More than 7,000 cities across 172 countries are expected to turn off their lights for an hour in support of Earth Hour this Saturday, 19 March at 8.30 PM local time. Every year, cities around the globe participate in the world’s largest collective environmental action for climate change by World Widelife Fund (WWF).

While the general objective of the movement is to stop the degradation of the earth’s natural resources, it poses more practical benefits – which are energy and cost savings through lighting. By turning the lights off, every common citizen can save 10 to 20 percent of their total household electricity usage. Put that in a picture of thousands of households in hundreds of cities, the figures grow into a much bigger number and can create a substantial international impact.

Turning it on then off again: how cost & energy effective is it?

The cost and energy effectiveness will usually depend not only on switching the lights off and then on again, but also depends on the type of light bulb used and the price of electricity in various cities. In order to calculate the exact value of energy savings by turning a light off, you firstly need to know the amount of energy use when a light is on.

Every bulb has a Watt rating printed on it. For instance, for a bulb with 40 watts rating, the amount of energy use in having it on for an hour is 0.04 kWh – just as the amount of energy you would save by switching it off for the same period of time. This amount could then be multiplied per cost of kWh of your own electricity cost.

Incandescent lights or bulbs are relatively inefficient, as only around 10%–15% of the electricity that this light consumes result in light, whilst the rest is turned into heat. Turning the bulbs off, even just for an hour, would help lower the room temperature and can benefit if applied in tropical countries across Asia. In this case, the value of the energy saved by not having the lights on will also be far greater than the cost of having to replace the bulb throughout its lifespan.

For fluorescent lights, the cost and energy benefits of turning it off are a bit more complicated. Many believe that fluorescent lights use a lot of energy to get started, and thus it is better not to turn them off for shorter periods. In this case, the Earth Hour movement holds its value, as turning off fluorescent lights for more than 5 seconds will save more energy than the amount of energy use of switching it on again.

The popular type of lamps in today’s era is debunking the myth of ‘it takes more energy to turn the lights on and off throughout the day then it does to leave them running’. There is an increase in power demand when a light is switched on, as the amount of energy use to supply the “inrush” is equal to a few seconds or less of normal light operation.

However, light bulbs nowadays take less than 1 second to light up, so unless the bulb hasn’t been replaced for at least 5 years – this applies to even the large lights we see in commercial buildings – turning it off for an hour poses an actual energy saving and cost benefits in a greater scale.

Global movement: the impact of collectively switching off lights

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Every year, Earth Hour has proven that the movement is stronger than people initially perceived it to be. To illustrate this, the Philippines saved up to 611 MWh of electricity in a mere one hour in 2009, which is said to be equivalent to shutting down a dozen coal-fired power plants for the same amount of time. The Philippines saw 10 million of its inhabitants from 647 cities and towns participate in the hour long lights-off.

According to the 2015 WWF report on Earth Hour, electricity consumption in Hong Kong dropped by 4.08%, which is equivalent to a reduction in CO2 emission of approximately 138 tons.

On the other hand, in India, the focus of the campaign this year is instead on the potential of solar energy as a viable and renewable source of power. With approximately 300 clear sunny days throughout the year, India has a capacity to harness 5,000 trillion kWh of energy per year, significantly exceeding its total annual energy needs.

From the statistics above, it is evident that every country has a substantial role in reducing energy consumption through the event. If one country can contribute towards the reduction of energy intake, imagine how much energy can be saved up on a global scale within a one-hour interval.

The movement strongly encourages everyone – be it citizen, government, an organization, or even a whole city – to switch off their lights for an hour. Andy Ridley, the event’s CEO and co-founder, believes that Earth Hour can go beyond 60 minutes and hopes that each individual can contribute more in energy savings.

“Although Earth Hour  aims to turn off the lights for 60 minutes, the main goal is to push it beyond the given hour and make it a habit of using less energy through lighting. We want  people to experience the difference with and without electricity. The biggest challenge, however, is to build a global collective movement far beyond the event itself ”  – Andy Ridley, CEO & Co-Founder of Earth Hour

Switching off the lights in a span of an hour seems like a simple task, yet the overall effect can be massive by incorporating a powerful message to tackle climate change. Earth Hour is calling on citizens across the globe to support not only the campaign by switching off non-essential lights for an hour, but also calls for the government’s commitment to move forward with renewable energy for a sustainable future. So what are you waiting for? Participate in Earth Hour and make a small yet significant change for generations to come.

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