Traffic lights consist of a number of small lamps and in Christchurch there are about 240 controlled intersections. At each intersection, there are between 32 and 42 lamps, averaging at about 34 lamps, half of which will be on at any time. We can calculate the energy used, as follows:
No. intersections X No. lamps used X kilowatt rating of lamps = total watts
thus:
240 intersections X 34 lamps/2 X 67 watts = 273,360 watts
Or, more commonly referred to as: 273.36 kilowatts. This is the power required by the traffic lights. As the traffic lights are continuously operational, this is an annual energy requirement of approximately 2,395,000 kilowatt hours.
Council decided that reducing this load would be immediately beneficial and easy to implement so all the 67 watt incandescent lamps were changed to 35 watt quartz halogen lights.
This saved 142 800 watts or 1,144,000kilowatt hoursa year.
Further advances in technology have introduced light-emitting diode (LED) lighting, so Council may reduce the energy load even further as these lights require onlyfive watts of electricity. New intersections are supplied with LED lamps upon commissioning and, as the old lamps are replaced, the number of LED lights will slowly increase.
The benefits of the project
- A reduction in electricity use of 1,144,000 kilowatt hoursa year.
- Reduction in Council costs.
- Longer life of lamps resulting in decreased maintenance costs.
- Relatively small implementation costs.
Things to consider for your business or home
- Can I change some of the lighting installed, particularly in high or utilitarian use areas to lower wattage lamps?
- Are there lights that are difficult to change that could benefit from the new longer lasting lamps, even if those lights aren't often used?
- Do I have lighting that would be particularly suited to LED lamps, such as high definition lighting or architectural lighting?
- Do I have solar powered lighting that would operate for longer using the lower wattage lights?
