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Increasing the efficiency of LED street lighting by 15% via optical design

Periodic Reporting for period 1 - PearlLight+ (Increasing the efficiency of LED street lighting by 15% via optical design)

Reporting period: 2015-09-01 to 2016-06-30

In cooperation with leading researchers of the field, Hungaro Lux Light developed a highly innovative design method for manufacturing LED lenses and covers optimised to the desired illumination pattern and the specific LED chip used. This optimisation improves light throughput by 15% on average compared to currently available lenses. This solution can greatly improve the luminaires efficiency, contributing to considerable energy and cost saving, as well as opening new market opportunities for Hungaro Lux Light.
This proposal aims a Phase 2 project for the software automation of Hungaro Lux Light’s design process and industrialisation of the new coating layer as the last major step before the market introduction of the new range of highly competitive luminaires.
About 60% of the electricity costs for a municipality is street lighting. Recently, the wider deployment of innovative LED lighting solutions has been made a priority by the European Commission , . At the same time, LED street lighting is one of the most problematic areas of lighting, where specific processes and special equipment are still half way under development. The problem arises from the fact that there are special standards for street lighting (as opposed to homes, offices, etc. ) that specify not only the level of illumination, but also the uniformity of light on the surface, the quality of light and amount of glare. Furthermore, light pollution in street lighting should be reduced and the effectiveness of lighting will result in less energy consumption.
LED light sources are under constant development by the market leading large enterprises with immense RTD budgets – however, most of this effort has been focused on improving LED chip efficiency, improving light intensity per used energy from ~100 lm/W (lumens per Watt) to ~150 lm/W within the last few years (talking about commercially viable solutions for street lighting circumstances and warm white colour). LED light source development is no potential market ground for SMEs, but Hungaro Lux Light has an important task of being able to adapt the newest LED chips to their luminaires. LED driver electronics are already above 95% efficiency, leaving little room for development.
The main area where LED-based street lighting can still be improved is the light throughput efficiency of the lens and the transparent cover of the luminaire. The loss in the optical path for a typical street lamp can be as high as 25%. This is caused by two components, the secondary optics and the plastic cover. The weakness of generic lens designs mean a 15-20% loss in the optical path, from the LED chip to the air inside the lamp (secondary optics). The plastic cover of the lamp will reflect part of the light back into the housing, resulting in further losses up to 5-10%. Overcoming these losses has a direct effect on power reduction, allowing to maintain the same light level with reduced input power.
There are several LED chip manufacturers continuously improving their products, so LED luminaire developers like Hungaro Lux Light has to keep up with the rapid improvement of the LED chips. To match up with this development, Hungaro Lux Light has to redesign the fixtures on optical level each time there is an improved LED chip, which takes time and a lot of effort. Without applying new lenses, street luminaires cannot take advantage of recent developments.
An additional issue for lens design for outdoor luminiaries is compliance. In order to achieve compliance with standards at minimum energy consumption, special outdoor optical lenses have been developed, but not many are commonly available or commercially viable.

Hungaro Lux Light wants to introduce a new range of outdoor LED street lights with improved efficiency. With this solution customers can reduce their electrical power consumption even more than with the other current devices.

The main goal of Hungaro Lux Light is to deliver a new range of LED street lights achieving a
"Our project started on the 1st of September 2015, and currently in its 10th month. In the beginning we have started both the technical and non-technical tasks parallel. The first step of the development was focusing on the finalization of the System specification based on the detailed analysis of the market feedback and investigation of technical possibilities. The lens design software requirements state the ""what"" and the specification define the ""how"". During the preparation of the specification the functionality and technical details of our application were defined by selecting the most suitable solutions for the main functionalities for example luminance calculation or ray-tracing simulation. In terms of the coating process the currently available antireflective coating technologies, recently published related literatures and patents were investigated. The target substrate was selected, the possibly achievable transmission increase was evaluated and defined. The methodology of the coating process, the optimization process and the interim steps of the coating development was also specified.
The development of the coating and the software part continued parallel.

1. Software development

Based on the specification the Design process of the software itself and the related database could be done which resulted in defining and designing the main acting components and the relation/interfaces between them. These sub-modules are: 1) Luminance calculator : it calculates values that will be later validated against lumination evaluation class values 2) Ray-tracing simulator: for simulating the path of projected rays towards a detector surface 3) Search module: it aims to apply heuristics to obtain different lens geometry 4) Graphical User Interface : it hides the complicated processes from the user and to displays intelligible results to the user and finally 5) Database: the central information storage that contains the classification and the management system of all the different types of data needed for the operation of the software.
Once all the building blocks were defined and designed, the Implementation started which reached the level by now where the functional Test could also started. The first functional tests were executed by the end of June 2016. The software is under continuous test as it was planned in order to optimise, fine-tune the modules.

2. Coating process

The Precursol sol preparation and depostition task focused on the optimization of the antireflective coatings in laboratory environment. Based on our previous experiences and on literature survey a new recipe was developed for the synthesis of precursor sol in alcoholic media suitable for the preparation of mesoporous SiO2 sol-gel coatings. A method for the activation of the PC surface in order to promote the wetting of the surface and the adhesion between the surface and precursor sol was adapted from the literature. Mesoporous SiO2 sol-gel coatings were deposited from the precursor sol onto small surfaces of flat glass and PC and curved PC substrates by dip-coating. Light transmittance, thickness, refractive index and porosity of the coatings were determined by UV-Vis spectroscopy and ellipsometry. The withdrawal speed for coating deposition from the viewpoint of average transmittance increment compared to the light transmittance of solid substrate (PC or glass) in the LED lighting wavelength range (410 nm730 nm) was optimized. Following we were focusing on the Post treatment optimization and investigated the parameters of the different treatment processes to achieve stable and high transmittance surfaces. We have finalized the coating process on laboratory level and reached 7-8% increment in transmittance. We have continuously Tested the prepared samples, further tests are ongoing on the stability of the developed coating but we have very promising results. As a next step we have already started to raise the coating process from laboratory to industrial"
Sustainability, cost-effectiveness and low-maintenance costs are the key features to LED street lighting industry nowadays. There is a global trend in the needs of this innovative street lighting.
This innovative street lighting solution has numerous advantages over fluorescent lighting, the current industry standard. It is more energy efficient, has longer lifetime, has less maintenance requirements, uses no mercury and contributes to reduced climate control costs.
Hungaro Lux Light is manufacturer of the innovative LED luminaires. The business knowledge and the know-how of the lighting installation and luminaire area have been developed over two decades within the company. Major clients - like Raiffeisen Bank, BNP Paribas, Lidl, LEGO shop or Sofitel – are choosing the company because of reliable design, personalized solutions and great engineering work.
The company is among the trend leader companies who have modernised the street lighting in Europe with LED technology. Hungaro Lux Light wants to keep his leading position by setting up 4 coherent areas of business services in LED street light technology:

1. Production and sales of PearlLight+ LED Street Lamps
In cooperation with leading researchers of the field, Hungaro Lux Light developed a highly innovative design method for manufacturing LED lenses and covers optimised to the desired illumination pattern and the specific LED chip used. This optimisation improves light throughput by 15% on average compared to currently available lenses.
2. Lease-work of designing in lens design automation software
3. Sales of lens design automation software
4. Lease-work of anti-reflective coating

To protect our results, we have already submitted a patent application on the newly developed coating process.
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