Energy Conservation Techniques in Lighting Systems
(A) By replacing lamp sources :
The lamp sources used for lighting are :
(i) Filament lamps
(ii) Fluorescent lamp. While following types of lamps are mostly used for street lighting, factories etc.
(iii) Mercury vapour lamp.
(iv) Sodium vapour lamp.
- Halogen lamps can be used for public halls, factories studios, play grounds, car parking purposes etc.
- When we consider general lighting system, then mostly filament lamps or fluorescent lamp i.e. tube lights are mostly used.
- Filament lamps are more sensitive to voltage variation. A small reduction in voltage reduces its luminous output greatly, while a small increase in voltage increases its output but at the same time reduces its life.
- The same variations in case of fluorescent lamps are comparatively less.
- The luminous output of filament lamps goes on reducing with usage, which is due to slow vapourisation of the lamp filament and partly due to black deposit formed inside the lamp.
- In case of fluorescent lamps a change of ±1% of the supply voltage produces a change of about ± 1% in luminous output.
- The increase or decrease in voltage reduces lamp life, with increase voltage heating effect of electrodes is increases and they loose electron emissive material by evaporation.
- With reduced voltage, the current reduces causing sputtering at the electrodes reducing their life.
- The luminous output of incandescent lamps of 40 watt is nearly 10 lumens / watt while that of 40 watt fluorescent tube or lamp is nearly 40-50 lumens watt.
- Hence, replace incandescent lamps by fluorescent lamps of proper size.
- Compact fluorescent lamps (CFL) of smaller wattage will provide same illumination.
- Life of CFL lamps is nearly 10 to 15 times more than ordinary incandescent lamps.
- Energy consumption can still further be reduced by using electronic ballasts instead of electromagnetic ballast.
Lamp Replaced by
- Incandescent → Compact fluorescent lamp (CFL).
- Conventional fluorescent lamp → Energy efficient fluorescent lamp.
- Mercury vapour or sodium vapour lamp → Halide lamp.
- HPMV lamp → HPSV lamp.
- Filament lamps on panels → LED .
(B) Electric chokes / starters / ballast
- Saving can be achieved by selecting a ballast base for the CFL lamps separate from the bulb, which will help to change the bulb only at its life end.
- In case of compact fluorescent lamps, their colour rendering index should be seen, we should select lamps having CRI nearest to 100, which is best.
- Linear fluorescent tubes are suitable for kitchen, bathroom, utility area select suitable styles and lengths of these instead of incandescent lamps.
- If incandescent lamps of large size are used for light focus, halogen lamps with a special reflector may be used, replacing incandescent lamps, as they consume 40 to 50% less energy giving output similar to incandescent lamps. Hence, they should be used for lighting of gardens and pathways.
- Efficiency of lamps, whether incandescent or fluorescent goes on reducing up to life end hence we should not wait till the lamps blows out it must be replaced by new one when it is observed that it is giving less luminous output.
Advantages of high frequency ballast :
- Instant light.
- Light in weight.
- Operates at low voltage.
- Power saving = 35 %.
- Power factor improvement.
- Heat output is negligible that reduces load on air-conditioning.
- Enhances life of lamp.
Advantages of electronic ballast over electric ballast :
- Instant light.
- Lighter in weight.
- 35 % power saving.
- Power factor improvement.
- Heat output is less.
- Operates at low voltage.
- Enhances life of lamp.
(C) Using energy efficient luminaires :
- As explained previously, the incandescent lamps use only 5 to 10% of their energy to produce light and the rest is waisted in developing heat, hence their luminous efficiency is low as 10 to 12 lumens / watt.
- While the CFL or fluorescent lamps have a luminous efficiency of 40 to 50 lumens / watt, they are available in different sizes and shapes and can suitably replace the incandescent lamps, in position where they are required.
- Incandescent lamps of large capacity used for gardens, parks, roads, play grounds, flood lighting etc. be replaced by halogen lamps, sodium vapour lamps or mercury vapour lamps having more luminous efficiency.
Criteria for selecting energy efficient lamps (replacement option) :
- While replacing the lamps by higher energy efficiency, we must ensure that the required current rendering (CRI) is maintained, otherwise it has an adverse effect on the quality and rate of work output. Also the cost involved must also be considered.
- By any lighting method, electrical and mechanical accidents should be less.
- The glare to human eyes should be less by any lighting method.
- By proper selection of lighting method, surrounding conditions should be pleasant to every body. Energy efficient lamps → CFL, LEDs.
(D) Using light controlled gears :
- Generally, the outside lighting is made on and off at particular time of the day irrespective of the requirement.
- However, the wastage of such energy when it is not required can be saved by using light sensers i.e. a device that will use photoelectric controls, which will make the circuit on or off.
- When the illumination level goes below a particular level or when it goes above a particular level. So that wastage of energy can be saved.
- Use of controlled switches may be made in the wiring system, so that when necessary high capacity bulbs may be made on and when low illumination is required, less capacity bulbs can be used.
- Only a particular bulb can be kept on and other can be made off when not required giving much more saving in energy.
- Using light control gear :
- Install a microprocessor / infra-red controlled dimming or switching.
- Movement detectors / lighting sensors used feed signals to the controller.
- Optimum use of day lighting in combination with electric lighting.
- Installation of exclusive transformer for lighting (this reduces voltage related problems).
- This increases lighting efficiency.
- Install high frequency (HF) electronic ballast in place of conventional ballasts, this saves 35% energy.
(E) By installation of separate transformer/servo stabilizer for lighting :
- The luminous efficiency of lamps depends upon the voltage applied across its terminals.
- It gives its best output at rated voltage Small reduction in applied voltage greatly reduces its luminous output.
- When it is necessary that the voltage applied across them is properly maintained constant. This can be achieved by installing a transformer sub – station near the load so that variation in voltage will be negligible.
- However to such sub-stations different categories of loads are connected, which may act in such a way that there may be sudden voltage drop taken place and when such loads are made off, it may result in sudden rise of voltage, which will certainly affect on the luminous efficiency of the lamps.
- To obtain constant luminous output in particular installation it is necessary to stabilize the voltage.
- Hence for such purposes servo stabilizers are connected in the system of such premises, which will maintain the voltage constant in that installation for giving best luminous efficiency of lamps.
To obtain constant luminous output in particular installation , it is necessary to stabilize the voltage. Hence such purposes, servo-stabilizers are connected in the system of such premises which will maintain the voltage constant in that installation for giving best luminous efficiency of lamps. maintenance programs.
(F) Periodic survey and adequate maintenance programs :
- Depreciation in lumen output of the lamp occurs with time due to blackening of lamp , evaporation element material or reduction of electron emitting materials from fluorescent tube etc. The actual amount of light to be provided by the source is greater by 50 to 100% on account of depositing on the reflector surfaces.
- Hence, a periodic survey is necessary for a particular installation , in which we have to clean all shade lamps, surface of lamps and remove dirt, dust etc. accumulated on the surface inter and outer of shades and outer surfaces of lamps etc.
- See that blackening of lamps at the electrodes of fluorescent lamps has taken place or not if it is observed replaced them by new ones. If the lamps are in use for long time do not wait for blowing out, replace for better luminous efficiency.