Technical–Economic Analysis of the Solutions for the Modernization of Lighting Systems

Round 1

Reviewer 1 Report

The manuscript reports technical and economic analysis of the lighting system at the Babes-Bolyai University Sports Hall. The analysis shows that the investment for LED lighting system is amortized within a maximum of 17 months. 

1. The introduction of this manuscript is too long, and the background knowledge introduced in the first five paragraphs is too broad. The author should simplify and revise the introduction and quickly introduce the research topic that replacement of lighting system.

2. The value of illuminance including Emin, Emax and Emed is obtained by using the luxmeter in Table 2. How long does it take to test each time with the luxmeter?

3. As we all know, global energy prices have fluctuated sharply since 2022. If the electricity price in Romania rises in the future, what kind of impact will it have on the conclusion of this manuscript?

4. The word "Led" in line 121 should be "LED".

Author Response

Dear Reviewer,

Thank you for your careful analysis of our work. We have taken into account your suggestions and recommendations.

 

Comments and Suggestions for Authors

The manuscript reports technical and economic analysis of the lighting system at the Babes-Bolyai University Sports Hall. The analysis shows that the investment for LED lighting system is amortized within a maximum of 17 months. 

1. The introduction of this manuscript is too long, and the background knowledge introduced in the first five paragraphs is too broad. The author should simplify and revise the introduction and quickly introduce the research topic that replacement of lighting system.

We have revised and reformulated the introduction:

The European and global energy crisis, as well as the continuing rise in the price of electricity, are leading to a slowdown in activity, especially for large energy consumers, thus having a negative impact on the workforce [1]. This requires measures for rational use and optimization of energy consumption.

In the case of household consumers, reducing the demand for electricity can be done by using sustainable and energy-efficient systems.

In some cases these light sources are high consumers of electricity and lead to alteration of the quality of the electricity by the deformation of the voltage and current waveform [4] caused by the introduction of harmonics. These reduce the puere factor [5] and cause reactive energy costs.

Respecting the quality indicators of the lighting systems is a necessity. It is known that lighting values above and below the limits given in the standards may cause certain diseases to occur to persons working in that area, such us: eye fatigue, headaches, sleep disturbances, etc.

Optimal operating solutions are also implemented to reduce power consumption (dimming depending on a pre-set timetable [7], smart remote measurement and control systems with GPS, GPRS/4G technology [8], automatic detection of people, environmental conditions, lighting defects [9]).

In the case of street lighting, an appropriate level of lighting helps pedestrians to detect obstacles and recognize facial emotions [14], gives a sense of security for people who work outdoors at night [15], and can also reduce the risk. of crime or robbery by the jump of ambient light [16].

2. The value of illuminance including Emin, Emax and Emed is obtained by using the luxmeter in Table 2. How long does it take to test each time with the luxmeter?

We have introduced the following explanation:

In order to perform the measurements, it was necessary for the lighting sources to be connected at least 20 minutes in advance, so that the luminous flux emitted by them was stabilized. After exposing the photosensitive cell to the luxmeter, an adjustment time was required at a certain illumination level, so a time of approximately 5 minutes was required for each measurement performed, so that the measured value could be stabilized.

3. As we all know, global energy prices have fluctuated sharply since 2022. If the electricity price in Romania rises in the future, what kind of impact will it have on the conclusion of this manuscript?

We have come to the following conclusion:

Given the fact that the prices of lighting sources and especially of electricity have increased a lot since 2022, the investment in replacing the classic lighting systems will pay off quickly. Thus, the proposed solution is a priority, which will contribute to increasing energy efficiency and the sustainability of lighting systems.

4. The word "Led" in line 121 should be "LED".

The word Led in line 121 has been replaced by LED.

Author Response File: Author Response.pdf

Reviewer 2 Report

Dear authors,

your paper is interesting, but outdated. You're remplacing very low yield technologies by highly efficient ones, so the ROI is quite short. This kind of outcome does not come to a surprise for peoples working in the field.

It could be accepted if there were some innovation, like f.i. presence detection; or comparing the energy balance of one room with presence detection and lamp dimming to one with fixed switch-on / switch-off time.

Another potential innovation is to analyze how to handle rooms with very high ceiling and finding some way to ensure lamp lifetime is quite high.

Without innovative content, the paper can not be accepted in its present state.

 

Author Response

Dear Reviewer,

Thank you for your careful analysis of our work. We have taken into account your suggestions and recommendations.

 

Comments and Suggestions for Authors

Dear authors,

your paper is interesting, but outdated. You're remplacing very low yield technologies by highly efficient ones, so the ROI is quite short. This kind of outcome does not come to a surprise for peoples working in the field.

 

Regarding the fact that the work is outdated, we agree that the replacement of lighting sources with energy efficient sources is not a novelty, being applied by many entities globally, but one must take into account their number in the geographical area where the study was conducted (context in which the Green Deal package was adopted at European level, being available for projects that are part of the logic of green energy adoption and energy efficiency, including improving the energy efficiency of buildings). Furthermore we consider that it is not enough to just replace the sources, without making a thorough analysis of the type of sources to be chosen and their characteristics (emitted flux, photometric curve, color temperature, protection factor, lifespan), reported to the characteristics of the space in which they will be located and the activities that take place in that space (sports activities). In the paper we also presented the luminotechnical coefficients resulting from the numerous measurements and calculations, which establishes the quality of the luminotechnical lighting system. In Romania, due to the level of financing granted to educational institutions, such investments did not have priority, the funds received were used responsibly for laboratory equipment, maintenance of buildings in optimal technical parameters, and on the energy efficiency level were taken into account: exterior insulation, installation of double-glazed windows and heating systems, leaving out changing the lighting system. This analysis was carried out to identify the solution to reduce energy consumption, using minimum investment costs, so as to achieve the optimum between the funds invested and the reduction of energy consumption.

 

 

 

 

It could be accepted if there were some innovation, like f.i. presence detection; or comparing the energy balance of one room with presence detection and lamp dimming to one with fixed switch-on / switch-off time.

Another potential innovation is to analyze how to handle rooms with very high ceiling and finding some way to ensure lamp lifetime is quite high.

Without innovative content, the paper can not be accepted in its present state.

 

In order to highlight the need to use other methods of reducing electricity we have included in the introduction:

Other solutions that help reduce electricity consumption are the use of light dimming systems emitted by lighting sources. A study carried out in 115 metro stations in Barcelona found that by using intelligent lighting control systems, depending on the occupancy of the stations, a reduction of 36.22% in the basic consumption of lighting systems was achieved [32 ]. A similar percentage reduction in electricity (30% was also identified in the case of street lighting that uses an adaptive lighting system depending on traffic conditions [33].  Moreover, in order to ensure an adequate level of lighting, it is necessary to periodically clean the lighting systems [32].

In Romania, there are a large number of educational institutions that have an outdated lighting system and are large consumers of energy. The share of funds allocated for the purchase of lighting systems to reduce energy consumption is low. This paper shows the savings that are made only by replacing lighting sources with energy efficient sources, without considering the use of modern technologies for detecting the presence or reducing the luminous flux according to a predetermined schedule or by the light from outside

 

In the Results chapter we have introduced the following analysis:

If it is considered that presence sensors are introduced in the current lighting system (except for the lighting system in the halls where there are sports activities) and the average duration of operation of the lighting sources in the analyzed spaces (except for the handball and gym rooms) is 2 hours / day it is determined:

• the amount of energy consumed by the current lighting system: (13)

where P_t1 represents the power in the lighting system with sensors and Pt2 represents the power in the lighting system without sensors. There is a 15.55% reduction compared to the situation in which the lighting system does not have presence detection sensors.

• the amount of energy consumed by the proposed lighting system:

                               (14)

There is a reduction in energy consumption of 64.1% compared to the situation in which the lighting system would be maintained and presence detection sensors would be introduced in transit areas and a reduction of 69.69% compared to the current situation.

 

In the conclusions, we have introduced the following:

If the modernization of the analyzed lighting system would only consider the replacement of sources and the installation of presence detection sensors, for the analyzed situation the energy consumed would be reduced by approximately 69.69%, so a substantial reduction. The analysis did not take into account the energy consumption of the sensors and their frequency of use, this being the subject of a future analysis (during the pandemic, such measurements could not be made as the spaces were not used to their full capacity due to the imposed legislative restrictions).

 

In the chapter on discussions, we have introduced some innovations that can contribute to further reducing the electricity consumed:

The solution for replacing lighting sources can be complemented by other solutions that contribute to even lower power consumption. Thus, there can be installed presence detection sensors and the lighting level can be reduced by dimming systems. We can conclude that the more complete and complex is the technical solution for modernizing the lighting system, the lower is the energy consumption.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and suggestions for Authors:

The topic is interesting and it is adapt to this journal. There are few comments and/or suggestions to improve the manuscript.

 

-Clarify better the innovation of this work in the abstract and in the main text.

 

-A short paragraph introducing the problem statement should be included at the end of the Introduction section. What is the central problem in a sentence that manuscript wants to solve?

 

-Please, avoid lumped references. What is the contribution of each reference?

 

-Please search references to the equations. Equations should always be accurately and clearly referenced. 

 

-The technical parameters of the instrument shown in Figure 1 shall be presented in a table and the accuracy of the instrument shall be described. The calibration characteristic of the instrument shall also be described.

 

-RON should be converted into EUR or USD to make the results more internationally understandable.

 

-The discussion and conclusion chapter should be divided into a discussion and a conclusion chapter, according to the MDPI specification.

 

-Extend the conclusion with more general usability. What are the benefits of the results in a global context? Please explain this better in the manuscript.

 

-At the end of the study need to create a nomenclature / abbreviation table with units.

Author Response

Dear Reviewer,

Thank you for your careful analysis of our work. We have taken into account your suggestions and recommendations.

 

Comments and suggestions for Authors:

The topic is interesting and it is adapt to this journal. There are few comments and/or suggestions to improve the manuscript.

 

-Clarify better the innovation of this work in the abstract and in the main text.

 

In the abstract we introduced the innovative character of the work:

 

The innovative aspect is based on linking the measurements with the determination of power and the proposal of modernization solutions, which shows the need for investments to ensure the quality of the system and the increase of energy efficiency.

 

In the introduction we presented the innovative character of the paper:

 

The innovative aspect of the study is based on presenting the photometric measurements and the calculation of the luminotechnical coefficients, combined with the measurement of the installed power and the total installed power in each space and with the modernization proposal, respectively with the calculation of the installed capacity in the lighting system proposed. In order to keep the investment as low as possible, we have only proposed to replace the current sources with LED sources, keeping the same luminaires.

 

 

 

-A short paragraph introducing the problem statement should be included at the end of the Introduction section. What is the central problem in a sentence that manuscript wants to solve?

 

At the end of the Introduction section we mentioned:

 

If we replace the current lighting sources with energy efficient ones, the electricity consumption will be reduced by more than 50%, simultaneously with the realization of a lighting system that meets the quality luminotechnical coefficients, provided in the standards.

 

-Please, avoid lumped references. What is the contribution of each reference?

We removed all grouped references and specified the contribution of each reference. We have kept grouped only the references that indicate the calculation relations of the photometric coefficients, because all four bibliographic sources have the same relations.

Optimal operating solutions are also implemented to reduce power consumption (dimming depending on a pre-set timetable [7], smart remote measurement and control systems with GPS, GPRS/4G technology [8], automatic detection of people, environmental conditions, lighting defects [9]).

If after replacement of light sources the lighting quality indicators are not within the range indicated, a design optimization is required using specialized software [19], which means finding the optimal solution for positioning the stalk [20], the length and inclination of the harp [20], the source of illumination, according to the photometric curve [22].

 

 

-Please search references to the equations. Equations should always be accurately and clearly referenced. 

 

We have introduced references to the equations described in the methodology used in the analysis. The relations to which we did not mention the bibliographic sources and those in the results were adapted for the current case study.

 

-           installed power capacity in each area (area a) calculated according to the number of lighting sources and their power [34] by the relation:

 

-           total installed power capacity in the lighting system at Moroasa Sports Hall, calculated according to the powers installed in each space [34], by the relation:

 

 

-The technical parameters of the instrument shown in Figure 1 shall be presented in a table and the accuracy of the instrument shall be described. The calibration characteristic of the instrument shall also be described.

 

We presented the technical parametric table of the instrument, we described its accuracy and calibration.

 

The measurement of the illumination values was performed using the digital lux meter shown in fig. 1, which technical parameters are presented in Table 1 [33].

Table 1 Technical parameters of the digital lux meter

Measurement unit                        [lx]	Measurement errors [lx]
0 ÷ 20	0.01
0 ÷ 200	0.1
0 ÷ 2000	1
0 ÷ 20000	10

 

 The luxmeter belongs to the UNitest range, it was manufactured in accordance with the ISO 9002 - NFX 50-121 Standard, and the calibration is done at 3 years, using a standard light source, with a color temperature of 2856 K. The luxmeter is powered by a 9 V battery, the disply is LCD digits. The use of the luxmeter for measurements is done only after exposing the photocell, for 15 minutes, to ambient lighting, to stabilize the phenomenon of photometric conversion.

 

 

-RON should be converted into EUR or USD to make the results more internationally understandable.

 

In the paper we converted RON to EUR

 

 

-The discussion and conclusion chapter should be divided into a discussion and a conclusion chapter, according to the MDPI specification.

 

The discussion and conclusions chapter was divided into discussions and conclusions, according to your indications and MDPI recommendations.

 

 

-Extend the conclusion with more general usability. What are the benefits of the results in a global context? Please explain this better in the manuscript.

We have extended the conclusion to a general use.

 

The resulting conclusions show the need for technical and economic analysis of the lighting systems used. In the context of EU government funding for energy efficiency projects, even a modernization based solely on the replacement of lighting sources leads to a substantial reduction in electricity consumption.

-At the end of the study need to create a nomenclature / abbreviation table with units.

We have made the table with abbreviations.

Author Response File: Author Response.pdf