In 2019 Dunedin City Council procured an integrated design, build, operate, and maintain project to replace approximately 14,000 HID streetlights on DCC roads point for point with 3000K LED.
Concept And Brief
The project sought a lighting solution which would deliver:
- energy savings
- maintenance savings
- improved safety
- visual comfort and wellbeing
- improved astronomical night sky and
- ecological considerate outcomes.
The project required that the lighting solution comply with the Australian and New Zealand Road lighting standard AS/NZS 1158. Some existing column positions may not make this compliance possible, so this needed to be cater for too. The original tender documents featured a quality-weighted scoring criteria, which favoured proposals with a superior design methodology towards that goal.
Broadspectrum (now Ventia) was partnered with LDP to deliver the lighting design scope for the project.
The initial project requirements sought to present evidence of:
- an innovative design approach
- analysis of a wide array of luminaire options in each specific light location
- to extract the optimal solution in terms of lighting compliance for the lowest energy consumption for every individual street light location in the city.
To deliver design calculations, drawings, reports and specification for 14,000 streetlights in a very condensed 8-month design programme.
The strong project emphasis on compliance with the New Zealand outdoor lighting standard AS/NZS 1158 was a marked difference from other NZ Council LED replacement examples. Other replacement projects have opted for a less burdensome “no worse than existing” level of assurance regarding compliance, or assigned alternative target parameters in test geometries which may not align with site-specific road geometry.
While the DCC project requirements accepted that non-compliances would occur where existing infrastructure was incompatible with compliant results, the expectation was on LDP to demonstrate their understanding of the project ambition and advance methodologies to minimise non-compliances through design-based solutions. The ultimate realisation of this goal logically involved full design calculations for every single luminaire in its native roadway geometry. Adopting this approach and delivering within the acceptable timeframe and cost constraints would have posed an unprecedented and daunting challenge for any design team. However, this is where the LDP Design Team has been proven to excel, making the apparent impossible, possible.
Ventia selected two well-suited luminaire models for the project, the AEC I-Tron for V-roads and Orangetek TerraLED Mini for P-roads. Combinations of optic, lumen package, and LED module/chipset count created a palette of 24x optical variants for use in the design phase. Each of these variants could be dimmed to an operating output setpoint via a Central Management System (CMS).
This exceptional range of specification variants improves the odds of levering compliant results and achieving greater energy savings outcomes.
The project emphasis on enhanced safety warranted that the design approach conducted full calculations for V-to-V intersections, and curves on V-roads, as these are locations at high risk of road traffic accidents.
Reducing skyglow and enhancing astronomical outcomes were critical aspects of the project. Dark sky areas in other regions of the South Island, such as the Mackenzie Basin, were garnering strong media coverage and public support. Dunedin had established a connection with the opportunity to view the Aurora Australis. The achievement of dark sky outcomes through the rollout was highly valued by all project stakeholders. Zero tilt was required to eliminate any risk of direct upward waste light. This limitation would pose a challenge to design compliance, as many existing luminaires on V-category roads were already at greater than 0° tilt to overcome unfavourable road width.
Enhanced ecological outcomes were a primary objective of the project. Sensitive coastal ecology of the Otago Peninsula and northern coastal settlements of Waitati, Waikouaiti, Warrington, and Karitane required special attention to mitigate the effects of blue light into the surrounds.
A 100% design approach with a “Lean Lighting” ethos was chosen to accomplish the goals of Dunedin City Council. This approach was highly challenging but achievable. Success hinged on several consecutive aspects of the design methodology being robustly attended to:
- Interrogation and cleansing of the DCC RAMM input data
- Manipulation of the RAMM data into formats useable by the LDP calculation platforms and software
- Calculation in a manner that achieves a “Lean Lighting” result – right light, in the right place, at the right time, with the right evidence to prove compliance and demonstrate extent of comparison conducted
- Presentation of design results in a manner that is legible, consistent, and effective for construction
Custom LDP proprietary algorithms were used to rationalise the DCC RAMM asset inventory extract into manageable blocks of data which could be imported into an area calculation platform and drawing software for a rolling programme of road lighting design.
High resolution scaled aerial imagery was used to correct luminaire locations to the column shadow point in the aerial, with associated allowance for bracket outreach, to position the luminaire as accurately as feasible in the calculation and drawing platform.
Approved industry software was utilised for every individual V-Category spacing across the extents to specify the optimal luminaire variant and output for the given road geometry, as determined from RAMM attribute data and LDP’s innovative measurement and checking techniques of the information. These LDP innovative techniques were employed to undertake this calculation work in a time-efficient and high-accuracy manner.
An approved industry software was also utilised as a first step in the P-Category work. An additional LDP propriety calculation tool was built to allow the LDP Design Team to enter unique spacing information (mounting height, road reserve width, existing column spacing distance, single sided or staggered arrangement, target P-subcategory) and return the optimised LED count/lumen package/optic/dimming setpoint combination from the P-Category luminaire palette.
Area Calculation Platform
The second step in the P-Category work utilised a tailored area calculation platform to eliminate weaknesses in industry spacing calculation software for NZ P-category road conditions. Instances for P-Category roads where spacing calculations lose validity in real world applications include:
- Road reserve boundary irregularities (e.g. where road reserve boundaries widen or narrow, are not parallel, or otherwise locally vary)
- Roads with bends, corners, radiuses or anywhere where luminaires are not oriented normal to the boundary and parallel to each other
- Non-linear road reserve elements (e.g. turning heads of cul-de-sacs)
- Any spacing for which the arrangement between luminaires is dissimilar e.g. mounting height, offset, luminaire specification.
In all the above cases, generally accepted luminaire spacing generators would normally fail, as the calculation is only valid where bounding luminaires are equivalent in specification and mounting arrangement and the spacing geometry in between is straight and consistent. Any design approach utilising this methodology alone project-wide would have had an inferior claim to compliance and the level of investigation into an energy efficiency optimised solution. This leaves energy savings unattained and the adopting authority exposed. Therefore, LDP had to approach the challenge quite differently to ensure the achievement of all that was expected and required.
To achieve this, LDP utilised an innovative area calculation module to complete reliable and precisely accurate calculations for compliance on P-Category roads, intersections, and other specified locations, to deliver inherently more robust and task-specific outcomes than spacings based on weakly assumed parameters.
The LDP software used offered very fast yet accurate area lighting design outputs and outperformed other industry accepted street lighting design software packages in terms of rate of calculation, ease of use, and quality of output through an inbuilt auto populating reporting function, ideal for rapidly communicating input parameters and compliance results for the design task undertaken. The LDP utilised software, bulk imported luminaire locations from curated RAMM data, auto populating the design area with lighting assets. It calculated in real time, allowing “on the fly” adjustments to luminaire parameters such as dimming ratio without recalculating and interrupting workflow.
The speed of the optimisation and cross-checking processes facilitated by these innovative LDP techniques and mix of software platforms allowed LDP to target individual specification improvements which would have been totally infeasible using the standard and available industry software alone.
The result was certainty for Dunedin City Council that, out of the hundreds of variants of luminaire available for each and every spacing, the best was always selected.
The project was calculated spacing by spacing, street by street to establish:
- Compliance of every V-category spacing, P-category road, and specified area with the relevant lighting category
- Luminaire specification and dimming setpoint (by the selected CMS Central Management System) to achieve optimal lit condition
- Areas where levels fell short of compliance were flagged for improvement via new civil works (additional columns and luminaires) as a separate project
- Overall energy savings profile of the project.
Output was exported from LDP’s innovative area illuminance design platform to fully specified and detailed construction drawings. Design features report, Energy report, and Safety in Design (SID) documents were populated, reporting methodology, energy savings, and compliance outcomes. A V-category calculation register was populated presenting the spacing calculation results for each V-cat luminaire optic tested in every V-cat spacing across the entirety of the project extents. Illuminance calculation reports were generated for each P-category street, V-to-V intersection, and specified area calculated in the project. RAMM data was re-annotated to allow the DCC database to be updated as required.
The design output successfully passed detailed peer review by independent, external, professionally qualified and experienced reviewers.
This commitment to 100% design for 14,000 streetlights was successfully delivered within the required 8-month timeline and within the agreed budget.
The full design approach with “Lean Lighting” compliance enhanced outcomes for every success criterion directed by Dunedin City Council:
- Energy savings –
- maximised through selecting the most energy-efficient combination of optic/lumen output/dimming setpoint for each luminaire, tailored to each individual luminaire’s unique road geometry, minimising energy usage while maintaining agreed lighting performance
- energy savings based on initial RAMM data vs the optimised LED design totalling 4,113.70 MWh, representing a project-wide energy reduction of 61.8%
- Maintenance savings –
- maximised as above, through minimum required driver and LED current, reducing thermal stress on luminaire components and reducing failure potential
- Improved safety, achieved through –
- 100% design with capable luminaires and a broad optical palette within which to test multiple design possibilities
- pursuing compliance with AS/NZS 1158 as the project benchmark, as opposed to “no worse than existing” whereby existing non-compliant arrangements are likely to remain non-compliant
- use of versatile and effective software strategies and innovative custom-built propriety calculation and measurement tools to reduce calculation processing time, retain high and exacting accuracy, allowing more bandwidth to pursue compliant design results within the accepted programme/costing envelope
- comprehensive testing and reporting of compliance outcomes, such that areas proven to be non-compliant due to unfavourable infrastructure can be prioritised for remedial works as budget permits
- Improved visual comfort and wellbeing, achieved through –
- optimised specification for each location, minimising over-lighting and thereby reducing unnecessary light spill out of the task area
- use of 3000K luminaires in residential areas
- Improved astronomical night sky and ecological outcomes, achieved through
- the “Lean Lighting” project design principle, with a greater proportion of generated light being directed into the task area via optimised luminaire specification, and less light generated by the installation overall, resulting in less light reflected upwards into the night sky or out into the environment
- use of full cut-off LED luminaires, certified through the International Dark-Sky Association Fixture Seal of Approval to minimise light spill to the sky
- installation at 0° tilt (horizontal) throughout the project extents
- use of 3000K LED luminaires across the project extents, constituting a much-reduced blue light profile compared to 4000K luminaires
- use of 2200K narrow-band amber LED luminaires in areas of sensitive coastal ecology, including Otago Peninsula, Waitati, Waikouaiti, Warrington, and Karitane, eliminating blue light from the emission spectra altogether
- use of a dynamic Central Management System (specified by Ventia), allowing dimming at certain intervals during the night if required.
The brief was fully satisfied and provided a solution that exceeded the expectations of Dunedin City Council and all Stakeholders.
The result of the design has made a positive contribution to the enhancement of the Dunedin City night time visual scene and to the potential enjoyment and safety of both human and non-human users.