2. 1. BACKGROUND
The major objectives of energy audit in lighting system
include:
Measurement and comparison of illumination levels at various
locations
Measurement of total power consumption of all lighting feeders
Calculate the installed load efficacy in terms of lux/watt/m²
(existing vs. design) for general lighting installation.
Compare calculated value with the norms for specific types of
interior installations for assessing improvement options.
To suggest ways and means to optimize the illumination levels and
to optimize the power consumption at different locations.
To identify energy saving measures and quantify the energy and
cost savings.
3. 2. STEPS INVOLVED IN CONDUCTING THE
ENERGY AUDIT
The steps involved in conducting energy audit of
lighting plant are:
Data collection
Observations, measurement and Analysis
Exploration for energy conservation measures with
detailed techno economic calculations
Report preparation
4. 3. DATA COLLECTION
Collect the single line diagram of electrical drawing pertaining to lighting
Obtain the lighting fixture details for each section
Typical format for data collection of lighting details is given Table 13-1
Table 13-1
5. For illumination level required refer Annexure-
13.1,where recommended illumination values as per IS:
3646 (Part-1) –1992 for various areas in power stations
are provided.
If the plant has separate transformers for lighting circuit,
provide the details of transformer
Details of energy saving retrofits installed in the plant
(such as voltage controllers, sensors, controllers, timers,
etc)
Details of on & off mechanism of lighting circuits
Details of energy meters provided in the lighting circuit
and sections served by these meters
Details of energy consumption monitoring of lighting
systems
Energy consumption of lighting circuit
6. 4. INSTRUMENTS REQUIRED
The following instruments are required for
conducting the energy audit of
lighting system :
Power Analyzer: Used for measuring electrical
parameters such as kW, kVA, pf, V, A and Hz of
class 0.5 accuracy
Lux meters
Measuring tape
On line energy meter instruments – (calibrated)
7. 5. Measurements & Observation to be made:
While conducting the audit carryout a detailed survey for the
following
Monitor the condition of lighting fixtures
Lux measurements at various places (Number of measurement
to be carried out is given in the following sections)
Measurement of power parameters kW, kVA, Current, Voltage,
power factor, harmonics, frequency of all feeders
Room dimensions
Counting of installed fixtures Vs number of fixtures in operation
Maintenance practices – for cleaning, replacement, etc
8. 6. OBSERVATIONS AND ANALYSIS
A. System familiarisation and operational details
Detailed interactions with the plant personnel have to be
carried out to get familiarisation for system detail and
operational details. Pre visit to the plant can be made to
get familiarisation of lighting system
9. B. Observations on house keeping and maintenance
practices interactions and surveys to be carried out on :
House keeping measures in up keeping of luminaries
Failure rate of lamps and ballasts
Replacement procedure of failed lamps
Procurement options
Maintenance practices
Operational practices (on / off controls)
If any energy saving retrofits are installed in the plant then
the operational status of the retrofits can be assessed
10. Identify the areas where poor illumination and excess
illumination is provided
Assess the various alternate lamps / luminaries
applicable for various sections
Type of panel lamps or sign lamps used – to explore
possibility of using LED lamps
Observations on other loads which are connected to the
lighting circuit and their energy consumption
11. C. Exploration of energy conservation possibilities
While conducting the energy audit explore for various energy
conservation measures such as
Look for natural lighting opportunities through windows and other
openings. Derive way to improve natural lighting during the day
time
In the case of industrial lighting, explore the scope for
introducing translucent sheets
Use of energy efficient lighting methods / products /
equipments /retrofits
Maximize sunlight use through use of transparent roof sheets,
north light roof, etc.
Examine scope for replacements of lamps by more energy
efficient with due consideration to luminaries, color rendering
index, lux level as well as expected life comparison.
Performance of luminaries which are commonly used are given
in the Annexure
12. Replace conventional magnetic ballasts by more energy efficient
ballasts, with due consideration to life and power factor apart
from watt loss.
Select interior colours for light reflection.
Assess scope for delamping
Assess scope for re-arrangement of lighting fixtures
Modify layout for optimum lighting.
Providing individual / group controls for lighting for energy
efficiency such as:
On / off type voltage regulation type
Group control switches / unitsis provided
Occupancy sensors
Photocell controls
Timer operated controls
Modify switches / electrical circuit
13. Install input voltage regulators / controllers for energy efficiency
as well as longer life expectancy for lamps where higher
voltages, fluctuations are expected.
Replace energy efficient displays like LED's in place of lamp
type displays in control panels / instrumentation areas, etc.
Opt for better reflector in lighting
Cleaning of reflector at regular interval
In power plant, locations like HT/LT switchgear rooms, cable
galleries etc which sites / locations are rarely visited, lighting
circuits may be modified in such a way that keeping 25% to 30%
lights always “ON” and remaining lights controlled by simple
ON/OFF switch provided at the entrance of the room / hall
Opportunities to reduce the power consumption/ improve the
energy efficiency of other loads which are connected to the
lighting circuit
14. Some good practices in lighting are:
Installation of energy efficient fluorescent lamps in place
of "Conventional" fluorescent lamps.
Installation of Compact Fluorescent Lamps (CFL's) in
place of incandescent lamps.
Installation of metal halide lamps in place of mercury /
sodium vapour lamps.
Installation of High Pressure Sodium Vapour (HPSV)
lamps for applications where colour rendering is not
critical
Installation of LED panel indicator lamps in place of
filament lamps.
15. Light Control :
Grouping of lighting system, to provide greater
flexibility in lighting control
Installation of microprocessor based controllers
Optimum usage of day lighting
Installation of "exclusive" transformer for lighting
Installation of servo stabilizer for lighting feeder
Installation of high frequency (HF) electronic ballasts
in place of conventional ballasts
16. D Recommendations
Each energy conservation measure should discuss :
The back ground
Analysis and suggestion
Energy savings evaluation (Estimated – before and after)
Impact on energy consumption after implementation
Economic feasibility
Investment required and payback period
Monitoring and verification of energy savings after
implementation
Efforts and resources required for sustainability of energy
savings
The vendors/ suppliers/ manufactures details
