There has been a change in focus as to which bulbs are best for household use due to developments in lighting technology.  As CFL and LED type bulbs are much more energy efficient in comparison to halogen type bulbs it is a better choice to convert to these if possible to save money on energy costs and to reduce energy use.  It is helpful to understand the differences between these technologies in order to make the best choice for which light bulb to use.

Energy Efficiency and Luminous Efficacy

Energy efficiency is a major factor in choosing between these bulbs.  Lumens are the way the amount of light emitted by a bulb is measured and this can be used across all technology types.  Below is a table that compares the average amount of lumens used per watt for each type of technology:

Energy Saving Halogen bulbs are an improved version of the older style incandescent bulbs and standard halogen bulbs. They contain a small amount of halogen gas and this helps redeposit tungsten atoms back onto the filament.  This when compared to standard halogen bulbs extends the bulb's life and allows it to operate at a higher temperature for a slightly better energy efficiency.  They typically use 25-30% less energy than a traditional incandescent, but still consume 2 to 4 times more energy than a comparable CFL or LED bulb.

CFLs use electricity to excite mercury vapour, which then produces ultraviolet (UV) light. This UV light then stimulates a phosphor coating on the inside of the glass tube, causing it to emit visible light that is safe for everyday use. They use a lower amount of watts to produce the same amount of lumens when compared to halogen and energy saving halogen bulbs.

LEDs are the most modern and currently available highest standard of lighting technology especially for energy efficiency. They produce light via electroluminescence.  This is where an electric current passes through a semiconductor diode. They are able to produce a far greater percentage of electricity into light and a minimal amount into heat compared to their older counterparts.

Are LED bulbs more energy efficient than CFL bulbs?

Yes, it is very rare to find a CFL bulb that will be more energy efficient than a LED version.  CFL lamps have presented a great leap in energy saving technology but LED lamps have surpassed these as well often offering 20-50% better luminous efficacy.  LED bulbs will use less power (fewer watts) to produce the same amount of light (same lumens) as a comparable CFL.   LED lights instantly turn on at full brightness and are not as affected on/off cycling (being switched on/off).  

Light Quality and Aesthetics

Light quality is an important factor when choosing a light:

• Halogen bulbs are known for their high-quality light.  They provide a warm, crisp white light with a high CRI often measuring around 100. This has been found to be an aesthetically pleasing light that is useful for tasks requiring accurate colour perception.
• CFLs once had a reputation for poor light quality in their earlier days as they produced a “cool” or “harsh” colour compared to halogen and incandescent lights.  Modern CFLs however are available in a wider variety of colour temperatures and have a quicker warm time than when they were first produced.  Their CRI however is often lower than halogen or LED bulbs. 
• LEDs are available in a vast range of colour temperatures, ranging from very warm white to daylight.  High-quality LEDs can also achieve a CRI comparable to halogen bulbs, making them suitable for virtually any application.

Lifespan and Cost

LEDs easily come on top in terms of lifespan which leads to them needing to be replaced less often.  Whilst they may have the highest initial purchase price, this is a long term investment as due to their longevity and low energy consumption they will have a much lower cost over time. CFLs have a mid-range price and a good lifespan, but this still falls short when compared to LEDs. Halogen bulbs are cheaper to buy at first but they have a short life and high running costs due to the amount of wattage needed to produce the same amount of light.

What are the disadvantages of halogen light bulbs?

Despite the high CRI of these bulbs and their lower initial cost, halogen bulbs come with several significant drawbacks compared to CFL and LED bulbs:

1. Low Energy Efficiency: They consume considerably more energy than both CFLs and LEDs as they require more wattage to produce the same amount of light which leads to higher electricity bills.
2. Short Lifespan: The average lifespan of a halogen bulb is typically under 3,000 hours meaning that they require frequent replacement compared to the tens of thousands of hours offered by LEDs and CFLs.
3. Heat Output: Halogen bulbs operate at very high temperatures as a lot of the energy they use produces heat. This can be a potential fire hazard if the bulbs are placed near flammable materials or do not have a lot of space around them to dissipate the heat.
4. Sensitivity to Oils: The quartz glass envelope of the bulb is highly sensitive.  If you touch the bulb with bare hands the oil from your hands can potentially weaken the glass and cause it to shatter when the bulb reaches its operating temperature.
5. Environmental Impact: While they do not contain mercury like CFLs lamps do, their shorter lifespan means they need to be replaced more often leading to a larger amount of bulbs needing to be disposed of. 

In summary, LED bulbs stand out as the better choice for the majority of lighting requirements.  Energy saving halogen bulbs do offer a small improvement compared to incandescent light and CFLs more so than halogen but as described above LEDs stand head and shoulders above them due to the variety of LED light options available and their high energy efficiency.