The similarities and distinctions between LED and halogen downlights boil down to how they get the job done.
One employs incandescence (heats a filament to emit light) while the other one utilises electroluminescence (uses voltage to produce light).
It’s easy to confuse the two because they are both mounted in the ceiling cavity, can cast a wide beam of light and generate a similar amount of brightness.
Downlights and spotlights are important in decor and are utilised by designers and homeowners to gentrify their spaces.
Spotlights have a penchant for drama, highlighting a certain area of the room while casting a shadow on the rest of the space.
A desk lamp is one such light, expected to burn three times brighter than the illumination in the room.
Spotlights are also used to illuminate artwork, architectural features, plants and workspaces.
Downlighting is much more subdued and is used to add a moderate amount of light in certain areas of your room.
Rooms with a lot of natural light during the day but insufficient night light benefit from this technique. Since they can have a wide beam angle, downlights are used for large area illumination.
Although halogen bulbs have been used for downlighting for decades, CFL (compact fluorescent) and LED lighting have become the preferred options in homes and offices.
The general consensus is that the latter works just as hard as the halogen bulb but consumes less energy.
Many are transitioning from halogen downlights to LED for their energy rating, durability, architectural look and safety.
This is not to mean that halogen downlights are good for nothing. Their cons are well known but so are their benefits.
Image from flickr by Peter Burgess
Halogen downlights are an advanced form of incandescent lights.
They use a highly pressurised gas from the halogen group of elements (chlorine, iodine, bromine, fluorine, astatine and tennessine) which are known for their reactivity.
The history of the halogen bulb can be traced back to 1882 when chlorine usage in lamps was patented to prevent blackening.
Around 77 years later, General Electric patented a lamp that used iodine as halogen gas.
Bulbs up to this point were made of a large thin glass envelope that contained argon or nitrogen and a tungsten filament.
Electricity would heat up this filament to 2,500 degrees Celsius, making it white hot. This process of incandescence would result in visible bright light and too much infrared heat.
The tungsten would also evaporate and deposit on the glass envelope resulting in a visible dark spot that would reduce light output.
You’d have to replace the bulb after 1,000 hours of use or less, because the filament would get thinner and eventually break.
This led scientists to come up with the halogen lamp which would last longer and mitigate wasted energy from infrared heat.
Image from flickr by Dmitry Dzhus
Halogen lamps have a much smaller, high silica or fused quartz envelope that is strong enough to contain the high pressure gas.
As the ductile tungsten filament evaporates, it combines with the halogen gas and deposits the atoms on the filament, thus making it stronger.
This recycling program makes the bulb last longer, burn hotter (the quartz envelope withstands higher temperatures than glass) and shine brighter than the standard incandescent bulb.
The quartz envelope is too close to the filament so the bulb is hotter compared to a standard bulb.
Unfortunately, halogen downlights, just like their predecessors, generate too much heat.
This is a concern for users who live in areas with high cost of heating, ventilating and air conditioning (HVAC), which is why they are being replaced by LED lamps.
Image from flickr by CreeLEDLighting
LED technology has been around since 1907 when British experimenter Joseph Round realised that voltage applied to a silicon carbide crystal could emit yellow light.
By the 1960s LED was already being used in small electronic devices and has grown in popularity since.
Presently, LED is used to light up advertising display boards, swimming pools, arenas, retail shops and art galleries.
The use of LED technology has been known to result in higher sales and sounder sleep. Did you know that people with seasonal affective disorder during winter can benefit from LED?
LED lights can also be used in human centric lighting (HCL) to treat people who suffer from depression and anxiety disorders.
Known for their dazzling colors, LEDs are significantly smaller in size than halogen lights and consume very little power.
The colour is determined by the amount of current as well as the material of the semiconductor which enables manufacturers to create multi-coloured bulbs.
Electroluminescence is much more energy efficient. Unlike halogen lamps which heat up, LEDs are cool to the touch as most of their energy is converted to light.
Image from flickr by CreeLEDLighting
Fact: Hot objects emit light. Take for example a candle flame, burning hot plate or even a house on fire.
Energy has to be discharged if the electrons in the burning object are to go back to their original state.
In this way, packets of energy called photons are released, their colour determined by the temperature level during combustion.
A temperature of 950°C emits red light, 1,100°C gives out yellow, 1,500°C shines blue and 2,500°C results in white light.
So how come LEDs – or Light Emitting Diodes – cast a bright light while giving off less heat?
LEDs don’t have a filament and depend on the movement of electrons on a semi-conductor to produce light.
Each LED has two terminals – an anode and cathode enclosed in a plastic envelope. A suitable voltage is applied which makes the electrons combine with the electron holes and release photons.
Most LED bulbs are designed in a round shape so that the photons may be focussed in one direction.
Of course, as they get older, LED downlights grow dimmer but you can expect them to last at least 25,000 hours while still maintaining 70% of the brightness.
Unlike LEDs, halogen downlights use a filament within gas and are limited to infrared light.
LEDs, though, glow when an electric current passes through the semi-conductor and their light ranges from infrared, red, orange, blue and others in the colour spectrum.
Unlike halogens, which burn hot, LED downlights are safe to touch and do not cause fires when they come into contact with flammable material.
This has seen the medical field embracing LED technology even more. Imagine how hot and uncomfortable surgeons, as well as patients, would be if they used halogen lamps in operating theatres.
This is a scale which specifies a bulb’s ability to render colours and is based on a 100-Watt incandescent lamp, ranging from 0 to 100.
LED bulbs are not as bright as their counterparts – their CRI rating is between 80 (cheap) and 98 (high-end). Halogen lamps have a CRI rating of 100, which is similar to daylight.
Let’s compare how bright a halogen lamp shines (when it consumes a certain amount of energy) with its LED counterpart.
A 100-Watt (amount of energy used) LED downlight produces 11,500 lumens (light output visible to the human eye) while a 100-Watt halogen light will produce 1,900 lumens.
This occurs because 90% of the energy produced by a halogen lamp is wasted on heat.
The main purpose of a downlight is to produce light,not heat, and halogen lamps consume considerably higher wattage to produce the same amount of brightness as an LED.
LED bulbs can last from 25,000 to 50,000 hours, while halogen downlights average 1,500 to 2,000 hours.
We’re talking more than 10 years’ lifespan for LEDs compared to 1 year for halogen downlights.
Halogen downlights require a qualified electrician to run checks from time to time and are hazardous if not properly installed.
They must also be fitted with a heat guard due to their high running temperatures.
Each year, you have to set aside a significant amount of cash for recurring maintenance costs, such as new lights, fixtures, labour and a skyrocketing electricity bill.
Although LEDs are expensive during installation, they save you energy and money in the long term.