Question
K1. In a high bay facility, the lights are mounted on the ceiling wich is 13 meters above the floor. The
lighting level on the floor is 500 Lux. No use is made of space between 7 meters and 13 meters
above the floor. In a theoretical sense – that is, using the fundamental law of illumination – what
would be the light level in Lux directly below a lamp if the lights were dropped to 7 meters?
K2. Find the number of lamps required to provide a uniform 500 Lux on the working surface in a 15
× 10 room using the lumen method. Assume two 3 000 lumen lamps each per fixture, and assume
that LLF is 0.65 and CU is 70%.
K3. Find the RCR for a 10 by 15 rectangular room with lamps mounted on the ceiling at a height of 3
meters and the work surface is a 60 cm bench.
K4. Find the coefficient of utilization for a 10 by 15 rectangular room with a ceiling height of 3
meters, a ceiling relectance of 70% and a wall reflectance of 50% using the photometric chart.
K5. The efficacy of a light source refers to the color rendering index of the lamp.
K6. Increasing the coefficient of utilization of fixtures in a room will in many instances increase the
number of lamps required.
K7. Wich HID lamp has the highest efficacy – for the same wattage?
A. Mercury vapor
B. Metal halide
C. High pressure sodium
K8. One disadvantage to metal halide lamps is a pronounced tendency to shift colors as the lamp
ages.
A. True
B. False
K9. A 25 000 square metre high bay facility is presently lit with 800 twin 400 watt mercury vapor
fixture (4585 watts per lamp including ballast). What are the annual savings of replacing the existing
lighting system with 800 single 400-watt high-pressure sodium fixtures (465 watts per lamp including
ballast )? Assume 8 000 hours operation per year, an energy cost of R0.20 per kWh, and a demand
cost of R50 per kW-month.
K10. Calculate the lighting related HVAC energy for a system with direct lighting energy of 1 000kWh.
The HVAC system with a COP of 3 operates 50% of the time and the light heat impacting the HVAC
load is 90%.
K11. Calculate avarge annual lamp replacements for the following system:
1 000 each 3- lamp fixtures
Annual fixture operation = 4 000hrs
Average rated lamp life = 25 000hrs
,K12. Calculate the group reamping intervals for the following system:
1000 each 3-lamp fixtures
Annual fixture operation = 4 000hrs
Avarege rated lamp life = 25 000hrs
Group replaced lamps at 70% of rated life
K13. A garment manufacturing plant. Lights are on 9 hours/day. The ceiling height is about 4m.
suggest an appropriate light source.
a. Incandescent
b. Fluorescent
c. Metal halide
d. High pressure sodium
e. Low pressure sodium
K14. Fluorescent lamps should be replaced when:
A. All lamps in a fixture have burnt-out
B. As soon as the first lamp fails
C. As a group, when they reach a chosen lumen depreciation level
D. One by one as they fail
K15. Which of the following light source has the lowest lumen depreciation? Which the hihest?
A. Mercury vapor
B. Metal halide
C. High pressure sodium
K16. Old system: incandescent hallway recessed downlighting in 12’ ceiling:100 fixtures @ 75 watts
(@$3.50): operating hours: 15 hrs/day, 6 days/week (4 680hrs/yr). $0.08/kWh and $4/kW.
New system: screw-in fluorescent lamps (82 CRI) with integrated magnetic ballast: downlighting
reflectors 100 fixtures @ 22 Watts (including ballast operation) what are the annual savings when
replacing the old system with new system?
K17. Old system: office lighting consisting of 360 fluorecent 2’×4’ fixture; operating hours:
14hrs/day , 5days/week (3 640 hrs/yr0:each fixure draws 188 watts with 4 standard cool white 40-
watt cool white 40-watt fluorescent lamps @ (@$2) and 2 standard magnetic ballasts. $0.08kWh and
$4/kW.
New system: each fixture now draws 112 watts with 4 tri-phosphor F40T8 32 watt fluorescent
lamps and 1 electronic T-8 instant start mode ballast. What are the annual savings when replacing
the old system with the new system?
K18. Uncontrolled system: six conference rooms, each with four 4 lamp fluorescent fixtures (188
watts) operating 10 hrs/days, 5 days/week (2 600 hrs/yr); lamps @ $2.
Controlled system: when conference rooms are unoccupied for longer than five minutes, the
fixtures are now automatically turned off; they now operate about 7 hrs/day, 5 days/week (1 820
hrs/yr) what are the annual savings when replacing the old system with the new system?
, K19. A lighting survey of a 400 m2 office building identified the following fixtures:
30 – 4 tube fixtures @ 192 watts/fixture
10 – 100 watt incandescent floodlights
20 – 75 watt task lamps
What is the lighting densitly in W/m2 of this facility:
A. 82.7
B. 46.7
C. 56.4
D. 20.7
E. 10.1
K20. A building currently has the following lighting system:
Present: 196 mercury vapour light fixture size: 250 watt/lamp, 285 watt/fixture, including ballast
ypu have chosen to replace the existing with the following:
Proposed: 140 high pressure sodium fixture size; 150 watt/lamp, 185 watt/fixture, including ballast
the facility operates 24 hours/day. Approximate the heating effect if the heating system efficiency is
80%, fuel costs $5.00/GJ and there are 200heating days in a year.
A. $4 446/yr
B. $2 490/yr
C. $6 900/yr
D. $5 290/yr
E. $3 240/yr
K21. Estimate the increase in heating energy resulting from retrofitting 20 fixtures:
Present system: fluorescent lamps (88 W/fixture)
Proposed system: T-8 (51 W/fixture)
Building coincident heating hours: 800hr/yr
Heating system efficiency: 80%
K22. A commercial office building has an open room with ten occupants that has one side consisting
of large windows. The space is used from 8 am until 10 pm and a timer shuts off the lights from
10pm until 8 am. What kind of lighting system would most likely save the most money compared to
a standard fully artificial lighting system?
a. A standard T8 lighting system designed to provide a level of 500 lux, along with an ultrasonic
occupancy sensor
b. A standard T8 lighting system designed to provide a level of 400 lux everywhere in the space,
together with CFL task lights that would provide an additional 100 lux at each desk or task
location
c. A T8 lighting system with dimmable electronic ballasts, several lux sensors to ballasts to
provide a measured total light level of 500 lux.
d. Answer b along with passive infrared occupancy sensors
e. Answer b, but with low CRI T8 lamps
f.
K1. In a high bay facility, the lights are mounted on the ceiling wich is 13 meters above the floor. The
lighting level on the floor is 500 Lux. No use is made of space between 7 meters and 13 meters
above the floor. In a theoretical sense – that is, using the fundamental law of illumination – what
would be the light level in Lux directly below a lamp if the lights were dropped to 7 meters?
K2. Find the number of lamps required to provide a uniform 500 Lux on the working surface in a 15
× 10 room using the lumen method. Assume two 3 000 lumen lamps each per fixture, and assume
that LLF is 0.65 and CU is 70%.
K3. Find the RCR for a 10 by 15 rectangular room with lamps mounted on the ceiling at a height of 3
meters and the work surface is a 60 cm bench.
K4. Find the coefficient of utilization for a 10 by 15 rectangular room with a ceiling height of 3
meters, a ceiling relectance of 70% and a wall reflectance of 50% using the photometric chart.
K5. The efficacy of a light source refers to the color rendering index of the lamp.
K6. Increasing the coefficient of utilization of fixtures in a room will in many instances increase the
number of lamps required.
K7. Wich HID lamp has the highest efficacy – for the same wattage?
A. Mercury vapor
B. Metal halide
C. High pressure sodium
K8. One disadvantage to metal halide lamps is a pronounced tendency to shift colors as the lamp
ages.
A. True
B. False
K9. A 25 000 square metre high bay facility is presently lit with 800 twin 400 watt mercury vapor
fixture (4585 watts per lamp including ballast). What are the annual savings of replacing the existing
lighting system with 800 single 400-watt high-pressure sodium fixtures (465 watts per lamp including
ballast )? Assume 8 000 hours operation per year, an energy cost of R0.20 per kWh, and a demand
cost of R50 per kW-month.
K10. Calculate the lighting related HVAC energy for a system with direct lighting energy of 1 000kWh.
The HVAC system with a COP of 3 operates 50% of the time and the light heat impacting the HVAC
load is 90%.
K11. Calculate avarge annual lamp replacements for the following system:
1 000 each 3- lamp fixtures
Annual fixture operation = 4 000hrs
Average rated lamp life = 25 000hrs
,K12. Calculate the group reamping intervals for the following system:
1000 each 3-lamp fixtures
Annual fixture operation = 4 000hrs
Avarege rated lamp life = 25 000hrs
Group replaced lamps at 70% of rated life
K13. A garment manufacturing plant. Lights are on 9 hours/day. The ceiling height is about 4m.
suggest an appropriate light source.
a. Incandescent
b. Fluorescent
c. Metal halide
d. High pressure sodium
e. Low pressure sodium
K14. Fluorescent lamps should be replaced when:
A. All lamps in a fixture have burnt-out
B. As soon as the first lamp fails
C. As a group, when they reach a chosen lumen depreciation level
D. One by one as they fail
K15. Which of the following light source has the lowest lumen depreciation? Which the hihest?
A. Mercury vapor
B. Metal halide
C. High pressure sodium
K16. Old system: incandescent hallway recessed downlighting in 12’ ceiling:100 fixtures @ 75 watts
(@$3.50): operating hours: 15 hrs/day, 6 days/week (4 680hrs/yr). $0.08/kWh and $4/kW.
New system: screw-in fluorescent lamps (82 CRI) with integrated magnetic ballast: downlighting
reflectors 100 fixtures @ 22 Watts (including ballast operation) what are the annual savings when
replacing the old system with new system?
K17. Old system: office lighting consisting of 360 fluorecent 2’×4’ fixture; operating hours:
14hrs/day , 5days/week (3 640 hrs/yr0:each fixure draws 188 watts with 4 standard cool white 40-
watt cool white 40-watt fluorescent lamps @ (@$2) and 2 standard magnetic ballasts. $0.08kWh and
$4/kW.
New system: each fixture now draws 112 watts with 4 tri-phosphor F40T8 32 watt fluorescent
lamps and 1 electronic T-8 instant start mode ballast. What are the annual savings when replacing
the old system with the new system?
K18. Uncontrolled system: six conference rooms, each with four 4 lamp fluorescent fixtures (188
watts) operating 10 hrs/days, 5 days/week (2 600 hrs/yr); lamps @ $2.
Controlled system: when conference rooms are unoccupied for longer than five minutes, the
fixtures are now automatically turned off; they now operate about 7 hrs/day, 5 days/week (1 820
hrs/yr) what are the annual savings when replacing the old system with the new system?
, K19. A lighting survey of a 400 m2 office building identified the following fixtures:
30 – 4 tube fixtures @ 192 watts/fixture
10 – 100 watt incandescent floodlights
20 – 75 watt task lamps
What is the lighting densitly in W/m2 of this facility:
A. 82.7
B. 46.7
C. 56.4
D. 20.7
E. 10.1
K20. A building currently has the following lighting system:
Present: 196 mercury vapour light fixture size: 250 watt/lamp, 285 watt/fixture, including ballast
ypu have chosen to replace the existing with the following:
Proposed: 140 high pressure sodium fixture size; 150 watt/lamp, 185 watt/fixture, including ballast
the facility operates 24 hours/day. Approximate the heating effect if the heating system efficiency is
80%, fuel costs $5.00/GJ and there are 200heating days in a year.
A. $4 446/yr
B. $2 490/yr
C. $6 900/yr
D. $5 290/yr
E. $3 240/yr
K21. Estimate the increase in heating energy resulting from retrofitting 20 fixtures:
Present system: fluorescent lamps (88 W/fixture)
Proposed system: T-8 (51 W/fixture)
Building coincident heating hours: 800hr/yr
Heating system efficiency: 80%
K22. A commercial office building has an open room with ten occupants that has one side consisting
of large windows. The space is used from 8 am until 10 pm and a timer shuts off the lights from
10pm until 8 am. What kind of lighting system would most likely save the most money compared to
a standard fully artificial lighting system?
a. A standard T8 lighting system designed to provide a level of 500 lux, along with an ultrasonic
occupancy sensor
b. A standard T8 lighting system designed to provide a level of 400 lux everywhere in the space,
together with CFL task lights that would provide an additional 100 lux at each desk or task
location
c. A T8 lighting system with dimmable electronic ballasts, several lux sensors to ballasts to
provide a measured total light level of 500 lux.
d. Answer b along with passive infrared occupancy sensors
e. Answer b, but with low CRI T8 lamps
f.
