Variable Speed Drive Volumetric Tracking (VSDVT) for Airflow Control in Variable Air Volume (VAV) Systems

Transcription

1 EL-HH--5-4 Vaiable peed Dive Volumetic Tacking (VDVT) fo Aiflow Contol in Vaiable Ai Volume (VAV) ytem Mingheng Liu, Ph.D., P. E. Enegy ytem Laboatoy, Univeity of Nebaka-Lincoln ABTRACT An aiflow contol method ha been developed fo vaiable ai volume (VAV) ytem. Thi aiflow contol method i named VD volumetic tacking (VDVT) ince both the upply and etun aiflow ae detemined uing ignal of the vaiable peed dive (VD) intead of the flow tation. It pefomance i tudied and compaed with the fan tacking (FT) method uing model imulation. The VDVT maintain a contant building peue and the equied outide aiflow unde all load condition, educe the annual etun ai fan enegy by up to 5%, and the annual upply ai fan enegy by up to 3%. Thi pape peent the VDVT method, the ytem model, and the imulation eult. INTRODUCTION Aiflow contol of VAV ytem ha been an impotant deign and eeach ubject ince the VAV ytem wa intoduced. An aiflow contol method hould: (1) enue the aiflow to each pace o zone; () contol outide ai intake popely; and (3) maintain the poitive building peue. eveal method have been developed to enue the ai delivey to each pace o zone. Thee method include the tatic peue contol method and the dampe poition contol method. The tatic peue contol method maintain a ufficient tatic peue in the main duct (often /3 down team of the main duct) to enue the equied aiflow to each pace o zone. It pefomance ha been poven to be eliable ove many yea of ue. The fan powe i lowe unde patial load condition. The tatic peue eet can futhe deceae the fan enegy unde the patial load condition [1,, and 3]. The optimal eet of the tatic peue i citical fo minimizing the upply fan enegy. Hatman [4] popoed modulating the fan peed to maintain at leat one teminal box dampe full open fo moden DDC ytem, whee the AHU contolle can acce all teminal box infomation diectly. When popely deigned and maintained, thi method conume minimal fan enegy. Recently, Wei et al [5] impoved thi method by integating it with the tatic peue eet technique to pevent malfunctioning unde eveal typical building opeating poblem. Unfotunately, thi method can not be ued in building which have pneumatic teminal box contolle. In thi pape, an optimal tatic peue eet chedule i ued. The typical building peue contol method include the fan tacking (FT), the diect building peue contol (DBP), and the volumetic tacking (VT). The FT method et the etun fan peed at o lightly lagging the upply fan peed. Unde patial load condition, the building peue deceae a the total aiflow deceae [6, 7, 8, 9, and 1] ince the etun ai fan daw elatively lage amount of ai fom the building. The FT doe not enue contant o poitive building peue unde patial load condition. The DBP method modulate the etun ai fan peed to maintain the et point of the peue diffeence aco the building envelope. Thi can be poblematic in a lage building, whee it i difficult to meaue the peue diffeence popely ince the vaiation of the peue diffeence aco the entie envelope i fa lage than the et point. Hence, if the peue diffeence aco the envelope cannot be meaued accuately, thi method hould not be ued. The VT method meaue both the upply and etun aiflow uing flow tation. The etun ai peed i modulated to maintain the equied diffeence of the upply and etun aiflow. Thi method i vey effective when the equipment location and pace ae available fo the aiflow tation [11, 1]. Howeve, accuate meauement of aiflow ha poved difficult if not impoible fo mot of the ytem due to lack of the appopiate length of taight ductwok. Theefoe, thi method ha limited pactical value [9, 13]. In thi tudy, the volumetic tacking i ued. The VD ignal and the fan peue head ae ued to detemine the aiflow ate. Outide ai intake contol often ue one of the following method: the fixed dampe poition, the diect method [14], the plenum-peue contol, and the CO demand contol. In many building, it i a common pactice to et both the outide and the etun ai dampe to fixed poition to contol the Poceeding of the Thiteenth ympoium on Impoving Building ytem in Hot and Humid Climate, Houton, TX, May -,

2 EL-HH--5-4 outide ai. The dampe poition ae detemined duing ytem teting and balancing poce. The outide ai intake i eithe highe o lowe than the equied aiflow when the total aiflow i diffeent with the teting condition. The diect method meaue the outide aiflow diectly uing a flow tation. The contolle modulate the outide ai dampe to maintain the equied outide aiflow. A minimum outide ai duct o a fan i often equied [15, 16, and 17] in ode to meaue the aiflow accuately. The diect method povide good outide ai contol when the outide aiflow can be meaued accuately. Unfotunately, in many building, the ai leakage of the maximum outide ai dampe may by-pa the flow tation and theefoe, educe the accuacy of the outide ai meauement. The plenum-peue contol method maintain the mixed ai chambe peue at a equied level by adjuting the etun ai fan peed o the etun ai dampe [13]. The outide ai dampe eve a the flow mete. ince the dampe ha to be modulated duing the economize cycle, the hyteei of the ai dampe can caue ignificant aiflow vaiation [18]. The outide aiflow may vay ignificantly even the plenum tatic peue i contolled popely ince the peue dop aco the outide ai filte inceae a the dit built up. The CO demand contol method maintain the epeentative cabon dioxide at it et point by modulating the outide ai dampe. Thi method povide eliable outide ai intake contol fo typical occupancy [1, 19,, 1, and ]. In thi tudy, the CO demand contol method i ued. An impovement i made to pevent the outide ai backflow though the eleae duct building peue when the mechanical exhaut i highe than the occupancy feh ai equiement. In thi tudy, a new aiflow contol method i developed fo VAV ytem. Thi method implement the volumetic tacking uing the VD peed ignal and the fan peue head intead of aiflow tation, contol the outide ai intake uing the impoved CO demand contol technique, and contol the upply ai fan uing an optimal tatic peue eet chedule. ince the volumetic tacking i implemented uing the VD ignal, thi method i, called the VD volumetic tacking (VDVT). Thi pape peent the pincipal of the VDVT method and tudie it pefomance uing imulation. VDVT METHOD Figue 1 peent the aiflow contol chematic of the new VDVT method. The phyical (had) input ignal include the upply and etun fan head, the upply and etun ai tatic peue, the etun ai tempeatue, the mixed ai tempeatue, the outide ai tempeatue, the etun ai o the citical zone CO concentation. The output ignal include the upply fan VD peed, the etun fan VD peed, the outide ai dampe poition, and the etun and eleae ai dampe poition. T Releae Ai Dampe o MD MD Outide Ai Dampe PR T CO R Retun Ai Dampe H VFD upply Ai Fan P.H. H VFD Retun Ai Fan Figue 1: Aiflow Contol chematic of the VDVT Method The VDVT ha fou contol loop: the upply fan peed, the etun fan peed, the etun ai dampe, and the outide ai dampe. Fo the upply fan peed loop, the contolled vaiable i the upply ai tatic peue. The contolled device i the VD of the upply fan. Thi contol loop maintain the et point of the upply ai tatic peue by modulating the upply fan VD peed. To minimize the upply fan enegy, the upply ai tatic peue i eet to maintain the duct ytem eitance unchanged unde the patial load condition. Accoding to the fluid dynamic theoy (auming tubulent flow), the peue lo i popotional to the quae of the flow ate. Theefoe, to maintain the duct eitance unde the deign condition, the tatic peue hould be eet popotional to the quae of the aiflow ate unde patial load condition. If the duct eitance i kept unchanged, the flow atio equal the fan peed atio accoding to the fan law. Theefoe, the optimal tatic peue eet chedule i expeed by equation 1. p = c + p d ω ω d T m C.C. T P Conditioned pace (1) A poitive contant c i added to the optimal eet chedule to tabilize the contol loop. ince the Poceeding of the Thiteenth ympoium on Impoving Building ytem in Hot and Humid Climate, Houton, TX, May -,

3 EL-HH--5-4 eet chedule ue the contol output eet a the contolled vaiable, the fan peed will educe to zeo without adding the contant c. tictly peaking, the optimal eet chedule applie to the unifom zone load patten only. If the vaiation of the zone load atio i mall, a mall coection facto can be ued. Othewie, a lage coection may be equied. Equation 1 may eult in a tatic peue et point highe than the deign value when the VD peed i high, o eult in an unealitic low et point when the VD peed i low. Theefoe, neithe of thee high and low tatic peue et point hould be ued. The high et point caue the exceive fan enegy. The low et point may not be able to enue the ai delivey to each zone. ince the flow become lamina at lowe flow ate while equation 1 only applie to the tubulent flow, a low limit hould be elected baed on the minimum tatic peue equiement of teminal box, the duct layout, and othe infomation. If the calculated et point i highe than the deign value, the deign value hould be ued. If the calculated value i le than the low limit, the low limit value hould be ued. Fo the etun fan peed loop, the contolled vaiable i the etun aiflow ate. The contolled device i the etun ai VFD. The contolled loop output i the etun fan VFD peed. The etun aiflow et point equal the diffeence of the upply aiflow and the building exhaut and ai exfiltation. = (), ex inf The upply aiflow can be calculated uing equation 3 baed on the upply fan VD peed and the fan head (ee Appendix A fo detail). H a1 ± a1 4a a ω ω = (3) a The exhaut aiflow i teated a a contant ince it depend on the building envelope only. Theefoe, the tighte the building envelope i, the malle the value. The etun aiflow i calculated uing equation 4 accoding to the etun fan VD peed and the etun fan head. H b1 ± b1 4b b ω ω = (4) b The contol loop modulate the etun fan peed to maintain the etun aiflow et point. Fo the outide ai dampe loop, the contolled vaiable ae the etun ai tatic peue and the etun ai o the citical zone CO concentation when the economize i not activated, o the mixed ai tempeatue when the economize i activated. The contolled device i the outide ai dampe. The et point of the CO concentation hould be pedetemined uing engineeing pincipal. The et point of the etun ai tatic peue i zeo. The contolle modulate the outide ai dampe to maintain both the CO and the etun ai peue et point only when the etun ai dampe i in it maximum open poition. If the etun ai tatic peue i lowe than the et point, the contolle inceae the outide ai dampe openne egadle of the CO concentation. Thi pevent the negative building peue when the feh ai equiement of occupant i le than the mechanical exhaut and the exfiltation. When the economize i activated, the contolle modulate the outide ai dampe to maintain the mixed ai tempeatue et point. Fo the etun ai dampe loop, the contolled vaiable i the etun ai o the citical zone CO concentation when the economize i not activated, o the mixed ai tempeatue when the economize i activated. The contolled device i the etun ai and the eleae ai dampe. The eleae and the etun ai dampe ae intelinked. When the eleae ai dampe i in the minimum poition, the etun ai dampe i in the maximum poition. The etun ai dampe loop i activated only when the outide ai dampe i in the full open poition. The contolle deceae the etun ai dampe openne if the CO concentation i highe than the et point, o if the mixed ai tempeatue i highe than the cold deck et point duing the economize cycle. Othewie, the contolle inceae the etun ai dampe openne. The VDVT method minimize the fan enegy uing the optimal tatic peue eet and decoupling the outide and etun ai dampe; implement the volumetic tacking uing the VD peed and the fan head; and ue CO demand contol to minimize outide ai intake. The mathematical and phyical model of the VDVT ae peented in the next Poceeding of the Thiteenth ympoium on Impoving Building ytem in Hot and Humid Climate, Houton, TX, May -,

4 EL-HH--5-4 ection. It pefomance ae imulated and compaed with the FT method. PERFORMANCE ANALYI Thi ection compae the VDVT with the FT uing imulation. The impact of each key contol meaue i alo invetigated. Both the ytem modeling and imulation eult ae peented in thi ection. Aiflow Model Figue peent the aiflow chematic of the VAV ytem. The aiflow ytem i divided into fifteen egment. Each egment can be expeed uing the flow eitance facto (), which i defined a the atio of the peue lo and the quae of the aiflow ate though the egment. The flow eitance facto epeent the hydaulic chaacteitic of the ductwok, coil, filte, and fitting. The minimum eitance facto i calculated uing equation 5 and the deign infomation. The coection facto f depend on both the dampe poition and the type of the dampe. Accoding to MACNA [3], the coection facto i expeed uing equation d d = d +.377d f Oppoed Paallel (7) The aiflow loop ha thee joint. Theefoe, thee aiflow balance equation fom the famewok of the VAV ytem aiflow model. = ex + inf (8) = + (9) c c o = + (1) el el 11 1 P 9 R 1 8 R 7 ex Whee: ex = C (11) 1 O RC 13 P P m Figue : Aiflow chematic of VAV ytem The eitance facto ae contant except fo the egment, 6, 1, and 13. The value of the eitance facto ae calculated uing equation 5 baed on the deign infomation (ee Appendix B fo detail). P b 15 inf pb pb 15 inf = pb pb < 15 (1) p p > el = p p < (13) P i pm i = (5) pm < i o = pm The flow eitance facto of the egment, pm > , and 13 depend on both the dampe poition (d) (14) and the minimum flow eitance facto. The value of the flow eitance facto ae calculated uing p pm Equation 6. c = + + (15) i, i =, i =,1,13 (6) Both the upply and etun aiflow ae indiectly f detemined by balancing fan head and ytem peue lo. Poceeding of the Thiteenth ympoium on Impoving Building ytem in Hot and Humid Climate, Houton, TX, May -,

5 EL-HH--5-4 i ω ai = pm + ( ) + p (16) i= ω i ω bi = p p + ( ) + p (17) i= ω The upply and the etun fan powe ae calculated uing equation 18 and 19, epectively, accoding to the fan head, the aiflow ate, and the fan efficiencie. E E H = c (18) η H = c (19) η Whee: 1 + e + e ω ω η = e () η = f + f + f (1) 1 ω ω Equation 5 to 1 conit of the aiflow model of the VAV ytem. The equation et ha a total equation with 6 vaiable and i theefoe ovedetemined. ix moe condition mut be added in ode to imulate the ytem pefomance. Thee ix additional condition allow define the pecific ytem input and the opeation and contol chedule when pefomance imulation i conducted. Pefomance imulation Eight imulation wee pefomed to tudy the VDVT pefomance. The tudy ue the FT method a the bae cae. The full occupancy i aumed in thi tudy. The upply ai fan peed and the upply ai tatic peue ae the pimay input fo all the imulation. The fit two cae ae labeled Fan Tacking-1 and the Fan Tacking-. In both cae, the etun ai fan peed equal the upply ai fan peed. In the FT- 1 cae, the etun, eleae, and outide ai dampe poition ae elected to povide the equied minimum aiflow when the upply fan povide 1% deign aiflow to the building. In the FT- cae, the dampe poition ae elected to povide the equied minimum outide aiflow when the upply fan povide 6% of the deign aiflow to the building. The outide ai, the etun, and the eleae ai dampe ae fixed at the initial condition egadle the load condition. Contant tatic peue et point i ued fo both cae. The thid and the fouth cae add the tatic Peue Reet (PR) in the FT-1 and FT- cae. The PR eet the tatic peue popotionally to the quae of the aiflow. The coection contant i elected a zeo in thi tudy. The fifth cae add the CO demand contol (DC) in the FT-1 cae. The ixth cae add both the PR and DC into the FT- cae. The eventh cae ue both the volume tacking (VT) and the DC. The eighth cae add the PR to the eventh cae. The eighth cae epeent the pefomance of the VDVT method. The fit two cae epeent the bae cae. The imulation wee pefomed baed on an exiting AHU. The deign upply and etun aiflow ae 16.5 m 3 / and 14. m 3 / (35, and 3, cfm), epectively. The minimum outide ai intake i 3.8 m 3 / o 8, cfm. The um of the mechanical exhaut and ai exfiltation i.4 m 3 / o 5, cfm. The deign fan head ae 1,375 Pa (5.5 inh O) fo the upply fan, and 55 Pa (.1 inh O) fo the etun fan. The tatic peue et point i 5 Pa o inh O. The detailed ytem deign infomation i attached in Appendix B. Figue 3 peent the imulated outide ai intake atio, the building peue atio, and the upply and etun fan powe atio. The imulation eult how that the outide ai intake deceae a the total aiflow deceae when the FT method i ued (Figue 3a and 3b). The FT-1 povide le outide ai to the building unde the patial load condition. The FT- povide moe outide ai to the pace when the total aiflow i highe than 6% of the deign aiflow. In both FT-1 and FT- cae, the building peue deceae fom the deign value to negative a the total aiflow deceae. When the upply aiflow i le than 54%, the etun ai i eleaed fom the outide ai duct to the outide in the FT-1 due to the ove-peuization of the etun fan. The FT method i pone to IA poblem o high themal enegy conumption, and building peue contol poblem. Poceeding of the Thiteenth ympoium on Impoving Building ytem in Hot and Humid Climate, Houton, TX, May -,

6 EL-HH--5-4 Fan Powe Ratio.4 1. Outide Ai - Building Peue -1.. Fan Pow e - R. Fan Pow e Total Aiflow Ratio (a) FT-1 Outide Ai and Building Peue Ratio Fan Powe Ratio.4 1. Outide Ai Building Peue. Fan Pow e R. Fan Pow e Total Aiflow Ratio (b) FT- Outide Ai and Building Peue Ratio Fan Powe Ratio.4 Outide Ai 1. Building Peue -. Fan Pow e -1. R. Fan Pow e Total Aiflow Ratio (c) FT-1 & PR Outide Ai and Building Peue Ratio Fan Powe Ratio.4 Outide Ai 1. Building Peue Fan Pow e R. Fan Pow e Total Aiflow Ratio (d) FT- & PR Outide Ai and Building Peue Ratio Fan Powe Ratio.4 Outide Ai 1. Building Peue -. Fan Pow e R. Fan Pow e Total Aiflow Ratio (e) FT & DC Outide Ai and Building Peue Ratio Fan Powe Ratio.4 Outide Ai 1. Building Peue Fan Pow e R. Fan Pow e Total Aiflow Ratio (f) FT & DC & PR Outide Ai and Building Peue Ratio Fan Powe Ratio.4 Outide Ai 1. Building Peue Fan Pow e - R. Fan Pow e Total Aiflow Ratio (g) VT & DC Outide Ai and Building Peue Ratio Fan Powe Ratio.4 Building Peue Outide Ai Fan Pow e - R. Fan Pow e Total Aiflow Ratio (h) VDVT Outide Ai and Building Peue Ratio Figue 3: imulated Outide Ai Intake Ratio, Building Peue Ratio, upply and Retun Fan Powe Ratio Poceeding of the Thiteenth ympoium on Impoving Building ytem in Hot and Humid Climate, Houton, TX, May -,

7 EL-HH--5-4 Figue 3c and 3d peent the eult of the FT with PR. The tatic peue eet impove the building peue and the outide ai contol, and deceae the fan powe. The minimum building peue atio i impoved fom 3. to. The outide ai intake atio ae elatively cloe to the deign value. Fo example, the outide ai intake atio i deceaed fom.18 to 9 fom the FT- cae unde the full load condition. The fan powe i much lowe. Fo example, the fan powe atio i deceaed fom 3% to 1% when the aiflow atio i 6%. Figue 3e peent the eult of the FT with the DC. The DC maintain the contant outide ai intake at deign level and ha no impact on the building peue contol. ince the impoved DC method minimize the eitance of the etun and the outide ai dampe, the fan enegy i lowe than the FT method. Fo example, the fan powe i appoximately 5% lowe unde the full load condition. It i impotant to point out that the pope outide ai intake doe not enue the poitive building peue in a VAV ytem. Figue 3f peent the eult of the FT with both the DC and the PR. The DC maintain the contant outide ai intake and deceae the upply fan powe. The PR deceae both the upply and the etun ai fan powe, and impove the building peue contol. Again, the pope outide ai intake doe not enue the pope building peue. Figue 3g peent the eult of the VT with the DC. Both the outide ai intake and the building peue ae contolled at the equied level. The etun ai fan powe atio i ignificantly lowe than the upply ai fan powe atio ince the etun aiflow atio i lowe than the upply aiflow atio unde patial load condition. Figue 3h peent the eult of the VDVT method. The VDVT maintain both the building peue and outide ai intake popely with the minimum themal and fan enegy. Compaing with FT-, the VDVT deceae the outide ai intake atio fom.18 to 1 unde the peak load condition. Figue 4 peent the imulated the VDVT fan powe aving againt the FT method. The fan powe aving i expeed a the atio of the powe aving ove the deign fan powe. The maximum fan powe aving i 37% fo the etun fan and 17% fo the upply fan. The annual aveage enegy aving atio could be up to 5% fo the etun fan and 15% fo the upply fan ince the total aiflow vaie between.7 to.95 mot of the time fo typical VAV ytem. The VDVT could deceae the annual fan enegy by up to 5% fo the etun ai fan and 3% fo the upply ai fan if the annual aveage fan powe i 5% of the deign value uing the FT method. Fan Powe aving Ratio Retun Fan upply Fan Total Aiflow Ratio Figue 4: Potential Fan Powe aving of the VDVT Method CONCLUION The VDVT method ha been developed fo the aiflow contol in VAV ytem. Thi method can be ued fo typical AHU, which have pogammable contolle, ince the volumetic tacking i implemented uing the VD peed ignal and the fan head. The VDVT enue the equied outide ai intake and the poitive building peue unde all load condition with minimal themal and fan enegy. The annual fan enegy aving i up to 5% fo the etun fan and 3% fo the upply fan. Unde the full load condition, the VDVT educe the outide ai intake by 1. time of the deign value compaing with the FT contol. NOMENCLATURE a Regeion contant fo upply ai fan b Regeion contant fo etun ai fan c Unit conveion facto, tatic peue coection facto d Dampe poition ( to 1) e Regeion coefficient of upply ai fan efficiency veu the aiflow unde full peed f Coection facto, egeion coefficient of etun ai fan efficiency veu the aiflow unde full peed H Fan head (Pa o inh O) P Peue (Pa o inh O) Aiflow ate (l/ o cfm) Flow eitance facto Poceeding of the Thiteenth ympoium on Impoving Building ytem in Hot and Humid Climate, Houton, TX, May -,

8 EL-HH--5-4 p Peue lo (Pa o inh O) ω Fan peed (RPM) ubcipt b Building d Deign ex Exhaut inf Infiltation/exfiltation m Mixed o Outide ai Retun c Re-ciculated el Releae upply, et point REFERENCE 1. Waen M. and Nofod L. K., Integating VAV Zone Requiement with upply Fan Opeation, Jounal of AHRAE, Vol. 35, no. 35, pp Roe R. J. and Kopko W. L., A Novel Method fo Reetting Duct tatic Peue fo Vaiable Ai Volume ytem. Poceeding of ACEEE 1994 umme tudy on Enegy Efficiency in Building, Vol. 5, pp Liu M., Zhu Y., Claidge D.E., and White E., Impact of tatic Peue et Level on HVAC Enegy Conumption and Indoo Condition. AHRAE Tanaction 1997, Vol. 13, pt.. 4. Hatman T., TRAV-A new HVAC Concept, Jounal of Heating/Piping/Ai Conditioning, July 1989, pp Wei G., Liu M., and Claidge D. E.,. Integated Dampe Poition and tatic Peue Reet fo the VAV upply Ai Fan Contol. ubmitted to AHRAE. 6. Gadne F, T., Pat Load Ventilation Deficiencie in VAV ytem. Jounal of Heating/Piping/Ai Conditioning, Febuay 1988, pp Mumma. A. and Wong Y. M., 199. Analytical Evaluation of Outdoo Aiflow Rate Vaiation v. upply Aiflow Rate Vaiation Invaiable-Ai- Volume ytem When the Outdoo Ai Dampe Poition I Fixed. AHRAE Tanaction 199, Vol. 96. Pat 1, olbeg D. W., 199. Meauement fo the Contol of Feh Ai Intake. AHRAE Jounal, Januay 199, Vol. 3, no.1, Elovitz D. M., Minimum Outide Ai Contol Method fo VAV ytem. AHRAE Tanaction 1995, Vol. 11, Pat, Mudai D., Hall J. D., and Weling E., Enegy Cot and IA Pefomance of Ventilation ytem and Contol. IA 96, Path to Bette Building Envionment, Baltimoe, Octobe Kettle J. P., Minimum Ventilation Contol fo VAV ytem-fan Tacking v. Wokable olution. AHRAE Tanaction 1995, Vol.11, Pat, Avey G., The Intability of VAV ytem. Jounal of Heating/Piping/Ai Conditioning, 199, 64(): Cohen T., Poviding Contant Ventilation in Vaiable Ai Volume ytem. AHRAE Jounal, May 1994, pp Atkinon G. V., VAV ytem Volume Contol Uing Electonic tategie. AHRAE Tanaction 1986, Pat B, Janu G. J., Wenge J. D., and Nele C. G., Outide Ai Flow Contol fo VAV ytem. AHRAE Jounal, Apil 1995, Vol. 37, no. 4, Kettle J. P., Contolling Minimum Ventilation Volume in VAV ytem. AHRAE Jounal, May 1998, Vol. 4, no. 5, Mumma. A., 1. Dedicated OA ytem. AHRAE IA Application, Winte 1, Vol.., No. 1, Kakow K. I., Reduction of Hyteei in PI-Contolled ytem. AHRAE Tanaction 1998, Vol. 14, pt mith R. B., Vaiable Ai Volume Building Ventilation Contol ytem. Poceeding of AHRAE Confeence IA 87, Alington, Viginia, May 1987, Meckle M., Demand-Contol Ventilation tategie fo Acceptable IA. Jounal of Heating/Piping/Ai Conditioning, May 1994, pp Capente. C., Enegy and IA Impact of CO -Baed Demand-Contol Ventilation. AHRAE Tanaction 1996, Vol. 1, pat.. chell M., and Int-Hout D., 1. Demand Contolled Ventilation Uing CO. AHRAE Jounal, Febuay 1, vol. 43, no., MACNA, HVAC ytem Teting, Adjuting & Balancing, heet Metal and Ai Conditioning Contacto National Aociation, Inc. Chantilly, VA. APPENDIX A Equation 3 i deduced baed on the fan cuve and the fan law. The pocedue i lited below. Auming the fan cuve can be expeed uing a econd ode polynomial equation unde the full peed: Poceeding of the Thiteenth ympoium on Impoving Building ytem in Hot and Humid Climate, Houton, TX, May -,

9 EL-HH--5-4 H = a + (a-1) + a1 a If the fan i unning unde patial peed, the fan head and the aiflow i coelated uing equation a- accoding to the fan law. H = ω ( a + a / ω + a ( / ω) ) (a-) ω 1 Hω a1 ± a1 4aa ω ω = (a-3) a APPENDIX B The deign peue lo and the aiflow ate ae lited in the table below fo each aiflow loop ection. When both the fan head and the fan peed ae given, the fan aiflow i deduced a: Table 1: Deign Peue Lo and Aiflow Rate fo Each Aiflow Loop ection. egment Peue Lo Aiflow Note (Pa/inH O) (m 3 //cfm) 1 1.5/5 16.5/35, Outide ai ductwok 5/ 16.5/35, Outide ai dampe 3 1.5/5 16.5/35, Ductwok 4 and 5 85/ /35, Ductwok, filte, and coil 6 5/. 16.5/35, Down team of the tatic peue eno 7 and 8 475/ /3, Retun ai duct 9 1.5/5 14./3, Releae ai ductwok-1 1 5/.1 14./3, Releae ai dampe /5 14./3, Releae ai ductwok /5 14./3, Re-ciculate ai ductwok /.1 14./3, Re-ciculate ai dampe /5 14./3, Re-ciculate ai ductwok /5.45, Building envelope Poceeding of the Thiteenth ympoium on Impoving Building ytem in Hot and Humid Climate, Houton, TX, May -,