Lighting can consume up to 40% of energy in commercial premises, depending on the nature of the business and type of lighting used. Street and public lighting is the single largest source of carbon emissions for local governments.
The biggest impacts on electric lighting requirements and design come from the architectural orientation, massing, ceiling height, and section profiles that determine daylight availability in a building.
Lighting designers should be involved early in the design process of new buildings or retrofits. A good energy efficient lighting strategy relies on an integrated approach.
Existing lighting systems
Many lighting efficiency opportunities can be easily implemented with little or no capital investment or need to redesign a lighting system. These include turning lights off manually or automatically when not needed, or removing excess lamps from over-lit areas.
There are excellent opportunities for energy saving whenever upgrades or refurbishments are planned. Options for upgrading energy-efficient lighting can be applied to all types of commercial, industrial and service facilities, and may include replacing light fittings and lamps, optimising lighting layout, and adding more circuits and switches for greater control and automation.
Old-style incandescent (including halogen) bulbs are highly inefficient, burning most of the energy they use as wasted heat. This also makes them a fire risk.
Light emitting diodes (LEDs) use up to 75% less energy and emit 90% less CO2 than the old halogens. They also last up to 25 times as long, which greatly reduces the need for changing or maintenance. This is especially useful where fittings are difficult to access.
LEDs also generate less heat than halogens meaning the load on air conditioning is reduced.
LEDs emit 50% less CO2 than compact fluorescent lights (CFLs) and, unlike CFLs, don't contain toxic mercury.
Quality of LEDs can vary, however, so look for reputable name-brand products.
Many cities and towns across Australia and the world have upgraded their public lighting to LED (or are planning to) in recent years. Switching to LED streetlights can reduce energy consumption by up to 50% across a metropolitan area. Adding smart remote management into the mix can increase that to 80% for certain applications.
Good lighting design includes consideration of daylighting, the admission of natural light.
Window design must strike a balance between the admission of daylight and not allowing harsh, direct sunlight into the eyes of workers or reflected glare from surfaces.
Heat levels from direct sun also need to be controlled. Curtains and shades should always be used in conjunction with daylighting strategies.
A daylight-optimised building footprint is essential for new building designs. For many buildings, there are several effective measures to maximise natural lighting indoors:
- daylight-optimised interior design, incorporating furniture, space planning, surface colour and texture
- daylight redirection devices
- daylight-responsive electric lighting control
- high-performance glazing.
Innovations are bringing down the costs of high-tech windows, such as low emissivity (‘low-e’) glass opening up daylighting options while minimising glare and heat gain in commercial buildings.
Lighting controls and sensors
An occupancy sensor (a type of motion sensor) detects when a room or area is occupied and when it becomes vacant. Lighting is adjusted accordingly. This offers hands-free convenience and substantial energy-saving. Occupancy sensors are ideal for meeting rooms, storage and print rooms, and bathroom facilities.
Outdoor motion-activated lights illuminate an area when people approach or enter it, such as a carpark or building entrances. Along with the energy benefits, motion-activated lights provide convenience, safety and added security.
Timer controls do not respond to changes in occupancy but are instead pre-set based on the expected use of rooms. This is useful when room occupancy times are consistent and predictable.
Lighting timers can be manually operated or automated. Manual timers are plug-in units that are adjusted to set lighting times. Automated timers are generally in-wall programmable digital units that can be integrated with a building management system (BMS).
Electrodeless induction lamp and LEDs
The induction lamp’s main advantages are long life, ease of replacement and low maintenance. These lamps have mostly been applied where high lamp replacement is difficult and expensive.
The efficiency of induction lamps range from about 56lm/W to 80lm/W. This is less impressive than some LEDs (90lm/W or more) which are also claiming equivalent lamp life and lower long-term capital costs. As LEDs further improve in power output and live up to the predictions of lamp life, they can be expected to compete increasingly successfully with induction lamps.
Simulations and new building materials
Computer simulation helps designers provide daylighting without needing direct sunlight. New glazing materials admit light while blocking infrared and ultraviolet light. Double-glazed windows admit light while halving heat conduction, and various low emissivity coated glass can also help to manage radiant heat gain.
Other innovations include light pipes, panels that reflect light onto ceilings, and aerogel panels that insulate whilst letting in daylight.
Smart pole street lighting
LED smart poles are already in use in many cities around the world. The poles are operated via a centralised online hub to remotely control and monitor street lighting and other services. Automated sensors detect ambient local conditions, such as visibility, traffic and weather. The poles integrate with the Internet of Things (IoT) cyberscape.
Smart light poles are ideal for installation at university campuses, housing complexes and industrial estates.
See the Lighting Manufacturer website for more information on smart light poles.
Disposal of mercury-containing lamps Australian Government
Energyrating.gov.au Australian Government
Energy Efficient Lighting Guide NSW Government