Discover 8 easy ways to reduce your electricity costs
Did you know lighting consumes about 1/3 of the total electricity used by your building? If you lease a space and only pay directly for the 'tenant energy' then lighting is likely to account for at least half of your energy bills. Lighting also has a profound effect on the feeling of well-being and productivity of staff. So it makes sense to ensure your office lighting performs at its best and as energy efficiently as possible. Here's what you can do:
1. Turn off lights that aren't needed
2. Use daylight
3. Maintain the lighting system
4. Selectively reduce the number of lamps in over-lit areas
5. Use triphosphor fluorescent lamps
6. Install high-efficiency reflectors
7. Replace incandescent light fittings with fluorescent or efficient halogen options
8. Fit timers or occupancy detectors
Energy-saving measures 1 to 5 provide cost-effective savings in a large number of retrofit situations and should be the first to be carried out. Measures further down the list are cost effective only under certain conditions, so the costs and benefits should be carefully weighed before deciding to implement them.
When electricity prices rise, all retrofit opportunities become more cost-effective, but the order of effectiveness will stay the same.
1. Turn off lights that aren't needed
This is the easiest way to save energy. Frequent switching can reduce lamp life but it is more economical to switch off fluorescent lights that aren’t being used for at least 10 minutes (source: EECA). You can encourage people to switch off by:
- Making lighting switchable in zones of less than 100m². This is especially good in open plan offices where people work after hours – they can switch lighting on in their immediate work area only
- Setting up lighting to switch in rows parallel to your building’s windows, so you can manually control the artificial lighting relative to how much daylight is coming through
- Using automatic sensors that detect movement (or lack of) – these are particularly good when there is no specific ‘ownership’ of the space (eg. conference rooms, staff rooms).
2. Use daylight
Studies have shown that workplaces with high daylight levels typically enjoy greater levels of employee job satisfaction, leading to higher productivity and greater task accuracy. It is also free so it pays to maximise its use.
- Place desks near windows so people can use daylight, but make sure they are not dazzled or distracted by direct sunlight through windows or reflections on the screen. Ideally, light for manual tasks should come from the 'non-writing' side of the desk
- Arrange switching so people who use daylight can switch off the lighting near their workstation
- Make the most of high level windows and skylights that are common in industrial facilities. Keeping windows clean and unobstructed is also important if utilising natural lighting.
- Consider automatic daylight reactive dimming control that precisely controls how much light is received on the work surface.
3. Maintain the lighting system
As lighting systems age, the light levels on desks and other working surfaces can drop by over 50%. Loss of output from lamp, and dirt on the reflecting and diffusing surfaces of the light fitting can be offset by:
- Bulk-replacing the lamps and cleaning the fittings – huge labour cost savings can be made as this is typically the biggest cost component when changing lamps
- Cleaning or repainting room surfaces. Light colours on walls and ceilings will raise illumination levels substantially.
In older installations, yellowed diffusers may drastically reduce light levels and should be replaced. Fittings installed in the 60s and 70s may contain toxic chemicals called PCBs. As it is no longer legal to use equipment containing PCBs, checks of older installations should be performed by an electrical contractor, and PCB containing equipment replaced.
4. Remove unnecessary lamps
Energy savings of 5%-15% can often be made by selectively removing lamps from areas such as passageways that have more lighting than they need (often the result of office rearrangement); as well as other areas where a design provides too many fittings and lamps. A light meter can be used to check that light levels are adequate. It is advisable to mark empty holders to avoid accidental re-lamping by maintenance personnel.
5. Use new generation triphosphor fluorescent lamps
When lamps are bulk-replaced during periodic maintenance, use new generation triphosphor lamps. You'll get higher light output for the same power consumption and lower rate of light loss as they age. Their improved colour rendering considerably improves the visual quality of working spaces. Also, the number of lamps can be adjusted during the bulk re-lamp to optimise light levels and uniformity (a light meter is required to do this correctly).
6. Install high-efficiency reflectors
One of the most common light fittings used in commercial offices is the recessed "troffer" with a prismatic diffuser covering the lamps. Light is lost inside the fitting because of the box shape plus the fact the white paint does not reflect light efficiently. To address this issue, try specially shaped reflectors of silver or aluminium that can be custom-made and fitted behind the lamps. They improve the efficiency of the fitting by up to 40% and can allow further energy savings as fewer lamps are required. In older offices with poor lighting, light levels can be brought up to standard with no extra expenditure of energy.
7. Replace incandescent with fluorescent
This is cost effective because:
- Low-voltage and mains voltage tungsten halogen lamps use about four times the energy of fluorescent lamps to produce the same amount of light
- Fluorescent lamps last four times as long as tungsten halogen lamps
- Tungsten halogen lamps are intended for display and flood-lighting, but are often misused as a source of general lighting. A range of compact fluorescent fittings is available to replace tungsten halogen fittings.
8. Fit timers or occupancy detectors
Timers that switch lights off after a preset period are a good idea in large areas where no one is responsible for turning off the lights. They can also be useful in isolated areas used for short periods, like stack rooms. Some timers give a warning before switching the lights off, and can be reset if light is still needed. Occupancy detectors are another option in large areas where lights are left on by mistake. These turn lights off if no movement is detected for around 15 minutes, turning them on again when anyone enters the space.