Lighting Facts

Lighting Products

Low-energy lighting is fast becoming the norm as old, inefficient bulbs are phased out.
The new technology is developing quickly and there’s a wide range of products to choose from. These are the main technologies currently used in a regular household

Known as tungsten filament or GLS (General Lighting Service) bulbs, traditional light bulbs are extremely inefficient. Only about 5% of the electricity they use is converted into visible light. The tungsten filament bulb was invented about 100 years ago. The filament is heated up until it glows, giving off a yellowish white light. The lamps do not last long because the filament gradually evaporates. If you have any of these light bulbs left in your house, you should change them now and start saving money right away

These use a very similar technology to GLS lamps, but run at a higher temperature making them slightly more efficient. In homes, they are mainly used in spotlight downlighters. Although they are more efficient than old-fashioned GLS bulbs, they are often used in large numbers and so the total amount of electricity used to light a room is often higher than any other option

Many rooms with halogen downlighters are brighter than they need to be so you may be able to save money by installing lower output bulbs.

he ideal energy efficiency alternative to a halogen downlighter is an LED. But if you do want to use halogen lamps, look for ones with Energy Saving Label – they use 30% less electricity than an equivalent standard halogen while giving out exactly the same light, and are the most energy-efficient halogen bulbs on the market

TCompact fluorescents, or CFLs for short, use a completely different technology from halogens or GLS bulbs. A gas inside a glass tube is charged up so that it glows. This causes a coating on the inside of the glass tube to ‘fluoresce’, giving off the white light that we want. CFLs use about 20% to 25% of the electricity that an equivalent GLS lamp will use.

CFLs are the lamp of choice for most standard light fittings in a house. They can also be found for spotlight fittings, but these are not yet widely available and tend to be expensive.

Modern CFLs do not flicker, and they can reach full light output quite quickly, though they cannot reach full output instantly the way other technologies do. Choosing a good quality CFLs with Energy Saving Label not only will last up to ten times longer than traditional incandescent lamps and luminaires but also will have a better color rendition and will reach their maximum output quicker

A LED lamp is a Light-Emitting Diode (LED) product that is assembled into a lamp (or light bulb) for use in lighting fixtures. A diode is a simple solid state electronic device that allows electricity to flow in one direction only. A light-emitting diode, as the name suggests, emits light as the electricity flows through it.

LED lamps have a lifespan and electrical efficiency that is several times better than incandescent lamps, and significantly better than most fluorescent lamps. Like incandescent lamps and unlike most fluorescent lamps (e.g. tubes and CFL), LED lights come to full brightness without need for a warm-up time; the life of fluorescent lighting is also reduced by frequent switching on and off. Initial cost of LED is usually higher, but they are the most efficient option of all, they last far longer than any other technology, and they will pay for themselves several times over before they need replacement.

Some LED lamps are made to be a directly compatible drop-in replacement for incandescent or fluorescent lamps. An LED lamp packaging may show the lumen output, power consumption in watts, color temperature or description ("warm white") and sometimes the equivalent wattage of an incandescent lamp of similar luminous output.

Electrical efficiency of LED devices is higher than other lighting and continues to improve, with some chips able to emit more than 100 lumens per watt. LEDs do not emit light in all directions, and their directional characteristics affect the design of lamps. The light output of single LEDs is less than that of incandescent and compact fluorescent lamps; in most applications multiple LEDs are used to form a lamp, although high-power versions (see below) are becoming available.

LED chips need controlled direct current (DC) electrical power; an appropriate power supply is needed. LEDs are adversely affected by high temperature, so LED lamps typically include heat dissipationelements such as heat sinks and cooling fins

A dark lamp shade can easily absorb more than half the light output of a bulb before it has the chance to light up your room. So you can save energy and money simply by using more transparent shades or fittings that let more of the light spill out directly.

The most efficient fitting will usually be one where you can see the light bulb. You may have to spend more on the bulb to find an attractive low-energy option.

Some fittings, especially spot light fittings, have a reflective inside to direct as much of the light as possible in the required direction. This can increase efficiency if light is required mostly in one place. Halogen spotlights have the reflective surface as part of the bulb, and LEDs give out directional light anyway, so don’t need a reflector.

Some fittings have a glass or other transparent diffuser to hide the bulb without losing much light output. It is worth cleaning these from time to time to make sure light output doesn’t drop off.

Some light fittings are designed only to take CFLs – you couldn’t fit an inefficient GLS into them even if you wanted to. The fitting contains the ballast (electronic circuitry) that most CFLs have in the bulb itself. So when the tube eventually fails you only have to replace the tube, not the whole lot.

Unfortunately, the tube-only CFLs that you need for these fittings are much more expensive than standard CFLs, so you save less money with this type of fitting. And with GLS bulbs being phased out there’s no real benefit in having a CFL-only fittig

Lighting Output

We’ve probably all bought a low-energy light bulb at some point and been disappointed with the result. It said “100watt equivalent” on the packet, but when you got it home it just wasn’t that bright.

The problem is that “100watt equivalent” doesn’t actually mean anything precise. The 100W figure is a measure of the electricity consumption of an old inefficient bulb, and is not a measure of brightness. This has allowed some manufacturers to make exaggerated claims, leading to confusion and disappointment. Unfortunately the same problem exists with LEDs. There are plenty of good LED products out there, but some companies are making extreme claims for very poor bulbs.

If you want to know how bright a light bulb really is you need a figure that measures its actual light output. Fortunately, bulb manufacturers now have to quote the light output on all new bulbs. Once all the old stock has been cleared from the shelves, every new bulb you see in the shops will have its light output in Lumens clearly printed on the packet.

Light Output (Lumens) LEDs (Watts) CFLs (Watts) GLSs (Watts)
300 ~ 450 4 ~ 5 8 ~ 12 40
600 ~ 900 6 ~ 8 13 ~ 18 60
1100 ~ 1300 9 ~ 13 18 ~ 22 75-100
1600 ~ 1800 16 ~ 20 23 ~ 30 100
2600 ~ 2800 25 ~ 28 30 ~ 55 150
Frequent On/Off Cycling No effect Shortens lifespan Some effect
Turns on instantly Yes Slight delay Yes
Durability Durable Fragile Fragile
Heat Emitted Low (3 btu’s/hr) Medium (30 btu’s/hr) High (85 btu’s/hr)
Sensitivity to temperature No Yes Some
Sensitivity to humidity No Yes Some
Hazardous Materials None 5 mg mercury/bulb None
Replacement Frequency
(over 50K Hours)
1 5 40+


The sun gives out white light, and that is the sort of light we’re used to living in much of the time. But old fashioned light bulbs give out a much yellower light. When we’re indoors out eyes adapt to this and we think of this as “white”. If we then see a light source that is genuinely white, it actually looks blue by comparison. We call this a cold light, because we associate blue with cold and red or yellow with warm.

Most low energy bulbs – CFL or LED – are designed to mimic old fashioned bulbs to some extent, and are usually described as “warm white” or “soft white”. This will usually be the preferred option for general household use. Bulbs that are sold as “cool white” or “pure white” are likely to look less attractive in the home, but may be appropriate for workplace lamps and anywhere where clear vision rather than ambience is the priority. “Daylight” bulbs are the whitest of all, and are usually only used by artists and others who need to match colors correctly.

Color Rendering

This is slightly different from color. Two light bulbs can both give out white light, but certain color will not show up well when illuminated by the first bulb, while they look fine under the second bulb. This means the first bulb has a lower Color Rendering Index (CRI).

Traditional bulbs have a CRI of 100. A good CFL will have a CRI of 80 or more, which is good enough for normal domestic use. Most LEDs have a CRI of 90 or more, so are usually fine. However, if you buy bulbs with CRI of less than 80 there is a rick that the quality of light in your home will look a bit odd.