LITTLE BITS THAT MATTER IN ENERGY EFFICIENCY (2) - Copy

• TURN OFF THE LIGHTS WHEN OUTSIDE IS BRIGHTER.    

By Ahmed Lawal, Professional Energy Auditor (PEA) slight Energy.

In 2016, lighting was responsible for 15% of global electricity consumption and 5% of global carbon emissions. To address the expected 50% increase in lighting demand by 2030, the Global Lighting Challenge was initiated during COP21 in late 2015. The goal was to rapidly deploy 10 billion high-efficiency, high-quality, and affordable lighting fixtures and bulbs. Implementing a global transition to advanced lighting technologies like LEDs would result in a 50% increase in light fittings, while reducing electricity consumption by 50%. Maximizing the use of daylight through efficient lighting design and deploying well-designed lighting control systems for nighttime use are crucial aspects of this transition.

The initial step in lighting design involves determining the appropriate lighting level in lux (illuminance). For office spaces, this typically falls between 300 and 350 lux according to standards. The illuminance level is inversely proportional to the square of the distance from the light source. It also depends on factors such as floor finish, wall material and paintings, roof material and painting, and the distance between the light source and the measurement point. Implementing an appropriate Building Management System allows for effective control of both internal and external building lights, resulting in significant energy savings. One common control mechanism is the vacancy/occupancy switch, which uses a Passive Infrared sensor to turn on lights when someone enters a room and turns them off when the room is vacant. External lighting can be controlled using photocells that activate the lights as daylight diminishes, combined with timers to reduce illuminance when there are fewer passers-by.

Different lighting technologies possess varying quantities and qualities such as luminous flux, luminous flux density, luminous efficacy, Color Rendering Index (CRI), lifetime, and price. It is important to examine these aspects when evaluating lighting technologies. Some of the lighting technologies include incandescent, tungsten halogen, fluorescent, high-intensity discharge (HID) like metal halides, high-pressure sodium (HPS), low-pressure sodium (LPS), mercury vapor, and light-emitting diode (LED). Understanding the characteristics of each technology is crucial.

• Luminous flux: Measured in lumens (lm), it represents the amount of visible light emitted by a lighting source.
• Luminous flux density: Also known as illuminance, it is measured in lux (lm/m2) and indicates the amount of visible light per unit area.
• Luminous efficacy: Measured in lumens per watt (lm/W), it quantifies the amount of visible light produced per unit of power consumed.
• Thermal loss: Some lighting technologies generate more heat than light, making them preferable when warmth is desired rather than efficient lighting.
• Color Rendering Index (CRI): It measures how accurately a lighting source renders the true colors of objects to the human eye. The sun is considered to have a CRI of 100.
• Lifetime: The average lifespan (in hours) of a lighting technology.
• Price: The cost of each unit of a lighting technology.

By considering these qualities and quantities, individuals and businesses can make informed choices when selecting the most suitable lighting technologies for their needs.

LEDs have emerged as the top priority in the lighting industry due to their numerous advantages, as highlighted in the table. One key benefit is their exceptionally long lifespan, typically around 50,000 hours. This means that if used for 10 hours per day, LEDs can last approximately 13.67 years before needing replacement. Some newer LEDs can even reach lifespans of up to 100,000 hours. Moreover, LEDs are highly energy-efficient, wasting very little energy through infrared radiation. They can be designed to generate the full spectrum of visible light colors and are available in smaller sizes with faster switching capabilities.

While LED projects may come with higher initial costs, they offer a quick payback period due to their energy-saving properties. Implementing strategies such as occupancy switching, manual switching of LEDs, and daylight harvesting can result in significant energy and cost savings of up to 50%.

Although lighting may seem like a small portion of a building's overall energy load, adopting the practice of turning off lights when natural daylight is sufficient can lead to substantial long-term savings and contribute to a cleaner and healthier environment.

For more information and to benefit from our energy audit and energy efficiency services, please visit https://slightenergy.com.