Types of Light

Two key characteristics

All lamps create light but not all light is equal. Two key characteristics of light, colour rendering and illuminance, create unique effects for suitable for different applications.

• Colour rendering: a general expression for the appearance of surface colours when illuminated by light from a given source compared, consciously or unconsciously, with their appearance under light from some reference source. 'Good colour rendering’ implies similarity of appearance to that under an acceptable light source, such as daylight
• Illuminance: the amount of light that falls on a surface. It does not depend on the colour of the surface and is very easy to measure using a light meter (illuminance is measured in units of lux).

Light choices

There are many types of lamp in use in NZ business today – each with its own light quality and operating characteristics. Click on the list below for more details on the main choices.

• Incandescent lamps
• Low voltage halogens
• Mains voltage halogen
• Fluorescent lamps
• High intensity discharge (HID) lamps
• Metal halide lamps
• High-pressure sodium (HPS) lamps
• Mercury vapour lamps
• Light emitting diodes (LEDs)

Incandescent lamps

Incandescent bulbs have undergone few changes since they were invented back in the 19th century. They are gradually being replaced by newer technology lamps that emit the same amount of visible light using far less electrical energy.

Brief description

The traditional incandescent lamp may be cheap to purchase but is very poor at converting electricity into light. In fact only about 5% of the electricity used is converted into light (the rest is converted into heat). That's a huge waste of energy that costs you and our country money.

Traditional incandescents also don't last long – only about 1,000 hours compared to anything from 6,000 to 15,000 hours for an equivalent Compact Fluorescent.

Given these factors, they are not recommended for any office, industrial, retail, warehousing or educational application.

Low voltage halogens

In most cases, low voltage halogens are lamps integrated with a reflector. They are typically used in downlights or spotlights to produce a whiter light than that produced from mains voltage halogens.

Brief description

In most cases, low voltage halogens are lamps integrated with a reflector. Those without a reflector are typically known as ‘burner’ lamps. They are typically used in downlights or spotlights to produce a whiter light than that produced from mains voltage halogens. The filament is smaller too, making the light cleaner and crisper.

Low voltage halogens emit very precise light beams and come in a range of beam angles.

If you want to use one of these lamps, you'll need a transformer to convert the 240V main supply to a lower 12V AC. Most (but not all) transformers are dimmable.

Advantages

• Crisp, clean, full spectrum light in a focused beam in a range of beam angles
• Good 'sparkle' for retail applications.

Disadvantages

• Require separate low voltage transformer
• Can create a significant amount of heat (potentially increasing your air conditioning costs).

Energy efficient options

There are new low voltage halogen reflector lamps and bulbs that are designed with a special infra-red coating (IRC) on the bulb. These produce the equivalent or more light than a standard halogen and use 30% less electricity. This means you can use a more efficient 35W bulb everywhere you would normally use one that is 50W.

Recommendations

• If your business uses halogens for specific spotlighting applications, install a dimmer where appropriate and change to 30% more efficient IRC halogen spotlight lamps. These will last twice as long as the standard lamps
• If your business uses halogens for more general lighting, changing to an alternative form of lighting for improved space lighting and lower operating costs may be worth considering.

Mains voltage halogen

These are a poor substitute for low voltage halogens. If you must use them, do so only for task or spot lighting (and not general lighting). There are fluorescent replacement options but very few mains voltage energy efficient IRC (Infra Red Coated) bulbs are currently available.

Advantages

• Crisp, clean, full spectrum light in a focused beam
• No need for a transformer.

Disadvantages

• A longer filament than in 12V versions means shorter life
• Use more energy than IRC low voltage equivalent.

Ongoing development

More development is being undertaken on halogen lamps due to demand for its superior lighting characteristics. Low voltage halogens currently have an advantage over mains voltage halogens across most applications.

Fluorescent lamps

Linear Fluorescent Lamps, available in a range of colours to achieve a natural appearance, are the first choice for many business environments.

Brief description

Fluorescents lamps work differently from incandescents since light is produced by electricity flowing through a gas.

There are two main types - linear and compact.

All Linear and some Compact lamps require control gear for their operation. Household Compact Lamps (Energy-saver or CFL-i Lamps) have their control gear built into them and can be plugged directly into a suitable light socket.

Linear versions come in three 'whites': warm white (2700K), cool white (4000K), and cool daylight (6500K); Linear lamps are not currently able to be retrofitted into existing light fittings as they require control gear for their operation.

Integrated compact fluorescents (CFL-i) can be used in this way and they are a great replacement for incandescent and mercury vapour lamps – typically a 45W CFL can replace a 200W incandescent or an 80W mercury vapour lamp.

Advantages

• Fluorescents convert electricity up to eight times more efficiently than incandescents
• Long tubes evenly spread the light into the room so they are more suitable for lighting large open spaces like open plan offices or workshops
• High luminous efficacy
• Long life.

Disadvantages

• Unlike incandescents, some fluorescents - such as older units that have magnetic ballast - don't instantly switch on. This makes them less suitable for places where the lights will be switched on and off frequently. Fluorescents with electronic ballasts have a much shorter and more reliable start time
• Some fluorescent lamps' light output depends on ambient temperature, so be careful about the temperature of the application area.

Ongoing development

Manufacturers are working on improved lamp and gear packages that offer higher luminous efficacy, better lumen maintenance and overall higher efficiency.

You also have the choice of fully dimmable fluorescent high bay options, which have broad tolerance to input voltage and offer redundancy if one lamp fails (this latter type of lamp can be a good alternative to metal halide bays.

Retrofitting

It is possible to retrofit existing T12 and T8 fluorescent installations with T5 lamps in order to improve efficiencies. This is a relatively new technology and the process needs to be undertaken with care as some products may not work in all installations or not perform as expected and have other undesirable characteristics.

This level of conversion may also have implications with regard to any warranties that may apply to the existing fittings and associated new components.

High intensity discharge (HID) lamps

Brief description

With the exception of mercury vapour lamps, high intensity discharge lamps are amongst the most efficient light sources for commercial applications. Producing a large amount of light from a very small space, they have been designed to compact dimensions so that light can be easily and accurately directed.

These lamps operate on the basis of the arc discharge. There is a constant arc between two electrodes that causes the gas filling to give light. This principle can be used with different metals and filler materials, including metal halide lamps, mercury vapour, each filler type giving distinct characteristics to the type of lamp in terms of colour appearance, colour rendering and efficiency.

Disadvantages

The main limitation of discharge lamps is they usually take about 5 minutes to achieve full brightness. In most cases if the power is interrupted or they are switched off when hot they will take up to 15 minutes to give full light again. However there are options known as 'hot-restrike lamps' that avoid that situation.

Metal halide lamps

Brief description

Metal halide lamps are a compact, powerful and efficient light source. Originally used in industrial applications, they are now available in a range of shapes and sizes. Some even come with built-in reflectors.

New reflector-type metal halide lamps are available in similar sizes to low voltage halogen lamps – they typically last three times longer and consume 25% of the energy.

Advantages

• High light output from a small point source
• White light with generally good colour rendering ability depending on type
• Lamp output not temperature dependant.

Disadvantages

• Inability to give light instantly – so you can't flick them on/off repeatedly
• Prone to colour shifting over time
• Require special light fittings and are not a retrofit option for most applications.

Ongoing development

Manufacturers are working on even higher lumen packages thanks to new pulse start technology. Their goal is high lumen maintenance and colour rendering in the order of 90% (comparable to that of fluorescents).

 

High-pressure sodium (HPS) lamps

Brief description

High pressure sodium lamps are a compact, powerful and efficient light source. They are typically used in street lighting and industrial applications where reproduction or colour is not important.

Advantages

• High light output from a small point source
• Lamp output not temperature dependant.

Disadvantages

• Very low colour temperature and poor colour rendering
• Inability to give light instantly or hot-strike – so you can't flick them on/off repeatedly
• Require special light fittings
• Not a retrofit option for most applications except as upgrade for some mercury vapour lamps.

Ongoing development

Minimal due to poor lighting quality.

 

 

Mercury vapour lamps

Mercury vapour lamps are now considered 'old school' – significant gains in light quality can be achieved by replacing them with newer technologies.

They rarely burn out completely but suffer from lumen depreciation, producing 50% less light every five years (to the point of becoming ineffective despite drawing the same amount of power as new). Another sign of ageing is the increased warm-up time (which can take up to eight minutes).

 

 

 

 

 

Light emitting diodes (LEDs)

Brief description

LEDs are solid state semiconductors – they have no moving parts and no filament that can be broken. They are ideal as simple and efficient light sources for creating fascinating lighting effects and innovative lighting solutions but their successful adaptation to general lighting applications has yet to be demonstrated.

The only problem is their initial purchase price right now. Some LEDs are cheap – this is reflected in the low quality of the light they produce – whereas other LEDs are expensive but produce light of a very high quality. Because of this large variance, you should be wary of the quality and wide range of manufacturers that produce them.

Advantages

• Wide colour palette
• Excellent colour saturation
• Low power consumption and long life make them particularly economical
• Great for illuminating linear and even freeform structures
• Also suitable for backlighting surfaces.

Disadvantages

• LEDs need to dissipate lots of heat so they have big heat sinks on the back of them
• Variations in quality between brands
• Price is still an issue but reducing quickly
• Direct replacements for halogens are coming but reliability still currently an issue.

Ongoing development

The range of potential business LED lighting applications continues to grow. LED is fast becoming an equal alternative especially for spot and feature lighting applications. Street and car park LED solutions are now becoming popular.