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The right light level

Wondering if you have too little lighting? Many NZ offices are more likely to have too much.

AimOffice - right amount of light for 320 lux

Many offices are over-lit because the level is set for the entire room. Circulation areas need only half the light of work areas. There are significant savings to be made in designing the lighting to work more closely with the desk layout.

Most small and open plan offices only need to be lit to 320 lux over the entire floor area, work that involves finer levels of detail may require more lighting.

Invest in a lux meter

To measure the light in your business you'll need a good quality lux meter, which you can buy for less than $60 (if you have a safety officer, he or she may already have this device).

You should measure lux levels at four to five different points in each space, usually one to two hours after sunrise or before sunset. If the space is mostly used at night, do the test at night. Likewise, if it is mostly used during the day, do the test in the daytime.

In these areas... ...aim for this level of lighting*.
Office space
Entrance foyers and reception areas
320 lux
Filing and storage rooms, walkways in open
plan areas, seminar rooms
240 lux
Live storage fine material 160 lux
Passageways and toilet blocks
Live storage bulky items
80 lux

* These levels are minimum averages, with a time allowance built in to compensate for lamp outputs dropping over time and dust accumulating on fittings.

Manage reflectance

ReflectanceReflectance is the amount of light that bounces back off a surface (eg. wall or ceiling).

A lighter coloured room with a 90/70/20% reflectance ratio (ceiling/walls/floor respectively) requires 70% less energy to create the equivalent illuminance of a room with a ratio of (70/40/20%). Compare these figures with the absolute minimum reflectance recommended by the New Zealand Green Building Council (65% ceiling and 40% wall reflectance).

Lighter-coloured rooms provide better daylight distribution and improve brightness ratios, thereby creating spaces that are more visually comfortable. These significant improvements are possible at little or no additional cost - rooms need to be repainted every few years so why not try lighter tones to brighten your space?

Cellular office

In a small office it should be possible to vary the lighting level to suit the task at hand and the amount of daylight entering the space. Typical reading and writing work in such an environment requires lighting to 320 lux.

Switching or control systems should be configured so that staff can adapt the lighting levels as necessary. An occupancy detector can also be used to switch off lighting when no one is in a room.

Large open plan office

Open plan officeIn this type of space, you need to take into account the needs of a broad range of people and task requirements: there are workplaces, conference and meeting spaces, material storage and circulation spaces.

Try to limit glare from light fittings, windows and other bright surfaces from any viewing angle. This is easier said than done in offices where desk locations can't be moved around easily. To maximise the efficiency of the lighting system, its design and implementation should be carried out as part of an integrated fit-out, where lights are designed with desk location and orientation in mind.

Conference / meeting / board rooms

Conference lightingThe lighting should be adaptable to meet the range of tasks that go on (eg. fine detail work, informal discussions, slideshows and video conferencing).

Lighting on the meeting table should be at least 320 lux but you should be able to reduce this to around 240 lux when tasks require less detail. You may need to be able to reduce light levels further if a data projector and screen is to be used. Avoid too much directional lighting over the central table if you don't want people's faces looking unnatural due to shadowing. And keep the surrounding vertical walls brightly lit to avoid contrast between people's faces and the background.





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