A Multi-Criteria Assessment Procedure for Outdoor Lighting at the Design Stage

Assessing the electricity energy efficiency of university campus exterior lighting system and proposing energy-saving strategies for carbon emission reduction

This paper presents efficiencies research and energy-saving strategies for carbon emission reduction of the exterior lighting system of Avşar Campus of Kahramanmaraş Sütçü İmam University, Turkey. Once the campus's average energy consumption for the previous five years was calculated, it was found to be 18,802 Megawatt hour/year (MWh/year), with 6,203 carbon dioxide (CO₂) tons/year emissions. Also, the annual electrical energy consumption for exterior lighting was calculated as 670,395 MWh/year, with annual emissions of 221,170 CO₂ tons/year. Inefficient lamp choices in exterior lighting systems and longer than necessary operating times have been identified as the causes of these high values. That's because High-Pressure Sodium (HPS) lamps with an installed power of 109,050 Kilowatt (kW), which have a low efficiency but a high energy consumption, provide for 70% of exterior lighting. Thus, seven unique energy-saving strategies have been designed with the aim of decreasing total energy consumption and achieving more cost savings as well as less harmful emissions released into the atmosphere. All of the strategies were designed under the following three headings: dimming method, optimization of lamps' operation times, and retrofitting lamps with new and technological ones. The study's novelty lies in the creation of seven unique energy-saving strategies for the first time in light of the three headings highlighted, as well as their adjustment to a sophisticated campus with such high energy consumption. Once all of the proposed strategies are compared to the current system, it has been discovered that strategy-7 saves 81.656% energy consumption (547,418 MWh/year), 180,599 CO₂ tons/year saving, and € 49,268 (€/year) cost-saving. Such a low energy consumption is vital for a rapidly growing and expanding campus in terms of carbon emissions, cost savings, and environmental quality.

The Effect of Spill Light on Street Lighting Energy Efficiency and Light Pollution

Street lighting is usually designed to meet luminance (or illuminance) requirements of technical standards and recommendations with minimum possible lighting installation power consumption. However, with the expansion of street lighting in growing cities caused by increasing traffic intensity, the disturbing effects of street lighting on the surroundings are often neglected in the design of lighting systems. Light emitted outside the area to be lit (spill light) causes an increase in complaints from residents and an increase in lighting installation power consumption. Therefore, this paper proposes an analysis of the effect of spill light on the energy efficiency of the street lighting systems.

Quantitative Assessment of Architectural Lighting Designs

There has recently been a great interest in the outdoor lighting that is energy-efficient and does not intensify a light pollution phenomenon. In architectural lighting, these demands are difficult to implement and rarely analyzed. However, it is possible to introduce and use certain parameters based on the utilization factor for the quantitative assessment of floodlighting design in terms of both light pollution and energy efficiency. This paper presents the definitions of new parameters and the results of their calculations for several typical architectural objects. Different lighting concepts were created for each object together with appropriate computer simulations. The research shows a high potential for usefulness of new parameters in the design process. The floodlighting utilization factor is characterized by relatively low values of around 35%. In addition, obtaining the recommended lighting power density value below 2.2 W/m2 does not sufficiently determine the correctness of the design implementation considering the natural environment. This determines a great potential for opportunities to improve the implemented designs and provides a basis for redefining the currently used approach in architectural lighting. In order to create high-quality, sustainable solutions, all quantitative parameters should be analyzed simultaneously in addition to the esthetic visual effect issue.

Lighting Standards Revisited: Introduction of a Mathematical Model for the Assessment of the Impact of Illuminance on Visual Acuity

Purpose

Primary objective of present study is to introduce a contemporary methodology for the lighting standards update addressing both normophakic and pseudophakic patients.

Methods

For the sake of our study, we theoretically estimated the intraocular-to-crystalline lens iIluminance ratio (ICIR) and the intraocular lens (IOL) luminous efficiency function V_IOL(λ) as a new lighting benefit metric. Then, in a sample of 24 pseudophakic patients (38 eyes) implanted with the trifocal diffractive IOL Panoptix (SG) and in a control group (CG) of 28 normophakic participants (50 eyes), uncorrected distance visual acuity (UDVA) was measured at illuminance of 550lx (optimal UDVA). Following dark adaptation, illuminance was gradually raised from 20 lx until illuminance level that the patient reached his/her optimal UDVA. This measured illuminance at this point was defined as the minimum required illuminance level (MRIL). MRIL and UDVA for illuminance levels between 20 and 550lx in SG were compared with the corresponding values in CG. MRIL calculation allowed the construction of a predictive mathematical model that estimates the impact of environmental lighting on UDVA.

Results

ICIR for Panoptix eyes ranged from 54.00% to 55.99%. Both groups had significantly higher UDVA at 550lx compared to 20lx (p < 0.05). CG had significantly higher UDVA than SG at 20lx (7.20 letters, p = 0.045), while no significant difference was detected at 550lx (0.40 letters, p = 0.883). SG required significantly more illuminance than CG to maintain their UDVA (MRIL_SG= 191.05lx, MRIL_CG= 122lx, p = 0.007). Our predictive model suggests suboptimal UDVA in a series of lighting directives for normophakic and Panoptix eyes.

Conclusion

This is the first study to introduce the V_IOL(λ) as a new lighting benefit metric and a mathematical model that quantifies the impact of illuminance on UDVA in normophakic and pseudophakic patients.

Clinicaltrials.gov Identifier

NCT04263636.

Reviewing the Role of Outdoor Lighting in Achieving Sustainable Development Goals

The Sustainable Development Goals (SDGs) aim at providing a healthier planet for present and future generations. At the most recent SDG summit held in 2019, Member States recognized that the achievements accomplished to date have been insufficient to achieve this mission. This paper presents a comprehensive literature review of 227 documents contextualizing outdoor lighting with SDGs, showing its potential to resolve some existing issues related to the SDG targets. From a list of 17 goals, six SDGs were identified to have relevant synergies with outdoor lighting in smart cities, including SDG 3 (Good health and well-being), SDG 11 (Sustainable cities and communities), SDG 14 (Life below water) and SDG 15 (Life on land). This review also links efficient lighting roles partially with SDG 7 (Affordable and clean energy) and SDG 13 (Climate action) through Target 7.3 and Target 13.2, respectively. This paper identifies outdoor lighting as a vector directly impacting 16 of the 50 targets in the six SDGs involved. Each section in this review discusses the main aspects of outdoor lighting by a human-centric, energy efficiency and environmental impacts. Each aspect addresses the most recent studies contributing to lighting solutions in the literature, helping us to understand the positive and negative impacts of artificial lighting on living beings. In addition, the work summarizes the proposed solutions and results tackling specific topics impacting SDG demands.

Influence of Replacement of Sodium Lamps in Park Luminaires with LED Sources of Different Closest Color Temperature on the Effect of Light Pollution and Energy Efficiency

According to the European Union (EU) regulations, EU members are obligated, among others, to improve the energy efficiency in the outdoor lighting sector. One of the ways to consider this fact is to install LED sources in luminaires. Due to the reasonable lighting requirements for the lighting of squares and parks, the cheapest way to modernize lighting is to replace conventional discharge lamps with LED sources in park luminaires. Using nine typical park luminaires, the influence of replacing classic sodium lamps with LED sources on the effect of light pollution and energy efficiency was analyzed. Using data, such as a photometric solid and a relative spectral distribution, simulation calculations were carried out in DIALux software and our own calculation tool to consider this issue. The studies considered 156 LED sources of different spectral distributions and a wide range of color temperatures from 1000 K to 9753 K as well as different color rendering index (CRI) values. The conducted studies showed that the replacement of sodium lamps with LED sources is not necessarily associated with an increased negative impact on the effect of light pollution. It was also found also that the CRI value has an influence on the degree of light pollution.

Simulation and Analysis of Floodlighting Based on 3D Computer Graphics

The paper presents the opportunities to apply computer graphics in an object floodlighting design process and in an analysis of object illumination. The course of object floodlighting design has been defined based on a virtual three-dimensional geometric model. The problems related to carrying out the analysis of lighting, calculating the average illuminance, luminance levels and determining the illuminated object surface area are also described. These parameters are directly tied with the calculations of the Floodlighting Utilisation Factor, and therefore, with the energy efficiency of the design as well as the aspects of light pollution of the natural environment. The paper shows how high an impact of the geometric model of the object has on the accuracy of photometric calculations. Very often the model contains the components that should not be taken into account in the photometric calculations. The research on what influence the purity of the geometric mesh of the illuminated object has on the obtained results is presented. It shows that the errors can be significant, but it is possible to optimise the 3D object model appropriately in order to receive the precise results. For the example object presented in this paper, removing the planes that do not constitute its external surface has caused a two-fold increase in the average illuminance and average luminance. This is dangerous because a designer who wants to achieve a specific average luminance level in their design without optimizing the model will obtain the luminance values that will actually be much higher.

Development of an Indicator System for Local Governments to Plan and Evaluate Sustainable Outdoor Lighting

Outdoor lighting offers many benefits to its users and is often considered a necessity for an active lifestyle when living in modern society. Sustainable outdoor lighting should fulfil the functional needs of the users, be cost- and energy-efficient, and result in minimal environmental impact. So far, a limited number of studies have been able to present clear strategies on how to plan and use outdoor lighting to ensure that it contributes towards sustainable development. Therefore, this study aimed to answer the following questions: (1) How many of the previously established sustainability indicators are already used by municipalities in their lighting planning? (2) Which types of indicators are not used by municipalities? Another aim of the study was to further develop the framework of sustainability indicators by adding new indicators that were identified from lighting plans of Swedish municipalities and the existing literature. In this study, lighting master plans from 16 randomly chosen Swedish municipalities with varying population sizes were analyzed. The results show that few sustainable indicators are used by the municipalities’ lighting plans, especially in the social dimension. The existing framework of sustainability indicators was developed by adding new indicators. Furthermore, 28 new indicators were identified, eight originated from new studies and the literature, and 20 originated from the municipalities’ lighting master plans. This study shows that there is a need for guidelines and recommendations for working with outdoor lighting from a sustainability perspective, especially in the social dimension of sustainability, where most of the new indicators were identified.

Virtual Reality System and Scientific Visualisation for Smart Designing and Evaluating of Lighting

The current lighting solutions, both in terms of design process and later implementation, are becoming more and more intelligent. It mainly arises from higher opportunities to use information technology (IT) processes for these purposes. Designs cover many aspects, from physiological to including technical. The paper describes the problems faced by any designers while creating, evaluating them, and presenting the final results of their work in a visualisation form. Development of virtual reality (VR) technology and augmented reality, which is now taking place before our eyes, makes us inclined to think how to use this reality in lighting technology. The article presents some examples of applying VR technology in various types of smart lighting designs, for interiors and outdoor objects. The performed computer simulations are compared to reality. Some surveys, in terms of visualization rendering, were carried out. In the article, the current capabilities and main limitations of virtual reality of lighting are discussed, as well as what can be expected in the future. The luminance analysis of the virtual reality display is carried out, which shows that this equipment can be used in lighting technology after the appropriate calibration. Moreover, an innovative lighting design system based on virtual reality is presented.

Ceiling and Wall Illumination, Utilance, and Power in Interior Lighting

The common use of electric lighting in interiors has led to the need to search for user- and environmentally-friendly solutions. In this research, the impact of the luminaires and room parameters on the selected parameters of general lighting in interiors was assessed. To achieve the objective of this work, a computer simulation and statistical analysis of results were conducted. The illuminance uniformity on work plane, ceiling and wall relative illuminances, utilance, and normalized power density of lighting installations for 432 situations were analyzed in detail. The scenarios were varied in terms of room size, reflectance, lighting class, luminaire downward luminous intensity distribution, and layout. The lighting class was a factor having the highest impact on ceiling and wall illumination, utilance, and power. It was also shown that the impact of lighting class on ceiling illumination, utilance and power, was different in interiors of various sizes. The impact of reflectances and luminaire layouts on the analyzed parameters was significantly lower. The results also demonstrated that the use of different lighting classes gave the possibility of reducing the power of general lighting in interiors at a level of 30% on average. Based on the results, a classification of energy efficiency in general lighting in interiors was also proposed. Understanding the correlations between the lighting system used and the effects achieved is helpful in obtaining comfortable and efficient lighting solutions in interiors.

Pilot Measurement of Illuminance in the Context of Light Pollution Performed with an Unmanned Aerial Vehicle

This article presents the methodology and results of pilot field illuminance measurements using an unmanned aerial vehicle (UAV). The main goal of the study was to quantify the luminous flux emitted in the upper hemisphere (toward the sky) based on obtained measurement data. The luminous flux emitted toward the sky is the source of undesirable light pollution. For test purposes, a height-adjustable mobile park lantern was constructed, at the top of which any type of luminaire can be installed. In the pilot measurements, two real opal sphere-type luminaires were considered. The lantern was situated in an open area located away from a large city agglomeration. To determine the unusable luminous flux, illuminance was measured, placing the necessary measuring equipment on board a UAV. The measurements were supplemented with the registration of illuminance on the ground upon which the lantern was installed. Based on these data, the useful luminous flux was calculated. The findings show that UAVs may be successfully used for the assessment of the influence of lighting on the light pollution effect.

Revision of Threshold Luminance Levels in Tunnels Aiming to Minimize Energy Consumption at No Cost: Methodology and Case Studies

Because of the absence of lighting calculation tools at the initial stage of tunnel design, the lighting systems are usually over-dimensioned, leading to over illumination and increased energy consumption. For this reason, a fine-tuning method for switching lighting stages according to the traffic weighted L20 luminance is proposed at no additional cost. The method was applied in a real –case scenario, where L20 luminance of the access zone at eleven (11) existing tunnels was calculated. The traffic weighted method of CR14380 was used in order to calculate the actual luminance levels for the entrance zone. The new transition zone, which decreases luminance curves, was produced and compared with the existing ones. Thus, a new switching control was proposed and programed for the Supervisory Control and Data Acquisition (SCADA) system of the tunnel. The signals of the corresponding eleven L20 meters for a period of eight days were used and the corresponding annual energy consumptions were calculated using the proposed switching program for each tunnel. The results were compared with a number of scenarios in which the existing lighting system was retrofitted with Lighting Emitting Diodes (LED) luminaires. In these scenarios, the new luminaire arrangement was based not only on the existing luminance demand value for the threshold zone, but also on the newly proposed one with two different control techniques (continuous dimming and 10% step dimming). The fine-tuning method for switching resulted in energy savings between 11% and 54% depending on the tunnel when the scenario of the existing installation at no extra cost was used. Energy savings, when LED luminaires were installed, varied between 57% (for the scenario with existing luminance demand value for the threshold zone and 10% step dimming) and 85% (for the scenario with the new calculated luminance demand and continuous dimming).