Lighting Res. Technol. 2015; Vol. 47: 740–759

Lighting energy performance determination for Turkey FS Yılmaz MSc, Arch and AK Yener PhD Faculty of Architecture, Istanbul Technical University, Istanbul, Turkey Received 18 February 2014; Revised 24 May 2014; Accepted 5 June 2014 Energy certification of buildings is promoted by the current energy policy of the European Union. The Building Energy Performance Regulation was published in 2002 and since then several studies have been conducted in European countries. The lighting energy requirements of buildings are determined using the methodology described in the European Standard EN 15193 which takes into account the required visual comfort conditions. In Turkey, a new national calculation methodology, Building Energy Performance-Turkey (BEP-TR), has been developed based on Turkey’s particular conditions. In this paper, the BEP-TR lighting module is briefly described. Its use is then demonstrated by the prediction of the lighting energy requirements for a prototype primary school classroom in different locations in Turkey. The paper also performs a sensitivity analysis of the BEP-TR methodology on the developed daylighting and electric lighting design alternatives.

1. Introduction Energy efficiency and sustainability are fundamental topics in architecture due to growing energy demand and excessive consumption of energy and other natural resources. It is stated by the European Commission that 50% of energy demand in the EU is currently provided by imported supplies and this is estimated to reach 70% in the next 20–30 years.1 It is known that there is a close interaction between energy use in buildings and environmental responsive building design. Therefore, the building design phase should represent a major route to reducing energy consumption. Buildings consume about 40% of all energy and Address for correspondence: Feride Sener Yılmaz, Faculty of Architecture, Istanbul Technical University, 34437 Istanbul, Turkey. E-mail: [email protected]  The Chartered Institution of Building Services Engineers 2014

generate about 33% of greenhouse gases in Europe.2 Considering this remarkable amount of energy consumed by the building sector, the current energy policy of the European Union aims to reduce the energy consumption and CO2 emissions of buildings. The Energy Performance of Buildings Directive (EPBD) 2002/91/EC requires all EU countries to enhance their building regulations and introduce energy certification methodologies for buildings in order to monitor and reduce energy consumption.3,4 The European Standard EN 15193 Energy Performance of Buildings – Energy Requirements for Lighting specifies a calculation methodology for the evaluation of lighting energy used for indoor lighting on an annual basis and provides a numerical indicator for certification purposes, which can be used for existing and for new or renovated buildings.5 The European 10.1177/1477153514541455

Lighting energy performance determination for Turkey Standard EN 12464-1 Light and Lighting – Lighting of Work Places – Part 1: Indoor Work Places defines lighting requirements for indoor work areas that should be followed in order to obtain proper lighting solutions.6 Turkey, being a candidate member of the European Union, has approved the Building Energy Performance Method with several adaptations to meet Turkey’s specific conditions. In Turkey, an Energy Efficiency Law was published in May 2007 with the aim of promoting the efficient use of energy and the protection of the environment.7 Following this law, the Building Energy Performance Regulation was accepted in December 2008 by the Ministry of Public Works and Settlement and a team was formed to develop a national calculation methodology for Turkey.8 The Building Energy PerformanceTurkey (BEP-TR) method and calculation tool was prepared in 2010.9 The lighting module of BEP-TR has been prepared based on EN 15193 with several modifications designed to meet Turkey’s diverse conditions.10 In the development of the BEP-TR Lighting Methodology, lighting team members took an active role in consulting for the Turkish Ministry of Public Works and Settlement and participated in several national and international workshops associated with the adaptation of related CEN standards for defining a national energy performance calculation methodology in Turkey.11 The developed BEP-TR methodology was approved by a national technical referee committee. A number of national/ international papers dealing with the BEP-TR Lighting Module have been presented by the BEP-TR lighting team members in order to exchange ideas, discuss common problems and local solutions on a scientific basis.12–15 This paper examines the process of adapting EN 15193 and the potential performance of the developed BEP-TR

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methodology for Turkey’s specific conditions using the example of a prototype primary school building. The aim of this paper is to explore the effects of different design options on visual comfort conditions and lighting energy requirements of spaces through a case study using the BEP-TR methodology. Since primary school buildings constitute an important sector of the total building stock, energy reduction in these buildings is essential. As primary school buildings have occupancy hours generally coinciding with the daylight hours, large energy savings should be reached when proper daylighting systems are used in educational buildings.

2. Implementation of the BEP-TR lighting module The BEP-TR lighting module has been prepared based on the comprehensive method specified in EN 15193 but with several modifications to take into account Turkey’s national and geographical conditions. In this part, general information on the lighting energy performance determination in buildings according to BEP-TR is given. In the implementation process of BEP-TR, providing visual comfort conditions according to EN 12464-1 is a prerequisite. The total annual lighting energy requirement of a building is the sum of energy used for illumination and luminaire parasitic energy as shown in equation (1). Wt ¼ WL, t þ WP, t ðkWhÞ

ð1Þ

where WL,t WP,t

energy used for illumination (kWh) luminaire parasitic energy (kWh) Lighting Res. Technol. 2015; 47: 740–759

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The energy used for illumination is calculated using equation (2). n WL, t ¼ ðPn  Fc Þ  ½ðtD  Fo  FD Þ o þ ðtN  Fo Þ =1000 ðkWhÞ ð2Þ where Pn Fc tD tN Fo FD

total installed lighting power (W) constant illuminance factor daylight time usage (h) non-daylight time usage (h) occupancy dependency factor daylight dependency factor

Pn is the total installed lighting power in a room. This is dependent on light source selection. The constant illuminance factor (Fc) relates to the usage of the total installed power when constant illuminance control is in operation. The daylight time usage (tD) and non-daylight time usage (tN) depend on the occupation period of the investigated building type and the daylight hours of the given location. Daylight hours are the hours between sunrise and sunset, the difference between sunrise and sunset defines the astronomically possible sunshine duration at a certain location. EN 15193 specifies default tD and tN values for different building types and it is additionally noted that national values are to be substituted. In the implementation process for the BEP-TR lighting module, these values are obtained considering the location of different cities as well as the occupation period of different building types in Turkey. The occupancy dependency factor (FO) depends on the proportion of the time that the space is unoccupied as well as the occupancy-dependent lighting control system factor. The daylight dependency factor (FD) depends on the daylight penetration into the space, the daylight supply factor and the Lighting Res. Technol. 2015; 47: 740–759

daylight dependent electric lighting control and it is calculated on an annual basis. The luminaire parasitic energy (WP,t) is the energy consumed in period t by the charging circuit of any emergency lighting luminaires and by the standby control system controlling the luminaires when the luminaires are not operating. This can be established using equation (3). In order to apply this equation, certain stand-by power values of emergency lighting systems and lighting control systems should be obtained from their manufacturers.     WP, t ¼ Ppc  ty  ðtD þ tN Þ þ ðPem  tem Þ =1000 ðkWhÞ

ð3Þ

where Ppc total installed parasitic power of the controls in the room or zone (W) ty standard time year (h) (8760 hours) tD daylight time usage (h) tN non-daylight time usage (h) Pem total installed charging power of the emergency lighting luminaires in the room or zone (W) tem emergency lighting charge time (h)

The Lighting Energy Numeric Indicator (LENI) is a measure used for the classification of the energy used in a building as defined in EN 15193. This value is used to compare the energy consumption of the buildings with similar functions but with different dimensions and configurations. In the BEP-TR lighting methodology, AESG which is similar to LENI but with Turkish expression is specified. The AESG of the examined building is compared to the AESG of a reference building. According to this comparison, the energy consumption of the building is defined. With the AESG indicator, it is possible to classify the lighting energy requirements of buildings for certification.

Lighting energy performance determination for Turkey The calculation of the AESG is given in equation (4).  AESG ¼ W=A ðkWh=m2  year ð4Þ where W total annual lighting energy consumption including the parasitic power (kWh/year) A total area of the building (m2).

3. Lighting energy performance determination using BEP-TR In this part of the study, the BEP-TR methodology is applied to a prototype primary school. Primary school buildings should be carefully designed to present adequate visual comfort conditions in order to protect the eyehealth of their young users, keep their learning performance at a high level and provide them with psychologically and physiologically pleasing conditions. In Turkey, several prototype projects have been developed by the Ministry of National Education for primary schools to be constructed with a standard architecture. In order to reduce the lighting energy consumption, electric lighting should be designed as a complement to daylight and luminaires should be controlled with respect to daylight availability in the classrooms. Hence, the optimum design of primary school classrooms is important in order to obtain comfortable conditions while reducing their energy consumption. Since Turkey is a country lying between latitudes 368 and 428 N, and longitudes 268 and 458 E with diverse geographic conditions, several climate conditions occur resulting in different daylighting conditions. According to the results of a previous study, five main climate types dominate Turkey. They are temperate-dry, hot-humid, hot-dry, cold and temperate-humid.16 This study covers five different locations in Turkey

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Table 1 City location and representative climate type Cities

Representative climate type

Latitude

Ankara Antalya Diyarbakır Erzurum Istanbul

Temperate-dry Hot-humid Hot-dry Cold Temperate-humid

408 368 378 398 408

000 540 540 060 540

N N N N N

Longitude 328 308 408 418 298

540 420 120 240 060

E E E E E

using cities representative of these climate types (Table 1). Each of these cities shows variations in terms of their location, cloud cover ratio, sunshine duration, number of sunny days annually and turbidity index, and therefore have different external illuminances. Amongst these cities, Istanbul is most northern at a latitude of 408 540 N, Antalya is most southern at a latitude of 368 540 N, Erzurum is located furthest east with at a longitude of 418 240 E and Istanbul is furthest west at a longitude of 298 060 E. 3.1. The investigated classroom The investigated prototype primary school classroom has dimensions of 7.95 m  6.65 m with a 3.2 m height. The classroom’s total area is 52.86 m2. The reflectances of the internal surfaces are in the recommended ranges given in EN 12464 (ceiling 70%, walls 50%, floor 20%). There are no external obstructions and windows have no solar control devices. The reference plane height (m) is taken as 0.67 m. The occupation time of the school building is between 08.00 hours and 17.00 hours and the building is not occupied during the summer holiday (July–September).17 3.2. Design alternatives The design alternatives are of three types: daylighting design alternatives, electric lighting design alternatives and lighting control alternatives. 3.2.1. Daylighting design alternatives

Daylight is supplied through three side windows for the base case classroom. Lighting Res. Technol. 2015; 47: 740–759

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Table 2 Daylighting design scenarios Daylighting scenarios

Transparency ratio

Obstruction

Shading device

Glazing type

D1 D2 D3

Transparency ratio variations

27.6% 40% 50%

No No No

No No No

Clear glazing Clear glazing Clear glazing

D4 D5 D6

Presence of external obstruction

27.6% 40% 50%

Yes Yes Yes

No No No

Clear glazing Clear glazing Clear glazing

D7 D8 D9 D10 D11 D12

Presence of shading device

27.6% 40% 50% 27.6% 40% 50%

No No No No No No

Yes Yes Yes No No No

Clear glazing Clear glazing Clear glazing Low-E glazing Low-E glazing Low-E glazing

Presence of low-E glazing

Each window’s dimensions are 1.3 m  1.8 m constituting a transparency ratio of 27.6%. Double layer clear glazing is used in this classroom with a light transmittance value of 80%. The base case is assumed to be oriented south and the windows are unobstructed. The windows do not have any solar control devices in the base case daylight scenario. The developed scenarios of the selected space take the form of transparency ratio variations, presence or non-presence of external obstructions, glazing type variations and presence of solar control devices where essential. A total of 12 daylight scenarios are developed and evaluated for the five representative cities. Therefore 60 different daylighting scenarios are obtained. These daylighting design scenarios are presented in Table 2. In Table 2, three different transparency ratios are suggested and named as D1, D2 and D3. The availability of daylight is reduced in dense urban environments therefore in order to further evaluate the impact of neighbouring buildings on the lighting energy performance; presence of an external continuous obstruction across the windows is introduced in daylight scenarios D4, D5 and D6. The obstruction angle is considered as 308, measured from the centre part of the window. A shading device is suggested for obstructing direct sunlight. Therefore, a solar control Lighting Res. Technol. 2015; 47: 740–759

device with a profile angle of 458 is proposed for the scenarios D7, D8 and D9. The proposed shading device which is a metal fixed ‘L’ shaped element with a reflectance of 50% helps to control the penetration of direct sunlight into the south-facing classroom. A section of the shading device is shown in Figure 1a and a view of the fac¸ade with integrated shading device is presented in Figure 1b. In order to evaluate the impact of glazing material selection on the lighting energy performance, two kinds of glazing materials are implemented in the daylight scenarios. Both of these glazing types are available and commonly used in the Turkish construction market.18 Scenarios D1–D9 are designed to have clear double glazing with a visible transmittance value of 80% having a thickness of 8 mm (4 þ 4 mm). Scenarios D10, D11 and D12 are designed to have low-E coated glazing in order to provide control of heat gains and losses through windows while permitting daylight transmission. Selected low-E glazing has a visible transmittance value of 69% and a thickness of 12 mm (6 þ 6 mm). 3.2.2. Electric lighting design alternatives

In order to determine the energy performance of buildings using the BEP-TR methodology, the electric lighting system should be designed to comply with EN 12464-1, so this

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180

50

Lighting energy performance determination for Turkey

90

45°

(a)

(b)

Figure 1 Proposed shading device section (a) and its integration with the fac¸ade (b)

Table 3 Electric lighting design scenarios (in the luminous intensity distribution figures C0–C180 ¼ solid line, C90–C270 ¼ dashed line) Electric lighting scenarios

Luminaire and luminous intensity distribution

A1

Lamp type: Tubular fluorescent (2 x T26 36 W/840) Luminaire type: Direct, surface mounted. Luminaire luminous flux: 6200 lm Ra: 80 UGR: 519 Luminaire wattage 71 W

A2

Lamp type: LED Luminaire type: Direct, surface mounted Luminaire luminous flux: 3350 lm Ra: 480 UGR 519 Luminaire wattage: 47 W

is a prerequisite for the BEP-TR Lighting Module. The required illuminance in classrooms is 300 lux, the maximum unified glare rating (UGR) is 19, the minimum colour rendering index (Ra) of the light sources selected is 80 and the minimum illuminance uniformity is 0.6. In the prototype primary

school classroom’s lighting projects, the light sources to be used are specified as 2  36 W fluorescent lamps. In this study, an alternative light source is proposed. In Table 3, the details and the photometric data for the electric lighting design alternatives are presented. Lighting Res. Technol. 2015; 47: 740–759

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The first electric lighting alternative (A1) consists of six direct, surface mounted luminaires equipped with tubular fluorescent lamps (2  T26 36 W/840). This luminaire has a total luminaire luminous flux of 6200 lm, a luminaire wattage of 71 W and the lamps have a colour rendering index (Ra) of 80. The light output ratio (LOR) of this luminaire is 53%, representing the proposed luminaire for the prototype primary school classrooms. The visual comfort conditions are evaluated for this proposal by using the Dialux Lighting Simulation Program.19 According to the obtained simulation results, the calculated average illuminance within the classroom for A1 is 308 lux. The uniformity calculated on the desk area is 0.701. UGR levels are calculated for two different positions representing the student’s and teacher’s field of view and the obtained UGR results lie between 15 and 18 which is below 19 as specified in EN 12464. The second electric lighting alternative (A2) uses a lower luminaire wattage and a newer luminaire technology (LOR: 100%) using 6 LED luminaires each with a wattage of 47 W. The proposed luminaire has a luminous flux of 3350 lm and a colour rendering index (Ra) greater than 80. For alternative A2, an average illuminance of 307 lux is obtained on the horizontal work plane. The calculated UGR values are in the range 10–17. The illuminance uniformity calculated on the desk area is 0.712. It is apparent that both electric lighting schemes meet all the criteria for classrooms specified in EN 12464-1:2011. The calculated illuminance distributions for A1 (a) and A2 (b) are given in Figure 2. 3.2.3. Lighting control strategies

Lighting controls are essential components of lighting systems, serving multiple purposes and ranging from simple to advanced control types.20 According to EN 15193, lighting control systems are mainly classified into Lighting Res. Technol. 2015; 47: 740–759

two groups: systems with or without automatic presence or absence detection. In this part of the study, a total of six lighting control types that are also cited in EN 15193 are applied to scenarios (A1 and A2) and each of them are given a name (C1–C6). Details of the proposed lighting control scenarios are given in Table 4. These scenarios use appropriate lighting control equipment with the necessary product details being obtained from their manufacturer. C1 represents the manual control of luminaires in the classroom. In addition to this, an automatic signal may also be included which automatically switches off the luminaire at least once a day to avoid needless operation during the night (C2). C3 represents the control system switching the luminaires automatically on whenever there is presence in the space, and automatically switching them to a state with reduced light output (of no more than 20% of the normal ‘on state’) no later than 5 minutes after the last presence in the space is detected. In addition, no later than 5 minutes after the last presence in the room as a whole is detected, the luminaires are automatically and fully switched off. C4 represents the control system that switches the luminaires automatically on whenever there is presence in the space, and automatically switches them entirely off no later than 15 minutes after the last presence is detected in the illuminated area. For C5, lighting control can only be switched on by a manual switch in the area and, if not switched off manually, the system is automatically switched to a state with reduced light output (of no more than 20% of the normal ‘‘on state’) by the automatic control system no later than 15 minutes after the last presence in the illuminated area is detected. In addition, no later than 15 minutes after the last presence in the room as a whole is detected, the luminaires are automatically and fully switched off. Finally for C6, switching on of the luminaires is done manually and when

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6.65m

(a)

6.00 5.42 5.13

0.80 0.50 0.00 0.00 0.50

1.80

3.10

4.40

5.70

7.00 7.45 7.95m

6.65m

(b)

6.00 5.42 5.13

0.80 0.50 0.00 0.00 0.50

1.80

3.10

4.40

5.70

7.00 7.45 7.95m

Figure 2 Illuminance distribution in classroom for scenario A1 (Eav: 308 lux) (a) and scenario A2 (Eav: 307 lux) (b)

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Table 4 Lighting control scenarios

non-daylight time usage (h), an occupancy dependency factor and a daylight dependency factor.

Systems without automatic presence or absence detection Manual on/off switch Manual on/off switch þ additional automatic sweeping extinction signal

C1 C2

Systems with automatic presence or absence detection Auto on/dimmed Auto on/auto off Manual on/dimmed Manual on/auto off

C3 C4 C5 C6

they are not switched off manually, they are automatically and entirely switched off by the automatic control system no later than 15 minutes after the last presence is detected in the classroom.5 Twin lamp circuit DALI electronic ballasts with a dimming range of 1–100% are proposed with a stand-by power of 0.3 W and a circuit power of 70.5 W each for A1.21 For scenario A2, LED drivers with a dimming range of 1–100% are used with a standby power of 0.4 W and a circuit power of 77 W assuming full load at 100% output (0.91 efficiency value).21 A lighting router is selected as appropriate to both fluorescent and LED schemes with a stand-by power of 2.5 W and a running power of 7.5 W at full loading.21 A detector powered from the lighting router is also used in the investigated space.21 3.3. Determination of lighting energy performance Energy performance calculations are performed for the investigated classroom space, details of which are given below. 3.3.1. Calculation of energy consumption used for illumination

Energy consumption for illumination using BEP-TR methodology is calculated by considering the total installed lighting power (W), a constant illuminance factor, daylight and Lighting Res. Technol. 2015; 47: 740–759

 Calculation of total installed lighting power (Pn) The first electric lighting alternative (A1) is calculated to have a total installed luminaire power of 426 W (71 W  6) for C1 and C2 and this value includes the electronic ballast losses when the lamp is on as declared by the luminaire manufacturer. The power supplied to the lighting router and sensor is also taken into consideration for scenarios C3, C4, C5 and C6 and then the total installed lighting power is calculated as 434 W. The second electric lighting alternative (A2) is calculated to have a total installed lighting power of 282 W (47 W  6) for C1 and C2. When the LED system is equipped with a lighting control strategy, the total installed lighting power is calculated as 290 W for scenarios C3, C4, C5 and C6.  Calculation of constant illuminance factor (Fc) In this study, the effect of constant illuminance factor is evaluated for lighting control scenarios C3 and C5 having a dimmable luminaire connected to a room-based photocell for detection. For these lighting control scenarios, the constant illuminance factor (Fc) is taken as 0.9 (default value as expressed in EN 15193) depending on a maintenance factor assumption of 0.8 for both luminaires as suggested by their manufacturer. For other scenarios without a dimming lighting control system (C1, C2, C4 and C6), this value is considered as 1.  Calculation of occupancy dependency factor (Fo) The occupancy dependency factor (FO) is determined using three different formulations depending on the value of absence factor (FA). Absence factor for the investigated

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Table 5 Calculated occupancy dependency factor (FO) values Systems without automatic presence or absence detection Manual on/off switch Manual on/off switch þ additional automatic sweeping extinction signal

C1 C2

Systems with a utomatic presence or absence detection Auto on/dimmed Auto on/auto off Manual on/dimmed Manual on/auto off

C3 C4 C5 C6

classroom represents the portion of the time that the space is unoccupied and it is taken as 0.25. Equation (5) is applied in order to calculate this factor for the six different lighting control types. The occupancy-dependent lighting control system factor has standard values in EN 15193 as a function of the lighting control system used. The calculated occupancy dependency factor (FO) values are given in Table 5. Fo ¼ Foc þ 0:2  FA ðif 0:2  FA 50:9Þ

ð5Þ

where FA absence factor FOC occupancy-dependent lighting control system factor

 Calculation of daylight dependency factor (FD) The BEP-TR lighting module considers the annual calculation of FD values as a function of daylight supply factor and daylight dependent artificial lighting control factor and it can be calculated by equation (6). The daylight dependency factor depends on daylight penetration which in turn is dependent on parameters such as room dimensions, window dimensions, obstructions, glazing type, the coefficients a and b, latitude and maintained illumination.12 FD ¼ 1  ðFDS  FDC Þ

ð6Þ

FOC

FO

1.00 0.95

0.95 0.90

FOC

FO

0.95 0.90 0.90 0.80

0.90 0.85 0.85 0.75

where FDS FDC

daylight supply factor daylight dependent artificial lighting control factor

The daylight supply factor FD,S, values for the investigated cities are taken from the BEP-TR lighting module methodology.10 The daylight dependent artificial lighting control factor is determined by the type of lighting control used and the daylight penetration. Daylight supply to a space depends on the specific geometry of the given space, the transparency index (IT), the depth index (Ide) and the total window area on the fac¸ade opening (AC). The total window area on the fac¸ade differs according to the transparency ratio. Therefore, it is calculated separately for each daylight scenario. The area benefiting from daylight (AD) is dependent on the space geometry, the height of the lintel above the floor and the height of the task area (reference plane) above the floor. For the investigated classroom, variations of transparency ratio do not cause any change in the daylight benefitting area since the height of the lintel above the floor and the height of the task area (reference plane) are the same for each scenario. Therefore, the area benefiting from daylight is 40.35 m2 for all 12 daylight scenarios, a significant proportion of the 52.86 m2 floor area of the classroom. Lighting Res. Technol. 2015; 47: 740–759

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Table 6 Daylight penetration classification for 12 daylight scenarios Daylight Daylight Width of Height of Window Total Transparency Obstruction Daylight Daylight scenario window window area (m2) window index, It index, Io factor (DC) factor penetration area (Ac) classification (m) (m) 2 (m ) (D) D1 D2 D3

1.30 1.80 2.36

1.80 1.80 1.80

2.34 3.24 4.24

7.02 9.72 12.72

0.17 0.24 0.32

1.00 1.00 1.00

4.21 5.55 7.04

1.60 2.11 2.68

Weak Medium Medium

D4 D5 D6

1.30 1.80 2.36

1.80 1.80 1.80

2.34 3.24 4.24

7.02 9.72 12.72

0.17 0.24 0.32

0.70 0.70 0.70

2.95 3.88 4.92

1.12 1.48 1.88

Weak Weak Weak

D7 D8 D9

1.30 1.80 2.36

1.80 1.80 1.80

2.34 3.24 4.24

7.02 9.72 12.72

0.17 0.24 0.32

0.00 0.00 0.00

0.00 0.00 0.00

0.00 0.00 0.00

None None None

D10 D11 D12

1.30 1.80 2.36

1.80 1.80 1.80

2.34 3.24 4.24

7.02 9.72 12.72

0.17 0.24 0.32

1.00 1.00 1.00

4.21 5.55 7.04

1.38 1.82 2.31

Weak Weak Medium

The daylight factor classification of the investigated scenarios is calculated and the daylight penetration of the spaces is categorized as strong, medium, weak and none. The categorization is done in accordance with calculated daylight factor (DC) and daylight factor classification (D) values, using the specifications given in the BEP-TR methodology. In order to provide this classification, transparency index, depth index and obstruction index are taken into consideration and these values are evaluated for each daylight scenario (D1–D12). In Table 6, the calculated factors regarding the daylight penetration classification are given. Results indicate that increasing the transparency ratio for the investigated configurations differently effects daylight factor classification. For example, the transparency ratio variation between scenarios D1 and D2 leads to different daylight penetration classifications. On the other hand, changing the transparency ratio from 40% to 50% causes no direct influence on the daylight penetration categorization. This simply comes from the broad ranges of the four daylight penetration categories (strong, medium, weak and none). According to the daylight penetration results, the presence of shading devices or Lighting Res. Technol. 2015; 47: 740–759

external obstructions prevents the changes in daylight penetration categorization despite the increase of transparency ratio. The reason for this is the effect of obstruction index (IO) on daylight penetration classifications. The transmittance value of the glazing has a significant impact on daylight penetration categorization. The results obtained for D2 and D11 clearly show that as the transmittance of the glazing is reduced, the daylight penetration categorization changes from medium to weak. In the case D4 and D5 where the investigated space is obstructed by a continuous obstruction with an obstruction angle of 308, daylight penetration categorization changes directly from medium to weak. The presence of shading devices is found to have a significant impact on daylight penetration. EN 15193 assumes that when the overhang obstruction angle is over 67.58, daylight penetration categorization is ‘none’. The angle measured between the centre part of the window and the lower end of the shading device is 768 therefore scenarios D7, D8 and D9 are said to have no daylight penetration. After performing the daylight penetration categorization for the different daylight scenarios, FD values are calculated considering

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Table 7 Calculated daylight dependency factor (FD) values Daylight scenarios

Daylight penetration

Lighting control type

Ankara

Antalya

Diyarbakır

Erzurum

Istanbul

D1-D4-D5-D6-D10-D11

Weak

D2-D3-D12

Medium

D7-D8-D9

None

Manual Automatic Manual Automatic Manual Automatic

0.85 0.42 0.73 0.32 1 1

0.84 0.39 0.72 0.29 1 1

0.84 0.40 0.73 0.30 1 1

0.84 0.41 0.73 0.31 1 1

0.85 0.43 0.74 0.33 1 1

daylight supply factor and the daylight dependent artificial lighting control factor according to equation (6). These values are obtained taking into consideration daylight penetration categorization, lighting control type and location of the given building. In Table 7, daylight dependency factor calculation results are given. According to the obtained daylight penetration categorization, each daylight scenario is grouped as weak, medium and none. It is clear from the daylight dependency factor results that the presence of automatic lighting control decreases daylight dependency factor values and location also has different effects on obtained values according to the latitude of the selected city.  Calculation of daylight time usage and nondaylight time usage The daylight time usage (tD) and nondaylight time usage (tN) depend on the true solar time and can be calculated considering the occupation period of investigated building types and daylight hours. In EN 15193, default values for annual operating hours related to building type are given. For educational buildings, tD is given as 1800 hours, and tN as 200 hours. Because of the different latitudes in Turkey, standardization of these values could result in unreal estimates of daylight hours for different locations. Therefore, the sunrise–sunset hours, tD  tN values are calculated in this study. In the year round calculations, differently distributed

weekends, summer holidays and daylight saving time are taken into account. In the BEP-TR building operation definitions, primary school’s occupancy hours are between 08:00 and 17:00 and they are not occupied during July, August and September.17 Table 8 gives calculated monthly and total tD  tN values (h) for representative cities as well as the default values in EN 15193 for annual operating hours related to education buildings. Throughout this study, the number of working days is assumed to be 22 days for each month except for February which is assumed to have 20 working days.17 As part of this study, national values are substituted by considering the sunrise–sunset hours for the 15th day of each month in the particular locations of Turkey’s cities and considering the operating hours of the buildings. A total of 1764 working hours is evaluated on a yearly basis for the occupancy of primary schools. According to the results, the highest tD value calculated is 1749 hours for Antalya and lowest is 1690 hours for Erzurum. It is clear that tD values are far superior compared to tN values. This reveals that there is a significant opportunity to reduce lighting energy consumption and increase the energy performance of primary school buildings since the use of these buildings coincides with daylight hours. On the other hand, the real effect of daylighting for the investigated location should be evaluated carefully and in a more comprehensive way using daylight Lighting Res. Technol. 2015; 47: 740–759

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Table 8 Calculated monthly and total tD  tN values (h) for representative cities Months

Ankara tD

tN

Antalya tD

tN

Diyarbakır tD tN

Erzurum tD

tN

Istanbul tD

tN

January February March April May June July August September October November December Total

191 180 198 198 198 198 0 0 0 198 185 183 1729

7 0 0 0 0 0 0 0 0 0 13 15 35

198 180 198 198 198 198 0 0 0 198 191 189 1749

0 0 0 0 0 0 0 0 0 0 7 9 15

183 178 198 198 198 198 0 0 0 198 176 174 1700

15 2 0 0 0 0 0 0 0 0 22 24 64

180 174 198 198 198 198 0 0 0 198 174 172 1690

18 6 0 0 0 0 0 0 0 0 24 26 74

196 180 198 198 198 198 0 0 0 198 189 187 1742

2 0 0 0 0 0 0 0 0 0 9 11 22

EN 15193

1800

200

1800

200

1800

200

1800

200

1800

200

calculation techniques or lighting simulation programs.

Table 9 Luminaire parasitic energy consumption for the two lighting scenarios

3.3.2. Luminaire parasitic energy consumption

Lighting control scenarios

Luminaire parasitic energy consumption (kWh) – A1

Luminaire parasitic energy consumption (kWh) – A2

C1, C2 C3, C4, C5, C6

12.59 21.00

16.79 34.28

In this study, the impact of parasitic power on lighting energy performance is considered for scenarios equipped with automatic lighting control systems. In order to determine the parasitic energy required for lighting control systems, certain stand-by power values of the designed control systems are obtained from their manufacturer. Luminaire parasitic energy consumption for each scenario is evaluated annually using equation (3) and the stand-by power of lighting control equipment given in Section 3.2.3. It is assumed that there is no emergency lighting system installed within the classroom so the presence of emergency lighting is ignored. The calculated luminaire parasitic energy consumption results are presented in Table 9.

and lighting control alternatives. A total of 12 different daylighting options, 2 different electric lighting system selections and 6 different control types are implemented in this research for five representative cities in Turkey. Consequently, 720 different design variants were examined and each of them is evaluated using the BEP-TR lighting methodology. The results are presented here in terms of their energy performance and AESG (LENI) results.

4. Results This section focuses on the results obtained for the prototype primary school classroom scenarios including daylighting design alternatives, electric lighting design alternatives Lighting Res. Technol. 2015; 47: 740–759

4.1. Lighting energy performance The lighting energy performance results for different design scenarios show that the selection of location, electric lighting system, lighting control system and daylight design

Lighting energy performance determination for Turkey

753

Table 10 Calculated lighting energy requirements for lighting design scenarios Cities

Ankara

Electric lighting Daylight Systems without automatic scenario penetration presence or absence detection W (tl) values (KWh)

Systems with automatic presence or absence detection W (tl) values (KWh)

C1

C2

C3

C4

C5

C6

A1

Medium Weak None

541 618 726

513 586 689

227 288 710

237 301 671

215 273 671

212 269 595

A2

Medium Weak None

366 418 489

348 397 464

171 212 494

178 221 468

164 203 468

161 199 417

A1

Medium Weak None

532 612 726

504 580 689

207 268 710

216 280 671

197 254 671

193 250 595

A2

Medium Weak None

360 414 489

342 393 464

158 199 494

164 207 468

151 190 468

149 187 417

Diyarbakır A1

Medium Weak None

539 617 726

512 585 689

224 284 710

234 297 671

213 269 671

209 264 595

A2

Medium Weak None

365 417 489

347 396 464

169 209 494

176 218 468

162 200 468

159 196 417

A1

Medium Weak None

543 619 726

515 587 689

231 291 710

242 304 671

220 276 671

216 271 595

A2

Medium Weak None

368 418 489

349 397 464

174 214 494

181 223 468

167 204 468

164 201 417

A1

Medium Weak None

541 619 726

514 587 689

229 291 710

239 304 671

217 276 671

213 271 595

A2

Medium Weak None

367 418 489

348 397 464

173 214 494

180 223 468

165 204 468

162 201 417

Antalya

Erzurum

Istanbul

alternatives all have direct effects on annual lighting energy performance when the BEPTR Lighting Methodology is used. In Table 10, the calculated lighting energy requirements for each lighting design scenario are given. Turkey, being a country with a high daylighting potential, can achieve lighting energy savings due to the effect of daylight contribution. The strength of association between geographic conditions and lighting

energy requirements is a key factor to be considered in this study. Diverse geographic conditions yield different values of lighting energy consumption due to the different latitudes and, hence, different tD  tN values. The base case design scenario with weak daylight penetration and the use of fluorescent lamps is calculated to consume 619 kWh annually for Istanbul (latitude 408 540 , longitude 298 060 ). On the other hand, this value Lighting Res. Technol. 2015; 47: 740–759

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decreases to 612 kWh for Antalya (latitude 368 540 , longitude 308 420 ). For Erzurum, which has the lowest tD values, the lighting energy performance results for the base case scenario are 619 kWh. These results outline the effect of building location on the lighting energy performance using the BEP-TR lighting methodology where, for EN 15193, the recommended tD  tN values would result in no difference in terms of lighting energy performance. The relationship between sunrise and sunset hours also has effects on the obtained tD  tN values. For example, the lowest tD values are calculated for Erzurum with 1690 hours since this is an eastern city with earlier sunset hours when compared to the other investigated cities. However, the lighting energy performance results for the base case scenario are calculated as 619 kWh for Erzurum (easternmost city amongst all) and 619 kWh for Istanbul (westernmost city amongst all). These results indicate that despite the longitude and tD  tN differences between Istanbul and Erzurum, lighting energy performance results for these cases are the same since latitude differences between these cities is another key consideration. There appears to be significant evidence to suggest that lighting control systems help reduce lighting energy consumption in buildings considerably. Amongst the control types, C6 produces the lowest lighting energy consumption while C1 causes the highest. The effect of lighting control type on lighting energy requirements is simply related to the general assumptions of occupancy-dependent lighting control system factor values given in EN 15193. Thus, the obtained findings indicate that selection of appropriate lighting control systems in buildings is likely to be increasingly important if lighting energy consumption of buildings is to be reduced. The use of daylighting is a major way to obtain energy efficiency in lighting; consequently the building design phase is an Lighting Res. Technol. 2015; 47: 740–759

important time to optimize the design alternatives from the visual comfort and energy efficiency points of view. In this study, 12 different daylighting design alternatives have been evaluated in terms of their lighting energy performance for five representative cities. It is apparent that the largest savings occur for the ‘medium’ daylight penetration scenarios. Not surprisingly, when there is no daylight penetration, the highest energy requirements occur. It is apparent from the results that all the different locations displayed similar patterns in terms of lighting energy performance predictions. However, there is a slight difference in the obtained findings when geographical conditions are taken into account. The obtained results clearly show that the selection of an energy efficient lighting system helps to reduce annual lighting energy requirements of buildings. Figures 3 and 4 show the calculated lighting energy requirements for scenarios A1 and A2, respectively. When a LED lighting system with a lower installed power (47 W) is selected (A2) instead of the fluorescent system (A1), lighting energy requirements are automatically reduced from 618 kWh to 418 kWh for Ankara, 612 kWh to 414 kWh for Antalya, 617 kWh to 417 kWh for Diyarbakır, 619 kWh to 418 kWh for Erzurum and 619 kWh to 418 kWh for Istanbul. These results indicate that special attention should be given to the light source selection in the lighting design process in order to improve lighting energy performance. 4.2. AESG (LENI) The LENI (AESG for BEP-TR) is an indicator used for classifying the lighting energy in buildings, comparing the LENI of the examined building with the LENI of a reference building. Reference LENI values for different building types are given in EN 15193 differing according to the extent to which the requirements listed in the lighting design criteria class table are fulfilled. For educational buildings, LENI values range from

Lighting energy performance determination for Turkey

755

800 C1

C2

C3

C4

C5

C6

700 600 500 400 300 200 100 0 Medium

Weak

None Medium

A1 Ankara

Weak

None Medium

Weak

None Medium

Weak

None Medium

Weak

A1

A1

A1

A1

Antalya

Diyarbakir

Erzurum

Istanbul

None

Figure 3 Calculated lighting energy requirements for A1 lighting design scenarios in different cities with different lighting control systems and different levels of daylight penetration

600 C1

C2

C3

C4

C5

C6

500

400

300

200

100

0 Medium

Weak A2 Ankara

None

Medium

Weak

None

Medium

Weak

None

Medium

Weak

None

Medium

Weak

A2

A2

A2

A2

Antalya

Diyarbakir

Erzurum

Istanbul

None

Figure 4 Calculated lighting energy requirements for A2 lighting design scenarios in different cities with different lighting control systems and different levels of daylight penetration

24.8 kWh/m2 year to 54.9 kWh/m2 year, depending on the presence of constant illuminance control and the lighting control strategy. It must be noted these values cover the lighting energy requirements of whole buildings including non-daylit areas. The calculated classroom LENI values for the different lighting design scenarios are presented in Table 11.

It is clear that the LENI values for the classroom are much lower compared to the LENI benchmark values in EN 15193. This is simply because these values are calculated per classroom and not for the entire building. It is also important to explain that the benchmark LENI values given in EN 15193 are calculated for a tD value of 1800 hours and a tN value of 200 hours. Whereas for the BEP-TR Lighting Res. Technol. 2015; 47: 740–759

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Table 11 Calculated LENI values for lighting design scenarios Cities

Ankara

Antalya

Diyarbakır

Erzurum

Istanbul

Electric lighting scenario

Daylight penetration

Systems without automatic presence or absence detection LENI values (kWh/m2 year)

Systems with automatic presence or absence detection LENI values (kWh/m2 year)

C1

C2

C3

C4

C5

C6

A1

Medium Weak None

10.23 11.69 13.74

9.70 11.09 13.03

4.29 5.45 13.43

4.48 5.70 12.70

4.08 5.17 12.70

4.00 5.08 11.26

A2

Medium Weak None

6.93 7.90 9.26

6.58 7.50 8.79

3.24 4.02 9.34

3.37 4.19 8.86

3.10 3.83 8.86

3.05 3.77 7.89

A1

Medium Weak None

10.06 11.58 13.74

9.54 10.98 13.03

3.92 5.07 13.43

4.09 5.30 12.70

3.72 4.81 12.70

3.66 4.73 11.26

A2

Medium Weak None

6.82 7.82 9.26

6.48 7.43 8.79

2.99 3.76 9.34

3.11 3.92 8.86

2.86 3.59 8.86

2.82 3.53 7.89

A1

Medium Weak None

10.20 11.67 13.74

9.68 11.06 13.03

4.24 5.36 13.43

4.43 5.61 12.70

4.02 5.09 12.70

3.95 5.00 11.26

A2

Medium Weak None

6.91 7.88 9.26

6.57 7.48 8.79

3.21 3.96 9.34

3.33 4.12 8.86

3.06 3.78 8.86

3.02 3.71 7.89

A1

Medium Weak None

10.26 11.71 13.74

9.74 11.11 13.03

4.38 5.51 13.43

4.57 5.76 12.70

4.16 5.22 12.70

4.08 5.13 11.26

A2

Medium Weak None

6.95 7.91 9.26

6.61 7.51 8.79

3.30 4.05 9.34

3.43 4.22 8.86

3.15 3.86 8.86

3.10 3.80 7.89

A1

Medium Weak None

10.24 11.71 13.74

9.72 11.11 13.03

4.33 5.50 13.43

4.52 5.76 12.70

4.11 5.22 12.70

4.04 5.13 11.26

A2

Medium Weak None

6.94 7.91 9.26

6.59 7.51 8.79

3.27 4.05 9.34

3.40 4.22 8.86

3.12 3.86 8.86

3.07 3.80 7.89

calculation, the tD  tN values are different for each city with much lower tN values given the daylight hours in Turkey. It is clear from the findings that primary school buildings that are mostly used in daytime have higher tD and lower tN values so that minimum lighting energy consumption can be achieved if a proper daylighting system is used. If this had not been the case, depending on the investigated building type and its occupancy hours, the annual lighting energy Lighting Res. Technol. 2015; 47: 740–759

requirements would be higher therefore resulting in higher LENI values.

5. Conclusion Energy certification of buildings is promoted by the current energy policy of the European Union so as to reduce energy consumption and CO2 emissions. BEP-TR is a recently developed national calculation methodology

Lighting energy performance determination for Turkey for Turkey to be used for building energy performance determination and building energy certification purposes. In architectural design, the decisions taken early in the process can greatly affect lighting performance, visual comfort conditions and the overall energy consumption of a building. As part of this research, an example prototype primary school classroom has been evaluated in terms of visual comfort conditions and energy performance using the BEP-TR methodology. Several design configurations involving daylighting, electric lighting and lighting controls are compared. This study is beneficial because it predicts the energy performance and visual comfort conditions of primary school buildings before a prototype primary school building is constructed. By doing so, necessary modifications could be made during the design stage in order to improve the lighting energy performance and supply comfortable visual conditions. Various design parameters affect the lighting energy consumption in primary schools, like the daylight availability, installed power and lighting control systems, all of which should be carefully examined during the design stage. As expected, lighting controls are found to have a significant impact on overall lighting energy performance. It is apparent from the results that using an appropriate lighting control system will help to reduce the lighting energy consumption of buildings by responding to different occupancy and daylight availability values. Results indicate that the presence of a lighting control system in a primary school classroom provides a reduction in the lighting energy consumption depending on the selected lighting control type. In order to further evaluate the real effect of lighting control type on lighting performance, future studies should be performed based on real data measurements and then comparisons should be made with the EN 15193 methodology.

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This study also clearly underlines the effect of architectural design parameters on lighting energy performance using the BEP-TR methodology. The values of the architectural design parameters should be determined based on local conditions by considering visual comfort requirements, current standards and regulations. Daylight is an efficient light source in architecture. The results revealed that, when considering daylighting assessing transparency ratio variations, presence or non-presence of external obstructions, glazing type variations and presence of solar control devices is essential. In EN 15193, daylight penetration is considered in four main groups such as strong, medium, weak and none. The EN 15193 methodology specifies the daylight benefiting zone in a room considering only the room geometry, window position and dimensions whereas in a dynamic daylight calculation, the daylight illumination in a space is specified by considering additional parameters such as the window orientation and the exterior daylight level throughout the year and day depending on local parameters. Furthermore, local parameters, such as the external illumination, depend on the geographic and climatic conditions and should be precisely determined and taken into account. Put another way, the categorization in EN 15193 does not accurately indicate the daylighting conditions the building will be exposed to throughout the year. The BEP-TR methodology provides a more sensitive and detailed calculation methodology which considers the local parameters in a more sophisticated way than the EN 15193 methodology, which provides standardized values for certain daylighting conditions. But still, additional work is needed to further validate, refine and expand the BEPTR lighting energy performance methodology. In future work, upgrading this calculation methodology is required in order to verify the accuracy and sensitivity of the developed methodology by comparing its Lighting Res. Technol. 2015; 47: 740–759

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predictions with results obtained by the use of sophisticated lighting simulation tools. Nevertheless, architects, lighting designers or engineers can all use the BEP-TR methodology now to determine the potential lighting energy requirements of their buildings easily and practically. Funding This research received no specific grant from any funding agency in the public, commercial or not-for-profit sectors. References 1 European Commission. Towards a European Strategy for the Security of Energy Supply. Brussels: EC, 2001. 2 European Commission. Financial Support for Energy Efficiency in Buildings. Brussels: EC, 2013. 3 European Commission. Directive 2002/91/EC, Directive of the European Parliament and of the Council of 16 December 2002 on the Energy Performance of Buildings. Brussels: EC, 2002. 4 Energy Performance of Buildings Concerted Action, Executive summary report on the interim conclusions of the concerted action supporting transposition and implementation of the Directive 2002/91/EC, CA – EPBD, 2008. 5 European Committee for Standardization. EN 15193: Energy Performance of BuildingsEnergy Requirements for Lighting. Brussels: CEN, 2007. 6 European Committee for Standardization. EN 12464-1: Light and Lighting: Lighting of Work Places – Indoor Work Places. Brussels: CEN, 2011. 7 Republic of Turkey Official Gazette. Energy Efficiency Law, 2 May 2007, Number: 26510, Ministry of Public Works and Settlement, Ankara, Turkey, 2007. 8 Republic of Turkey Official Gazette. Legislation on Building Energy Performance, 5 December 2008, Number: 27075, Ministry of Public Works and Settlement, Ankara, Turkey, 2008. Lighting Res. Technol. 2015; 47: 740–759

9 Republic of Turkey Official Gazette. BEP-TR National Calculation Method for Energy Performance of Buildings, 07 December 2010, Number: 27778, Ministry of Public Works and Settlement, Ankara, Turkey, 2010. 10 Republic of Turkey Official Gazette, BEP-TR National Calculation Method for Energy Performance of Buildings, Appendix 05 Lighting, 07 December 2010. Number: 27778, Ministry of Public Works and Settlement, Ankara, Turkey, 2010. 11 IEE-CENSE Workshop Final Report. Adaptation of CEN Standards for defining a national calculation methodology for energy performance of buildings in Turkey. CENSE_WP6.4.10_N02, ITU Faculty of Architecture, Istanbul, Turkey, 15 August 2009. 12 Yener AK, Sener F. Lighting energy performance in primary school classrooms: Proceedings of the CIE Lighting Quality and Energy Efficiency Conference, Vienna, Austria, 2010. 13 Sener F, Unnu SY, Yener AK. Lighting energy performance assessment tools for building certification systems in Europe: Proceedings of the 27th Session of the CIE, Sun City, South Africa, 2011. 14 Unnu SY, Sener F, Yener AK. Adaptatıon of EN 15193 Standard for Turkey: BEP-TR Methodology and case study applications: Proceedings of the 27th Session of the CIE, Sun City, South Africa, 2011. 15 Yener AK, Sener F. Lighting energy performance determination in buildings-development of a method for Turkey (in Turkish): Proceedings of the 8th National Lighting Congress, Istanbul, Turkey, April 14–15: 2011. 16 Berko¨z E, Ku¨cu¨kdog˘u MS, Yılmaz Z, Enarun D, U¨nver R, Kocaaslan G, Yıldız E, Yener AK, Ak F, Yıldız D. Energy Efficient Building and Settlement Design, Research Report, INTAG 201, Istanbul: The Scientific and Technical Research Council of Turkey, 1995. 17 Republic of Turkey Official Gazette. BEP-TR National Calculation Method for Energy Performance of Buildings, Appendix 01 Occupancy and Operation Schedules of Spaces, 07 December 2010, Number: 27778, Ministry

Lighting energy performance determination for Turkey of Public Works and Settlement, Ankara, Turkey, 2010. 18 Trakya Cam Sanayii AS. Architectural Glasses Catalogue. Retrieved 9 February 2014, from http://www.trakyacam.com.tr/0/26/0/ architectual-glasses. 19 Dialux. Dialux Official Website. Retrieved 10 December 2013, from http://www.dial.de/ DIAL/en/dialux.html. 20 Illuminating Engineering Society of North America. Lighting Handbook: Reference and

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Application. 10th Edition, New York: IESNA, 2011. 21 HELVAR. Component Catalogue 2013, Ballasts for fluorescent T8 Lamps. Retrieved 9 February 2014, from http://www.helvar.com/ sites/default/files/attachment_files/ Component_Catalogue2013_EN_ 31102013.pdf.

Lighting Res. Technol. 2015; 47: 740–759