Sustainable lighting can be described as minimising energy consumption and carbon emissions while still maintaining suitable illumination on an economically satisfactory basis. The optimum lighting levels vary for different activities as outlined by the Australian Standards in Table 1. Sustainable lighting programs implemented should achieve these recommended illuminance levels for the different tasks. The following items need to be assessed when considering a sustainable lighting program:
1. Lighting Technology
Energy efficient lighting technologies like fluorescent lamps can help lower greenhouse gas emissions and also significantly lower the running costs. Outlined below are the different types of lights and light fittings based on the information presented in the Tenant Energy Management Handbook and the Australian Greenhouse Office website.
+ Useful life 130000 -16000 hours
+ High energy efficiency
+ Commonly Used: T5 and T8
- Tubes are cheaper than CFL’s but require special light fittings
Compact Fluorescent lamps (CFLs):
+ Useful life: 8000 hours
+ High energy efficiency
+ Can be dimmed to 10% of their lighting output
- Expensive to buy compared to the incandescent and halogen bulbs but their long life makes them more efficient than the other two
+ Useful life: 2000 hours
+ More efficient compared to incandescent bulbs
- Slightly more expensive than incandescent bulbs
- Require special light fittings
+ Inexpensive to buy
- Useful life: only 1000 hrs
- Least energy efficient: Convert about 95% of the electrical energy used into heat.
- Federal government has announced the phase out inefficient light bulbs by 2010
Replace incandescent bulbs with more efficient alternatives
Use halogen lamps in places of infrequent and short period of use
Use fluorescent lamps and tubes in high usage areas such as workplace stations
Ballasts are devices used to start and control the voltage in fluorescent lamps. Some CFLs have ballasts built into them while others come with a separate tube and ballast. Electronic ballasts are more efficient compared to magnetic ones and should be used for frequent use lamps.
Reflectors help redirect light to the targeted areas and ensure maximum utilisation of the light emitted by the lamps. Specular mirror reflectors are more efficient than the standard flat white reflectors. These reflectors are especially efficient when used in retrofits along with T5 tubes and electronic ballasts in cutting energy costs by up to 50%. These reflectors are available as adhesive films and metal fittings.