Most sports halls, factories, storage sheds and other higher-ceiling structures use Metal Halide (MH) lighting, called high bays. Typical wattages are 400W or 250W per high bay lighting fixture. Given the long duration that lighting is typically used in an association or business, the ongoing costs can be extremely high, and non-uniform degradation can lead to uneven colouration of the lighting.
LED lighting is used to provide an alternative lighting technology. Due to much lower wattage for the same lighting output, the lighting-related costs are often reduced by over 50%. As a bonus, the maintenance costs associated with LED lighting are often far reduced, due to their superior lifespans and consistent colouring.
LED Lighting History and Overview
Three decades ago, LEDs were only really known for being the power indicators on electronic devices, as they were too weak to be of much use elsewhere. Today, however, LED is leading the way in the fight to produce increasingly efficient lighting by dramatically reducing energy consumption.
The high-brightness blue LED was introduced in 1993. Twenty times brighter than its green or red predecessors, this was the long-awaited enabler of white LED light. Then, as now, white LED light was produced by blending red, green, and blue light or by using a blue LED with a yellow phosphor. From this point on LED bulbs started their journey to take over the world of lighting.
All very well, but what is an LED?
The real science bit…
A Light Emitting Diode (LED) is a device that allows electrical current to flow in only one direction. It includes two conductive materials, placed in contact with each other. Electricity is applied to the diode so that atoms in one material are excited to a higher energy level. That energy is then released in the form of electrons into the second material, and this release of energy creates light.
How does this differ from traditional lighting?
Traditional incandescent lighting produces light directly by heat. A thin tungsten filament is warmed to about 2500°C by an electric current. Filament bulbs use 90% of their energy in maintaining this extreme temperature.
LED lighting boasts numerous benefits over rival technologies:
- Energy-efficiency: LED lighting offers energy savings of 80-90% over incandescent or halogen technologies and up to 50% over fluorescent lamps.
- Longer life: with typical lifespans of up to 50,000 hours, LED lasts 2 or 3 times longer than fluorescent lighting, and up to 50 times longer than incandescent. Maintenance costs are vastly reduced as a result.
- Instant light: unlike many fluorescent lights, LEDs require no warm-up time to reach full brightness.
- Eco-friendly: LED lighting has potential to drastically reduce carbon emissions. Around 20% of the world’s electricity is used on lighting. Unlike fluorescent lamps, LEDs contain no mercury, making disposal easier and cleaner. Longer lifespan relieves pressure on landfill sites.
- Reduced heat output: LED lighting has significant heat dissipation needs. However, unlike filament bulbs, an LED lamp does not project infrared heat in its beam. This increases suitability for lighting heat-sensitive items like artworks or food.
- Added durability: LEDs are a solid state form of lighting, resistant to vibration and shock. They are less delicate than incandescent or fluorescent lamps, and outperform competing technologies in cold temperatures.
Can I replace existing lights with LEDs?
Retrofit LED bulbs (ones that fit into existing bulb holders) are suitable in most situations. Close attention should be paid to heat dissipation needs, especially when replacing halogen reflectors in enclosed light fittings (e.g. recessed ceiling light). Advanced heat sink design in modern LED lamps overcomes the reliability problems seen in early models. Manufacturer’s guarantees are often supplied to back this.
A few words about dimming
LED lighting is excellent for dimming, maintaining energy efficiency at all light levels. However, not all LED lamps or fittings are dimmable. Dimmability is a property of the LED driver, so you need to shop specifically for it.
Many modern LED lamps are compatible with old dimmer switches, but the minimum load of a switch (often 60W) is a potential problem if you only want to dim a few lights. It is sometimes easier to install a new dimmer switch, with modern ‘trailing-edge’ dimmers being suitable for LED loads.
Dedicated LED fittings
LED light fittings are increasingly designed with non-replaceable LEDs, mainly due to their long LED lifespan. In this instance, the whole luminaire is replaced at the end of its useful life. One of the advantages is that designers can build light fittings that are fine-tuned for efficiency, with very little light being wasted.
Does the light from an LED reduce over time?
Yes, it’s a process called lumen depreciation, which affects LED and fluorescent lighting. Incandescent bulbs produce the same amount of light throughout their lifespan.
LED lifespan is usually measured to a point where it has lost 30% of original lumen output (known as 70% lumen maintenance, or L70). Lumens are used to measure the total amount of light produced, regardless of direction or beam angle.
Reducing carbon emissions
It is argued by scientists worldwide that we are heading towards potentially disastrous climate change due to excessive carbon emissions. The way we create and use our energy is all part of this equation and regardless of your stance, reducing your carbon footprint is definitely a positive way of doing your bit for the environment. You’ll be saving money at the same time!
LED in summary
LED lighting is energy efficient, long-lived, eco-friendly, robust, and all-round cool (except around its heat sink). In addition, it produces little or no UV, is unaffected by frequent switching, is naturally directional for precise control, and it’s compact. LED is the future of lighting.