# Affordable Smart Lighting for Smart Cities in Developing Economies Context

Georges Zissis

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Georges Zissis. Affordable Smart Lighting for Smart Cities in Developing Economies Context. International Conference on Energy and Applications (ICEA), Université de Djibouti, Mar 2025, Djibouti, Djibouti. hal-04972757

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# AFFORDABLE SMART LIGHTING FOR SMART CITIES IN DEVELOPING ECONOMIES CONTEXT

Georges ZISSIS<fnref n="1" /> *

**Abstract**— Today, lighting is responsible for 5% of worldwide CO₂ emissions. World's electricity demand for lighting attained 2,900 tera-watt-hours (TWh) corresponding to a global light energy production of 215 Plmh (peta-lumen-hours). It is foreseen that in 2040 the needs for electric lighting will increase by ~32% to reach 285 Plmh. The challenge for the next decade will be to harness the increase of electrical electricity use for lighting. Only light source technology evolutions are not sufficient to stem uncontrollable growth. Even the best commercialized LED lamps which are almost 2 times more efficient than fluorescent tubes, are not sufficient to inhibit the well-known rebound effect. Only a transition from the “conventional analogue” lighting technologies to “digital lighting” can help. Smart lighting will become the heart of the Internet of Things in smart cities and buildings. Smart Lighting is on the way to become the 4th revolution in the domain. It can achieve more than 40% additional energy savings and encompass rebound effect. Smart Lighting market size can exceed USD 98 billion by 2030 which is comparable to USD 134 billion revenue from global lighting industry. This paper highlights the evolutions in the domain of smart lighting technologies, its impacts and propose a model for making these technologies affordable for developing economies.

**Keywords:** Smart Lighting, Light Emitting Diodes, Energy Policies, Affordability.

## I. INTRODUCTION

As of 2009, electrical lighting for illumination consumed worldwide, in this single year, 2 650 TWh of electricity (this represented 19% of world electrical production). Since then thanks to various actions from governments and industry, the electricity consumption for lighting seems to be better mastered. Since then thanks to various actions from governments and industry, the electricity consumption for lighting seems to be better mastered. As of 2019, the estimated electricity used for lighting is around 2 900 TWh stabilized (less than 1% annual growth rate), or 13.7% of the world's annual usable electricity. [2] Even if the absolute value slightly increased in the last years, the relative part of lighting reduced drastically (~5.5% annual decrease rate). The observed decrease, in percent, of used electricity, is the effect of combined effort of technological developments and worldwide energy policies.

Beyond the implication of lighting in energy, greenhouse gas emissions and abiotic resources of our planet, to evaluate the full impact of electric lighting, we shall take into account some additional side-effects like the light pollution of the skies and the associated erosion of the biotopes. Sánchez de Miguel et al., shown that the power of global satellite observable light emissions increased from 1992 to 2017 by at least 49%. [5] The same authors conclude that, even if “these dynamics vary by region, but there is limited evidence that advances in lighting technology have led to decreased emissions.” [5] This shows the absolute need to intensify and coordinate world policy efforts to harness this problem.

At a first glance, combined action of the light emitting diodes (LED) technology and minimum energy performance standards for market control are responsible for harnessing the energy demand by the lighting sector. However, this situation can be compromised by several factors, that include the LED technology limits, the inevitable world population increase, the lack of efficient incentives as well as social behaviors of the end-users. Emerging Smart Lighting technology, can override these issues, but Smart Lighting is complex technology requesting specific maintenance from well-trained people, as well as, heavy initial investments that can jam the use from a large part of world's population.

<footnote n="1">¹ LAPLACE UMR-5213; Université de Toulouse ; georges.zissis@laplace.univ-tlse.fr</footnote>

<footnote>* Correspondence: georges.zissis@laplace.univ-tlse.fr;</footnote>
In this paper we will discuss (1) the technological evolutions of smart lighting systems and its components; (2) the expected impacts of smart lighting in energy and world's resources with a special focus to developing economies, and (3) the influence of public policies to make smart lighting systems affordable by low-income areas populations.

## II. METHODOLOGY

In our work, to assess the penetration and effects of smart lighting systems, we are based on analysis of more than 175 recent (2018 and after) free accessible documents and data harvested by open access databases for more than 150 countries. That way, analyzing more than 100 000 patents have been granted for LED Lighting from 2000 to 2022, we found that 33 800 targeted smart/connected lighting and lighting controls together. It is however very interesting to analyze the annual evolution of the number of patents by segment. We found that the number of patents concerning LED and OLED lighting is declining when the segment of smart (lighting controls and connected lighting) is increasing and the analysis of national trade data shows that the number of shipments follows closely the same tendency. We can thus anticipate that in the next years and during the next decade, smart lighting systems will supersede simple SSL systems. Further, analyzing various market reports, we found that historically, in 2013, the global smart lighting market industry size exceeded USD 5.7 billion. Among them, the market size of smart lamps and related accessories exceeded USD 1,2 billion. In 2022, the market revenue for smart lighting systems has been valued at around USD 18 billion. As shown in Figure 1, based on our data harvested from the literature our forecast shows that the segment will achieve USD 90+ billion by 2035 and this is comparable with the USD 133 billion revenue achieved in 2020 by legacy lighting industry. [2]

<figure><img src="image_2.png" /><figcaption>Fig. 1. Evolution of revenue for Smart Lighting Systems</figcaption></figure>

## III. RESULTS AND DISCUSSIONS

Using current technologies, without any additional concrete action in the near future, humanity's electric light needs are foreseen to attain, by 2040, at least 285 Plmh (peta-lumen-hours is the energy carried by the generated light). This corresponds to a light demand increase of 32% compared to 2020. [1] This is not good news for our planet! However, as humans can't live normally without the possibility to produce artificial light. Thus, it is obvious that coordinated actions between engineers, governments and market actors are necessary to harness the expected increase.

In fact, since the early 2000s, the rise of Solid-State Lighting (SSL) has been considered as the 3rd revolution in the domain of lighting. That way, from 2010 to 2020, the emergence of white-LED technology could moderate the energy consumption for lighting. For instance, LED technology developed so quickly that in 2022 best LEDs lumens per watt (lm/W) offer efficacies over 200 lm/W – double the efficacy of the fluorescent technology – with high color rendering and stability. Following
K. Lane, since 2010, the average efficacy of LEDs has improved by around 4 lm/W each year. [3]. Today, the best commercialized non-directional LED lamps are in the order of 210 lm/W over 15 times more efficient than incandescent and four times more efficient than compact fluorescent lamps (CFLs). [4]

Further, since 2015, minimum energy performance standards (MEPS) are widely employed as the key driver for efficiency improvements and inefficient incandescent lamps are almost banned worldwide, and many countries are now beginning to eliminate fluorescent lighting. Figure 2 shows the relative energy used by the most common lighting technologies from 2010 extended to 2030. This graphics use data from [6] with corrections to avoid the total energy demand overestimation. The effects of incandescent lamp ban are obvious. However, as the study has been published in 2019, the fluorescent lamp ban, effective from 2023, has not been included. The graphics shows also clearly that LED-modules technology will be dominant in the next years.

<figure><img src="image_3.png" /><figcaption>Fig. 2. Evolution and forecast of relative energy use for producing light by the most common technologies.</figcaption></figure>

However, despite these efforts electricity consumption for lighting increased in 2022, with greater efficiency not offsetting increased use of lighting. Despite the falling carbon intensity of electricity, CO2 emissions from lighting rose slightly in 2022. The emissions intensity of electricity, an important factor for CO2 emissions, fell too little to offset increased lighting demand [3]. This can be a concrete expression of the well-known “Jevons paradox” (or rebound effect”). In fact, Jevons' paradox occurs when technological progress (or government policy) increases the efficiency with which a resource is used (reducing the amount needed for a given use), but the lower cost of use induces an increase in demand enough that resource use is increased rather than decreased. Figure 3 give a graphical explanation of this paradox.
<figure><img src="image_4.png" /><figcaption>Fig. 3. illustration of Jevon's paradox</figcaption></figure>

Governments typically assume that increasing efficiency will reduce resource consumption, ignoring the possibility that the Jevon's paradox may arise. This tendency, if confirmed, shall be considered with the highest attention because may be the sign of reaching some limits of “SSL beneficial effect” and that even if we expect some further technology efficacy increase during the next 5 years.

Consequently, by just offering more efficient technologies, we knowingly are still not serving society as effectively as we could. To encompass this lack efforts shall, not only intensify, but they shall explore new technological horizons, include new concepts like circular economic, sustainability and affordability; more important, to be more efficient, efforts shall be coordinated at supra-national level. The challenge for the next decade will be to harness the increase of electricity demand, limit the associated greenhouse gas emissions and avoid undesirable effects on the biotope. The only light source technology evolutions, even supported by ambitious policies, are not sufficient to stem uncontrollable growth. We need real sustainable solution synonym to light-up smart, to a sustainable and affordable way, where it is needed, when it is necessary and as best as possible!

Solid-state lighting (SSL) and more precisely LED technology offer new control opportunities, encompassing rebound effect and maximizing the energy savings using connected/smart SSL systems, will become a challenge to address all these unforeseen, or just neglected till recently, issues. Indeed, smart lighting is a technology crafted for energy efficiency. At a first glance, to save energy, controls can be coupled with sensors. An obvious example: occupancy/motion sensors detect the presence of people in a room and automatically turn lights on or off based on occupancy. This is particularly useful in spaces like hallways, bathrooms, corridors and also in parking spaces, where lights can be automatically turned off when the space is empty. This kind of sensors are also installed some time in streetlighting configurations. Further, ambient Light sensors are used in daylight harvesting in buildings. This technique involves using sensors to measure the amount of day light entering a space and then adjusting electric lighting levels accordingly. The objective is to maintain a consistent light level while minimizing energy usage. Legacy “dummy” (personal tuning) controls can save up to 21% of energy and any combination of those techniques can to higher savings. Today, the use of sensors allows to achieve much better savings assuming that daylight use is not jammed by architectural elements. Smart Lighting can achieve more than 70% additional energy. But what is smart lighting?

Generally speaking, a smart technological object, including smart lighting, is characterized by an intelligent sensing technology that is increasingly being integrated with internet technologies, thereby allowing the react to and communicate with the changing environment around it. In principle, this is
leading to optimal operation and global improvement in efficiency. Based on the fact that a such "smart" lighting system shall serve at best the human needs and reduce as much as possible the impacts on environment and biotope, Zissis et al., proposed in 2023 the following definition [2]:

"A smart lighting system has a principal function which is to produce, at any moment, the right light: where it is needed and when it is necessary. It should adapt the quantity and quality of light to enhance visual performance in agreement with the type of executed tasks. It must guarantee well-being, health and safety of the end-users. It should not squander passively the resources of our planet and limit actively the effects of light pollution on the biotope, or, any other impacts on the environment. Further, the system could offer additional optional services to the end-users".

Only the transition from the conventional legacy ("dummy") lighting technologies to "digital" driven smart lighting can do it and that because use of smart technologies assists, in the most cases, the end-user to take the good decision. That way, smart lighting is becoming the 4th revolution and it expected to be the "heart" of the "Internet of Things" in smart cities and smart buildings

To achieve such ambitious objectives to a sustainable manner, Zissis et al., introduced in 2023, the SSL² concept, that defines a "Sustainable Smart Lighting (the 1st "SSL" in SSL²) system uses and optimizes to an intelligent way the best existing technology (Solid State Lighting, the 2nd "SSL" in SSL²) to best fulfil present needs for electric light of humans and reduce undesirable side-effects, without compromising the ability of future generations to innovate." [2]. Figure 4, illustrates the SSL² concept.

<figure><img src="image_5.png" /><figcaption>Fig. 4. Illustrating the SSL² concept for lighting</figcaption></figure>

Even if SSL² concept leads to sustainable smart lighting solution, it doesn't respond to the question related to the affordability of the system. Indeed, as smart lighting system is a complex object that needs special care by specialized persons. For this kind of systems, initial investment is heavy and maintenance is expensive all over the system's life span. This may jam the use of such systems in developing economy countries and deprive poor populations/areas by the possibility to use efficient environmental-friendly technologies. Solutions are urgently needed here!

A first answer to this challenge could be the development of "modular" smart lighting systems. The initial cost of the basic system that saves energy and improves quality of life shall be affordable to all, while additional high-level functions can be more expensive and can be added on request. Why not imagine an additional tax imposed to these high-level functions that comes in reduction of the basic system cost? Policy making is needed here.

Further, it is possible to develop new economic models that implies public-private partnerships and lead to making an expensive system available at low (or zero) cost and payback the remaining cost based on energy savings and greenhouse gas reduction. In that case, concerned population has to pay
only for the final product: the used quantity of light. Collaboration between industry and governments is needed here.

Finally, to reduce maintenance costs, it is necessary to train local people as engineers and technicians to maintain the system at affordable price. Adapting or creating curricula of education organisms, at different levels, are necessary here.

## IV. CONCLUSIONS

Today, lighting is responsible for 5% of worldwide CO₂ emissions corresponding to an annual electricity demand of 2 900 TWh (13.7% of the works net electricity production). Beyond energy use and greenhouse gas released in the atmosphere, lighting has important indirect impacts on abiotic resources use (minerals), it is responsible for direct degradation of biotopes, it impacts every day's life, health and wellbeing of humans. It is however impossible to eliminate artificial light. The challenge for the next decade will be to harness the increase of electricity demand, limit the associated greenhouse gas emissions and avoid undesirable effects on the biotope. The only light source technology evolutions, even supported by ambitious policies, are not sufficient to stem uncontrollable growth. Smart Lighting technologies can be the solution to this challenge. However, the only technological solutions is neither sustainable nor affordable. We need to invent a real sustainable and affordable solution. If the SSL² concept leads to sustainable smart lighting solution, it doesn't respond to the question related to the affordability of the system. In this paper we presented some very first and simple proposals leading to affordable systems for developing economies. Are-they achievable? Are-they the best options? This paper doesn't answer these questions, but it open the ground for cross-discipline brainstorming.

**Acknowledgments**, this work has been supported by European Commission JRC-Ispra and International Energy Agency 4E-SSLC platform.

## References

[1] Zissis, G.; Kitsinelis S., Topical Review, State of art on the science and technology of electrical light sources: from the past to the future, J. Phys. D: Appl. Phys. (2009), 42, 173001 (16pp), doi: 10.1088/0022-3727/42/17/173001

[2] Zissis, G.; Bertoldi P., A Review of Advances in Lighting Systems' Technology – The way towards Lighting 4.0 era, IEEE Open Access Journal of Industry Applications, (2023), 5, pp 111-120, doi: 10.1109/OJIA.2023.3263182

[3] Lane, K., Lighting, online International Energy Agency web: https://www.iea.org/energy-system/buildings/lighting#tracking, Last update on 11 July 2023

[4] Scholand, M.; Zissis, G., Targeting 100% LED lighting sales by 2025, in Technology and innovation pathways for zero-carbon-ready buildings by 2030, International Energy Agency, online https://www.iea.org/reports/targeting-100-led-lighting-sales-by-2025, updated September 2022

[5] Sánchez de Miguel, A.; Bennie, J.; Rosenfeld, E.; Dzurjak, S.; Gaston, K.J., First Estimation of Global Trends in Nocturnal Power Emissions Reveals Acceleration of Light Pollution. MDPI Remote Sens. (2021), 13, 3311, doi.: 10.3390/rs13163311.

[6] Spectaris and Messe München GmbH report, Light as the key to global environment Sustainability, Berlin/Munich, June 2019