Adaptive, Dynamic and Intelligent Lighting
Previously, most lighting applications were designed to ensure suitable visual conditions, to support the most demanding visual task anticipated, whilst also taking into account requirements to provide adequate levels of visual comfort and aesthetics. In most cases this was a static lighting solution because the options to change light levels, luminance distribution, or light source spectrum were limited. Tasks, occupants, and needs change from time to time, making control over the lighting desirable, if unattainable. Advanced LED and controls technology make the unattainable possible; now, the key questions are also for CIE how to define the user needs for various applications and how best to set up lighting systems to be adaptive and intelligent in response.
The user should be the focal point of any lighting application, regardless of whether the lighting is for a work place, for home and leisure, or artistic impression. Guidance documents provide quantitative photometric parameters for many applications. These include: horizontal and vertical illuminance and luminances, the luminance and illuminance distributions, light source chromaticity color rendering, and energy performance. The photometric parameters today are based on visual needs for adequate light to see and sufficient control to prevent discomfort associated with glare. There is increasing interest in adding parameters to address ipRGCinfluenced light responses (also known as integrative lighting or human-centric lighting), although such criteria for these parameters have not yet been established.
The Role of Adaptive Lighting
The role of adaptive lighting (sometimes called "smart lighting") is to adapt in a holistic way the whole set of lighting parameters to the current needs of users depending on current conditions, changing in response to changing conditions that include the availability and quality of daylight, occupancy pattern of users, and user preferences. Dynamic lighting can change according to pre-set dynamic variations or in response to manual controls, but adaptive lighting detects current conditions and response accordingly. If automatic functions are incorporated, and even more, if these are based on advanced technologies like fuzzy-logic, genetic algorithms or neural networks, we can call such systems "intelligent".
The adaptability of a lighting system can be classified into four levels:
• Level 1 - adaptation using time schedules based on statistics
• Level 2 - adaptation on demand using local sensors or individual
local controls
• Level 3 - adaptation with links to intelligent systems such as Building
Automation Systems (BAS) for buildings and Intelligent Transport
Systems (ITS) on selected roadways
• Level 4 - adaptation combining the options of Levels 2 and 3,
for example:
° scheduled changes in light source color or level to mimic daylight
patterns, with or without local occupancy detection, task tuning,
or daylight harvesting
° adaptation with links to ITS systems on all roadways with electrical
and lighting management systems (ELMS) control
° luminance monitoring
° lighting-on-demand - lights that are activated by immediate need and
otherwise are dimmed or switched off, e.g. with Connected Vehicle
Technology or in response to local occupancy signals
° smart city and smart building applications
How to Use the Technologies for Adaptive Lighting
The technologies to provide adaptive lighting are already in the marketplace and are accepted by some jurisdictions. Nonetheless, we have an inadequate understanding of how best to use these technologies, meaning that installations might not serve users well, and in the worst case, might lead to harm. Lighting researchers can generate the knowledge needed to support the best application of adaptive lighting technologies.
The International Commission on Illumination (CIE) understands the importance and urgency to deal with problems of adaptive, dynamic and intelligent lighting in all application fields. Hence, this topic is a highlight of CIE's research strategy.
Key research questions are:
• What is the impact of adaptive lighting on user behavior or reactions,
such as occupants' space perception or driver safety?
• How should the system adapt itself to the circumstances to provide
optimal lighting? For example:
° Could the system detect individual needs for varying visual conditions?
° Could roadway lighting vary depending on traffic composition,
traffic density, and weather conditions?
• What are the relations between lighting settings and user safety
and comfort?
• Which types and levels of dynamics are acceptable in a
lighting installation?
• Which types of input and feedback (e.g. road surface luminance
monitoring, photocells, presence detection, algorithms for integrated
multi-sensor input, automated fault detection) are necessary to
ensure system usability?
• What are the energy and operational costs and benefits of adaptive lighting?
• Could adaptive exterior lighting have ecological benefits beyond
energy savings?
The CIE has previously published two technical reports that fully (CIE 222:2017) or partly (CIE 205:2013) deal with problems of dynamic, adaptive and intelligent lighting in buildings.
CIE 222:2017 - Decision Scheme for Lighting Controls in Non- Residential Buildings
This report offers guidelines in order to balance lighting quality, user comfort and energy efficiency in lighting controls solutions for lighting in nonresidential buildings (i.e. for commercial, institutional and industrial buildings). It provides a decision scheme with a focus on the user requirements (visual comfort, performance, personal control) to determine the most applicable control solution, including the consequences for possible savings. In this, it assumes that there are no technological or financial hurdles. The decision scheme identifies 16 possible control strategies, for both daylight and electric lighting, and provides guidance for which strategy would be most effective in each of the 12 cases defined by space usage and occupancy.
CIE 205:2013 - Review of Lighting Quality Measures for Interior Lighting with LED Lighting Systems
This report provides information on the suitability of existing lighting quality measures when applied to (commercial) interior LED lighting systems. It identifies the gaps and weaknesses in existing quality measures, recommends new quality measures and includes suggestions for required research.
CIE Technical Committees Are Addressing Adaptive Lighting in Transport and Roadway Applications
TC 4-51 - Optimization of Road Lighting:
Objective of this TC is to develop guidance on optimization of road lighting to balance the benefits and costs where primary issues include accident risk and energy consumption.
C 4-47 - Application of LEDs in Transport Lighting and Signaling:
This TC aims to review the application and methods of measurement of LED Systems in transport lighting and signaling and to provide recommendations for the visual characteristics of LED signals and lighting as far as they affect the visual performance of the users of the transport system.
Summary & Conclusion
Current research on adaptive lighting was a focus of discussion during the CIE Topical Conference on Smart Lighting, held earlier this year in Chinese Taipei. The conference addressed key questions in this field and provided space for topical tutorials, a panel discussion on standards needed for smart lighting and a site demo presenting a practical application of smart lighting at a pier in Keelung City.
Although adaptive lighting installations are few in number today, the pace is increasing. The time for researchers to address the CIE Research Agenda questions is now, so that the future of adaptive and intelligent lighting rests on a solid foundation of research and standardization.
