Two aspects of lighting standardisation currently underway appear unique to Australia ( perhaps innocence or foolhardiness or just self confidence led to involvement!) - obtrusive effects of exterior lighting and tolerance / accuracy in lighting.
Australian Standard AS4282 "Control of the Obtrusive Effects of Outdoor Lighting" has been in place for 18 months but only as an interim standard in view of it breaking new ground. The Standards interim life ended on the 5th Dec.1996, but at a recent meeting to review its status the Standard has been unanimously endorsed as a full Standard with minor amendments.
The Standard identifies specific effects on residents, transport and astronomy and the relevant light technical parameters (LTP) involved eg. The vertical illuminance at the windows of affected properties. Recommended maximum values of the LTPs are given to control obtrusiveness to tolerable limits.
The values and method of application change according to the time of day. Before a curfew or designated hour (unless otherwise set down, 11pm or 2300hrs) the limiting values have as their objective the facilitation of the intended outdoor activity whilst giving recipients of spill light relief from it being excessively obtrusive. The use of conventional lighting technology but with application of good practice will generally be satisfactory.
After the curfew the requirements are much more onerous and the objective here is maintaining the integrity of the amenity and environment of properties around the lighting installation. If lighting is to be operated during these hours, then particular attention will need to be given to the limitation of spill light, requiring a very detailed analysis of the situation in order to comply.
Further sections of the Standard deal with design and operation to minimise spill lighting, calculation of LTPs and demonstrating compliance with the Standard. Finally there is a lengthy appendix covering the basis of the Standard, mainly studies from Germany & Australia and precedents set down by Government ordinances. All adding up to the first National Standard on the subject.
It should be noted that road lighting is not covered by this Standard; in a recent part revision of the Australian road lighting standard (AS1158) a limit was placed o the emission of light above the horizontal from luminaires used on traffic routes. Limits for luminaires used on residential roads and other outdoor public spaces are to be expected as the revision continues.
A draft standard "Lighting System Performance - Tolerances and Accuracies" is at an advanced stage. The object of the standard is to heighten awareness of the uncertainties in lighting design, possible action to minimise these and to engender reasonable expectations of the overall accuracy of lighting design and measurement verification.
One problem tackled at the outset is to differentiate clearly between accuracy and tolerance (do you know the difference?). Most lighting standards call up minimum values, ie. no tolerance downwards but infinite upwards!. In reality clients and designers normally aim towards the minimum because of cost and energy constraints.
But the question remains what level should the designer aim for to make sure of achieving, when installed, the minimum, or any other, level set in the clients brief.
Note that the designer has been mentioned several times already: the designer has been taken as the principal actor in the play. However in the draft standard all the other actors are identified and their roles and what is expected of them, with respect to subject, are set out.
Of course it turns out that from concept through design to installation, lighting is a complex process, involving many actors and uncertainties, the view taken is that a heavy handed approach requiring the designer to calculate and state the accuracy of design is unrealistic. Rather the standard sets out what precautions a designer can be expected reasonably to take and document to ensure the uncertainties in a design and subsequent installation and verification, are minimised.
As with the "obtrusive light" standard the emphasis is on promoting this aspect as a routine part of lighting design, not something that is thought about only when on installation the lighting is found to be faulty and fix it up remedies are sought and blame needs to be allocated.
Both of these standards were requested by the lighting industry through the Illuminating Engineering Society. Experience has shown that, when it comes to facing up to the results, reactions are mixed: from welcome of another aid in ensuring only good lighting is ever produced to condemnation of more control on the industry and inhibiting members from doing it their way regardless.
The drafters look forward to the early part of this year and response to "Tolerances and Accuracy" - again do you know what these terms mean and imply to lighting?
Note: Any comment or query regarding this report can be addressed to Dr. Fisher via regrw@acay.com.au