The lighting ecology debate is dominated by the forthcoming restrictions on sales of incandescent lamps and the promotion of compact fluorescent lamp (CFL) alternatives. There is a lot of ignorance and vested interest at play and this is not helpful for people looking for useful information about lighting their homes.

This section of our site will try to provide access to a range of opinion including our own, which we will seek to keep as objective as we can.

One strand of opinion is that of lighting designers, a large number of whom are angered by the drive towards CFLs and the effective banning of what they see as a perfectly acceptable lamp, when used correctly. See the Professional Lighting Designers Association at www.pld-a.org for more on this.

The major lamp manufacturers tend to promote their new technologies and by and large are more responsible than they are sometimes given credit. They take a technology view and promote the highest efficacy of light source. However their marketing departments inevitably present their products in the best possible light. This can lead to a partial picture, omitting inconvenient information that does not fit with their message.

So what are the main issues?

1. Light source efficacy. This means the efficiency of the bulb (or more correctly lamp) at converting electricity into light. It is usually measured in lumens/watt, but you will often see that directional lamps (halogen/LEDs) often describe their output in candela, which is only meaningful if you are comparing lamps with the same beam angle. The efficiency of lamps is sometimes misleading because systems losses on elements like transformers, ballasts and drivers are often not included. These means that the electrical lighting system (see 3. below) may be much less efficient than the figures on the lamps alone would suggest.
2. Spectrum. The quantity of light is only part of the story, quality is also important. Quality in this instance means how well balanced is the light across the visible spectrum. One guide to this is something called CRI number (colour rendering index where daylight = 100). An example of the importance of CRI is a sodium streetlight, which is very efficient and produces a lot of light in lumens, but difficult to read by because the CRI of the light is so low. Higher colour quality lamps produce more useful light, but this is not reflected in their lumen output, so it only fair to compare the lumen outputs of lamps with a similar CRI. However it should be said that CRI does become relatively less important as it approaches 100 (Tungsten halogen and incandescent lamps have a CRI=100) and since there are very few CFL lamps with a CRI above 90, we must accept a threshold of around 80 for most useful comparisons. Many LEDs have not managed to reach this threshold yet.
3. System losses. This is the power lost in the electrical driver, ballast or transformer running the lamp. These are generally not quoted and are sometimes significant. Ballasts, transformers and drivers have inductive or capacitive characteristics that leads to reactive power on the overall lighting circuit. This means that more power has to be supplied to the circuit than actually consumed by the lamp. The true circuit requirement can be found by multiplying the volts (240v) by the current (amps) of the rated lamp. If you do this with a CFL you will find that the volt/amp (va) rating is much higher than that of the wattage, whereas with incandescent lighting it would be the same. This difference is called power factor. Unfortunately the circuitry of integrated CFL lamps ( the ones that fit standard bayonet and screw sockets) does not allow for good power factor correction. This can mean that homes will create lighting circuits with much higher power requirements than their wattage suggests. Electricity bills are in watts, but generators supply VA, so although domestic bills may be no higher, the cumulative effect on CO2 emissions can be significant.
4. Optical losses. These are light losses within the fitting that effects its capacity to fulfil its function. Light Output Ratio (LOR) is the percentage of light that actually leaves the fitting. CFL is a good lamp for fittings where light is required in all directions, but much less good as the angle of desired light output gets smaller. Halogen reflector lamps are by contrast very optically efficient for directional lighting, but less so when lighting in all directions. Halogen downlights are effective at spotlighting because they do not often have diffusers and the reflector pushes almost all the light from the fitting in the direction it is needed. Directional LEDs are also potentially similarly very efficient as their reflector and lens design improves.
5. Toxicity and waste. There are several common toxic elements used in lighting products, most notably mercury (Hg) and some phosphors in fluorescent lamps. There is a significant body of opinion that believes that the toxicity inherent within CFL waste makes them a questionable ecological option. Manufacturers are making efforts to reduce the mercury in lamps and improve their potential for recycling. However it is an issue if you are replacing lamps (incandescent/tungsten halogen) with no toxic content. The overall weight of waste over a given period is an issue of comparison. The extra weight of an individual CFL has to be compared with that of a higher number of halogens.
6. Embedded energy.This is the energy required to produce the lamp in the first place and ship it to its point of use. The extra weight and components of CFLs count against on the same basis as waste, but of course more halogens have to be shipped over the same period. Good information on embedded energy is very difficult to obtain and we would not hazard to make any judgement on this issue.

These are not the only issues of ecology in the debate on lighting and we will add more information as it becomes available.