International Year of Light 2015

Lighting represents almost 20 percent of global electricity consumption according to the International Energy Agency. The future development of society in both developed countries and emerging economies around the world are intimately tied up with the ability to effectively light our cities, workplaces, homes, schools and recreation areas.

ighting provides safety and security, provides access to education, enhances architecture, and improves our quality of life. We take it for granted and often notice it only by its absence. However, as cities worldwide develop it is essential to employ new and innovative lighting design techniques and technologies that improve energy efficiency cost and control, that easily can be adapted to local needs. 

Light is not only visual

Light plays a vital role in our daily lives and is an imperative cross-cutting discipline of science in the 21st century. It has revolutionised medicine, opened up international communication via the Internet, and continues to be central to linking cultural, economic and political aspects of the global society.

On 20 December 2013, The United Nations (UN) General Assembly 68th Session proclaimed 2015 as the International Year of Light and Light-based Technologies (IYL 2015).

This International Year has been the initiative of a large consortium of scientific bodies together with UNESCO, and will bring together many different stakeholders including scientific societies and unions, educational institutions, technology platforms, non-profit organizations and private sector partners. The Global Secretariat is located at the Abdus Salam International Centre for Theoretical Physics in Trieste, Italy.

In proclaiming an International Year focusing on the topic of light science and its applications, the United Nations has recognised the importance of raising global awareness about how light-based technologies promote sustainable development and provide solutions to global challenges in energy, education, agriculture and health. 

Light as a drug

Light has been known for a long time to enable sight, safety and orientation. But light can do more than enable vision. Light has the power to energise, relax, increase alertness, cognitive performance and mood. Light is the most powerful regulator of the day-night-rhythm of people. Every day light exposure adjusts and stabilises the duration and timing of our sleep-wake cycle. Moreover, light is known to be an effective treatment for a variety of conditions that include mental disturbances such as Seasonal Affective Disorder (SAD) and certain kinds of sleep disorders.

The ability of light to achieve these various non-visual effects depends on the spectrum, intensity, and temporal pattern of the light, as well as the light-exposure history and preceding sleep behaviour of the individual. Therefore, the optimisation of a Human Centric Lighting solution for a given non-visual effect is only possible when this user context is accounted for. This requires a dedicated and tailor-made design, based on a profound understanding of the personal and environmental conditions of the use-case(s). A “one size fits all” Human Centric Lighting solution does not exist, and one may even do more harm than good when applying a solution beyond the context and scope it was designed for.

Can you see the stars?

In most large cities of the world, it is no longer possible to appreciate the beauty of the night sky. Inefficient public lighting both wastes energy and causes “light pollution” that hides our universe from us. 

“Light pollution” is a form of environmental degradation in which excessive artificial outdoor lightings, such as street lamps, neon signs, and illuminated sign boards, affect the natural environment and the ecosystem. The wasteful light emitted directly upwards or reflected upwards from poorly-designed artificial light sources can be scattered by clouds, fog, and pollutants like suspended particles in the atmosphere. The night sky is thus brightened, leading to a reduced number of stars visible in the sky due to a decrease of the light contrast. 

Light over the world

From India, Brazil and Iran, to Italy, Cuba and Senegal, throughout the course of 2015 the world will be paying their own local tributes to light with a series of events, lectures and festivals. To find out more visit