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| HOW CAN I SAVE ENERGY? |
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| INDOOR LIGHTING |
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The daily demand for electricity can be graphically illustrated against time as above. This curve, also known as the load curve, is characterised by peaks and dips corresponding to various electricity usage scenarios.
The first peak (between 5.30 a.m. and 6.30 a.m.) occurs due to electricity usage at the break of dawn. Working people and school children are at their busiest at this hour. This peak starts receding around 7.00 a.m. when households set off to work or school. The trough at 7.30 a.m. is when most people are commuting to work/school, hence electricity usage in establishments is minimal. The subsequent slow peak, up to 9.00 a.m., symbolises the initial working hours of a typical day. This is followed by the commercial working load, which begins at 9.30 a.m. and follows suit to 6.30 p.m., during which the electricity usage is high.
The abrupt sharp peak around 6.30 p.m. is due to household electricity usage at evening and nightly hours. This peak is known as the ‘peak demand’ and lasts till about 10.30 p.m. Household lighting and television usage are the main contributors to this peak demand.
Therefore, you could contribute to reduce the peak demand by adopting energy efficient lighting practices.
Let us see how this can be done.
A 15 Watt compact fluorescent lamp gives as much light as a 75 Watt incandescent lamp. Yet, the two bulbs would impact your electricity bill very differently. See below.
If the two bulbs were lit for 4 hours per day per month, the cost would be; |
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Compact Fluorescent Lamps (CFLs) – energy saving devices
CFL uses only 1/5th of the energy of incandescent lamps. Saves up to 80 % of energy
1 CFL = 10 incandescent lamps
CFLs have many advantages over incandescent lamps.
Cost effective.
High efficacy – higher output of light
6 – 12 times longer lifetime than incandescent lamps
Environmentally friendlier, for they last longer and need to be disposed less frequently.
Not dangerous, if used as instructed. CFLs contain a small amount of mercury, less than that found in dental fillings and wrist watch batteries. |
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| CFLs are Also |
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Available in a wide range of shapes, sizes and colours to suite your taste.
The colour depends on the Correlated Colour Temperature (CCT). CCT is the measure of colour whiteness (chromaticity) in degrees Kelvin (K). Higher CCT makes an object more bluish-white while lower CCT makes an object more reddish-white. Warm light usually has a colour temperature below 3200 K while cool temperature is above 3200 K. Incandescent bulb has a CCT of 2800 K. |
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| Colour temperature K |
Light description |
Application |
| 2700 ~ 3000 |
Warm white |
Colour similar to incandescent bulb, ideal for kitchens, bathrooms. Reflects natural skin tones and wood colour. Attract lesser insects. |
| 3000 ~ 3500 |
Neutral white |
Standard colour for fluorescent lamp and CFL. Slight yellow to pure white. Ideal for rooms. |
| 4100 |
Cool white |
Pure white colour for general use. Ideal for rooms, offices |
| 5000 ~ 6500 |
Daylight |
Simulates natural daylight |
| >6500 |
Cool daylight |
White light with a slight blue tone. Ideal for retail shops, commercial purposes |
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| Energy Labelling |
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| Purchase CFLs with three or more star ratings. The higher the number of stars, the more efficient the lamp is. |
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| Replace incandescent lamps with CFLs. The following chart may help you to pick the right candidate. |
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Incandescent lamps (Watts) |
CFLs (Watts) |
20 |
5 |
40 |
7 |
60 |
11 |
75 |
15 |
100 |
20 |
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| “QUALITY RULES OVER PRICE” |
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Though the initial cost of purchasing a CFL is higher than that of an incandescent lamp which gives out similar light output, a CFL proves to be a great saving in the long run. It saves both money and energy. Follow the example below, and you will understand. |
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(1)
CFL (20 W)
Incandescent (100 W) |
Lifetime in hours is,
6000
1200 |
Cost in rupees is,
500
40 |
(2)
CFL
Incandescent |
Energy (kWh)
6000*20/1000 = 120
1200*5*100/1000 = 600
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Energy cost, if a unit is 10 rupees
1200
6000
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(3)
CFL
Incandescent |
Total cost = energy cost + cost of purchasing (LKR)
1200 + 500 = 1700
6000 + (40*5) = 6200 |
In the long run, lighting a CFL for 6000 hrs costs only 1700 LKR, whereas lighting 5 incandescent lamps to get the same amount of light costs 6200 LKR.
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| Adopt the following to reduce wastage |
- Turn off lights when not in use
- Use task lighting: focus the beam only where it is necessary, as in using a table lamp while studying
- Keep bulbs clean to ensure maximum emission of light. Over time, dirt build up reduces light output.
- Make the best of daylight
- Decorate rooms with light colours.Light coloured walls, ceilings, tiled floors reflect light.
- Limit outdoor lighting. Use only if essential.
- Fluorescent lamps (tube lights) save energy when used with electronic ballasts.
- LED (Light Emitting Diodes) are very long lasting and efficient.
- Installing a skylight can provide your home with daylighting and warmth. When properly selected and installed, an energy-efficient skylight can help minimize your heating,cooling, and lighting costs.
- Take advantage of daylight by using light-colored, loose-weave curtains on your windows to allow daylight to penetrate the room while preserving privacy. Also, decorate with lighter colors that reflect daylight.
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