Energy Efficient Lighting

Latest OSRAM Study

A recent Osram study shows that LED lamps are more energy-efficient than light bulbs even when the energy used during the manufacturing process is factored into the equation. The report, "Life Cycle Assessment of Illuminants", shows that over the entire life cycle of an incandescent bulb from manufacturing to disposal, the energy it uses is almost five times that used for compact fluorescent lamps (CFLs) and LED lamps. Another key finding reveals that CFL and LED lamps use less than 670 kWh of energy during their entire life compared to about 3,302 kWh for incandescent lamps, which translates into an 80 percent energy savings.

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Energy Efficiency Best Practice Guide: Lighting

Lights have been transformed again and again from the days of tallow candles and whale-oil lamps. The humble domestic light bulb is now coming under serious pressure as technological advances increasingly push it into the background.

Many opportunities exist, which did not exist a decade or so ago, for saving energy and money through improvement to both the way lights are used and the type of lights you use.

For a typical office building, lighting might typically account for 50% of electricity consumption. In manufacturing, warehousing and industrial situations, the costs are still large, and so are the potential savings.

Investment in more efficient lighting can have a very quick payback time - usually between one and three years, often sooner.

This fact sheet will take you through the process of identifying the light levels and types of installations you need, and how to get the best out of your system.

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Choice of lights

The type of lighting you choose will affect the amount of energy used, and therefore the size of your lighting bill.

Incandescent lamps

The light bulb is a bit like the T-Model Ford, you can have them in any colour, but why would you want to? Light bulbs are cheap, which is good. They are also very inefficient, which is bad. Wasted heat energy is a huge, costly and unwanted by-product. They have a short life span (about 800-1,000 hours) and therefore require a lot of maintenance.

Fluorescent tubes

Fluorescent lamps are very efficient for areas where lighting is required for long periods of time. They have a life of between 8,000-16,000 hours. Their extended life makes sense where maintenance and replacement are difficult.

They are between two and ten times the price of a light bulb, for about ten times the life. In terms of energy, fluourescents use about 70% less electricity than incandescent lamps of similar output.

The most efficient tubes have a "triphosphor" coating and will produce about 15% more light for the same electrical energy as a standard tube. They also have a longer life than normal fluorescent tubes. Market penetration has brought the cost down – if bought in bulk, you will pay something around $3 a unit for a box of 100.

Compact fluorescent lamps

Compacts have all the energy saving benefits of standard fluorescent tubes, plus they have a bayonet fitting so they can be used to replace incandescent lamps. Their extended life makes sense where maintenance and replacement are difficult.

High Intensity Discharge lamps

Sodium lamps are high intensity discharge lamps, which are useful in exterior situations such a car parks and loading yards, or internally where factory ceilings are high.

They combine the benefits of high output and efficiency, but have a yellowish color which some people dislike. In some cases they may need to be augmented by fluorescent tubes at workstations where good task lighting is needed.

Mercury high discharge lamps are widely used in warehouses, factories and gymnasiums with high ceilings. They have a low initial cost, but poor efficiency overall. In addition, they create significant disposal problems as a result of their use of the heavy metal mercury.

In most situations, mercury lamps can be replaced by metal halide lamps with much improved efficiency.

Extra low voltage (12v)

Beloved of interior designers, these fixtures use small, high temperature halogen lamps fitted into a reflector the size of a jam lid. They are becoming popular in a variety of situations, but require a transformer and heavier wiring than normal installations.

ELV lighting is slightly more efficient than incandescent globes, but does not hold a candle to fluorescents in terms of energy efficiency. Short life, low efficiency and high lamp costs give high total ownership costs.

Note: They are low voltage but not low energy users.

Electrodeless Lamps

In contrast to conventional fluorescent lamps, the electrodeless lamp generates light without electrodes in a closed "ring" with no starting point and no end point. The energy is "injected" via ferrite rings from outside using magnetic fields. (Induction principle).

The lamp therefore has no points that can wear out and last longer than conventional lamps. Some of the main characteristics include

• Long lamp life of 60,000 hours.(Four times the normal service life of conventional fluorescent lamp)
• High luminous efficacy of 80 luminous/watt
• Instant flicker free start
• Excellent quality of light and high luminous flux

Lighting levels

In any office, factory or installation, the level of light required in any business will be determined by what tasks need to be performed in a given area.

Offices may need to be well lit for eight hours a day, meeting rooms for only one or two hours a day. Corridors do not require the same level of light as do work benches where small parts are assembled. Interior parts of a large building require more artificial light than those areas close to windows.

Light levels can be measured with a small meter in units called lux.

Lighting controls

It is always cheaper to turn lights off than to leave them on. Do not fall for that old urban myth. Lights that are left on in empty rooms, or when daylight is available to do the job are costing you money.

Light controls can help reduce the dependence on people to switch lights off. There are a range of technologies available to give you greater control over energy usage:

Key lock switches

Switches requiring a key can replace the standard switch in areas rarely in need of lighting during the day. This enables the switch to be used only by authorised staff.

Time switches

These control the amount of time that lights are switched on. There are a couple of types available:

• Push-button or time delay switches that provide a pre-set time period of light (from 10 seconds to 30 hours) after they are switched on. Approximate cost $20-80 plus labour.
• Lighting controllers provide centralised, remote and local control of electrical loads by switching the power on and off. Seven day, time-of-day scheduling, holiday scheduling and manual override can all be programmed into the system. Approximate cost >$3000.

Voltage reduction technology

Equipment is available that can be wired into the lighting power supply in order to reduce the voltage applied to all lights. The reduced voltage leads to less power consumption and an overall reduced light output. These devices may be appropriate where areas are uniformly overlit and delamping is considered inappropriate.

Occupancy Sensors

There are several available sorts. Their prime purpose is to automatically switch lights on or off by detecting either existing light levels or the movement of people.

The approximate cost will vary but for, say, a room of 100m2 you could expect to pay $150-200. Three types of sensor can detect room occupancy:

• passive infra-red sensing - used for small areas with infrequent occupancy. Useful for security (low sensitivity);
• ultrasonic sensing - useful for office areas (medium sensitivity);
• microwave sensing - used for large internal areas or external areas with infrequent occupancy (high sensitivity).

Occupancy sensors should not be used in areas where unexpected switching off could cause safety problems. Also, rooms used at night should not be left totally dark if automatic controls switch off lights. Minimal lighting should still be available.

Energy Smart Lighting Strategies

The basic rules are:

• maximise the use of natural daylight;
• do not over-light non-critical areas;
• use energy efficient lamps and control technology;
• do not light unoccupied areas.

Delamping

Delamping is a simple and effective method of reducing your lighting costs in overlit areas. It involves removing one or more fluorescent tubes from your existing fluorescent fittings.

When delamping ensure that lighting remains uniform throughout rooms or work areas. In triple tube fittings, remove the center tube. Lighting levels should be measured at the place where work is performed and should not include ambient daylight.

Each 36 watt fluorescent tube removed will save about $8-9 a year, based on usage of approximately 40 hours a week.

Savings can be calculated for delamping by the following equation:

Annual savings ($) = (N x P x H x T)/1000 (plus the cost of ongoing replacement of removed tubes)

Where: N= number of lamps removed

P= power rating of lamps

H= number of hours of usage per year

T= electricity charge per kWh (tariff)

Rewiring

In many situations, rewiring may be too expensive for the direct cost savings available. However, it can be very cost effective to take advantage of the opportunities presented when other building or wiring work is being conducted. Rewiring means improving switching arrangements to maximise energy efficiency and saving. Lights near windows should be rewired to switch independently from the dim areas within a room. Switches can be rewired to take account of the usage patterns of work areas, particularly if you have shifts, or groups of people who start work early, or stay back after hours.

Typically, a multi-gang switch plate by the entrance of an area such as an office building results in every light on the floor being switched on. The entrance switch could be rewired to provide background lighting only, with local switches located throughout the area so that people need only turn on the lights they are using.

A D-I-Y Lighting Audit

We’ve talked about types of lighting, what level of lighting is necessary for different activities, and various improvement strategies. Now you are ready to do a walk-through audit of your own workplace.

Examine your lighting needs as you take a walk around your place of business. You have in your hand a lux meter purchased from a nearby electronics shop and a pad and pencil.

Make a rough sketch of each work area. Mark the position of light installations and note their type.

In office areas ask yourself the following questions:

• Are light fittings clean? Removing or replacing inefficient or degraded diffusers and reflectors can double light output in some cases.
• Can you remove lights or tubes in areas where less light is needed, such as near windows, circulation areas, above shelving, etc?
• Can you replace older type fluorescent tubes with more efficient triphosphor tubes?
• Would you consider selecting lighter colours and avoiding matt or heavily textured finishes when specifying colours for repainting - it has a big impact?
• Can you install daylight and/or movement sensors to control unwanted light use? Sensors are the most efficient means of providing adequate light when it is needed, without effort on the part of the occupants.
• Can timers be installed? Push button timers are the most common.

In warehouse or factory areas ask yourself:

• Are you making the most of natural light? Can you install skylights where possible (shaded and sealed in summer), so that lights can be switched off?
• Can lights be turned off after work?
• Are you (unnecessarily) using low voltage spot lights?
• How prevalent is the use of inefficient incandescent light globes?
• Are lights left on in unoccupied rooms?
• Does corridor or reception lighting need to be as bright as office lighting?
• Does the lighting near the windows need to be the same as in the centre of the room?
• In the carpark can you install daylight and/or movement sensors to control unwanted use?

Disclaimer

The information in this document is derived from various sources and is understood to be correct at the time of publication. However, the information may not be error free and may not be appropriate for a particular purpose. GreenBizCheck accepts no liability whatsoever to any person for any injury, loss or damage that may arise in connection with any use or reliance on the information.