A boiler room in a 600-bed hospital complex: study, analysis, and implementation of energy efficiency improvements

Ene gies 2014, 7, 3282-3303; doi:10.3390/en7053282 ene gies ISSN 1996-1073 www.mdpi.com/jou nal/ene gies A icle A Boile Room in a 600-Bed Hospi al Complex: S udy, Analysis, and Implemen a ion o Ene gy E iciency Imp o emen s Juan-Ca los F aile 1, Julio San-José 2,* and Ana González-Alonso 2 1 Ins i u e o Ad anced P oduc ion Technologies, School o Indus ial Enginee ing, Uni e si y o Valladolid, C/Paseo del Cauce 59, 47011 Valladolid, Spain; E-Mail: jc [email protected] a.es 2 Depa men o Ene gy Enginee ing and Fluid Mechanics, School o Indus ial Enginee ing, Uni e si y o Valladolid, C/Paseo del Cauce 59, 47011 Valladolid, Spain; E-Mail: [email p o ec ed] * Au ho o whom co espondence should be add essed; E-Mail: jul[email p o ec ed]; Tel.: +34-983-423-685, Fax: +34-983-186-462. Recei ed: 8 Ap il 2014; in e ised o m: 8 May 2014 / Accep ed: 13 May 2014 / Published: 19 May 2014 Abs ac : The aim o ene gy e iciency is o use less ene gy o p o ide he same se ice. In hospi als, ene gy e iciency o e s a powe ul and cos -e ec i e ool o educe g eenhouse gas emissions, uel consump ion, and also unning cos s. O e a six-mon h pe iod, he six gas- i ed boile s ha p o ide bo h a hospi al’s hea and ho wa e we e moni o ed. Analysis o he da a ob ained led o se e al ac ions being implemen ed in he hospi al boile oom con ol sys em o imp o e he e iciency o he hea p oduc ion sys em. Compa a i e s udies we e conduc ed, du ing simila wea he pe iods, o he pe o mance o he hospi al’s ho wa e p oduc ion sys em be o e and a e he con ols we e implemen ed. Resul s indica e ha he con ol ac ions applied p o ed o be e ec i e. Finally; he pape o e s a inancial; p ima y ene gy sa ing and CO2 educ ion analysis ha poin s o a 3,434.00 €/week sa ings in na u al gas consump ion; and a cu in CO2 emissions o 20.3 ons/week; as compa ed o he e e ence acili y. Keywo ds: ene gy e iciency; hospi al; boile oom con ol 1. In oduc ion Hospi als and heal h ca e buildings adi ionally ha e high ene gy demands o bo h mechanical powe and hea . Mechanical powe in he o m o elec ical ene gy is used o ligh ing as well as OPEN ACCESS Ene gies 2014, 7 3283 echnological and medical equipmen . Hea is equi ed o space hea ing needs, sani a y ho wa e , and s eam p oduc ion. Inc easing demand o com o in ooms coupled wi h high in e nal loads has led o a signi ican inc ease in cooling equi emen s o e he las decade. As a esul , hospi al hea ing and cooling sys ems which ely on con en ional Hea ing, Ven ila ion and Ai -Condi ioning (HVAC) uni s a e bo h ene gy in ensi e and expensi e. To educe ene gy use and g eenhouse gas emissions by hese acili ies, he heal h ca e sec o needs ene gy e icien solu ions ope a ing a he lowes cos [1]. This ene gy is o en used ine icien ly and may be due o he con ol/ope a ion o he building [2]. P ope ly unc ioning con ol sys ems (inpu and ou pu de ices, con olle s…), a e a signi ican con ibu o o ene gy e iciency. P oblems associa ed wi h building con ols and ope a ion a e a p ima y cause o ine icien ene gy usage. Ha dwa e ailu es, so wa e e o s, and human ac o s ela ed o he di icul y o use and unde s anding o con ol p oduc s all conspi e o p e en buildings om achie ing he desi ed ene gy e iciency. In a 60 building s udy, esea che s a Law ence Be keley Na ional Labo a o ies ound ha 50% o he buildings e idenced con ol p oblems; 40% e idenced HVAC equipmen p oblems; 25% employed Ene gy Managemen Con ol Sys ems (EMS) ha did no unc ion p ope ly; and 15% had missing equipmen [2]. This demons a es ha sol ing con ol ela ed p oblems con ibu es signi ican ly owa ds p ima y ene gy sa ing. Acco ding o he USA Depa men o Ene gy [3], o e 50% o he ene gy used in buildings is consumed by HVAC uni s and ligh ing sys ems. Howe e , esea ch has shown ha up o 40% o his ene gy can be sa ed by closely moni o ing he s a e o he building and applying sui able con ol s a egies [4]. The complexi y o he acqui ed senso y da a and he o e whelming amoun o in o ma ion p esen ed makes such con ol sys ems di icul o adjus o e en unde s and by esponsible building manage s [5]. The e a e a ound 800 hospi als in Spain, and he heal h sec o is eminen ly public in na u e, o he ex en ha 108,000 o he coun y’s 160,000 beds a e in public hospi als. Consump ion in he hospi al sec o in Spain eached 0.6 M ep, accoun ing o 6% o he o al se ice sec o consump ion, and ep esen ing expendi u e amoun ing o some 600 million eu os. Ene gy consump ion s udies pe o med in Spanish hospi als a e shown in Table 1, and e lec mean ene gy consump ion pe bed in one yea o he a ious a eas o consump ion [6]. Table 1. Mean ene gy consump ion pe bed and yea in Spanish hospi als. Hospi als Elec ici y (kWh/bed·yea ) Na u al gas (kWh·HHV/bed·yea ) Diesel (kWh·HHV/bed·yea ) P opane (kWh·HHV/bed·yea ) >300 beds 10,043 14,722 6,733 102 <300 beds 8,885 7,987 12,695 229 Hospi als p o ide a wide ange o se ices, each o which has i s own speci ic ene gy equi emen s. These needs, howe e , a e me h ough cen alized managemen sys ems. The ene gy consumed in a hospi al is di ec ly p opo ional o demand and in e sely p opo ional o sys em e iciency. Demand depends p ima ily on: he skin o he building, he use o which he building is pu , en ila ion equi emen s, p e ailing wea he condi ions in he a ea, and so on [7]. Ene gies 2014, 7 3284 Sys em e iciency equi es p ope ly designed sys em componen s, sui able in e ela ion amongs componen s and con ol s a egy o each elemen , as well as o he sys em as a whole. This is e lec ed when conside ing he a ious ac o s in ol ed in a cen alized hea ing sys em (see Figu e 1): (a) he unc ions o he equipmen (hea p oduc ion, dis ibu ion, and he mal emi ance); (b) he mal ese oi s (boile s, dis ibu ion, he mal emi ance, p emises, and ou doo en i onmen ); and (c) communica ion and egula ion (gene a o , dis ibu ion, he mal emi ance, gene al con ol). Figu e 1. Block diag am o a s anda d hea gene a ing sys em. The egula ion and con ol o all hese ac o s ha in e ene in a cen al hea ing sys em equi e Building Au oma ion and Con ol Sys ems (BACS). BACS include in o ma ion conce ning all signals om he buildings in o de o ge “in elligen buildings”. The sys ems in eg a ed in o he BACS pu sue di e se and e y di e en pu poses, so in eg a ion issues a e o pa icula impo ance. Compa ed wi h he ield o indus ial au oma ion, building au oma ion has speci ic and di e en cha ac e is ics [8]. This has c ea ed a la ge quan i y o esea ch o imp o e HVAC ene gy by moni o ing and egula ion BACS. Vakilo oaya [9] p esen ed he imp o ed ene gy e iciency o an ai cooling plan , in oducing he model-based g adien p ojec ion op imiza ion me hod. Chung [10] de eloped a communica ion so wa e ha collec s da a on ene gy consump ion and es ima es consump ion. Bujak [11] imp o es he ene gy e iciency o a s eam he mal powe plan using ma hema ical modeling; Klein [12] educed ene gy consump ion by inc easing he numbe o senso s and compu a ional suppo o he Ene gy Managemen Con ol Sys ems (EMCS). Yoshida [13] pe o med an analysis o ene gy supply in hospi als, based on a sensi i i y analysis. Ma and Wang [14] imp o ed he con ol s a egy o a cen alized cooling plan ’s e iciency. Beghi [15] has designed an adap i e con ol o a oile Ene gies 2014, 7 3285 ai -cooled chille , which has managed o inc ease ene gy e iciency by 3%–7.3%; while Liao [16] s udied a load p edic ion by occupa ion in comme cial buildings. Wes [17] p esen ed an op imised supe iso y model p edic i e con ol (MPC) sys em o hea ing, en ila ion and ai condi ioning (HVAC) in comme cial buildings. As is clea om hese e iews, imp o ing ene gy e iciency by de eloping new so wa e packages o BACS is a e y b oad esea ch ield, due o he la ge numbe o a iables and pa ame e s ha ha e o be conside ed. The EMCS cu en ly ensu es he sa e y and ope a ion o ene gy acili ies, bu he op imal ene gy e iciency o he ins alla ion s ill equi es wo k and expe imen a ion. This a icle desc ibes he imp o emen s in ene gy e iciency in a cen alized hea ing acili y in a 600-bed hospi al complex co e ing a buil -up a ea o 170,000 m2. The implemen ed imp o emen s educe he pe iods in which he hospi al’s hea p oduc ion sys em is on STANDBY, and he e o e, also educes he TRANSITION imes. Imp o emen s we e made o e he summe o h ee easons: (i) es s and adjus men s ha e less impac on he hospi al’s com o le el; (ii) esul s can be ully ex apola ed o win e , as well as pe iods be ween he ex eme seasons; and (iii) he cos o pe o ming es s is lowe , since hese a e ca ied ou when he boile s a e wo king a less powe . 2. Ma e ials and Me hods 2.1. Me hodology o Reducing Hospi al Cos s h ough Ene gy E iciency The ene gy e iciency o an HVAC ins alla ion is imp o ed by a p ocess o ene gy managemen . Ene gy managemen is a cyclical p ocess (see Figu e 2), wi h he ollowing sec ions: (i) Ini ial s a e; (ii) Analysis o in o ma ion; (iii) P oposed ac ions and implemen a ion; (i ) Analysis o esul s. Once hese ou phases a e comple ed, he p ocess o collec ing da a begins again o assess he imp o emen in ene gy e iciency and con inue he p ocess o con inuous imp o emen [18]. Figu e 2. Me hodology o inc easing he ene gy e iciency o an Hea ing, Ven ila ion and Ai -Condi ioning (HVAC) ins alla ion. This me hod is applicable o HVAC acili ies as a whole ( ull sys em) o o sub-sys ems. In bo h cases, he a iables which he pa icula en i onmen imposes on he sys em o sub-sys em need o be known. Gi en he complexi y o a 600-bed hospi al’s HVAC acili ies, he bes op ion is o unde ake he analysis in subsys ems. In his case, wo k began wi h one o he subsys ems which has he g ea es impac on he hospi al’s ene gy consump ion, he hea ing sys em. Since he case in hand was a ully Ini ial s a e Analysis o in o ma ion P oposed ac ion and implemen a ion Analysis o esul s Ene gies 2014, 7 3286 ope a ional hospi al, a s udy was ca ied ou o e he summe , since any p oblems in he HVAC sys em du ing he win e would p o e o ally unaccep able. BACS is a sys em which allows da a o be ga he ed and analyzed sys ema ically, and which in many ins ances enables he p oposed ac ions o be implemen ed, in such a way ha , h oughou he s udy, close a en ion mus be paid o he sys em’s con igu a ion and unc ioning [19]. The boile oom’s ene gy e iciency may be de e mined di ec ly as a a io be ween use ul powe and powe consumed. Howe e , i a mo e de ailed analysis is o be pe o med, an indi ec e alua ion should be ca ied ou in e ms o he sys em’s losses, linked o he use ul ene gy as indica ed in Equa ion (1): nconsump ioPowe Loss - ncomsump ioPowe = nconsump ioPowe powe Use ul =η ∑ (1) The hea s a ion e iciency is de e mined in speci ic pe iods o ime, which migh be annual, in win e , summe , and so on, using powe consump ion and loss o e a pa icula pe iod o s udy. O e a gi en pe iod o i s unc ioning, he sys em may be in one o h ee modes: (a) ON: when gene a o s supply ene gy o he sys em. In hese cases, i is assumed ha he building equi es ene gy. Losses associa ed o his mode a e:  Hea ing s ack loss (Ph).  Losses caused by he acili y’s con ec ion and adia ion (Pcd).  Losses caused by maladjus men s in he con ol sys em (P ). (b) STANDBY: when gene a o s supply no ene gy o he sys em. In hese cases, i is assumed ha he building equi es no ene gy. Losses associa ed o his mode a e:  Hea ing s ack loss caused by chimney d augh (Pi).  Losses caused by he acili y’s con ec ion and adia ion (Pcd).  Losses caused by maladjus men s in he con ol sys em (P ). (c) TRANSITION STAGE: when he sys em gene a o s swi ch om STANDBY o ON. In hese cases, he building changes om equi ing no ene gy o equi ing ene gy. Losses associa ed o his mode a e:  Losses caused by lue gas en (Pp ).  Losses caused by he acili y’s con ec ion and adia ion (Pcd).  Losses caused by maladjus men s in he con ol sys em (P ) [20,21]. When de e mining a sys em’s e iciency o e a gi en pe iod, he sys em is checked o see whe he i has been: in ON mode ( ON), in OFF mode ( STANDBY), o in ansi ion mode ( TRANSITION). The sys em’s o al ene gy loss is calcula ed as: ON h cd STANDBY i cd TRANSITION p cd Loss= ( + + )+ ( + + ) ( + + ) PPP PPP P PP× × +× ∑ (2) Powe consumed will be he powe o he boile (Pboile ) du ing he ime i was ON and is calcula ed as: ON boile Powe consump ion P= × (3) Replacing all hese e ms in he sys em’s e iciency exp ession o a speci ic pe iod gi es: Ene gies 2014, 7 3287 ON boile ON ON STANDBY STANDBY TRANSITION TRANSITION ON boile η= P P P P P × −× − × − × × ∑∑ ∑ (4) This exp ession e lec s how losses can be educed by using mo e e icien equipmen and eco e y sys ems when he sys em is ON, al hough losses canno be o ally elimina ed. Howe e , i is possible o elimina e losses when he sys em is in STANDBY o TRANSITION mode by sui ably adap ing he equipmen o demand and by elimina ing ansi ion pe iods. Imp o emen s in he boile oom’s ene gy e iciency will educe ansi ional pe iods, which will mean ha he boile s ope a e con inuously as much ime as possible. 2.2. Desc ip ion o he Ho Wa e Dis ibu ion Sys em in he Hospi al The boile and ho wa e dis ibu ion sys em in he hospi al came in o ope a ion in 2009. The hospi al comp ises se e al la ge buildings, consis ing o ou loo s, wi h 600 beds, ope a ing hea es, as well as echnical and consul a ion ooms. I ope a es e e y day o he yea on a 24-hou -a-day basis. Gas- i ed boile s we e ins alled o mee he hospi al’s hea ing demands. The boile oom comp ises a g oup o six gas- i ed boile s. These boile s a e he Eu obloc-supe s anda d model, manu ac u ed by Vulcano-Sadeca [22]. Bu ne s a e he Weishaup RGL (R: modula ing egula ion; G: gas and L: liquid uel) model, which combines diesel/na u al gas bu ne s. Fou boile s (B1, B2, B3, and B4) a e equipped wi h a hea powe o 4000 kW each. Boile 5 (B5) has a 2300 kW gene a o , and boile 6 (B6) has an 1100 kW gene a o . Such a a ie y o powe s allows a wide ange o possibili ies o adap o he hospi al’s ene gy equi emen s. Ho wa e p oduced by boile s is pumped h ough pipes by means o wo ci cui s:  P ima y ci cui ( ed in Figu e 3): The gas- i edboile s a e connec ed o his ci cui which is a closed loop. When ho wa e lea es he boile s, he supply pump uni s d i e i h ough he hea exchange s, ansmi ing hea o he ai and o he sani a y wa e . The wa e hen e u ns o he boile by means o e u n pump uni s.  Seconda y ci cui (blue in Figu e 3): The ho wa e lowing h ough his ci cui is used o supply hea ing equi emen s in ce ain a eas o he hospi al (pa ien s’ ooms, ope a ing hea es, and so on) by means o an coils, and o hea sani a y wa e s o ed in anks. In bo h cases, hea ans e is ca ied ou h ough hea exchange s. The low in he p ima y ci cui is a iable, while he low in he seconda y ci cui is cons an . The bypass enables di e ences in wa e low o be compensa ed o . This bypass also helps o aise he empe a u e o he wa e e u ning o he boile s, making he empe a u e jump in he boile he bes possible. Ene gy managemen and con ol sys ems (EMCS) in buildings a e widely used due o hei high po en ial o sa ing ene gy and cu ing consumed ene gy expenses. The goal o an EMCS is o combine indoo com o condi ions a he zone/ oom le el o he building wi h an ene gy sa ing s a egy, moni o ing he pe o mance o he o e all sys em and adap ing he con ol s a egy acco d-ingly [23,24]. Ene gies 2014, 7 3288 Figu e 3. P ima y and seconda y ci cui s o he hospi al’s ho wa e dis ibu ion sys em. The hospi al EMCS in eg a es senso s, ac ua o s, in e aces, con olle s, local a ea ne wo k (LAN) and wo PCs o moni o ing. All o hem a e in e connec ed in a cen alized con ol a chi ec u e. The EMCS con ols and moni o s a wide a ie y o se ices, such as adia o sys ems, an coil uni s, ai handle s, gas- i ed boile s, sani a y ho wa e , as well as moni o ing medical gases. All he con ol componen s o p oducing hea and domes ic ho wa e in he hospi al a e manu ac u ed by T end® (Ho sham, UK) [25,26]. A LON (Local Ope a ion Ne wo k) connec s all he con olle s T end wi h ade name IQL, and ou Local A ea Ne wo ks (LANs) link up he con olle s T end wi h ade name IQ2XX. T end 963 so wa e allows da a, con ol se ings, and he de elopmen o he new con ol s a egy o boile con olle s o be moni o ed. Figu e 4 shows he a chi ec u e o he EMCS sys ems wi h ou LANs, in e connec ed h ough an in e ne ne wo k by means o ca ds T end wi h ade name INC2. Two PCs in he hospi al con ol oom a e linked h ough LAN ne wo ks by means o ca ds T end wi h ade name CNC2. Figu e 4. The a chi ec u e o he hospi al EMCS. Ene gies 2014, 7 3289 The con olle s o he six boile s ha make up he hospi al’s hea gene a ing sys em a e linked o he LAN 4 ne wo k. Boile s 1, 2, 3, and 4 use con olle s T end wi h ade name IQ246, and boile s 5, and 6 use con olle IQ204. In addi ion, he Weishaup -B eme modula ing bu ne in each o he boile s allows he PID (P opo ional-In eg al-De i a i e con olle ) con olle pa ame e s o be egula ed. Imp o emen s in he con ol s a egies we e implemen ed and es ed in he p ima y ci cui o he hospi al’s ho wa e dis ibu ion sys em (see Figu e 4), and mo e speci ically in he unc ioning o boile s 5 and 6, which a e esponsible o supplying he hospi al’s hea ing equi emen s. 3. Applica ion o he Me hodology o Ene gy E iciency in he Hospi al 3.1. Hospi al Boile Con ol Sys em: Ini ial S a e The ini ial basic equi emen s ela ed o boile s 5 and 6 o p o iding he hospi al’s hea ing equi emen s a e:  The ho wa e supply empe a u e is con olled o mee he se poin , depending on which se ices a e equi ed by he hospi al. Se poin empe a u es may be ixed ( he same alue o e ime) o a iable (based on building loads o ou doo -ai empe a u e).  The mos e icien g oups o boile s a each momen should be used. Tha is, he g oups o boile s which bes i he speci ic needs a any gi en momen .  The numbe o boile s ops and s a s should be minimized, so as o educe bo h consump ion and mechanical wea . Regula ing he hea p oduc ion sys em o hea ing and sani a y ho wa e in he hospi al in ol es h ee pa ame e s which a ec sys em pe o mance:  Boile ho wa e supply empe a u e.  Bu ne powe .  Bu ne con olle PID pa ame e s. When we s a ed he analysis o he con ol sys em ha egula es boile s 5 and 6 o p o iding he hospi al wi h hea and ho wa e , he se poin o he ho wa e supply empe a u e was 77 °C. The bu ne s o hese boile s inco po a e a he mos a which, o sa e y easons, swi ches o when he wa e empe a u e ises 6 °C abo e he se poin (83 °C). The bu ne s o boile s 5 and 6 we e ini ially adjus ed so ha hei minimum ope a ing powe was 50%. These bu ne s a e con olled by PID. The de aul alues (gi en by he manu ac u e ) o hese bu ne s a e: • Maximumbu ne ope a ingpowe : 100% • Minimum bu ne ope a ing powe : 50% • Se poin ho wa e supply empe a u e: 77 °C • Sa e y s op ho wa e empe a u e: 83 °C • PID bu ne : Kp = 10 • PID bu ne : Ti = 10 s • PID bu ne : Td = 10 s Ene gies 2014, 7 3290 Using hese ini ial egula ion pa ame e s, da a o he hospi al’s hea p oduc ion sys em we e collec ed o e a six-mon h pe iod. The e olu ion o he “ho wa e supply empe a u e” and “bu ne powe ” was sa ed. Da a o hese a iables we e aken each wo seconds. Figu es 5 and 6 show some o he da a collec ed. Speci ically, Figu e 5 shows he e olu ion o he ho wa e supply empe a u e in boile 5 o one hou (ea ly a e noon: 12 h 50’–13 h 50’). Figu e 6 shows he bu ne ope a ion powe o boile 5 du ing he same pe iod o ime. Figu e 5. Boile 5: Ho wa e supply empe a u e (°C). Figu e 6. Boile 5: Bu ne ope a ing powe (%). 3.2. Analysis o In o ma ion Analysis o Figu e 5 indica es ha he ho wa e supply empe a u e akes a maximum alue o 84 °C and a minimum o 71 °C. The e is a wide oscilla ion o 13 °C o e one pe iod (ea ly a e noon: 12 h 50’–13 h 50’) when he hospi al hea ing equi emen s emain cons an . Ho wa e supply empe a u e should he e o e e idence “ e y ew” oscilla ions. Ene gies 2014, 7 3297 4.3. Resul s Analysis wi h Ac ions 1, 2, 3, and 4 Implemen ed Finally, Figu es 12 and 13 show he esul s achie ed a e implemen ing all he ac ions desc ibed abo e on boile s 5 and 6. Figu e 12 shows he empe a u e moni o ing o he ho wa e supply o boile 5 om 19 Augus 2011 o 30 Augus 2011. Tempe a u e se poin is cons an (77 °C) un il 23 Augus 2011. The se poin hen a ies ollowing he s a egy shown in Figu e 7. This se poin a iable is cha ac e ized by he ollowing alues: Minimum OT = 17 °C, maximum OT = 26 °C, minimum ST = 75 °C, maximum ST = 79 °C. This igu e shows ho wa e empe a u e oscilla ions o sui he a iable se poin p og ammed. Figu e 12. Boile 5: Ho wa e supply empe a u e e olu ion (°C) implemen ing ac ions 1, 2, 3, and 4. Figu e 13. Boile 5: Ho wa e supply empe a u e e olu ion (°C) and ou doo -ai empe a u e. Ene gies 2014, 7 3298 Figu e 13 shows empe a u e moni o ing o he ho wa e supply o boile 5 ( ed line) as compa ed o he ou doo ai empe a u e moni o ing (blue line) om 17 h (30 Augus 2011) o 09 h (31 Augus 2011). This igu e shows ha he supply empe a u e is lowe du ing he wa mes pa o he day (18 h–23 h). Du ing he nigh and ea ly hou s o he mo ning (23 h–8 h), when he ou doo ai empe a u e dec eases and demand is g ea es (due o i ing up machines and equipmen which lies idle o e nigh , and hospi al pa ien s using ba h ooms), he supply empe a u e is highe . The e o e, a e his analysis, we conclude ha he ou ac ions implemen ed on boile s 5 and 6 allow he boile con ol sys em o espond app op ia ely o changes in bo h ou side empe a u e and hospi al hea ing equi emen s. 4.4. P ima y Ene gy Sa ings, CO2 Reduc ion and Financial Analysis The hospi al is a majo ene gy consume . The company supplying na u al gas o e s access o an online applica ion h ough which all kinds o in o ma ion can be ob ained: consump ion, se ice condi ions, and oubleshoo ing. This applica ion allows us o choose be ween daily o hou ly consump ion depending on how much de ail we wan . To de e mine p ima y ene gy sa ing, a compa ison was made be ween he na u al gas consump ion in he week o 18 o 24 July 2011 (hospi al boile con ol sys em unning in ini ial s a e, wi h no ac ion o con ol implemen ed), and he week om 12 o 18 Sep embe 2011 (hospi al boile con ol sys em unning in ini ial s a e, wi h con ol ac ions 1, 2, 3, and 4 implemen ed). As i is summe , only boile s 5 and 6 we e conside ed in he s udy. The o he ou boile s a e no equi ed du ing he summe . We chose hese wo weeks because, as shown in Table 3, ou side empe a u es (maximum, minimum, and a e age) a e e y simila , sugges ing e y simila hea ing demands in he hospi al. Figu e 14 shows empe a u e a ia ions du ing days 18–24 July 2011, and 12–18 Sep embe 2011. Table 3. Tempe a u e alues du ing he weeks analyzed. Weekly empe a u es Maximum °C Minimum °C A e age °C 18–24 July 2011 27.7 14.2 20.9 12–18 Sep embe 2011 27.5 14.9 21.2 Figu e 14. Tempe a u e a ia ion du ing 18–24 July 2011 and 12–18 Sep embe 2011. Tempe a u e °C Ene gies 2014, 7 3299 Analysis o hospi al gas consump ion o e wo weeks, aken om he na u al gas company’s web applica ion, has allowed us o calcula e Table 4. Table 4. Ene gy, cos , and emissions du ing he week. Days Gas consump ion (Nm 3 ) Hea ing supply (kWh) Gas cos (€) CO2 emissions ( on) 18–24 July 2011 24,188.0 289,772 9,283.00 55.2 12–18 Sep embe 2011 15,239.0 182,557 5,849.00 34.8 Reduc ion (37%) 8,949.0 107,215 3,434.00 20.4 The inancial alua ion shown in his able was ob ained conside ing a p ice o 0.032597 €/kWh. This co esponds o he uni p ice o he a iable e m o he hospi al’s gas bill. Using he p ice conside ed and he consump ion eco ded, an es ima ed sa ing o 3,434.00 € was made be ween he wo weeks s udied. I his esul o one week we e ex ended o he whole o he summe pe iod (June–Sep embe → 16 weeks), he es ima ed sa ing in cos s would be: 3,434.00 €/week × 16 weeks = 54,944.00 € E en hough, in a la ge acili y such as a 600-bed hospi al, gas consump ion cos s a e eno mous, being able o cu his amoun by a ound 55,000.00 € ep esen s a conside able sa ing, and one no o be igno ed. Figu e 15 shows he cos o gas each hou o e he wo weeks analyzed in he s udy (1 week = 168 h). A compa ison is made be ween he cos o one week in July (18–24) 2011, and one week in Sep embe (12–18) 2011. The impac o he ou ac ions implemen ed in he con ol sys em o boile s 5 and 6 ela ed o CO2 emissions o e he wo-week moni o ing pe iod indica ed abo e was calcula ed, and is shown in Figu e 16. Figu e 15. Cos o gas consump ion (each hou ). Ene gies 2014, 7 3300 Figu e 16. CO2 emissions (g). The CO2 alues indica ed in his igu e a e calcula ed om he combus ion eac ion o na u al gas. Analysis o his eac ion allows us o es ima e he numbe o g ams o CO2 emi ed o each Nm3 o na u al gas bu ned: 22 4 4 2 3 3 4 24 4 4 1 mol CO 44 g CO 1 mol CH 830 g CH g CO 2282.2 1 mol CH 1 mol CO 16 g CH 1 m N CH m N CH ××× = (5) CO2 emissions a e a di ec unc ion o na u al gas consump ion a he acili y. As a esul , when he amoun o gas used alls, he numbe o g ams o CO2 emi ed in o he a mosphe e also alls. Figu e 15 indica es ha emissions co esponding o he week a e con ol ac ions we e aken (12–18 Sep embe 2011) a e clea ly lowe . CO2 emissions due o he imp o ed con ol sys em o boile s 5 and 6 a e 37% in he compa a i e s udy pe o med o he wo weeks chosen. This ep esen s a 20- on educ ion in he CO2 emi ed o he a mosphe e. 5. Conclusions The ac ions pe o med o egula e and con ol he hospi al boile s allow us o conclude ha : • The educ ion in he minimum limi o he bu ne powe has managed o p e en he boile om con inually swi ching on and o , as a esul o eaching high wo king empe a u es a momen s o low demand. • App op ia e PID con olle uning o egula e he boile bu ne allows ho wa e supply empe a u e a ia ions o be smoo hed. Tempe a u e peaks a e smoo hed and a e sho e . When dealing wi h changes in hospi al hea demand, he boile s a e able o espond apidly o changes and quickly s abilize. • Implemen ing a boile con ol sequence leads o a dec ease in he ime in e als in which he boile is ope a ed a high powe being achie ed. This inc eases boile li espan as well as mo e e icien unning. Thanks o he suppo boile , dis u bances caused by changes in hospi al hea demand a e damped mo e quickly, hus educing peak empe a u es in he ho wa e . Ene gies 2014, 7 3301 • A e implemen ing he a iable se poin , he ho wa e supply empe a u e o he boile inc eases and dec eases wi h he ou doo ai empe a u e h oughou he day, he eby educing empe a u e luc ua ions in he p ima y ci cui , so i ope a es mo e in line wi h hospi al hea demand. We conclude ha he ou well-designed ac ions implemen ed o imp o e he con ol s a egy o he hospi al boile s a e able o p o ide hea ing in a highly e icien manne . Con ol canno o e come a acili y’s design aul s, bu can imp o e i s pe o mance, as has been e idenced by he esul s achie ed in his pape . Financial analysis poin s o a 55,000 € educ ion in cos s in summe (June–Sep embe ), as compa ed o he cos s wi h he manu ac u e ’s o iginal con ol sys em. Fu he mo e, he sys em was able o cu CO2 emissions by o e 20 ons be ween June and Sep embe . The e is a o al p ima y ene gy sa ing ha co esponds o a 37% educ ion in CO2 emissionsas compa ed o he e e ence ins alla ion. These indings show ha a boile con ol sys em which implemen s he ac ions desc ibed will p o e an en i onmen ally iendly and inancially easible op ion o hospi al hea ing. Au ho Con ibu ions Juan-Ca los F aile and Julio San-José designed he con ol ac ions, p oposed and analyzed he es esul s, and w o e and e ised he manusc ip . Ana Gonzalez-Alonso de eloped con ol so wa e and human-machine in e ace o PLC and PC. All au ho s ead and app o ed he inal manusc ip . 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