Brighter & Sustainable

Lighting is an important part of modern existence: every activity, from classrooms in schools to dwelling units to the shopfloor in factories, needs proper lighting. Unfortunately, the source of light was mostly electricity from fossil fuels until recently. While the supply side of electricity is being addressed by moving away from fossil fuels to renewable energy from solar and wind, the demand side also needs to be addressed. This is where the nature of lights and bulbs and LED lighting as well as the maximum use of natural light in buildings becomes important.

Natural Lighting in Buildings and Offices

We have seen the importance of natural lighting in the article on Net Zero Buildings earlier. To elaborate on the theme, it is important to maximize the use of daylight in buildings, residences and offices, so that the need for electric light is minimized. One way to do so is to use ‘smart glass’ in window panes. These windows change their characteristics in response to variations in heat and light. This process, triggered by electricity, is called electrochromism. If triggered by heat, it is called thermochromism and if triggered by light, it is called photochromism. Such windows use the light and heat from the sun in the manner required: in winter, both heat and light come into the room and in summer, only light enters the room, keeping the heat out. Electrochromic, thermochromic and photochromic glasses are now available commercially. For example, the Boeing 787-9 Dreamliner uses electrochromic glass in its windows.

LED Lighting

LED or light emitting diodes are commonly used across the world for lighting and decorative purposes today. Diodes were, however, invented as far back as 1874 by Ferdinand Braun. Braun found that a particular type of crystal semiconductor conducts electricity only in one direction, acting like a switch. Later, in 1907, it was found that diodes also emit light when current flows through it. This property of diodes was used to great effect in the 1960s by companies such as General Electric, Texas Instruments and Hewlett Packard in the USA. In the 1990s, Japanese scientists invented LEDs, which shone bright.

LEDs are far superior and more efficient than the traditional incandescent light bulbs or even the fluorescent lights. While incandescent bulbs operate on the basis of heating a tungsten filament in vacuum, fluorescent lights ionize gases by electricity. LEDs, on the other hand, operate on the basis of converting electrons to photons. Incandescent bulbs are the most inefficient and emit only a little light and heat up fast, while using a large amount of energy. LEDs are super-efficient and convert 80 per cent of the energy used into light. LED bulbs are also long-lasting as compared to incandescent or fluorescent bulbs. Paul Hawken’s Drawdown says that a LED bulb can last for as long as 27 years if used for about 5 hours a day.

The downside of LED bulbs is their upfront cost (it is about 2-3 times of an incandescent or fluorescent bulb), but even that is falling.

The massive advantage that LED lights offer is being reaped in a number of rural areas of Asia and Africa around the world. The Millenium Villages Project in Malawi has displaced the polluting kerosene lamps with solar LED lanterns in a number of villages. The Light Up the World Foundation has been advocating the use of LEDs in off-grid rural areas. The Lumina Project in Western Kenya and China also demonstrated the effectiveness of replacing fuel-based lighting with solar-LED lighting, even on a commercial basis. In India, millions of solar-LED lights have changed the lives of rural communities by allowing students to study longer hours and shops to remain open longer. LED lamps are also being used extensively to light up urban streets, leading to energy and cost savings. Most cities across the world are now shifting to LED lighting in their streets, parks and other common areas.

Conclusion

LED lighting is not only more efficient, but is slowly becoming cost effective as well. In addition to having obvious climate benefits by replacing fuel-based kerosene lamps in rural areas around the world, LED lamps have also changed the lives of rural communities by keeping village hospitals lighted, shops open for longer hours and lighting up common areas such as roads.

The writer is Additional Chief Secretary, Department of Mass Education Extension and Library Services and Department of Cooperation, Government of West Bengal