UŠTEDA ELEKTRIČNE ENERGIJE ZA OSVETLJENJE - ANALIZA SLUČAJA FAKULTETA TEHNIČKIH NAUKA U ČAČKU

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1 UŠTEDA ELEKTRIČNE ENERGIJE ZA OSVETLJENJE - ANALIZA SLUČAJA FAKULTETA TEHNIČKIH NAUKA U ČAČKU M. M. Šućurović *, S. M. Stojković * i S. M. Dragićević * Fakultet tehničkih nauka u Čačku, Svetog Save 65, Čačak, Srbija * Apstract: Rad prikazuje rezultate merenja osvetljenosti i iniformnosti osvetljenja, kao i teorijsku analizu uštede električne energije za predložena rešenja zamene osvetljenja u edukativnoj instituciji. Merenja su izvršena u amfiteataru površine 280 m 2 sa 366 sedećih mesta na Fakultetu tehničkih nauka (FTN) u Čačku. Ustanovljeno je da osvetljenost ne zadovoljava vrednosti propisane standardom, kao i da je potrošnja električne energije veća u poređenju sa predloženim rešenjima primene energetski efikasnog osvetljenja. Teorijska analiza poboljšanja kvaliteta osvetljenja urađena je programom DIALux, kojim je izvršena analiza zamene postojećih inkadescentnimh svetiljki sa fluorescentnim i LED svetiljkama. Dobijeni rezultati pokazuju da se predloženim rešenjima može ostvariti smanjenje ukupne snage instalisanih svetiljki i potrošnje električne energije do 65%. Ključne reči: ušteda električne energije; osvetljenje. ELECTRICAL ENERGY SAVINGS IN LIGHTING CASE STUDY OF FACULTY OF TECHNICAL SCIENCES, ČAČAK M. M. Sućurović *, S. M. Stojković * and S. M. Dragićević * Faculty of Technical Sciences, Čačak, Svetog Save 65, Čačak, Serbia* Abstract: This paper presents the results of illumination level measurements and uniformity, as well as a theoretical analysis of energy savings for the proposed lighting replacement in educational institution. Measurements were performed in lecture hall area of 280 m 2 with 366 seats at the Faculty of Technical Sciences in Čačak. It was found that the illumination level does not meet the standard values and that the power consumption is increased in comparison with proposed energy efficient lighting implementation. Theoretical analysis of improving the quality of the lighting was done in DIALux software where the replacement of existing incandescent bulbs with fluorescent and LED lamps are analysed. The results show that the proposed solution can achieve a reduction of total power of installed lights and electricity consumption by 65%. Key words: electrical energy savings; lighting. 1. INTRODUCTION The electrical energy consumption is in appreciable growth related to other energy categories, first of all due to its efficiency and cleanliness. It could be said for electrical lighting that it is first spender of electrical energy, and today it presents one important share in the electrical energy consumption. Overall demand of electrical energy for lighting on the global level is about 19% of the total electrical energy production. Over 33 billions lamps are used in the world, and they consume about 2650 TWh of electrical energy [1,2]. Lighting requires as much electricity as is produced by all gasfired generation and 15% more than produced by either hydro or nuclear power. As far as the costs are of concern, costs for consumed electrical energy, equipment and work amount nearly 360 millions of dollars. Bills for consumed electrical energy are about two thirds of that value [2]. 1

2 Globally it accounts for 650 million tones of primary energy consumption and results in the emissions of almost 1900 million tones of CO 2 [1]. Sectors which make electrical energy consumption for lighting share on several parts. Their shares are presented in Fig. 1.: 43% of electrical energy consumption belongs to commercial sector, what is assessed to about TWh; 31% of electrical energy is distributed to residential lighting, which makes 811 TWh; 18% belongs to industrial sector, and amounts 490 TWh, as 8% of overall energy is used for outdoor lighting. Figure 1. World lighing consumption shares by sectorin 2005 [1] In 27 countries of European Union, share of electrical energy used for lighting is lower than on the global level, and amounts 14%. That share is presented in Fig. 2. The largest part of lighting electricity is consumed by the tertiary sector estimated at 164 TWh representing 40.2% of lighting consumption. The rest is distributed amongst the residential sector with an estimated consumption of 84 TWh representing 20.6% of lighting consumption, the industrial sector with an estimated 100 TWh representing 24.5%, and the outdoor stationary (mostly street lighting) sector with an estimated 60 TWh representing 14.7% of the total lighting electricity consumption as can be seen in Fig. 3 [1]. Figure 2. Lighting electricity consumption in the EU [1] Figure 3. Europe lighting consumption shares by sector in 2007 It is to be noted that some luminaires present highly inefficient consumer. Incandescent bulbs converse only about 5% of electrical energy in the visible light, as remainder part of energy transforms itself to heat. Compact fluorescent lamps are characterized by about 20% of efficiency. In order inefficiency to be presented, we can compare electrical lamps and bulbs with other 2

3 household appliances. For example, electrical heaters, washing machines, and toasters converse electrical energy into heat with efficiency of 70%. Electrical motors of hear fans are of 90% efficiency. This way, it can be seen that electrical lighting is very inefficient and that consumes a lot of energy. Accordingly, in this field great amount of energy can be saved, maybe more than in any other energy sector [3]. In this paper three cases are analysed for electrical energy consumption reduction. The analysis is related to big lecture hall in Faculty of technical sciences in town Čačak. Two goals are of main concern, namely reduction of electrical energy consumption, and improving of lighting quality. The DIALux software tool, made by DIAL [4], is employed. 2. LIGHTING OF THE LECTURE HALL CURRENT SITUATION In this part of the paper, the results of illuminance level and uniformity measurements in the lecture hall of Faculty of technical sciences in town Čačak are shown [5]. Figure 4 shows the values of illuminance level in the lecture hall during the day, with combined daylight and artificial lighting. The windows are on the right side of the room, on the right to the 14th column of the seats. The effect of daylight is very intense and obvious, which results in an uneven level of illuminance. The illuminance level decreases rapidly from the windows to the center of the lecture hall. The illuminance of lx occurs only in a few places, which are located in the immediate vicinity of the windows. Figure 5 presents the measuring points, layout of the windows and the position of long desks. It is easy to see the correlation between the geometry of the room and seating arrangement as well as the windows. Moving away from the lectern to the top of the hall, the height of the luminaires in relation to the workplace decreases. This has a direct effect on the increase of illuminance level. Figure 4. Illuminance level during the day, with combined daylight and artificial lighting (left) and at night with purely artificial lighting (right) [5] During the day, with combined lighting, the level of uneven illuminance is very high. The mean illuminance value is E m = 127 lx, which is too small according to the all required standards and recommendations. The lowest values of illuminance of a workplace are lx in row 14, column 14, which cannot be seen in the chart. The illuminance level in the first two rows is also insufficient because these rows are not illuminated with light coming from the windows. This is evident from Fig. 5, which shows the positions of the first three rows in relation to the windows. The value of illuminance uniformity is the ratio of the least illuminated place and the mean value, namely, 24/127 = 0.19, while the required uniformity is higher than U 0 >0.6. It is evident that the requirements of the standards were not fulfilled. According to [6], the requisite illuminance level of the workplace in the lecture hall is 500 lx, while the illuminance level in the immediate surrounding area should be higher than 300 lx. 3

4 Figure 5. The arrangement of measuring points (left) and the layout of windows and desks (right) [5] At night, as shown in Fig.1 on the right, the illuminance is more uniform and symmetrical in relation to the center of the hall because there is no influence of daylight. The illuminance is higher in the center, and it decreases towards the ends of the hall. The mean value is = 98 lx. Even in this case the illuminance is not adequate. The value of illuminance uniformity in the immediate surrounding area in relation to the work area is satisfactory, higher than 68/80 = 0.85 (second row on the left). 3. SIMULATION MODEL Analysis of the lighting of the lecture hall is done by simulation method using DIALux 4.12 software tool. Besides for internal lighting analysis, this software tool is also intended for exterior and road lighting analysis. The software uses the database with luminaries data of great number of manufacturers [4]. Figure 6 shows vertical and horizontal dimensions of lecture hall. Maximum length and width of hall is 19.5 m and 14.5m. In the lecture hall there are 16 rows of long desks, each desk with 24 sitting places. Height is not the same in all parts of hall, what can be seen in Fig. 6 (up). The luminaries are mounted on the ceiling. The walls and ceiling are modeled by material with some reflectivity. The walls color is mahogany brown, with reflection factor of 9%. The ceiling is modeled by material s color golden yellow with reflection factor of 61%. The lecture hall is modeled by insertion of luminaries, rows of long desks, windows, radiators, blackboard, and lecturer s platform. Calculation surface is positioned to height of desks, at the angle of 17 in relation to horizontal. In this way, the calculation of illuminance level is done according to standard [6]. Length of calculation surface is 15.8 m, as width amounts 12.5 m. 4

5 Figure 6. Vertical (up) and horizontal (down) view of lecture hall with dimensions 3. ANALYSIS OF POSSIBLE SOLUTIONS OF USING NEW TYPE OF LUMINAIRES Since the illuminance level in the lecture hall is not adequate, it is needed to replace current luminaries. New standard [6] impose much stronger demands than the previous one. Second reason of present-day bad lighting is inadequate maintenance due to high height of ceiling. First of all, it is mandatory to ascertain if the chosen number and type of luminaires satisfy good lighting criteria. After that, needed installed electrical power can be calculated. The electrical power values are to be employed in the remaining part of analysis. In this paper results of analysis of the three cases are presented, namely first with fluorescent lamps and reflector, second with downlight tubes, and third with downlight luminaires with LED source of light Implementation of luminaires with fluorescent tubes First analysed case deals with possibility current incandescent luminaires to be replaced with raster luminaires with fluorescent tubes (type: ELBA FIRA DP) [7]. The luminaire contains mirror shaped aluminium reflector with two fluorescent tubes. Figure of this luminaire and its polar diagram are presented in Fig. 7. Total electrical power of one luminaire is 132 W. Calculation of lighting of lecture hall gives 28 needed pieces of these luminaires (Fig. 8). That number of 5

6 luminaires satisfies standard s demands. There are four rows with seven luminaires in each row. An average illuminance level amounts E m =537 lx, as uniformity is U 0 = Isolines of illuminance level are shown in Fig. 8 (right). Taking into account number of luminaires and electrical power of one luminaire, it is calculated that total installed electrical power amounts 3696 W. Slika 7. Photo (left) and polar diagram (right) of raster luminaire with fluorescent tubes and reflector Figure 8. View of the lecture hall (left) and isolines of illumunance level (right) if raster luminaires with fluorescent tubes are implemented 3.2. Implementation of luminaires with compact fluorescent bulbs Second analysed case shows results of lighting calculation if downlight luminaires type FBH 059 2xPL-C/2P26W [8] are implemented. These are products of Philips, and use fluorescent lamps. The FBH family of recessed downlights come complete with a highly efficient frosted aluminum reflector and polished strip faceted upper surface. They are specially designed for compact fluorescent 10W/13W/18W/26W lamps. A standard ballast is integrated with the luminaires. Photo of the luminaire and its polar diagram are shown in Fig. 9. Total electric power of one luminaire is 65.6 W. It is needed to implement 78 pieces of these luminaries (Fig. 10), if we want to satisfy standard s demand. There are six rows with 13 luminaires in each row. An average illuminance level is E m =524 lx, as uniformity amounts U 0 = Taking into account number of luminaries and electrical power of one luminaire, it is calculated that total installed electrical power amounts 5166 W. 6

7 Figure 10 shows displacement of the luminaires on the ceiling (left). In the same figure (right), isolines of illuminance level are depicted. Figure 9. Photo (left) and polar diagram (right) of the downlight luminaire with compact fluorescent lamps Figure 10. View of the lecture hall (left) and isolines of illuminance level (right) if downlight luminaires with compact fluorescent lamps are implemented 3.3. Implementation of luminaires with LED sources of light The third solution uses Philips downlight LED luminaires of type Latina LED BBS160 (BBS160 D225 1xRDLM2000/840) [9]. This lamp is a basic range of LED downlights designed for general lighting in retail and office applications. This family ensures good quality of light combined with low power consumption, which means significant energy savings compared to traditional CFL downlights. Photo of this luminaire and its polar diagram are shown in Fig. 11. Total installed electrical power of one luminaire is 30.7 W. It is calculated by DIALux that 112 pieces of luminaries are needed (Fig. 12), if we want to satisfy the standard s demands. There are seven rows with 16 luminaires in each row. An average illuminance level is E m =551 lx, as uniformity amounts U 0 = Taking into account number of luminaries and electrical power of one luminaire, it is calculated that total installed electrical power amounts 3438 W. 7

8 Figure 11. Photo (left) and polar diagram (right) of downlight luminaire with LED source of light Figure 12. Display of the lecture hall (left) and isolines of illuminance level if downlight luminaires with LED source of light are implemented (right) 4. ELECTRICAL ENERGY COMSUMPTION In the previous section several types of luminaires which can replace current ones with incandescent bulbs are defined. Values of active powers of current incandescent bulbs, as well as of those defined in Section 3 are shown in Fig. 12. As can bee seen, the difference between obsolete and modern energy saving luminaires is very pronounced. Total power of current bulbs is 9800 W, because there are 98 bulbs of 100 W powers. 8

9 Figure 13. Values of active powers of current incandescent bulbs, Case 1: fluo tube, Case 2: downlight with compact fluo luminaire (CFL), and Case 3: downlight with LED luminaires The first solution of lighting (Case 1) implements raster luminaries with fluorescent tubes and is of 3969 W installed capacity. Using these luminaries, reduction of 6104 W installed active electrical power capacity would be achieved. In per cent, that is 62.3%. The second solution consists of implementation of downlight luminaries with fluorescent lamps, and is characterized by active electrical power of 5166 W. The reduction of installed capacity for lighting would be 4683 W, or in per cent, reduction amounts 47.8%. If luminaire with LED source of light would be implemented instead of luminaire with compact fluorescent lamps, total electrical power would be 3438 W. This value of installed capacity is lower than that of current incandescent bulbs lighting for 6362 W. In per cent, the reduction is about 64.9%. As far as electrical power is concerned, the best solution is implementation of downlight luminaire with LED lamps. Using this type of luminaire, it could also be reduced electrical energy consumption. We can suppose time during which luminaries are in operation. For example, let the luminaries are operated 1080 hours a year (six hours a day, twenty days a month, and nine months a year). In that case, electrical energy consumption of current incandescent bulbs is kwh/yr. Consumptions in the three analysed cases are: Case 1: the luminaire with fluorescent lamps: 3991 kwh/yr; Case 2: downlight luminaries with fluorescent tubes: 5579 kwh/yr; Case 3: downlight luminaires with LED source of light: 3713 kwh/yr. 4. CONCLUSION Because in lighting design energy inefficient sources of light are still used, it is possible great energy savings to be achieved in this area. Analysing lighting of lecture hall of Faculty of technical sciences in town Čačak, we showed that it is possible to replace current lighting with incandescent bulbs. In this way, besides improving of lighting quality, we can get a great reducing of electrical energy consumption. Analysed cases gave three solutions, which differs to luminaires type used. All the three of luminaires satisfy standard s demands about illuminance level and uniformity. Besides, a great saving in electrical energy consumption is achieved. For the operation time of 1086 h/yr it is possible to save up to 6853 kwh/yr. In per cent, that is 64.8%. In that case the luminaire with LED source of light is employed. Currently, detailed project of lighting improvement at Faculty of technical sciences is under way. 9

10 ACKNOWLEDGEMENTS This paper is the result of the investigations carried out within the scientific Project No supported by the Ministry of Education, Science and Technological Development of the Republic of Serbia. REFERENCES [1] De Almeida, A., Santos, B., Paolo, B., Quicheron, M., Solid state lighting review Potential and challenges in Europe, Renewable and Sustainable Energy Reviews, 34 (2014), pp [2] Waide P., Tanishima S., Light's Labour's Lost: Policies for Energy Efficient Lighting OECD/IEA, Paris, [3] D. S., Ginley, D. Cahen, Fundamentals of Materials for Energy and Environmental Sustainability, Cambridge University Press, Cambridge, [4] DIAL [5] Stojkovic, S., Dragicevic, S., Measurements and analysis of the illuminance level in educational institutions in Cacak, Proceedings, The Fifth Conference, BALKAN LIGHT 2012, Belgrade, Serbia, October 3-6, 2012, pp [6] European Standard EN /2011, Light and lightning Lighting of work places Part 1: Indoor work places [7] 3%20MATIS.pdf [8] [9] [10] neutralweiss-philips.html 10