1077-2618/11/$26.00©2011 IEEE

BY GIUSEPPE PARISE& LUIGI MARTIRANO

The impactof buildingautomation,controls, and

buildingmanagementon energy

performance

THIS ARTICLE ANALYZES THE METH-

odology for calculating the energy consump-

tion of lighting systems and the impact of

building automation and control systems

(BACSs). The article also promotes a comprehensive ecode-

sign (ED) of lighting systems, consisting of the adoption of

appropriate lighting components and adaptive-partitioned

architecture for electrical distribution systems and lighting

systems in general and independent local systems.

Improvements of the European

Union Toward Energy Efficiency

In recent years, the European Union (EU) has actively pro-

moted political campaigns toward energy efficiency and

renewable energy [1], [2]. EN 15193-1 standard [3] speci-

fies the calculation methodology for the evaluation of the

amount of energy used for indoor lighting.Digital Object Identifier 10.1109/MIAS.2010.939809

Date of publication: 21 January 2011

© STOCKBYTE

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BACSs allow the pursuit of intelli-gent energy management; it providescomplex and integrated energy-savingfunctions based on the actual use of abuilding, depending on the user’s realneed to avoid unnecessary energy use.Integrated solutions are available tomanage energy data, furnish perform-ance indicators, and provide analysisand control tools to decrease energyand maintenance costs without com-promising the comfort or productivityof the service.

Comprehensive EDThe intelligent management of energyefficiency (optimization of costs andquality) requires imagination, whichcan reveal opportunities, expose risks,and support strategic decision making.A comprehensive ED of an energy sys-tem is the assessment of quality, safety, and functional andenergy performances. System EDmeans to configure a systemstructure and architecture suitable to integrate all environ-mental aspects and to improve the environmental perform-ance throughout its whole life cycle.

The designer has to evaluate the initial costs for installa-tion aspects and consider energy performance and mainte-nance costs for operational aspects. Evolution of the electricallighting systems is required to meet the expected ED.

The authors provide a comprehensive ED of lightingsystems that consist of two basic criteria:

1) the adoption of the most favorable luminaire classes(direct, semidirect, general diffuse, semiindirect,indirect), lamps (tubular, compact, standard, high effi-ciency, high output), and ballasts (magnetic, elec-tronic, dimmerable)

2) the adaptive-partitioned architecture of electricaldistribution systems and circuits and lighting sys-tems in independent general and local systems sat-isfies the admissible illuminance value variable forthe kind of area in the same room and for eachworking area (WA) related to its actual use.

Criterion 1) promotes efficiency and energy savings.Adaptive criterion 2) allows for compliance with thelighting standards more easily than a lighting system notproperly partitioned and can satisfy the general and localrequirements of advanced electronic control systems.

In fact, criterion 2) allows the adoption of appropriateBACSs (manual integrated by automatic sensors) accord-ing to the prospected energy performance. The designcriteria imply a lighting system consisting of a combi-nation of different luminaire types to attain a lightingsolution structurally balanced between quality andenergy performances and between general and local light-ing requirements.

The following combinations of luminaires are includedfor general lighting: a) recessed or surface direct-downlight luminaires, b) recessed or semirecessed direct/indirectluminaires, c) suspended direct/indirect luminaires (whereceiling heights permit), d) wall washer luminaires, and e)local-lighting freestanding luminaires.

An operating solution based on cri-terion 2) is partitioning the lightingsystem in a flexible structure with amulticircuit configuration and gen-eral and local switching devices. Abasic formula could be to integratethe general system of room lightingwith local lighting devices, such asadopting freestanding luminaires po-sitioned individually for each task sub-areas (Figure 1).

A freestanding luminaire offers avery high local performance. It is alsocompatible with T5-fluorescent lampsand includes a floor-supported framehaving a base adapted to rest on thefloor, an overhead beam arrangement,and an upright member connected atits lower end to the base and at itsupper end to the beam arrangement soas to support it in a cantilevered fashion

over a work surface.The average uniformity of illuminance required in

the WA and in its surrounding area (SA) could beachieved by sizing the general lighting system in refer-ence to the minimum maintained value and integratingthe full illuminance on the task subareas by the local-fitted luminaires.

The flexible system can allow a double lighting control:discrete and linear regulation. A discrete regulation isallowable by partitioning the electrical circuit configura-tion and the lighting system in devices for general andlocal service. A linear regulation can be operated in opti-mized ranges by BACSs. In the same manner, standardsuggestions can be applied with more flexibility to satisfythe admissible illuminance value variable in each workingsubarea related to its actual use.

Lighting and EnergyRequirements of Workplaces

Lighting GoalsStandard EN 12464-1 [5] specifies the lighting require-ments for indoor work places, which meet the needs forvisual performance and comfort. Workplaces can now bedivided into WAs and SAs, with a width of at least 0.5 msurrounding the task area within the field of vision.

The maintained illuminance is defined as the valuebelow which the average illuminance on the specified sur-face is not allowed to fall. A discrete series of values areassigned for the maintained illuminance in the WAs.The recommended illuminance scale in lux is 20–30–50–75–100–150–200–300–500–750–1,000–1,500–2,000–3,000–5,000.

The 20 lx value corresponds to the minimum valueneeded to recognize a person’s face. The geometric stepof about 1.5 (near the gold ratio) between two contiguousvalues corresponds to an approximation factor of lower andperceivable difference in the illuminance-subjective sensi-tivity. To state it in another way, the human eye perceives achange in lighting level of 150% but may not perceive asmaller change.

ACOMPREHENSIVE

EDOF ANENERGY SYSTEM ISTHE ASSESSMENTOFQUALITY,SAFETY, AND

FUNCTIONAL ANDENERGY

PERFORMANCES.

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A uniformity of illuminance is required in the WA notlower than 0.7 and in the SA not lower than 0.5. When themaintained illuminance in the WA is recommended equalto 750, 500, and 300 lx, the illuminance in the SA is rec-ommended equal to 500, 300, and 200 lx. In continuouslyoccupied areas (COAs), the recommended minimummain-tained illuminance shall not be less than 200 lx. To meetthis standard, the designer has to consider the life cycle ofthe lamps and the prospective operating maintenance.

Energy Performance ofBuildings for Lighting SystemsLighting design and practice are continuously evolvingand may have substantial consequences on the energyrequirement. Standard EN 15193-1 [3] specifies the calcu-lation method for evaluating the amount of energy used forindoor lighting. Standard EN 15232 [4] gives a methodol-ogy to evaluate the impact of BACSs and technical build-ing management (TBM). It defines four different BACefficiency classes of functions for nonresidential and resi-dential buildings: 1) high-energy performance class, 2)advanced class, 3) standard class, and 4) no-energy effi-ciency class.

To estimate the actual energy efficiency of lighting con-trol systems is an important goal since an accurate evalua-tion could help and guide the designers toward the most

appropriate choice among a great number of available solu-tions. Particularly, the control strategies can be based ondaylight availability, room occupancy, or predefinedscenes, and the type of control can be automatic, manual,or both, using different management criteria.

EN 15193-1 [3] provides the lighting energy numericindicator (LENI) used for certification purposes and is use-ful in designing light control systems:

LENI ¼ W ½kWh=year�A ½m2�

,

where A is the considered useful area [m2], and W is thetotal annual energy used for lighting

W ¼ WL þWP kWh=year½ �

as sum of the WL estimated annual lighting energy and WP

the parasitic energy (emergency and standby controls). Thelight control systems also consume some energy in the standbymode so that a night-time switching is recommended.

Calculation of WL depends on the installed lightingpower corrected by three derating factors: FD daylightdependency factor, FC constant illuminance factor, and FOoccupancy dependency factor (Figure 2). An estimate ofthe lighting energy (WL) required to fulfill the illumination

General Lighting — Continuously Occupied Area (COA) — 250 lx — Two Recessed Direct-Down Light Luminaires 4 × 14 W — Discrete Regulation (Switching)

COA

WA

SACOA

4 × 18 W

4 × 18 W

1 × 54 W

4 × 18 W

4 × 18 W

Lighting: General On–Local Off

WASA

Lighting: General On–Local On

Local Lighting — Working Area (WA) — 500 lx — One Freestanding Luminaire 1 × 54 W — Linear Regulation (Dimming)

1Example of maintained illuminance values estimated on the working area (WA), surrounding area (SA), and continuouslyoccupied area (COA) of a 6 3 4 m office by a combination of two (4 3 14 W) recessed direct-down light luminaires(general lighting) and a 1 3 54 W freestanding luminaire (local lighting).

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function and purpose in the buildingshall be established using the followingequation [kW � h/year]:

WL ¼X PnFC(tDFOFD þ tNFO)

1,000,

where Pn is the total installed lightingpower in the considered area A [W], tDthe daylight time usage is the operatinghours during the daylight time [h], andtN the nondaylight time usage is theoperating hours during the nondaylighttime [h]. Standard EN 15193-1 [3]offers information, methods, and refer-ence values (Table 1).

The energy savings obtainable by adopting the manualor automatic control systems are

n (1 � F0) for occupancyn (1� FD) (tD/(tD þ tN)) for daylightn (1� FC) for constant illuminance.

Occupancy Factor FOThe occupancy dependency factor FO is defined as a factorrelating the usage of the total installed lighting power tooccupancy period in the room or zone. It depends on theabsence factor FA (Table 2).

Standard EN 15193-1 [3] alsodefines the lighting control systemsavailable for occupancy control:

1) Systems without automatic pre-sence or absence detection:Manual on/off switch withoutor with additional sweeping ex-tinction signal.

2) Systems with automatic presenceand/or absence detection (occu-pancy sensor): Auto on/dimmedor switched off and manual on /dimmed or auto off.

Figure 3 shows the possible energysavings using occupancy control sys-tems according to the different type ofcontrol. The higher line (continuous)

shows the behavior for manual on/automatic off control,and the other lower lines are for automatic on/off, manualon automatic off, and manual on/off, respectively.

Daylight Factor FDThe daylight dependency factor FD is a factor relating theusage of the total installed lighting power to daylightavailability in the room or zone, which is evaluated by

FD ¼1� (FD, S 3 FD,C)½ �AD

A,

TABLE 1. DAYLIGHT TIME USAGE tD AND NON-DAYLIGHT TIME USAGE tN MEASURED IN HOURSFOR THE DIFFERENT BUILDING TYPES.

Building Types

Default AnnualOperating Hours

tD tN to ¼ tDþ tN

Offices 2,250 250 2,500

Educationbuildings

1,800 200 2,000

Hospitals 3,000 2,000 5,000

Hotels 3,000 2,000 5,000

Restaurants 1,250 1,250 2,500

Sport facilities 2,000 2,000 4,000

Wholesale andretail service

3,000 2,000 5,000

Manufacturingfactories

2,500 1,500 4,000

TABLE 2. ABSENCE FACTOR FA FOR THE DIFFERENTOFFICE TYPES.

Room by Room Calculation

Building Type Room Type FA

Offices Cellular office1 person

0.4

Cellular office2–6 persons

0.3

Open plan office>6 personssensing/30 m2

0

Open plan office>6 personssensing/10 m2

0.2

Corridor 0.4

Entrance hall 0

Showroom/expo 0.6

Bathroom 0.9

Rest room 0.5

Storage room 0.9

Technical plant room 0.98

Copying/server room 0.5

Conference room 0.5

Archives 0.98

EN 15193-1PROVIDES THE

LIGHTING ENERGYNUMERIC

INDICATOR USEDFOR

CERTIFICATIONPURPOSES.

Daylight Use Presence Detection

Installed PowerParasitic Power

LENI

2LENI indicator and influencing factors.

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wheren FD,S daylight supply factor depends on the daylightpenetration (strong, medium, weak, none), the main-tained illuminance (300, 500, 750 lx), and the lati-tude angle of building location (Figure 4).

n FD,C artificial lighting control factor depends on day-light penetration and the control adopted: manualor automatic.

The ratio AD/A considers the area benefiting from day-light AD that is generally smaller than the considered areaA. When AD/A < 1 and the lighting system doesn’t allowa local control, FD has to be considered 1 (Table 3).

Figures 5 and 6 show the possible energy savings usingmanual or automatic daylight control systems for weak,medium, and strong daylight penetration.

Constant Illuminance Factor FCThe constant illuminance factor FC is a factor relating tothe usage of the total installed power when constant illu-minance control is in operation in the room or zone. Theuse of lighting installations decays the output, which isreduced by the level of accumulation of dust in the envi-ronment. The decay rate is estimated by the maintenancefactor (MF), which is the ratio between maintained andinitial illuminance.

As the task illuminance at the end of the lamp’s lifecycle is equal to the prospected standard maintained value,the system should provide a higher initial illuminance by afactor of 1/MF. In installations where a dimmable lightingsystem is provided, it is possible to automatically controlthe maintained value, eventually correcting the voltagedrops of electrical supply.

Case StudyThe authors studied a sample case adopting the standardmethodologies as design criteria to evaluate the energy andeconomic impact of manual/automatic control in lightingsystems. Simulations are made to evaluate the lightingenergy consumption (on a yearly basis) in a typical officeaccording to the different strategies. These simulationscompare different solutions of control systems (daylightdimming, dimming, or extinction according to room occu-pancy), assuming illuminance values of 300, 500, and 750 lx.They can be centralized or not. Moreover, different room

10.90.80.70.60.50.40.30.20.1

0

FD

,S

35 40 45 50 55 60 65Latitude (°)

StrongMediumWeek

4Daylight supply factor FD,S as a function of the sitelatitude and daylight penetration for a maintainedilluminance of 500 lx.

05

10152025303540

300 400 500 600 700 800Illuminance (lx)

Ene

rgy

Sav

ing

(%)

Strong Medium Weak

5Energy savings (1 � FD) by a manual daylight control system.

TABLE 3. FD,C AS A FUNCTION OF DAYLIGHTPENETRATION.

Control of ArtificialLighting System

FD,C

Weak Medium Strong

Manual 0.20 0.30 0.40

Automatic 0.75 0.77 0.85

01020304050

7060

8090

300 400 500 600 700 800Illuminance (lx)

Ene

rgy

Sav

ing

(%)

6

Strong Medium Weak

Energy savings (1 � FD) by an automatic daylightcontrol system.

0

20

40

60

80

100

120

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1Absence Factor, FA

Ene

rgy

Sav

ing

(%)

3Energy savings (1 � F0) by an occupancy control. Thehigher line (continuous) shows the behavior for manual on/automatic off control, and the lower lines are for automaticon/off, manual on automatic off, and manual on/off,respectively.

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configurations (position of luminaires and sensors, use ofblinds, fixed or variable presence) could be considered.

Table 4 shows the possible energy savings obtainable fora simple case of an office of 24 m2 at 42� latitude (Rome,Italy), adopting tD ¼ 2,250 h and tN ¼ 250 h (Table 1),with normal fenestration (medium weak daylight penetra-tion), considering an absence factor FA ¼ 0.4 and the day-light factor FD weighted by the ratio AD/A.

In reference to the condition of not using control, theenergy consumption could remain lower than 70 and 75%using manual controls and lower than 45 and 50% usingautomatic controls.

In an ED lighting, by adopting switching-controlled fixedluminaires for general lighting and dimming-controlled free-standing luminaires for local lighting, it is easy to lower theenergy consumption by about 30 and 55% (Table 4).

ConclusionsBy integrating the adoption of appropriate BACSs, com-bining the general system with local lighting devices, byoptimizing the performances in an easy way, is an adaptivecriterion to design the lighting system. Considering thatseveral organizations are taking on flexible working practices,a structural solution of adopting freestanding luminaires incombination with other types is now basic for providing aneasier flexible lighting installation.

Whether used on its own or in conjunction with otherlighting, freestanding or furniture-mounted lighting sys-tems offer a very practical solution. Although freestandinglighting in the form of uplighters or combined up and downlighting is available, its use is limited, and this trend has tobe inverted.

In conclusion, there are several key reasons for adoptinga more flexible approach to lighting, ranging from improvedvisual comfort for staff to reduced energy and maintenancecosts for lower cost of ownership.

The parasitic energy consumption could be estimatedby adding 1 kWh/m2/year for emergency lighting and5 kWh/m2/year for the automatic lighting controls. Theluminaires, both fixed and freestanding, are fitted with high-efficiency T5 lamps and electronic ballast.

References[1] European Council, “Directive 2002/91/EC of the European parlia-

ment and of the council of 16 December 2002 on the energyperformance of buildings,” Official J. Eur. Commun., vol. 4, no. 1, pp. L1/65–L1/71, 2003.

[2] CEN/BT WG 173 EPBD no. 36 Version V5, “Explanation of the gen-eral relationship between various CEN standards and the energyperformance of buildings directive (EPBD),” Umbrella document Euro-pean Committee for Standardization (CEN), Brussels, Dec. 2005.

[3] Energy Performance of Buildings–Energy Requirements for Lighting—Part 1:Lighting Energy Estimation, EN 15193_1, Mar. 2005.

[4] Energy Performance of Buildings—Impact of Building Automation, Controlsand Building Management, EN 15232, Oct. 2006.

[5] Light and Lighting–Lighting of Workplaces—Part 1: Indoor Workplaces, EN12464-1, 2002.

Giuseppe Parise (parise@ieee.org) and Luigi Martirano are withthe University of Roma La Sapienza in Rome, Italy. Parise is aFellow of the IEEE. Martirano is a Member of the IEEE. Thisarticle first appeared as “Impact of Building Automation, Controlsand Building Management on Energy Performance of LightingSystems” at the 2009 IEEE Industrial and Commercial PowerSystems Technical Conference.

TABLE 4. ESTIMATED LENI VALUES [kWh/m2/year AND %] FOR THE CASE STUDY, ASSUMING MAINTAINEDILLUMINANCES OF 300, 500, AND 750 lx.

MaintainedIlluminance

COAWA

300 lx 500 lx 750 lx

Fixed luminaires 3 3 (4 3 14 W) 5 3 (4 3 14 W) 7 3 (4 3 14 W)

Power density 8 W/m2 13.5 W/m2 19 W/m2

LENI kWh/m2/year % kWh/m2/year % kWh/m2/year %

No control 20 100% 33 100% 50 100%

Manual 15 75% 25 76% 35 70%

Automatic 9 45% 16 48% 23 46%

ED

MaintainedIlluminance

COAWA

250 lx 250 lx 250 lx

300 lx 500 lx 750 lx

Fixed luminairesFreestanding

2 3 (4 3 14 W) 1 3 39 W 2 3 (4 3 14 W) 1 3 54 W 2 3 (4 3 14 W) 2 3 55W

Power density 7 W/m2 8 W/m2 10.5 W/m2

LENI kWh/m2/year % kWh/m2/year % kWh/m2/year %

ED 11 55% 12 36% 14 28%

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