Iteratioal Joural of Eergy Egieerig 2015, 5(4): 67-73 DOI: 10.5923/j.ijee.20150504.01 A Eergy-Savig Cotrol System of Lightig ad Air-Coditioig Liked to Employee s Etry/Exist i the Zoe of the Office Yosuke Kaeko 1, Masahito Matsushita 1, Shiji Kitagami 2, Ju Sawamoto 3,*, Tetsuo Shiotsuki 4, Tatsuji Muaka 5 1 Iformatio Techology R&D Ceter, Mitsubishi Electric Corporatio, Kaagawa, Japa 2 Mitsubishi Electric Buildig Techo-Service Co. Ltd., Tokyo, Japa 3 Departmet of Software ad Iformatio Sciece, Iwate Prefectural Uiversity, Iwate, Japa 4 Departmet of Robotics ad Mechatroics, Tokyo Deki Uiversity, Tokyo, Japa 5 School of Iformatio ad Telecommuicatio, Tokai Uiversity, Tokyo, Japa Abstract We have developed a eergy-savig cotrol system that cotrols lightig ad air-coditioig cosiderig desk allocatio i the office. This lightig cotrol system makes the desk area that a perso uses brighter, but makes the lightig gradually dimmer with distace from the perso at a desk. I additio, the air-coditioig system cotrols temperatures oly for areas where someoe is at the desk, which ca be doe by cotrollig the o ad off time of the thermostat i the air-coditioig system. We evaluated this cotrol system by actual measuremet ad simulatios ad validated its effectiveess for the reductio of electrical power cosumptio. Keywords Lightig, Air-Coditioig, Eergy-Savig, Office 1. Itroductio Eergy cosumptio i office buildigs is icreasig. Lightig ad air-coditioig accout for the majority of power cosumptio i the office. Therefore, eergy coservatio methods of these facilities are importat. To achieve eergy-savig of the lightig without impairig comfort i the office, it is effective approach to tur off the lightig i the uecessary area, ad to keep appropriately illumiace. Therefore, covetioal studies have proposed cotrol systems that tur off lightig automatically i the uoccupied area usig a motio sesor ad cotrol brightess usig illumiatio sesors for the occupied area [1-3]. I additio, other covetioal studies have decided brightess of the area where persos are detected by optimizig method [4] [5]. Regardig the eergy savig of the air-coditioig, a covetioal method detects a chage i occupacy by motio sesors ad cotrol to tur o or off of the air-coditioig [6]. I additio, aother study has bee doe to divide the office floor ad cotrol oly those zoes for which someoe is at a desk to satisfy the target room temperature [7]. As discussed, i * Correspodig author: sawamoto@iwate-pu.ac.jp (Ju Sawamoto) Published olie at http://joural.sapub.org/ijee Copyright 2015 Scietific & Academic Publishig. All Rights Reserved covetioal studies, eergy coservatio is achieved by cotrollig lightig ad air-coditioig oly i the area of the office floor where someoe is at the desk ad oly whe someoe is there. As described i this paper, we propose a eergy-savig system that ca reduce the area i which brightess ad temperature should be satisfied while keepig the target brightess ad the target temperature. This proposed system pipoits locatios where brightess ad temperature should be satisfied. At this time, the proposed system detects a perso i the floor i cooperatio with a access cotrol system without usig motio sesors. Furthermore, the proposed algorithm cotrols lightig ad air-coditioig to maitai the brightess ad the temperature of the locatios. We evaluated the proposed system with a simulatio ad a experimetal evaluatio. As the results, we verified that the proposed system ca reduce power cosumptio compared with the covetioal meas while maitaiig the brightess ad the temperature where someoe is there. 2. Backgroud 2.1. Features of Office Lightig The lightig power cosumptio accouts for about 19% of the total of the commercial sector i the US [8]. Ad, its
68 Yosuke Kaeko et al.: A Eergy-Savig Cotrol System of Lightig ad Air-Coditioig Liked to Employee s Etry/Exist i the Zoe of the Office usage patter remais almost costat throughout the year. Therefore, it is possible to obtai a large eergy-savig effect throughout the year by applyig the eergy-savig methods for office lightig. While, i a office buildig, employee are costatly eterig ad leavig a floor, so lightig systems may tur o the zoe where there is ot a perso. So, it is a effective approach for reducig the waste to cotrol equipmet usig the eterig ad leavig iformatio such as the umber of employee i a floor, ad the presece or absece. Meawhile, with the icrease i the security cosciousess i compay, more access cotrol systems are istalled ito office buildigs. While the primary fuctio of the access cotrol system is to cotrol the etry ad exit of persos, it ca also be utilized as a meas to grasp the etry or exit iformatio such as the presece or absece of persos i the rooms. 2.2. Features of Air-Coditioig The air-coditioig exhausts about 65% of the total power cosumptio cosumed by a buildig i the US [9]. I geeral, a air-coditioig system cotrols room temperature at a certai level by its autoomous cotrol. However, cotrol methods i the geeral air-coditioig system do ot cosider whether someoe is at the desk or ot. Therefore, it sometimes maitais temperatures wastefully eve i areas that o perso is usig. Aother cotrol method aside from the autoomous cotrol of the system is rotatio cotrol. The rotatio cotrol divides a office floor ito N umber of groups, each with idoor uit. The system achieves eergy coservatio by switchig the thermostat o ad off. By applicatio of this cotrol method, we ca achieve eergy coservatio by switchig the thermostat o ad off depedig o whether someoe is at a desk or ot. However, eve i the same office floor, the room temperature might vary depedig o the distace from ducts ad widows. Therefore, i this rotatio cotrol, it is ecessary to determie the time iterval betwee the thermostat switchig o ad off by cosideratio of the variatio of the room temperature i the office, which is crucial also from the perspective of maitaiig the target room temperature. 3. Proposed Method This paper describes the eergy-savig cotrol system of lightig ad air-coditioig liked to employee s Etry/Exist, which uses etry ad exit iformatio obtaied from the access cotrol system ad the seat positio iformatio of each perso. Ad, the system cotrols automatically lightig ad air-coditioig so that each equipmet are tured o oly i the required area ad for the required time esurig a certai amout of illumiace oly o ad aroud desks people are sittig. 3.1. Structure of a Proposed System Figure 1 illustrates the structure of a proposed system. This system cosists of the access cotrol system (ACS), the lightig cotrol system, the air-coditioer cotrol system, ad the eergy-savig cotrol server. These systems ad the server are liked over the etwork. The ACS cosists of a autheticatio device ad some card readers. The ACS is equipped with two types of card readers for etry ad exit at each door o a floor. Whe employee passes a door, he passes IC Card over the card reader. Thereby, the iformatio of the employee who has passed a door is set to the eergy-savig cotrol server through the autheticatio device. Locatio detectio algorithm Lightig cotrol algorithm Air-coditioig cotrol algorithm Eergy-savig cotrol server TCP/IP Eergy-savig cotrol program Autheticatio device Lightig cotroller Gatherig server Air-coditioig cotroller Field etwork For etry For exit Card readers ZigBee Field etwork Lightig Network cotroller Wireless etwork Temperature sesors Outdoor uits Field etwork Idoor uits Access cotrol system Lightig cotrol system Air-coditioig cotrol system Figure 1. Structure of the proposed system
Iteratioal Joural of Eergy Egieerig 2015, 5(4): 67-73 69 The lightig cotrol system cosists of a lightig cotroller, a etwork cotroller, ad lightig fixtures. This system is able to tur o/off ad adjust the dimmig rate for each lightig fixture. The eergy-savig server, coected to the lightig cotroller through the TCP/IP etwork, is able to sed cotrol istructios to cotrol lightig fixtures by the BACet protocol [10]. Lightig fixtures which have received the cotrol istructios adjust brightess with iverter cotrol. The air-coditioig cotrol system cosists of a room temperature gatherig subsystem ad a air-coditioig cotrol subsystem. The room temperature gatherig subsystem is composed of a gatherig server ad temperature sesors. This server is coected to these sesors through the wireless etwork ad receives room temperature data from these sesors at fixed itervals. The air-coditioig cotrol subsystem is composed of a air-coditioig cotroller, outdoor uits, ad idoor uits. This cotroller is able to cotrol temperature settig, air flow directio, air flow stregth, thermostats o ad off, ad so o. The eergy-savig cotrol server is coected to this cotroller through the TCP/IP etwork ad is able to sed cotrol istructios to this cotroller. Thereby, this server is able to cotrol idoor uits ad outdoor uits. The eergy-savig cotrol server is istalled with a eergy-savig cotrol program. This program has implemeted a locatio detectio algorithm, a lightig cotrol algorithm ad a air-coditioig algorithm. The locatio detectio algorithm specifies the positio of the perso i the floor. The lightig cotrol algorithm ad the air-coditioig cotrol algorithm cotrol illumiatio ad room temperature so that the zoes where perso is i are satisfied to keep target illumiace ad target temperature. 3.2. Detectio Method of the Perso s Locatio i the Floor The locatio detectio algorithm detects the presece or absece of employees i the floor with data set by the ACS. Whe employee is out of the office floor, he passes IC Card over the card reader for exit. As a result, the door opes. O the other situatio, whe employee goes ito the office floor, he passes IC Card over the card reader for eter. By these actios of employees, the locatio detectio algorithm is able to idetify employees eterig ad leavig a room. The data to idetify each employee are icluded i each IC Card. These data are set to the locatio detectio algorithm whe employee passes IC Card. Thus, this algorithm is able to detect presece or absece of employees i the floor. I additio, the proposed system grasps seat positio iformatio of each employee. The proposed system detects positios where employees are at. 3.3. Lightig Cotrol Algorithm The lightig cotrol algorithm cotrols lightig fixtures by the two phases. We describe these phases i detail below. (1) 1st phase. The eergy-savig cotrol server detects employee withi a floor. Ad the, it specifies the zoe that should be illumiated, usig seat positio iformatio. Figure 2. 75% 75% 75% Perso 2m 1m (a) Determiatio method of dimmig rate aroud a perso r i r i+1 r i+2 r i+3 h θ ij I(θ ij ) e ij E j (b) The poit-by-poit method r i r i+1 r i+2 r i+3 E j Icrease (c) Ifluece of other perso ad sulight Lightig cotrol algorithm 1st phase 25% Stroger Other perso The lightig fixtures are tured o ad the dimmig rates are cotrolled oly aroud the zoes where persos are i. As the distace from the zoes icreases, brightess will decrease. For example, as show i Figure 2 (a), the dimmig rate of a lightig fixture withi oe meter from each perso are set to 75%, ad the lightig fixtures withi two meters are set to 25%. Through this dimmig cotrol, zoes ear the persos are kept bright, ad a sharp decrease i brightess is preveted. I additio, the lightig fixtures ear persos who have goe home or who are away from their desk for a meetig are automatically tured off. Here, the value 75% ad 25% are a example. I fact, these values are adjusted so as to satisfy the target illumiace of the perso. Therefore, the proposed system calculates the illumiace for a presece perso i the floor usig the poit-by-poit method. As show i Figure 2 (b), the system calculates the illumiace e ij which the lightig equipmet i give the poit j by Equatio (1). Here, C ij is a
70 Yosuke Kaeko et al.: A Eergy-Savig Cotrol System of Lightig ad Air-Coditioig Liked to Employee s Etry/Exist i the Zoe of the Office ifluece that the lightig fixture i gives the poit j, r i is a dimmig rate of the lightig fixture i, θ is a agle betwee the lightig fixture i ad the poit j, I is the itesity of the lightig fixture i, h is the floor height, ad M is a parameter to explai maiteace frequecy for lightig fixture. Further, sice the poit j is iflueced from the several lightig fixtures, the illumiace E j which is brightess of the poit j ca be calculated by Equatio (2). eij = C ij *ri (1) 3 2 C = I( θ )*cos ( θ )*M/h ij ij ij N j = ij i (2) i1 = E C *r The brightess of the poit j is chaged by chagig the dimmig rate. The proposed system chages the dimmig rates gradually util the calculated dimmig rates, to ot chage the brightess rapidly. (2) 2d phase. Whe the 1st phase was executed, it assumed that there is oly oe sittig employee i a floor. Therefore, the illumiace of the sittig perso s zoe is optimized uder the situatio i which the ifluece of the lightigs for eighbors is ot received. But, as show i Figure 2 (c), whe its ifluece is received, it becomes the overmuch illumiace. I additio, sice the widow seat is affected by the sulight, it becomes the factor of the overmuch illumiace. To solve these problems, the proposed method corrects the dimmig rates to egate the ifluece of the illumiace that received from the lightig fixtures for eighbors ad the sulight accordig to the followig procedure. Figure 3 shows a image of illumiace correctio cotrol. I the situatio of Figure 3 where the cotrol of the 1st phase was fiished, the dimmig rates was cotrolled r i %, r i+1 %, r i+2 %, r i+3 %,, r N %. Here, whe we defied corrected dimmig rates as r i %, r i+1 %, r i+2 %, r i+3 %,, r N %, the sulight iflueces for poit j as e_su j lx, the gap of the preset illumiace ad the target illumiace for the poit j asδe j, this relatioship is show i Equatio (3). E1= C i1 *ri C i1 *ri e_su1 i1 = i1 = E2 = C i2 *ri C i2 *ri e_su 2 i1 = i1 =... Ej = C ij *ri C ij *ri e_suj i1 = i1 =... E = C i *ri C i *ri e_su i1 = i1 = (3) Here, C ij is a ifluece that the lightig fixture i gives the poit j, it is same value that is show Equatio (1). The proposed method solves equatio (3), ad it determies r i %, r i+1 %, r i+2 %, r i+3 %,, r N. r i r' i r i+1 r' i+1 r i+2 r' i+2 r i+3 r' i+3 j e_su j e_su j+1 j+1 Figure 3. Lightig cotrol algorithm 2d phase 3.4. Air-Coditioigs Cotrol Algorithm I this proposed method, by cosiderig the fact that heat trasfers to each locatio uevely, it cotrols the thermostat o ad off to maitai the target room temperature where someoe is i the zoe. (1) Structure of air-coditioig cotrol fuctio ad operatio outlie. Figure 4 shows a structure ad operatio outlie of the air-coditioig cotrol fuctio. Figure 4 (a) shows the groud pla of the floor, ad also the figure shows the positios of the air-coditioers, the positios of the persos, ad the positios of the thermo-sesors. As portrayed i Figure 4 (a), the proposed method divides N umber of zoes i the whole office floor. Dotted lies shows zoes. Moreover, i the proposed method, a movable thermo-sesor is to be istalled i each zoe. (2) Method of switchig a thermostat o ad off It determies the timig of turig the thermostat o ad off at each group, which is doe by the variatio of the readig value at the thermo-sesor that is istalled i the zoe. The determiatio method i the case of heatig is show below. 1) Figure 4 (a) shows that Perso A is at Zoe 4 ad Perso B is at Zoe i+4. This proposed method sets the target temperature as T target ad the tolerace of the target temperature as w. I short, it cotrols the thermostat o ad off to maitai the temperature, T target ± w i the zoe beig used by someoe. 2) This proposed method turs the thermostat o i the air-coditioig util the room temperature for the zoe i reaches T target. Figure 4 (b) shows the time ecessary to tur the thermostat o to reach T target. I this Figure, the X-axis shows elapsed time after the air-coditioig has tured ito thermostat o, the Y-axis shows the measured value of the thermo-sesor. First, measure the room temperature util it exceeds T target w whe turig the thermostat o. Whe the room temperature exceeds T target w, set the thermostat o time t i that requires the room temperature to reach T target.
Iteratioal Joural of Eergy Egieerig 2015, 5(4): 67-73 71 This proposed method eables zoe i to reach the target temperature by turig the thermostat o durig time t i toward the zoe to which perso i belogs. Subsequetly, tur the thermostat off at each zoe. 3) This proposed method cotrols air-coditioigs to maitai room temperature of zoe i i the rage of T target ± w. The method moitors a temperature sesor that istalled i the zoe i cotiuously ad switches the thermostat off whe room temperature T i_b which the method measured this time decreases tha the value T i_a which the method measured last time. Coversely, the method switches the thermostat o whe T i_b rises tha T i_a. I additio, whe T i_b is lower tha T target - w, the method assumes thermostat o. Ad the method switches the thermostat off whe T i_b is higher tha T target w. Zoe 1 Zoe 2 Zoe 3 Zoe 4 Zoe i Zoe i+1 Zoe i+2 Zoe i+3 Zoe i+4 Zoe N Perso B temperature T target T target - w Idoor uit thermo-sesor Perso A a) Structure of air-coditioer ad zoe t i room, ad the sulight pours ito the room. As this evaluatio coditio, we assume that right uder lightig fixtures of the southermost lie are affected by 100lx by the sulight. Ad, we assume that there are six persos i the room. Widow Perso 20m Lightig fixture North Figure 5. Evaluatio coditio of the lightig cotrol 7.5m Figure 6 shows dimmig rates that the proposed method determied ad the calculated illumiace o the desk surface by the poit-by-poit method. Here, the target illumiace of the presece zoe is 500lx, ad the presece zoes are show by black poit i Figure 6. I additio, the illumiace level is expressed by gradatio. I the case of Figure 6, the calculated illumiace is 498lx ~ 500lx, we were cofirmed that there was little error about the target illumiace 500lx. Further, we were cofirmed that the illumiace ca be cotrolled so as to be lower with icreasig distace from the presece perso. 0 0 0 0 44 73 44 0 44 60 62 44 0 0 0 0 44 44 44 0 44 45 47 44 Measured temperature Figure 4. Air-coditioer cotrol method Elapsed time b) Determiatio method of the thermostat o time 0 29 29 29 0 0 0 0 42 42 42 42 0 29 67 29 0 0 0 0 0 0 0 0 a) Dimmig Rate [%] 499 501 500 4. Evaluatios ad Cosideratios of the Proposed Method I order to evaluate a effectiveess of the developed techology, we built a simulator ad a prototype system. 4.1. Lightig Cotrol Method We evaluate the proposed lightig cotrol algorithm by the simulator. Figure 5 shows a evaluatio coditio. The size of the room is 20 by 7.5 meters, ad 48 lightig fixtures are istalled. A widow is istalled i the south side of the 500 498 498 a) Calculated illumiace [lx] Figure 6. Simulatio result of the lightig cotrol
72 Yosuke Kaeko et al.: A Eergy-Savig Cotrol System of Lightig ad Air-Coditioig Liked to Employee s Etry/Exist i the Zoe of the Office Figure 7 illustrates a result of the average dimmig rate. I Figure 7, the proposed method is 22%, the geeral lightig is 53%. Here, the geeral lightig cotrol the lightig fixtures with uiform dimmig rate. I this case, we simulated while chagig dimmig rate util illumiace of the zoes where six perso are i become 500lx. Because the power cosumptio shows a proportio tedecy for stregth of dimmig, we ca cosider that the proposed method ca reduce a amout of power cosumptio tha the geeral lightig. The proposed method detects the perso, ad cotrols to arrow the area where brightess is ecessary. So, we ca get high effectiveess of the eergy-savig. 60 50 40 30 20 10 0 Figure 7. Average of dimmig rate 4.2. Air-Coditioer Cotrol Method We measure room temperature chage of the zoe where someoe is i ad the power cosumptio to evaluate the proposed method. We evaluate it based o a compariso with automatically cotrol of the air-coditioer. Figure 8 shows a evaluatio coditio. The size of the room is 14 by 8.5 meters, ad 4 idoor uits are istalled. Ad, the room is divided i the several zoes as show i dotted lies. We assume that there is oe perso i the Zoe1, ad we operate the proposed method ad automatically cotrol. I additio, the target temperature i the zoe where someoe is there is 22.0 degrees Celsius. thermo-sesor 2 Proposed method Zoe 2 Zoe 1 Average of the dimmig rate Perso A thermo-sesor 1 Geeral lightig Idoor uit Figure 8. Evaluatio coditio of the air-coditioer cotrol Figure 9 (a) shows a room temperature chage of Zoe1, ad Figure 9 (b) shows oe of Zoe2. Moreover, i Figure 9, the proposed method is show by solid lies, ad, the automatically cotrol is show by dotted lies. I Figure 9 (a), the room temperature of the proposed method rises util the lapse of 7 miutes from the start of the experimetal evaluatio. Ad, the average temperature that is from the lapse of 7 miutes to the lapse of 20 miutes is 21.7 degrees Celsius. O the other had, the room temperature of the automatically cotrol rises util the lapse of 10 miutes from the start of the experimetal evaluatio. Ad, the average temperature that is from the lapse of 10 miutes to the lapse of 20 miutes is 23.5 degrees Celsius. Also, as show i Figure 9 (b), the average temperature of the proposed method util the lapse of 20 miutes from the lapse of 7 miutes is 21.0 degrees Celsius. This temperature is lower 1 degree Celsius tha a target temperature. O the other had, the average temperature of the automatically cotrol util the lapse of 20 miutes from the lapse of 10 miutes is 22.4 degrees Celsius. Based o these results, we cofirmed that the proposed method ca cotrol the temperature of the oly specific zoe to close to the target temperature. room temperature [ ] room temperature [ ] 24 22 20 18 24 22 20 18 thermo-sesor 1 0 5 10 15 20 elapsed time [mi] a) Zoe1 thermo-sesor 2 b) Zoe2 proposed method automatically cotrol proposed method automatically cotrol 0 5 10 15 20 elapsed time [mi] Figure 9. Room temperature chages o zoe1/zoe2 Figure 10 shows the power cosumptio of the air-coditioer. The abscissa of the graph is the time axis, ad the ordiate represets the evaluatio value. Both results of the proposed method ad the automatically cotrol are show for compariso. The total power cosumptio values for 25 miutes are show i the far right-had side of the graph. As show i graph form, the proposed method is 0.9 kwh, ad the automatically cotrol is 1.3 kwh. From this result, we cofirmed that the proposed method could reduce power cosumptio tha automatically cotrol.
Iteratioal Joural of Eergy Egieerig 2015, 5(4): 67-73 73 power cosumptio [kwh] 1.2 1 0.8 0.6 0.4 0.2 0 Figure 10. Power cosumptio of air-coditioer 5. Coclusios I this article, we metioed to cotrol the lightig system ad the air-coditioig system for the oly zoe where someoe is i. We evaluated the proposed lightig cotrol algorithm by simulatio ad cofirmed that the proposed algorithm got the eergy savig effect while keepig the target illumiace of the zoe where perso is i. I additio, we evaluated the proposed air-coditioig cotrol algorithm by the experimetal evaluatio ad cofirmed that the proposed algorithm got eergy savig effect while keepig the target room temperature of the zoe where perso is i. By the above, we cofirmed that the proposed method is effective for the eergy savig of office buildigs. REFERENCES automatically cotrol proposed method 0-5 5-10 10-15 15-20 0-20 elapsed time [mi] [1] Y. Bai ad Y. Ku: "Automatic Room Light Itesity Detectio ad Cotrol Usig a Microprocessor ad Light Sesors", IEEE Trasactios o Cosumer Electroics, Vol. 54, No. 3, pp.1173-1176 (2008-8). [2] H. Kumagawa: "The Lightig Cotrol Techiques ad the Applicatios to Realize Eergy Savig", J. Illum. Egg. Jp., Vol. 90 No.9, pp.661-665 (2006-9) (i Japaese). [3] Y. Morimoto, ad M. Ota: "Eergy-Savig Cotrol for Office Lightig", Toshiba Review, Vol. 59 No.10, p.22-26 (2004-10) (i Japaese). [4] M. Pa, L. Yeh, Y. Che, Y. Li, ad Y. Tseg: "A WSN-based Itelliget Light Cotrol System Cosiderig User Activities ad Profiles", IEEE Sesor Joural, Vol. 8, No. 10, pp. 1710-1721 (2008-9). [5] C. Tomishima, M. Miki, M. Ashibe, T. Hiroyasu, ad M. Yoshimi: "Distributed Cotrol of Illumiace ad Color Temperature i Itelliget Lightig System", 6th Iteratioal Symposium o ECODesig2009, (2009-12). [6] T. Weg ad Y. Agarwal: "From Buildigs to Smart Buildigs Sesig ad Actuatio to Improve Eergy Efficiecy", i Proc. of the IEEE Desig & Test, Special Issue o Gree Buildigs, vol. 29, pp. 36-44, Sa Diego, CA, (2012-8). [7] T. Yamamoto ad S. Hayakawa: "Study o the Eergy Coservatio of Multi-Split Type Air Coditioers i the Uiversity Buildig - The Effect of Stoppig All Machies i the ight -", Tras. SHASE, No.154, pp.43-49 (2010-1) (i Japaese). [8] U.S. Eergy Iformatio Admiistratio, "Aual Eergy Outlook", http://www.eia.gov/forecasts/aeo/. [9] N. Forouzadehmehr, S. M. Perlaza, Z. Ha, ad H. V. Poor, "Distributed Cotrol of Heatig, Vetilatio ad Air Coditioig Systems i Smart Buildigs", i Proc. of the IEEE Global Commuicatios Coferece (GLOBECOM), Atlata, GA, (2013-12). [10] ASHRAE, "BACet ANSI/ASHRAE Addedum c to ANSI/ASHRAE Stadard 135-2004", http://www.bacet.org /Addeda/Add-2004-135c.pdf, (2006).