ORENOS

The aim of this project is to develop an indicator of the quality of artificial night-time lighting in Haute-Savoie using SDGSAT-1 satellite imagery. This indicator will enable local decision-makers to prioritize their actions to adapt, renovate or switch off lighting, with the aim of proposing lighting that is more economical, better adapted and less damaging to biodiversity.

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Night-time satellite view of the Annecy region, taken from the SDGSAT-1 satellite. © SDGSAT-1, CBAS / Map backgroundd : Open Street Map

Orientation of night lighting renovation by satellite observation

Overview

Light pollution is known to disrupt the functioning of living ecosystems and contributes to energy waste.

Against this backdrop, the ORENOS project is studying the quality of artificial lighting at night, focusing on the test area of Haute-Savoie (France). This mountainous department boasts a rich diversity of flora and fauna, but is under increasing pressure from urbanization, economic development and the densification of infrastructures. As the first most dynamic department in terms of demographic growth between now and 2050, the artificialization of land and the pressure on ecosystems will continue to increase, particularly in terms of artificial night-time lighting.

What's more, in 2017, according to ADEME, lighting accounted for 32% of the electricity consumed by local authorities. In fact, the challenges of managing and renovating the stock of public lighting represent a lever for energy savings that is widely used by local and regional authorities, although they sometimes lack the tools to do so effectively and with a global vision over a wide area.

The ORENOS project will develop an indicator of the quality of artificial night-time lighting in Haute-Savoie using satellite imagery, which can be used to adapt lighting to reduce its impact on biodiversity and save energy.

Methodology

The project will be based mainly on night-time images from the Chinese SDGSAT-1 satellite, supplied by the CBAS (International Research Center of Big Data for Sustainable Development Goals) at 10m spatial resolution. These night-time images contain radiance information, i.e. the light power emitted or reflected by a ground surface. As these images require radiometric and geometric pre-processing before they can be used, the work will begin with the development of an automated processing chain. The images available will be retrieved from the study area over four years, and annual radiance synthesis will be produced. From these images and the radiance peaks extracted, direct indicators will be derived that will make it possible to deduce the type of lighting suspected and/or the incorrect orientation of the luminaire. Indeed, the luminous flux can sometimes be directed towards the sky, which is inefficient from the point of view of human lighting and particularly disruptive to nocturnal aerial biodiversity.

The expected light will then be modelled on the basis of the type of road, local street lighting databases and in situ and satellite albedo measurements. The expected radiances will then be calculated and compared with the radiances observed by the SDGSAT-1 satellite. The differences obtained will provide an indicator of lighting quality (standard lighting, malfunctioning, over-lighting, unsuitable road surfaces). Another indicator of the presumed pressure of night-time lighting on biodiversity will be produced by cross-referencing the night-time radiance map with national and local databases providing information on biodiversity and natural environments.