Page 80 - GRIHA Manual Volume II - Introduction to National Rating System
P. 80
72 GrIha Manual: Volume 2
# Compact fluorescent lamps (CFLs): CFLs produce light in the same manner. Luminous efficacy of
CFLs ranges from 40–70 lumens/watt and they have an average life of 10 000 hours.
# High pressure sodium vapour lamps (HPSV): In high pressure sodium vapour lamps, light is
produced when electricity is passed though a mixture of mercury and sodium vapours. Main
source of light from the HPSV lamp is the sodium D-line and the light that is produced covers a
good part of the visible spectrum. However, it has a poor colour rendering index. These lamps are
characterized by high efficacy ranging from 58–110 lumens/watt and have a long life.
Most common uses include street lighting, security lighting, industrial lighting, public
lighting, storage yards, docks and station platforms.
# High pressure mercury vapour lamps (HPMV): In a high pressure mercury vapour lamp, mercury,
along with argon gas is contained within a quartz glass tube. This tube is mounted within an
outer bulb of borosilicate glass. Light is produced when electricity is passed through gaseous
mercury. These lamps have moderate efficacy ranging from 30–50 lumens/watt and a typical life
of about 12000 hours. The colour rendering index of HPMV lamps is not very good.
These are very popular in outdoor lighting applications like street lighting, parking areas,
lawn lighting and in warehouses, storage yards, docks. The new fluorescent lamps of today have
much better efficacy than HPMV.
# Metal halides: These are also known as ‘metal arc’ lamps. Metal halide lamps belong to the high-
intensity discharge (HID) category of lamps. In these lamps, high pressure mixture of mercury
vapours along with other metal compounds known as halides is contained in a compact arc
tube. These lamps have high efficacy and the light produced by these lamps has a natural white
colour.
These are commonly used for spot lighting in areas like city centres and parks. These are also
widely used in factories where high colour rendering indices are required. Metal halides have a
relatively high cost and an average life span of about 15 000 hours.
# Light emitting diodes: Light emitting diode (LED) is a semiconductor device that converts electricity
into light. Its functioning is based on the functioning of a normal diode. Diameter of each of the
diode is about one fourth of an inch. Although LEDs are very small in size, they can be combined
together for producing high intensity light output. They have a long life of approximately 50 000
hours under specified operating conditions.
LED technology has been improving over the years and in controlled laboratory settings
efficacy values as high as about 150 lumens/watt have been achieved for LED chips. However,
for lighting applications, due to driver efficiency, operating conditions and thermal and fixture
losses, the luminous efficacy of LED lamps is much lower.
# Compact fluorescent lamps (CFLs): CFLs produce light in the same manner. Luminous efficacy of
CFLs ranges from 40–70 lumens/watt and they have an average life of 10 000 hours.
# High pressure sodium vapour lamps (HPSV): In high pressure sodium vapour lamps, light is
produced when electricity is passed though a mixture of mercury and sodium vapours. Main
source of light from the HPSV lamp is the sodium D-line and the light that is produced covers a
good part of the visible spectrum. However, it has a poor colour rendering index. These lamps are
characterized by high efficacy ranging from 58–110 lumens/watt and have a long life.
Most common uses include street lighting, security lighting, industrial lighting, public
lighting, storage yards, docks and station platforms.
# High pressure mercury vapour lamps (HPMV): In a high pressure mercury vapour lamp, mercury,
along with argon gas is contained within a quartz glass tube. This tube is mounted within an
outer bulb of borosilicate glass. Light is produced when electricity is passed through gaseous
mercury. These lamps have moderate efficacy ranging from 30–50 lumens/watt and a typical life
of about 12000 hours. The colour rendering index of HPMV lamps is not very good.
These are very popular in outdoor lighting applications like street lighting, parking areas,
lawn lighting and in warehouses, storage yards, docks. The new fluorescent lamps of today have
much better efficacy than HPMV.
# Metal halides: These are also known as ‘metal arc’ lamps. Metal halide lamps belong to the high-
intensity discharge (HID) category of lamps. In these lamps, high pressure mixture of mercury
vapours along with other metal compounds known as halides is contained in a compact arc
tube. These lamps have high efficacy and the light produced by these lamps has a natural white
colour.
These are commonly used for spot lighting in areas like city centres and parks. These are also
widely used in factories where high colour rendering indices are required. Metal halides have a
relatively high cost and an average life span of about 15 000 hours.
# Light emitting diodes: Light emitting diode (LED) is a semiconductor device that converts electricity
into light. Its functioning is based on the functioning of a normal diode. Diameter of each of the
diode is about one fourth of an inch. Although LEDs are very small in size, they can be combined
together for producing high intensity light output. They have a long life of approximately 50 000
hours under specified operating conditions.
LED technology has been improving over the years and in controlled laboratory settings
efficacy values as high as about 150 lumens/watt have been achieved for LED chips. However,
for lighting applications, due to driver efficiency, operating conditions and thermal and fixture
losses, the luminous efficacy of LED lamps is much lower.
