APPLICATION AND VERIFICATION OF ENERGY BASELINE ESTIMATION METHOD BY SIMULATION

Transcription

1 Poeedings: Building Simulation 27 APPLICAION AND VERIFICAION OF ENERGY BASELINE ESIMAION MEHOD BY SIMULAION Masato Miyata, Haunoi Yoshida, akuo Iwata, Zhaoming Zhang, Yoihi anabe 2, adahio Yanagisawa 2 Depatment of Uban and Envionmental Engineeing, Kyoto Univesity, Kyoto, Japan 2 Osaka Pefetual Govenment, Osaka, Japan ABSRAC A ational method to estimate the enegy baseline of a building is indispensable in pefoming suh as eto ommissioning, on going ommissioning and ESCO (Enegy Sevie Company) pojets. Usually a statistial egession method is used to estimate a baseline. But the limitation of this method is that it annot evaluate the effet of hanges in opeational onditions suh as HVAC system and oupany shedule, oom tempeatues, amount of fesh ai intake in HVAC systems, weathe onditions, et. by whih enegy use is affeted. In these ases an estimation method based on simulation would be a good option. Howeve, few studies ae found about veifiation of the method based on expeiments using a eal building. heefoe we aied out an expeiment fo hanges of oom ai tempeatues and the fesh ai intake volume in a eal building and veified the auay of the baseline estimation method developed in ou pevious study. he esults show that the model an estimate the baseline hange with aeptable auay. KEYWORDS enegy use baseline, eto ommissioning, ESCO, ai-ondtioning load simulation INRODUCION When we intodue enegy onsevation measues to estimate how muh enegy is edued is a key issue. he diffiulty of estimating it is on the fat that enegy onsumption is elated to vaious opeational onditions suh as weathe, oupany, oom ai tempeatue set point, HVAC system opeation, et. whih hange with time and sometimes by use needs o by hane. If we an measue the edution dietly it is easy but it is not possible beause postetofit enegy usage is measuable but pe-etofit enegy use afte etofitting is not measuable. heefoe we need to estimate the pe-etofit enegy use unde speifi opeational onditions based on a model. his is defined as an adjusted enegy baseline. he U.S. Depatment of Enegy poposed fou options to estimate the adjusted enegy baseline. hese ae Options A, B, C and D whih ae explained in the Intenational Pefomane Measuement and Veifiation Potool (IPMVP 22). In Japan, it is used in most ESCO pojets. Option C is a method to estimate the enegy baseline by statistial linea egession. Option D is a method to estimate the enegy baseline by simulation. Although it equies muh infomation and manpowe, it an estimate the baseline with opeational ondition hanges; fo example, hanges in weathe, oupany and equipment opeation. Option D is theoetially onsideed moe auate than Option C. his method is impotant in baseline estimation beause opeational ondition hanges ou vey often in usual. We developed a method of Option D type (Miyata and Yoshida, et. al 26). he model has two submodules: a heating and ooling load alulation module and an enegy onsumption estimation module, whih onsists of the models of enegy onsuming equipment in a building. In this study the appliability of the fist sub-model is investigated by aying out an expeiment of hanging oom ai tempeatues and fesh ai intake volume intentionally using a eal building. HE BASELINE ESIMAION MODEL Figue shows an outline of the enegy baseline estimation model (Miyata and Yoshida, et. al 26). Ai-onditioning load estimation is pefomed using ACSES developed by the authos. he load alulation is aied out by the following equations that ae based on the esponse fato method (Yoshida, et. al 994). Q = Q Q + V ( h h ) () bn,, n Rn, a oan, on, n, Figue Adjusted enegy baseline model

2 Poeedings: Building Simulation 27 { ϕ ϕ ϕ } (2) Q = q + q + q n, tn, j tj, gn, j g, j n, j j, j= tn, = w ( en, j ef), j j= Rn, = ( n, j ef) R, j j= q A θ θ φ (3) Q θ θ φ (4) ACSES an alulates atual loads by inputting measued onditions suh as oom ai tempeatues and humidity, fesh intake ai volume, and opeation shedules of ai-onditioning systems, lighting systems and oupany. he equipment ae divided into two goups; equipment fo ai onditioning and the othes. Enegy onsumption of the equipment used fo aionditioning is alulated based on estimated ai onditioning loads. Enegy onsumption of the othe equipment is estimated using atual opeation shedules and enegy use statistis fo eah equipment. EXPERIMEN IN A REAL BUILDING Expeimental Building Opeation data wee gatheed in a mid-sale govenment building, with the floo aea of 6,69 m 2 and the ai-onditioned aea of 3,942 m 2, in Osaka, Japan. Figue 2 shows the plan and the oss-setion of the building. Figue 3 shows an outline of the ai onditioning system of the building. he building has two gas-fied absoption hilles (R- and R-2), five ai-handling units, and thity-thee fan-oil units. F : tempeatue measuement point : flow measuement point v w, F P- v P-2 w,2 F θ wi,2 It was built in 974, and enegy saving measues wee etofitted in 23 as an ESCO pojet. hey ae installation of invetes to the fan motos of ai handling units and pump motos, and eplaement of fluoesent lamps with high-effiieny ones. Measuement he measued data ae shown in able. hey have been aumulated fo one yea sine the summe in 25. Outside ai tempeatues and humidity and global sola adiation ae measued on the oof of the building. Figue 4 shows the views of measuing instuments. Room ai tempeatues and humidity ae measued at 7 points, whih loations ae shown in Figue 2. he aveage oom ai tempeatues and humidity ae alulated as an aea weighted mean using measued data. 7 θ () t = () (5) { θ, t S, } i ai Sa i = 7 θ wi, AHU (5 units) FCU (33 units) x () t = x () t S (6) {,, } i ai Sa i = P2- P2-2 P-9 P- Fesh ai intake volume is measued at the inlet of the ai intake hambe. he fesh ai intake loads ae alulated using the measued outdoo ai intake C R- R-2 θ wo,2 Figue 3 Ai-onditioning system θ wo, able Measued data Measued item Inteval Instuments Figue 2 Plan and oss-setion diagam of the expeimental building (X indiates oom ai tempeatue and humidity measuement points) Outside ai tempeatue and humidity Room ai tempeatue and humidity (7 points) mins mins empeatue and humidity eode Global sola adiation min Pyanomete Fesh ai intake volume mins Hotwie anemomete Inlet and outlet tempeatue of hilled wate (R-, 2) mins hemiste inseted in pipe Flow ate of hilled wate (R-, 2) mins Pitot-tube flow mete -969-

3 Poeedings: Building Simulation 27 Figue 4 Photogaph of measuement instuments (Left: Room ai tempeatue and humidity, Right: Fesh ai intake volume) volume as follows. { } Q () t = V h () t h () t (7) oa a oa oa he ai-onditioning loads ae alulated by the equation (8). 2, { θ, θ, } (8) Q () t = v () t () t () t w w k wi k wo k k= In this pape, Q is defined as the measued aionditioning loads. Expeiment fo the veifiation In ode to veify whethe the baseline estimation model an estimate the baseline shift auately due to the hanges of opeational onditions, expeiments wee onduted duing the summe in 26.. As the veifiation of the oom ai tempeatue hanges, the set point of the oom ai tempeatue was hanged intentionaly fo fou days as shown in able 2. Howeve, as Figue 5 shows a histogam of the aveage oom ai tempeatues measued fom June 22nd to Septembe 3th, 26, even if the set point of the oom ai tempeatue of the usual days is 27 C, the oom ai tempeatues ae not onstant, onsequently, they ae distibuted between 26 C and 29 C. he oom ai tempeatues of the expeimental days fall within the distibution. heefoe not only the tempeatues of the expeimental days but also the tempeatues unde the nomal opeation an be used fo veifiation. In ode to analyze the load hanges by fesh ai intake, the ai volume was ineased intentionaly in Septembe 5, 26 by opening the outdoo dampe so that the volume beomes appoximately double of the nomal opeation (2.46 m 3 /h m 2 to 5.63 m 3 /h m 2 ). Figue 6 shows a histgam of the fesh ai intake volume fom June 22nd to Septembe 3th. Although the distibution of the volume is not so wide as oom ai tempeatue ase, all the measued data ae used fo the veifiation. LOAD ESIMAION MODEL he ai-onditioning load estimation is aied out using a building simulation model. he building model is made using the design dawings. able 3 and able 4 show the wall onfigations and a list of intenal heat loads of the west-wing espetively as an example. he numbe of oupants is detemined by ounting the numbe of oupants in the building (26 pesons). he aloifi value of lighting and the offie mahines ae detemined by the numbe of devies suh as lighting fixtues, pesonal omputes, and opy mahines, et. In ode to veify the auay of the alulation model, the simulated loads between August and Septembe 3 ae alulated and ompaed with the measued loads. Figue 7 shows the esult ompaimg daily-aumulated values of the simulated and the measuted. he elative eo is appoximately.%, and %RMSE is appoximately.4%. his indiates able 2 Details of Expeiments Date Set point of oom ai temp. Usual 27 8/2, 8/ /6, 8/3 26 Date Fesh ai intake volume Usual 2.46m 3 /h m 2 9/5 5.63m 3 /h m 2 Fequeny [Days] σ =.75 Aveage 27.4 o C 8/3 8/6 8/2 8/23 Fequeny [Days] σ=.53 Aveage 2.46 m 3 /h. m 2 9/ Aveaged oom ai tempeatue [ o C] Figue 5 Histogam of oom ai tempeatue ( Fom June 22nd to Septembe 3th) Fesh ai intake volume [m 3 /h. m 2 ] Figue 6 Histogam of fesh ai intake volume ( Fom June 22nd to Septembe 3th) -97-

4 Poeedings: Building Simulation 27 Daily-aumulated ooling load [kwh] 4 Simulated Measued 3 2 6/24 7/ 7/8 7/5 7/22 7/29 8/5 8/2 8/9 8/26 9/2 9/9 9/6 9/23 9/3 Figue 7 Compaison of simulated and measued daily-aumulated ooling loads Exteio wall Inteio wall Room divide Ceiling Ceiling (top) Floo Floo (bottom) mota(2), nomal onete(5), light-weight onete(2) mota(2), nomal onete(5), mota(2) asbestos ement slate(6), plaste(9), still ai(2), plaste(9), asbestos ement slate(6) ok wool boad(2), gypsum boad(9), ai(6), nomal onete(3), mota(3) ok wool boad(2), gypsum boad(9), ai(96), styene(25), light-weight onete(5), mota(3), light-weight onete(), mota(3) linoleum(3),mota(3), nomal onete(3), ai(6), gypsum boad(9), ok wool boad(2) linoleum(3),mota(3), nomal onete(2), mota(3) that the simulation an estimate the loads auately. VERIFICAION OF HE BASELINE ESIMAION MODEL Veifiation method able 3 Wall onfiguation in west-wing of the building We examined whethe ooling loads depend on values of oom ai tempeatues and the fesh ai intake volume by ompaing those that ae measued duing expeiment and simulated. he veifiation is pefomed as follows. ) Defining thee vaiables Q, Q s, and Q s,, whee Q is the daily aveage of measued houly load, Q s, is the simulated by adopting eoded opeational onditions and Q s, is the simulated by adopting a onstant value fo oom ai tempeatue o fesh ai intake volume as the seasonal aveage. 2) aking the diffeenes of Q and Q s,, and of Q and Q s,, and defining those as d = Q Qs, and d = Q Qs, espetively. aking the defeene ( ut = θ θ ) of oom ai tempeatue θ and θ, able 4 Intenal ooling loads in west-wing of the building Oupants Caloifi value of lighting.66 peson/m 2 25 W/m 2 Caloifi 4F Sensible 5.49 W/m 2 value of 2,3F heat 8.45 W/m 2 offie F 5.9 W/m 2 appaatus Latent heat W/m 2 whee θ is the seasonal aveage of oom tempeatues (27.4 C), and the diffeene ( us = Qoa Qoa ) of Q oa and Q oa, whee Q oa is the seasonal aveage of the fesh ai intake load (22.5 kj/h). 3) aking seasonal aveage of Q, Q s, and Q s, as Q, Q s, and Q s, espetively. he diffeene of Q and Q s, gives simulation auay (Figues 8 and 9). 4) Applying linea egession analysis to d and u t. If the gadient of the egession line beomes zeo o the egession line holds hoizontal position it tells that the simulated loads depend on oom tempeatues o simulation an physially aount fo the ondition hanges. In addition when applying linea egession analysis to d and u t, and if the gadient of the egession line beomes positive o the egession line holds upwad slope, we eah to the same onlusion. heefoe we applied both appoahes to make the onlusion onfident (Figues 8 and 9). 5) Cheking the lineaity of the elationship between d and u t, and of d and u t. Based on the physial Figue 8 Compaison of measued ooling load with simulated ooling load Q s, Q Figue 9 Compaison of measued ooling load with simulated ooling load Q s, Q -97-

5 Poeedings: Building Simulation 27 theoy the elationship of the two vaiables is linea but we need to hek it by the following method. We divide opeational onditions into thee anges so as to make the numbe of points same in eah ange and alulate the aveage of both vaiables and hek the lineaity. his test is used as additional poof to the above veifiation if the value of R 2 of line egession is too small to pove the existene of oelation. Room ai tempeatue hange Figue and Figue 2 shows the elationship between d and u t, and d and u t espetively. We found that the linea egession line holds almost hoizontally ompaed to the Figue 2. his indiates that the simulated loads aount fo the oom ai tempeatue hanges, howeve the R 2 value is too small (.9) to pove it statistially. he eason why the elationship is not so definite ould be due to that the load hange aused by the oom ai tempeatue flutuation is not substantial. Aoding to the simulation esults it is known that the effet is only about 6 % of the total load. Howeve Figue shows the aveaged values of the thee anges align mostly on a hoizontal line that shows the existene of the linea elationship. Fom Figue 2 it an be seen that the gadient of the linea egession line has a lage negative value. his assists the above onlusion. Howeve still the R 2 value is not so lage (.42). In Figue 3 the aveaged values of the thee anges ae shown that shows the linea elationship vey lealy. Fesh ai intake volume hange Figue 4 and Figue 6 shows the elationship between d and u s, and d and u s espetively. he point isolated in the ight hand side oesponds to the expeiment of fesh ai intake volume hange on Sept. 5, 26. In this ase the gadient of the egession line of Figue 4 is smalle than that of Figue 6. his modestly shows that the volume hange an aount fo the load hange but the poof R 2 =.9 Diffeene of Q and Qs, 5-5 Diffeene of Q and Qs, 5-5 R 2 =.42 - Figue Relation between oom ai tempeatue and diffeene between Q and Q s, Diffeene of Room Ai emp. θ and θ - Figue 2 Relation between oom ai tempeatue and diffeene between Q and Q s, Diffeene of Room Ai emp. θ and θ Diffeene of Q and Qs, 5-5 σ = 3.4 σ = 24.2 σ = 26. Diffeene of Q and Qs, 5-5 σ = 4.3 σ = 28. σ = Diffeene of Room Ai emp. θ and θ Figue Relation between oom ai tempeatue and gouped diffeene between Q and Q s, (σ : Standad deviation of the eah goup) Diffeene of Room Ai emp. θ and θ Figue 3 Relation between oom ai tempeatue and gouped diffeene between Q and Q s, (σ : Standad deviation of the eah goup) -972-

6 Poeedings: Building Simulation 27 is not onfident. he othe method of using the aveaged points of thee anges annot also pove the fat. In onlusion the evidenes ae onsistent physially but they annot be poved in statistial manne. CONCLUSIONS Estimating the enegy baseline of a building is essential in pefoming eto ommissioning, on going ommissioning and ESCO (Enegy Sevie Company) pojets. In this study whethe aionditioning load an be estimated by simulation auately is veified based on expeimentation in a eal building. he followings ae the esults obtained. ) It was veified that oom ai tempeatue affets ai-onditioning loads and the quantity of the load hange an be estimated by simulation. 2) It is not statistially veified that the load is affeted by fesh ai intake volume. But at least no negative indiation was found against the elation. 3) he elationship between load and opeational Diffeene of Q and Qs, 5-5 R 2 =.4 onditions hange is identified as linea. NOMENCLAURE A w : Aea of extenal wall [m 2 ] a : Speifi heat of dy ai [J/g K] w : Speifi heat of wate vapo [J/g K] h on, : Enthalpy of outdoo ai [J/kg] h n, : Enthalpy of oom ai [J/kg] q g, n : Heat load by light though glass q tn, : ansmitting heat load though extenal wall q n, : Heat load by intenal heat emission [J] Q bn, : otal themal load Q : Measued themal load Q s, : Simulated themal load with onstant opeational ondition Q s, : Simulated themal load with measued opeational onditions S a : Ai-onditioned floo Raea 2 =.2 [m 2 ] S ai, 5 : Ai onditioning floo aea of oom i [m 2 ] v : Wate flow ate of hille Diffeene of Q and Qs, w, k -5 - f Diffeene of fesh ai load Qoa and Qoa Diffeene of fesh ai load Qoa and Qoa Figue 4 Relation between fesh ai load and diffeene between Q and Q s, Figue 6 Relation between fesh ai load and diffeene between Q and Q s, Diffeene of Q and Qs, 5-5 σ = 23.5 σ = 26.5 σ = 2.6 Diffeene of Q and Qs, 5-5 σ = 24. σ = 26.2 σ = Diffeene of fesh ai load Qoa and Qoa Figue 5 Relation between fesh ai load and gouped diffeene between Q and Q, (σ : Standad deviation of the eah goup) s Diffeene of fesh ai load Qoa and Qoa Figue 7 Relation between fesh ai load and gouped diffeene between Q and Q, (σ : Standad deviation of the eah goup) s -973-

7 Poeedings: Building Simulation 27 ( k =:R-, k =2:R-2) [m 3 /h] V oa, n : Fesh ai intake volume [kg/s] x i, : Measued humidity of oom i [g/gda] x : Aea weighted aveage oom ai humidity [ C] θ en, : Sol-ai tempeatue [ C] θ : Aea weighted aveage oom tempeatue [ C] θ i, : Measued tempeatue of oom i [ C] θ ef : Refeene tempeatue [ C] θ n, : Room ai tempeatue [ C] θ wi, k : Inlet hild wate tempeatue ( k =:R-, k =2:R-2) [ C] θ wo, k : Child wate tempeatue at outlet ( k =:R-, k =2:R-2) [ C] ϕ g, n : Weighting fato of heat gain of light [-] ϕ n, : Weighting fato of intenal heat gain [-] ϕ tn, : Weighting fato of extenal wall [-] φ Rn, : Heat absoption esponse fato of oom [-] φ n, : Heat tansfe esponse fato of extenal wall [-] Liu M., Zhu Y., et al: Aiflow Redution to Impove Building Comfot and Redue Building Enegy Comsumption A Case Study, ASHRAE ansations Reseah, Vol. 5 Pat, P ,999 Masato Miyata, Haunoi Yoshida, et al: Estimation of Exessive HVAC Enegy Consumption due to faulty VAV units, Building Simulation, 9th Intenational Confeene, pp , Canada, 25.8 Masato Miyata, Haunoi Yoshida, et al: Estimation of Enegy Baseline by Simulation fo On-going Commissioning and Enegy Saving Retofit, Intenational Confeene of Enhaned Building Opeation, Shenzhen, Vol.6-6-2, 26. Subsipt n : ime step REFERENCES Adam C., Ande P., et al: Commissioning Oiented Building Loads Calulations. Appliation to the CA-ME Building in Namu, Intenational Confeene Fo Enhaned Building Opeations, 24 Gieble,., M. Liu, and D. E. Claidge: Evaluation of Enegy Consevation Measues by Model Simulation, he Eleventh Symposium on Impoving Building Systems in Hot and Humid Climates Poeedings, 998. Haunoi Yoshida, oshio eai, Hioaki Sueyoshi: ansient Analysis of Ai-Conditioning Load and Room Conditions Consideing Simultaneous Heat and Moistue anspot of Multi-Layeed Constutions, Building and Envionment, Speial Issue 29.3,pp ,994 IPMVP New Constution Subommittee: Conepts and Options fo Detemining Enegy and Wate Savings Volume I, Intenational Pefomane Measuement & Veifiation Potool, 22.3 Keide, J.F. and Habel, J.S.: Pediting Houly Building Enegy Usage: he Geat Pedito Shootout -- Oveview and Disussion of Results, ASHRAE ansations Vol., pp.4-8,