ISCA Tips & Tricks-Dis-5 Light Pollution
By Andrew Aitken
The Dis-5 Light Pollution credit has troubled many designers and ISAPs alike. It is particularly problematic for motorway projects. The credit criteria reference AS4282 and AS1158 but compliance cannot be shown by assessing your design directly against these standards.
The savvy lighting designer will know that AS4282 does not address public lighting—including lighting for roads and motorways. It was designed to address the impacts of residential tennis court lighting on neighbouring residential properties. It is the reference to AS4282 that causes the most confusion with this credit.
As with all ISCA credits, submission evidence must address all requirements in the criteria, plus the additional guidance (‘must statements’). For this credit though, the details have proven to be confusing, so I am proposing below a simplified approach, which we’ve adopted on ISCA projects in the past. The simplified criteria are:
a) Temporary construction lighting should not be aimed towards sensitive receivers such as ecological habitats, residential properties or businesses adjacent to the project;
b) Horizontal light spill during asset operation should be controlled; and
c) The upward light ratio (or ULWR from AS1158) needs to be less than 5% for 95% of light fittings.
a) For the first part of this assessment, construction management plans for temporary lighting, together with a complaints procedure to investigate, manage and mitigate impacts, are required.
Submissions must also demonstrate that there will be at least one night-time lighting audit during construction. Evidence for a design submission should include an audit checklist, and for an As Built submission, a lighting audit report is required.
b) For the second part, the light spill is calculated in the horizontal plane. This can be confusing because the referenced tables in AS4282 have compliance requirements for lighting in the vertical plane. Designers must use these vertical plane illuminance numbers from Table 2.1 to assess the horizontal illuminance. Compliance is demonstrated with horizontal illuminance plots at ground level.
The most controversial part of compliance with AS4282 Tables 2.1 and 2.2 is the luminance requirements. Road lighting fittings cannot comply with the luminance requirements from AS4282 due to the high light output and relatively small emitting area of the fittings. Experience has shown that just addressing the illuminance values from Table 2.1 (and basically ignoring the luminance requirements) may be sufficient.
c) The last part should be particularly easy to demonstrate as the referenced standard AS1158 requires less than 3% UWLR for Category V roads. The ‘less than 5%’ benchmark is easily achieved on motorway projects as it is higher than the ‘less than 3%’ benchmark required in the lighting standard. The standard AS1158 compliance report is suitable for demonstrating compliance.
Hopefully ISCA will review this credit soon and remove confusing and inconsistent elements so that designers can respond with confidence and real environmental improvements can be achieved.
Andrew Aitken is an Associate with Losee Consulting and an ISAP.
Disclaimer: this article represents the author’s views and is not endorsed by ISCA.