Natural Lighting in the Workplace

7. (1989)

Although natural lighting has many disadvantages as a light source (uncontrolled illumination, variable illumination, glare, shadowing, etc.) and is not a necessary component of a safe and healthy working environment, it is never-the-less widely accepted as a desirable component of the working environment. Access to natural daylight not only provides an economic form of lighting, it provides the building occupant with an external visual panorama which is generally perceived as improving the quality of the working environment.

It is recommended that, where practicable, work activities be organised to give all staff access to natural lighting for at least part of their working day.

Included below are extracts from various Codes and Standards that discuss the question of natural lighting.

Australian Standard AS 1680-1976

Interior Lighting and the Visual Environment

4.1 Provision of Natural Light.
Wherever practicable some provision should be made for the admission of natural light by means of windows or rooflights, or both. The recommendations in Clauses 4.2 and 4.3 should be observed to ensure that both the natural and artificial lighting are used to best advantage.

Although people tolerate windowless working conditions when these cannot be avoided, an ability to see out appears to satisfy a basic human need which should not be underestimated merely because reasons for it are difficult to analyse. However, a large expanse of glazing is not necessary for this particular purpose; small windows (preferably at eye-level) will provide a link with the outside world which can benefit everyone in a large open-planned work area, even though the actual percentage of daylight on their task may be negligibly small.

4.2 Control of Sky Glare and Direct Sunlight Penetration.
Sources of natural light such as the sky, sun, or sunlit surfaces visible inside or outside the windows, should not be allowed to interfere with the visual comfort or efficiency of the persons in the area.

Occupational Safety and Health in Commonwealth Government Employment Code of Practice 203

Interior Lighting and Colour

3.1 Provision of Natural Lighting
Where practicable, some provision should be made for the admission of natural light by means of windows and/or roof lights, but adequate provision for the control of sky glare and the exclusion of unwanted sunlight must also be made. (See Clause 3.3.)

The quantity and quality of natural lighting benefits greatly from the provision of a well-planned colour treatment as recommended in Clause 1.4. In particular, a white or near-white finish on the roof or ceiling surface will help to increase the diffusion and penetration of daylight, especially in window-lit rooms. In the case of saw- tooth roof buildings especially, this diffuse reflected component is also beneficial in reducing the harshness of the uni-directional illumination from the roof lights.

Occupational Safety & Health Working Environment Series
No. 13

VDUs at Work

The visual environment
Of all the environmental elements, the visual environment is the most dominant as far as VDU operators are concerned. Although the information on the screen is an integral part of the visual environment, it has, for the sake of simplicity, been treated separately.

It may be thought that a wholly artificially lit environment may be more controllable and therefore more desirable, but experience has shown that the window plays a very important role in maintaining contact with the outside world. It would appear that humans have a psychological need to maintain this relationship. Therefore it is desirable that the VDU operators be located in an area adjacent to a window. However, it is imperative that the deleterious aspects of daylight be minimised. These aspects are discussed below.

• Direct discomfort glare from the windows.This can be minimised by installing blinds or louvres on the windows, or by positioning the operator in such a way that he or she is not directly facing an unshielded window. Refer to the companion publications Sunlight at work and Daylight at work for more information.
• High brightness images of the window reflected in the screen, either obscuring the text or creating an irritating distraction. This problem can usually be overcome by correct positioning of the screen relative to the window.
• Too high a value of illumination on the face of the screen, creating a 'veiling luminance' which reduces the contrast between the characters and the background. This can be easily identified if, by shielding the screen from the direct light with one's hand or a book, the contrast between a character and its background is increased - i.e. the characters are easier to read.
• If unwanted reflections or veiling luminances cannot be otherwise controlled, the fitting of a proprietary mesh filter is recommended.

For further information contact:
OHS Officer, e-mail: OHS.Officer@anu.edu.au