed low levels of circular light
patterns to illuminate wide areas of ground cover or landscaping.
5. Façade lighting: Façade lighting is used to accentuate building façades by placing light source
near the base and aiming it such that the façade is bathed with light.
6. Security lighting: Security lighting is used to illuminate those areas around the house that
have the potential of becoming a hiding place for intruders. This can be achieved by using a
combination of low-level lighting and down lighting or spot lighting.
Design recommendations
1. Standards: Exterior lighting requirements specified by the Energy Conservation Building Code
2007 of the Bureau of Energy Efficiency, Government of India, should be referred to while
designing outdoor lighting.
2. Uniform illumination: Exterior lighting design should be such that it provides uniform lighting
and avoids pockets of insufficient or excessive lighting.
3. Glare control: Glare is caused due to excessive luminance from unshielded light sources at the
eye level. Glare affects the visual performance as sudden change in the brightness of visual field
causes discomfort to the human eye. Therefore, glare problems should be limited to appropriate
locations, shielding and selection of fixtures.
4. Luminous efficacy: Efficiency of lamps is measured in terms of their luminous efficacy, which is
the ratio of luminous flux (lamp lumen output) to the power consumed by the lamp. It reflects
the energy conversion efficiency of a lamp for converting electricity to light form. By specifying
minimum allowable values of luminous efficacy of lamps, the total power consumption by
outdoor lamps can be optimized for required lumen output. Both these values are mentioned
on the lamp packaging/wrapper and can be calculated very simply.
5. Lighting power density (LPD): This term refers to the maximum lighting power required per unit
area of a building (watts per square metre or watts per square feet). LPD values should not
exceed the values specified by the Energy Conservation Building Code 2007.
Outdoor lighting sources
A few commonly used outdoor lighting sources are described below.
# Fluorescent lamps: Fluorescent lamps are gas discharge type of lamps and are very popular
nowadays as an alternative to incandescent lamps. Fluorescent lamps use electricity to excite the
low-pressure mercury vapours, and the ultraviolet energy produced by mercury atoms activates
the phosphorous to produce light. For proper operation, these lamps have inbuilt ballast for
regulating the flow of current through the lamp.
In fluorescent lamps, the quantity of light emitted and its colour is based on the composition
of phosphorous. Luminous efficacy of new generation fluorescent lamps ranges from 80–95
lumens/watt with an average life of up to 10 000 hours.
