Centre for Energy™

Lighting and Auxiliary Equipment

Lighting

Lighting consumes 10.5 per cent of the energy used in the Commercial and Institutional sector, and electricity powers all but a small fraction of that. Currently, the most common type of electric light is the incandescent bulb, followed by fluorescent tubes. Use of compact fluorescent bulbs is increasing primarily because they are much cheaper to operate and last much longer, although they cost more.

The reason for this is how each type of bulb creates light. Incandescent bulbs, which have remained largely unchanged since they were perfected by Edison in 1879, use electricity to heat a filament and create light. Fluorescent bulbs use electricity to excite a gas and create light. The problem with incandescent bulbs is that about 90 per cent of the energy used is given off as heat and 10 per cent as light.

In fact the growing concern over energy conservation has prompted some jurisdictions to ban incandescent bulbs completely by 2010.
There are, however, many types of light bulbs. The advantages and disadvantages of each are summarized in the following table.

Advantages	Disadvantages
Incandescent bulbs
Low initial cost Convenience and ease of replacement Small physical size Ease of light distribution control Instant start and restart time Available from 25 - 500 Watts and in many decorative shapes and colours Excellent colour rendition	Low efficiency (low light output per Watt) Comparatively short lamp life (rated life is 1,000 hours)
Energy-saving incandescent bulbs
Identical to incandescent bulbs but come in 34, 52, 90 and 135 Watts, to replace standard 40, 60, 100 and 150 Watt bulbs Energy savings due to lower power requirements	Not quite as intense as regular incandescent counterpart
Halogen bulbs
Light output is similar to that of regular incandescents Use up to 40 per cent less energy because of their quartz crystal and non-toxic halogen gas components Last up to twice as long as regular incandescents	Much hotter than regular incandescent bulbs Gas under pressure may cause soft glass bulbs to break
Fluorescent tubes
Available from 7 to 215 Watts Better efficacy (three to four times that of incandescent equivalent) Low lamp cost Wide range of colour output available Instant start Long life (typically 20 times that of a typical incandescent bulb)	Most designed for office environment so the lamp holders and bases may deteriorate in a high humidity environment with measurable ammonia levels; sealed fixtures are more suited to a barn environment Cold start ballasts are needed for many farm applications Colour rendering varies from fair to good More difficult to change lamps Cannot be dimmed without special equipment
Compact fluorescent bulbs
Low wattage and good efficacy, approximately four times that of a comparable incandescent bulb Long lamp life (rated life is 10,000 hours) Fit into incandescent sockets as direct replacements or with adapters Available from 5 to 150 Watts Start at temperatures down to -18° C (0° F) Sealed fixtures to prevent the entry of moisture, dust and gasses are available; the SL 18 is the only sealed model currently available	Relatively high initial cost compared to incandescent lamps May be larger physically than incandescent lamps they replace; check clearance for installation May not start below -18° C (0°F) Cannot be used in conventional dimmer switch Contain mercury
Mercury vapour lamps
Extremely long lamp life (rated at 24, 000 hours)	Less efficient than fluorescent, metal halide, high- or low-pressure sodium lamps Slow start up time: five to seven minutes until full light Colour rendering is poor for both clear and phosphor-coated lamps
Metal halide lamps
Extremely long lamp life (rated at 24, 000 hours) Sizes range from 32 to 1,500 Watts Most efficient source of "white" light available; more efficient than mercury vapour or fluorescent Good colour rendering	Warm up time is about five minutes and restart time about 15 minutes Less efficient than high- or low-pressure sodium lamps Most MH lamps can only be used in the prescribed position (i.e. horizontal burning lamps can only be mounted horizontally, vertical lamps must be mounted vertically); some universal lamps can be used in either direction
High-pressure sodium lamps
Lamp size ranges from 35 to 1,000 Watts Warm up time is three to four minutes with restart time about one minute Long lamp life (rated at 24,000 hours) Most efficient source of "golden-white" light; more efficient than MH lamps	Colour rendition is poor to good Improved colour rendering lamps have shorter lamp lives and poorer luminous efficiencies Less efficient than low-pressure sodium lamps
Low-pressure sodium lamps
Lamp sizes range from 18 to 180 Watts Long lamp life (rated at 14,000 - 18,000 hours) The highest efficacy of all light sources	Poor colour rendition - everything appears yellow or muddy
Light Emitting Diode or LED Lamps
Longest lamp life (50,000 hours) Very efficient, approximately 2 Watts to produce 100 lumens Low heat production Do not contain mercury Small size Very durable	Still somewhat expensive, although prices are decreasing