A lux meter is a powerful tool you can use to identify significant energy savings. Use your lux meter to pinpoint over-lit areas in your office, then delamp to reduce energy use.
Using the lux meter Measure lux levels at four to five different points in each room either at night (if the room is used at night), or at around one to two hours after sunrise or before sunset. If delamping in summer remember that in winter night time comes much faster and the sun is much lower. Measure lux levels at a time that corresponds roughly to the earliest or latest the room is to be used in the middle of winter. Measure light levels at table or waist height. Minimum recommended light levels in the horizontal plane are shown in the table below for various areas, from AS 1680:1990: Interior Lighting. | Circulation and amenity areas |
| | Toilets, change rooms, locker rooms, cleaners rooms | 80 | | Corridors, passaways, ramps | 40 | | Stairs | Internal: 80 External: 20 | | Entrance halls, lobbies, foyers | 160 | | Waiting rooms | 160 | | Enquiry desks | 320 | | Other |
| | First aid | Rest rooms: 40 Treatment rooms: 400 | | Cafeterias | General: 160 Counters: 240 | | Kitchens | General: 160 Food preparation: 240 | | Administration areas |
| | Filing areas | Simple, clear detail: 240
Difficult, fine detail: 320 | | Office | General tasks involving typing, reading, writing: 320 Background:160 | | Meeting rooms | 320 | | Training rooms, seminar rooms | 240 | | Photocopying | 240 | Beware: light is multidimensional.
When delamping remember the light is multidimensional, but with your lux meter you are only measuring light at one level, horizontally. Reflections, glare, shadows, areas of bright contrasts can make visual tasks difficult. The amount of light in the vertical plane is also important for some tasks. The colour and brightness of surfaces, particularly walls, ceilings and floors, also influence light levels and light uniformity. Generally clean white walls and ceilings make visual tasks easier. Taking delamping too far can lead to a workplace which is gloomy and depressing, especially if the ceiling and walls are darker colours or in need of paint. Some small very bright spots on walls or ceilings can cheer up an otherwise gloomy environment. Consult a lighting professional if in doubt. How to delamp Delamping of fluorescent fittings achieved most easily by removing the starter. Removing the tube, and putting a sticker in its place indicating that it has been deliberately removed and is not to be replaced, will make the change more permanent. One tube can be removed in double fluorescent fittings. If it seems too dull replace the remaining tube with a brighter triphosphor tube that uses no more energy, or even brighter quadphosphor tube. You can fit a reflector onto the remaining tube to increase light levels even more. In triple fittings you have the choice of removing one or two tubes. It may be possible to remove two tubes and put in a single quadphosphor tube with reflector, reducing your energy use by nearly two thirds. Check that the lamp relights properly after delamping. This is unlikely to be a problem with individual ballasts or a single ballast supplying two lamps operating in parallel, but will cause problems if lamps are in series on the one ballast.
Fluorescent lamps contain mercury, a highly toxic substance that remains in the food chain and environment. All lamps which are removed must have their mercury reclaimed in a mercury recycling centre. Insist that your contractor provides evidence that removed lamps have been received at a mercury reclaim centre. Bruce Rowse, Energy Doctor Pty Ltd. www.energydoctor.com.au
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