Elsevier

Measurement

Volume 136, March 2019, Pages 466-477
Measurement

Smart lighting as basic building block of smart city: An energy performance comparative case study

https://doi.org/10.1016/j.measurement.2018.12.095Get rights and content

Highlights

  • We investigated we can save optimizing delivery time and intensity of a street light.

  • Pre-defined regulation save a power consumption of 38%.

  • Traffic adaptive regulation save a power consumption of 60%.

Abstract

The aim of this work is to simulate and compare the energy savings potentially applicable to the consumption data of the Smart Street pilot system located at the ENEA Casaccia R.C. (Rome). The astronomical lighting system energy consumption (baseline) is compared to the simulation of a pre-defined regulation: it allows the lights dimming (and therefore a reduction of consumptions) based on a statistics averages of the traffic flow rate, differentiated according to the day of the week. Then the baseline consumption is compared to the simulation of an adaptive configuration based on the traffic flow rate.

Introduction

The great part of the energy consumption in Europe depends by urban areas and produces notable emissions of greenhouse gasses (GHG). Over 90 million of lighting pales count more than 50% of public energy consumption and about 60% of relative costs. Street lighting plays a relevant role both for the security and for life quality in urban areas. Innovations in lighting such as Solid State LED (SSL) promise to user an energy saving in about one half and a notable reducing of maintenance costs [1].

A forward integration with adaptive technologies for smart city, increases sustainability in line with EU policies toward a cost-efficiency lightening and guarantees a remarkable reduction of environmental impact [2], [3], [4], [5]. For these reasons, urban development policy is increasingly shifting to smart lighting as a subset of the broader concept of smart city, composed by this range of topics:

  • Smart Environment

  • Smart Energy

  • Smart Mobility

  • Smart Governance

  • Smart Economy

  • Social/Participation

  • Information and Communication Technologies (ICT)

We consider the smart lighting as a subset of the smart city that is focused on two themes: smart energy and smart mobility (see Fig. 1). It does not focus on lighting only (i.e.: through signal control and management) but it covers also other aspects, such as data connectivity, safety of citizens, energy consumption, Internet of Things (IoT) and many others [6].

The initiatives undertaken by the European Union in terms of environmental sustainability (Europe 2020 objectives) and digital innovation and the evident contraction of resources available to public administrations make necessary to adopt of new policies for territorial governance, smart solutions that can exploit the potential made available by new technologies [7], [8], [9], [10].

The energy efficiency measurements, regarding the modernization of the lighting network and the energy requalification of buildings, are in line with the Smart City model. This technology will allow to the Local Administrations to release resources for the implementation of further innovation measures, among these:

  • The rationalization of the use of the road lighting.

  • The development of Wi-Fi internet connectivity near the street lamps installed in strategic areas of the municipal area and with a higher density of users [11].

  • Info-mobility interventions that encourage an integrated development of local mobility (smart mobility), with a view to reduce travel by private car in favour of public transport, rail and bycycle mobility [12].

  • The intensification of video surveillance, thanks to the availability of broadband connections, to allow initiatives to analyse traffic flow rates and increase safety interventions [13].

  • The implementation of initiatives for tourism promotion, through the development of computer applications that can be used on the move, allowing visitors to experience the territory in an interactive manner, quickly access information on museums, in-depth areas and useful services [14], [15].

  • The installation of electric recharging points for the development of both electric and motor cycle mobility in the direction of a reduction of polluting emissions in urban spaces [16].

  • The development of protocols and devices for the IoT (Internet of Things), i.e. an intelligent network of sensors and devices distributed throughout the territory, connected to the Internet, able to detect environmental parameters and interact with the domestic users to optimize consumption [17], [18], [19].

Nevertheless, what is meant by efficient and smart lighting? Efficient lighting is a light source that, using LEDs, guarantees a lower level of energy consumption [20]. Through the use of software and hardware solutions that allow monitoring and control of the use of light sources adapting them to environmental conditions (in a broad sense), Smart lighting maximizes their effectiveness and energy efficiency [21].

According to the Graduate school of Business of “Politecnico of Milan”, the market of smart solutions for public lighting has assumed values between € 60 and € 70 million in 2015; furthermore, the difference between the adoption of LED light sources and that of smart solutions is evident. In fact, the latter, affected only about 30% of the total number of LED lights installed in 2015 and therefore represents less than 0.5% of the total public lighting infrastructure in the Italian territory.

The future use of over 650,000 LED-equipped lights has been estimated by 2020: a notable leap forward (+90%) compared to the 2015 data. In fact, if we consider the overall effect of substitutions and new infrastructures by 2020, the cumulative value of LED solutions in public lighting will be of about three and a half millions of light points: it is estimated that in 2020 the LED light source market stands at € 1.5 billion.

As regards investments, it is estimated that in 2020 the smart solutions market stood at around € 195 million: despite the significant growth compared to 2015 (+40%), it is clear that the smart technology market is slower than the one of efficient lighting solutions. The ratio between the two markets was, in 2015, equal to 6.4: the estimate rises only to 7.9 in 2020.

In the following Table 1, we see the growth prospects of public lighting over the 2015–2020 time frame [20].

The system examinated in this paper is the Smart Street pilot system located at the ENEA Casaccia R.C. (Rome) [7]: it is a public street lighting line managed in an automatic (programmable) way. the general architecture is described in detail in Section 3.

The Casaccia R.C. Smart Street system presents several innovations, including:

  • Advanced Switching system, which allows remotely managing all activities and monitoring the faults occurrences.

  • Stabilization and regulation of lighting depending on traffic status and weather conditions.

  • Tele control and data transmission (PLC).

  • “Intelligent streetlight” services (e.g., video surveillance, traffic monitoring, environmental monitoring, etc.).

In the Section 2, we will describe three real cases of application of the smart lighting philosophy and in particular “Smart Basilicata” in Potenza, the “Brescia living” project with particular reference to smart lighting and, at last, the “Life-Diademe” project in Rome. In the Section 3, we will explain in detail the various parts and subsystems of the Casaccia plant. Later, we will show all the applicable Italian regulations and their points of contact with our project. Finally, after establishing a baseline power consumption profile, we will go on to compare the simulations of the pre-defined regulation and adaptive implants.

Section snippets

Case studies and heritage

In this section, we will illustrate three typical cases of the application of the smart city concept, three case studies that show different application strategies through different technical and management solutions. Three Italian cities (Potenza, Brescia and Rome) welcome new technologies in order to improve the quality of life of citizens.

The lighting system

The Smart Street pilot site is located at the ENEA Casaccia R.C. (Rome): the system is a public street lighting line managed in an automatic (programmable) and manual way. Fig. 3 shows the general architecture. Thanks to the sensors that the system is equipped with, it is possible to program the switching of lights, according to the ephemeris tables (local sunrise and sunset), based on a pre-set and fixed timetable. The system is able to respond dynamically, thanks to the presence of smart

Standards and Norms

In our study, we will refer to various standards issued by the UNI (Italian Board for Standardization) which define the minimum services that must be guaranteed in road lighting. The parameters that allow the dimming of the light with the significant energy savings related are defined. Finally, all the instrumentation and methodologies for measuring critical parameters of lighting systems are defined.

In detail, the standards, we will refer to, are the following:

  • UNI 11248:2016“Road lighting –

TAI plant

The TAI (Traffic Adaptive Installation) is an adaptive system with a real time regulation: the operating lighting category is chosen by sampling the traffic flow rate: Fig. 5 explains the decision/logic scheme. The hourly traffic flow rate is determined by transforming the count for a period of 15 min, differentiated for vehicles, people or cycles.

TAI Algorithm constraints:

  • 1.

    Only one variation in the lighting category can be applied for each counting period.

  • 2.

    The reduction in the lighting category

Real power parameters

In the LED datasheet, it is indicated a power consumption related to a maximum intensity (100%) the value of 101 W but, considering the non-unit power factor, the load losses and 4 W of the PLC communication system, the actual power measured for each individual lamp is about 96 W.

The measured power variations are not linked by a linear function to the change in light intensity of the LED, which can be controlled via the dimmer. While, dimmer and light intensity are instead linked by a linear

Power consumption and class reduction

In the Table 5 below, we have the relationship between the power actually absorbed, the dimming performed by the LED driver, the luminous flux and the category reduction: the parameters of the last column are in reference to the relative standard.

Baseline data

This is the baseline i.e. the detection of traffic and power consumption of the system: the instantaneous consumption and the number of vehicles that have passed along the road detected every 15 min. This detection was continuous from 14/01/2018 to 07/04/2018 for a total of 12 weeks and 84 consecutive days.

In Fig. 8a, we can see the consumption of the baseline configuration while in Fig. 8b the traffic flow rate, as supplied by the system, without processing.

In Fig. 9a we can see the average

Conclusions

In this paper we investigated how much we can save on energy consumption by simply optimizing delivery times and intensities of a public street lighting managed by techniques of smart lighting. In Table 6, we can see a comparison of the total consumption between the baseline, pre-defined and adaptive regulation: the first column shows the type of regulation adopted, the second column the total consumption and the last shows the percent difference between the baselines; the last two columns

Acknowledgments

Smart Basilicata, Brescia Smart Living, are projects funded by Italian Ministry of Education, University and Research (MIUR) (Bando MIUR 2012 DD591/2012).

LIFE-DIADEME project is a project Co-funded by LIFE-Programme of the European Commission called LIFE15 CCM/IT/000110 DIADEME.

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