In 2009, in an effort to reduce global energy consumption, the EU Commission decided to move toward a complete ban of incandescent light sources by 2020. Their progressive replacement by highly efficient light sources is expected to reduce energy consumption for lighting by 30%.
Among all existing technologies, solid-state lighting (SSL) represents the solution of the future, however, according to a recent study (1), many SSL products do not fulfill the claimed specifications and a deep market penetration of LED modules is at risk. The main problems are decreasing light intensity and varying light chromaticity due to aging and temperature, as well as poor uniformity of large-area luminaires and poor lighting quality.
The main objective of the LASSIE-FP7 (Large Area Solid State Intelligent Efficient luminaires) consortium is to implement large-area and low-cost intelligent SSL modules with high efficiency and high lighting quality, while assessing their environmental footprint. The project targets in particular the professional and architectural lighting sectors. LED-based point source luminaires have been already investigated, but market requirements for intelligent, large-area solid-state light sources have not been met yet. In order to achieve luminaires with high intensity, good uniformity and high color rendering performance, significant intelligence has to be added to the LEDs.
Today in developing countries there is still lack of access to basic needs such as electricity. Thus, it is important to teach children how to generate light in a sustainable way, which can benefit the improvement of their living conditions and make an impact on their communities.
The project started in Kenya. The idea was to provide children with safe electricity. Most of them still use kerosene lamps for studying during the night. Such lamps are toxic and highly threatening for their lives and families. Thanks to the support of Siemens Stiftung, the project has now equipped several schools in Africa and South America, among them, one in Peru, with a 10-Watt Solar Light System, a recharging station, and LED lights. Now children learn how to use solar cells and build their own lights.
Students from the school “Fundación Niños del Arco Iris” building the solar system. Credit: Fundación Niños del Arco Iris.
Welcome to the lighting revolution
In lighting applications, the adoption of light-emitting diodes (LEDs) and organic LEDs promises to reduce lighting energy use dramatically over the next few decades. There is an equally marvellous scientific revolution in biology and psychology. In 2002, we learned conclusively that there is a class of photoreceptive cells in the retina, the intrinsically photoreceptive retinal ganglion cells (ipRGCs), that is separate from the rod and cone cells that transduce visual signals (1). Thus, the eye-brain connection is far more complex than previously thought, and the more we learn the more complex we find it to be (2). Ever since this discovery, debate has raged concerning how to apply this knowledge, and how quickly to do so (3).
One reason for caution is that lighting installations serve many functions, and our recommendations reflect this complexity. As I wrote in a previous blog entry, lighting quality exists at the nexus of the needs of individuals, the environmental and economic context, and architectural considerations. Strong evidence is needed to intelligently blend new discoveries into coherent guidance in balance with the other considerations.
Simplified schematic diagram of two eye-brain pathways, taken from CIE 158:2009. Light received by the eye is converted to neural signals that pass via the optic nerve to these visual and non-visual pathways. POT = Primary optic tract. RHT = Retino-hypothalamic tract. LGN/IGL = Lateral geniculate nucleus / Intergeniculate leaflet. SCN = Suprachiasmatic nucleus of the hypothalamus. PVN = Paraventricular nucleus of the hypothalamus. IMLCC = Intermediolateral cell column of the spinal cord. SCG = Superior cervical ganglion. CRH = Corticotropic releasing hormone. ACTH = adrenocorticotropic hormone. (c) CIE, 2009. Used by permission.
People have looked up to the sky at night for millennia. Some have searched the stars for the answer to the question “where are we going?” sometimes figuratively (astrology), and literally (for navigation). In the 20th century, the stars started to disappear from the night sky, as glow from electric lights in cities outshone them. These days, some citizen scientists are looking to the night sky to find out whether the widespread adoption of LED lighting is making the problem of skyglow worse or better.
In many citizen science projects, the main or only role of participants is to collect data. We wanted to change that for our project, and put the data and tools to analyze it back into the hands of the public. Our new web application, my sky at night, does just that.
The image below shows skyglow data collected in Europe from four different sources: visual observations from our Loss of the Night app (LON), visual observations from the Globe at Night project (GAN), observations with the Dark Sky Meter app for iOS (DSM), and observations taken by citizen scientists with a Sky Quality Meter (SQM). You can filter by year and project to decide which data to show in your browser (selecting all data will take a while to download, clicking on “load only displayed area” will help speed this up).
“Groups of skyglow observations in Europe. Credits: Christopher Kyba & interactive scape”.
The International Year of Light and Light-based Technologies 2015 (IYL 2015) has showcased the incredible importance of bringing light to the hundreds of millions around the world living off grid. It has also seen unprecedented momentum in support of off-grid renewable energy in making that vision possible.
Micro-hydro plant, Peru. Credit: Practical Action.