Potentials for energy savings and long term energy demands for Croatian households sector Pukšec, Tomislav ; Mathiesen, Brian Vad; Duic, Neven

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1 Aalborg Unverstet Potentals for energy savngs and long term energy demands for Croatan households sector Pukšec, Tomslav ; Mathesen, Bran Vad; Duc, Neven Publshed n: Appled Energy DOI (lnk to publcaton from Publsher): /j.apenergy Publcaton date: 2013 Document Verson Accepted author manuscrpt, peer revewed verson Lnk to publcaton from Aalborg Unversty Ctaton for publshed verson (APA): Pukšec, T., Mathesen, B. V., & Duc, N. (2013). Potentals for energy savngs and long term energy demands for Croatan households sector. Appled Energy, 101, General rghts Copyrght and moral rghts for the publcatons made accessble n the publc portal are retaned by the authors and/or other copyrght owners and t s a condton of accessng publcatons that users recognse and abde by the legal requrements assocated wth these rghts.? Users may download and prnt one copy of any publcaton from the publc portal for the purpose of prvate study or research.? You may not further dstrbute the materal or use t for any proft-makng actvty or commercal gan? You may freely dstrbute the URL dentfyng the publcaton n the publc portal? Take down polcy If you beleve that ths document breaches copyrght please contact us at vbn@aub.aau.dk provdng detals, and we wll remove access to the work mmedately and nvestgate your clam. Downloaded from vbn.aau.dk on: december 15, 2018

2 Potentals for energy savngs and long term energy demands for Croatan households sector Tomslav Pukšec Department of Energy, Power Engneerng and Envronment Unversty of Zagreb, Faculty of Mechancal Engneerng and Naval Archtecture Bran Vad Mathesen Department of Development and Plannng, Aalborg Unversty Department of Energy, Power Engneerng and Envronment Unversty of Zagreb, Faculty of Mechancal Engneerng and Naval Archtecture ABSTRACT Households sector n Croata represents one of the largest consumers of energy today wth around 75,75PJ, whch s almost 29% of Croata s fnal energy demand. Consderng ths consumpton, mplementng dfferent mechansms that would lead to mprovements n energy effcency n ths sector seems relevant. In order to plan future energy systems t s mportant to know future possbltes and needs regardng energy demand for dfferent sectors. Through ths paper long term energy demand projectons for Croatan households sector wll be shown wth a specal emphass on dfferent mechansms, both fnancal, legal but also technologcal that wll nfluence future energy demand scenaros. It s mportant to see how these mechansms nfluence, postve or negatve, on future energy demand and whch mechansm would be most nfluental. Energy demand predctons n ths paper are based upon bottom-up approach model whch combnes and process large number of nput data. The Model wll be compared to Croatan natonal Energy Strategy and certan dfference wll be presented. One of the major conclusons shown n ths paper s sgnfcant possbltes for energy effcency mprovements and lower energy demand n the future, based on careful and ratonal energy plannng. Dfferent fnancal, legal and technologcal mechansms can lead to sgnfcant savngs n the households sector whch also leads to lesser greenhouse gas emssons and lower Croatan dependence on foregn fossl fuels. 1. KEYWORDS Future energy demand, households sector, energy effcency, energy savngs, bottom-up modellng

3 2. INTRODUCTION Households sector presents one of the most mportant energy consumers n Croata. Wth ts 29% [18] of the whole Croatan fnal energy demand, households sector presents also a bg opportunty for energy savngs n the n upcomng perod. Unfortunately, years of neglgence, lack of buldng regulatons and not obeyng current buldng codes has lead to neffcent buldng stock wth hgh energy consumpton as a result. Consderng ts mportance regardng natonal energy balances t would be very mportant to know what trends to expect n the households sector regardng future energy demand [1-4]. One of the key elements would be to analye future energy demands dependng on a few key elements nfluencng households sector: avalable surface ncrease, energy effcency mprovements and buldng codes regulatons. Ths paper wll present the connecton between above mentoned elements and fnal energy demand of a household sector. In order to capture and quantfy ths connecton a Households Energy Demand Model (HED Model) has been developed. HED Model s based on a bottom up approach analyss n order to quantfy and descrbe all the key elements nfluencng energy demand n a more concse way [9-13]. Top down methodology or ts fragments were also consdered for ths research [14-17] but ts aggregated approach would not allow a precse combnaton and quantfcaton of dfferent elements and mechansms that would nfluence energy demand [5-8]. HED Model s focused on calculatng heatng and coolng demand as well as energy demand for house applances, hot water and cookng. Results and scenaros calculated and presented n ths paper are compared to Croatan natonal energy strategy and certan conclusons are presented based on that comparson. 3. METHODOLOGY HED Model s based on summarng dfferent sub-categores of households sector n order to get general overvew mage on energy consumpton. Ths way deeper nsght of a certan subcategory can be obtaned n order to see dfferences n energy consumpton dependent on dfferent factors n a long perod of tme. HED Model s made for long term energy demand projectons, n ths paper tll 2050, and s focused on fnal energy demand projectons of Croatan households sector. In order to develop the methodology that would be used to model future energy demand certan sub-categores are ntroduced: space heatng, applances, hot water and cookng. Detaled descrpton of above mentoned sub-categores and ther specfc propertes wll be presented n the followng paragraphs Surfaces and populaton In order to start modellng actual energy consumpton and demand, frst a detaled model that would predct the fluctuaton of avalable surfaces of the households sector needed to be done. Modellng future avalable surfaces of Croatan households sector s made through avalable future populaton nformaton avalable from Croatan Bureau of Statstcs. Avalable future surfaces fluctuatons are calculated for all 21 Croatan countes wth the man parameters beng populaton number and specfc avalable surface: A Where: county, P M (1) A - total avalable surface n a certan county (m 2 ), P - populaton of a certan M - specfc avalable surface (m 2 /person), - year for whch the calculaton s made

4 Model calculates new avalable surface n the system and summares t n order to have precse nformaton regardng surface dstrbuton for the heat energy consumpton calculaton. Same prncple goes for renovated buldngs as well, wth an excepton of renovaton paste ndex whch s set by the user. Model calculates demolshed surfaces for each year through hstorc ndex whch can be mported n to the model by the user. N A A 1 D Where: N - new avalable surface n certan county (m 2 ), county (m 2 ) (2) D - demolshed surface n certan R A 1 S Where: R - renovated avalable surface n a certan county (m 2 ), S- renovaton paste ndex Populaton nformaton and future fluctuaton tll 2050 are taken from Croatan Bureau of Statstc and they are not modelled but just mported as nput nformaton for HED Model. (3) 3.2. Space heatng and coolng Calculatng heat demand of an entre sector has proven to be a challengng task because of adjustments of all specfc characterstcs n calculatng thermodynamc behavour of an outsde envelope appled to a whole sector. That s why HED Model frst calculates energy consumpton for the base year, whch s set to 2007, because the output data s already known. Ths s also a way to calculate all unknown parameters whch are later used n the model for the calculaton of future energy demand Heat demand Heat demand s determned based on the prevously calculated avalable surface dstrbuton among all Croatan countes whch s combned wth clmatc nformaton characterstc to a certan county. Base calculaton of heat demand s made by deductng heat gans from heat losses. Heat losses are determned as heat transfer by transmsson and ventlaton whle heat gans are determned as solar heat gans and nternal heat gans. Q ( Qt Qv ) ( Qs Q ) (4) Where: Q - total heat demand (PJ), Qt - heat transfer due to transmsson (PJ), Qv - heat transfer due to ventlaton (PJ), Qs - solar heat gans (PJ), Q - nternal heat gans (PJ) Calculaton s based on monthly procedure whch roughly follows ISO [19] norm for energy performance of buldngs. Heat transfer due to transmsson s based on outsde envelope surfaces whch are calculated based on avalable surfaces, thermal transmttance and temperature dfferences. Qt h Ae U T t (5)

5 Where: h - share of heated space, Ae - avalable envelope surface (m 2 ), U - thermal transmttance (kw/m 2 K), T - temperature dfference between outsde monthly average temperature and nsde temperature (K), t - duraton of calculaton step (h) When calculatng avalable envelope surface, user can defne the rato between wndows and walls as well as future mprovements regardng the envelope. Future mprovements are set through dfferent thermal transmttance factors for walls and wndows for every year of the calculaton. Temperature dfference for every county s based on real clmatc data whch are mported nto the model. Heat transfer due to ventlaton s calculated prmarly based on ar exchange rate whch s subject to modfcaton by the user. Qv cp q T t (6) Where: - ar densty (kg/m 3 ), cp - ar heat capacty (J/kgK), q - arflow (m 3 /h) Internal heat gans are calculated based on the ISO norm [19] whch regulates nternal heat gans per square meter of resdental space whle solar heat gans are based on wndow surfaces and solar radatons whch s a subject of geographcal locaton, n ths case one of 21 Croatan countes. Qs Where: element, (kw/m 2 ) c Aw g af ps I t (7) Aw - effectng collectng area (m 2 ), g - solar energy transmttance of transparent af - frame reducton factor, Coolng demand ps - shadng reducton factor, I - solar rradance Coolng demand through HED Model s calculated based on coolng degree days snce ths method turned out to be the most approprate for calculatng whole resdental sector. Ths methodology was used because followng prevously presented methodology used for heatng demand ddn t produce satsfyng results when observng coolng demand. Qc c Ae U Dd (8) Where: c - share of surface cooled, Dd - coolng degree days As well as n calculatng heat demand, user can set the rato between wndows and walls as well as set the thermal transmttance for both wndows and walls for future perod as a result of envelope mprovements Electronc applances Electronc applances are dvded nto: large applances, small applances and lghtnng. Ths type of dvson s made based on dfferent databases [21] n order to follow exstng methodology and consumpton results and data. Based on ths methodology ar-condtonng goes to large applances category and s calculated separately snce coolng demand s calculated nsde the HED Model. In ths case base year calculatons are essental n determnng startng nput data and calbratng t wth avalable lterature nformaton. HED Model can calculate energy consumpton and future energy demand both through avalable

6 surfaces as well as populaton nformaton. For the purposes of ths paper surface calculaton s used. The frst step of the calculaton s that the Model calculates startng values that are verfed through base year of the calculaton. Afterwards user can set the energy effcency mprovements for specfc consumpton for future perod. E sp l A (9) Where: E - fnal energy consumpton of a certan electrc applances category (PJ), sp - specfc consumpton of a certan electrc applances category (kwh/m 2 ), l - energy effcency mprovements ndex n a certan year Snce coolng demand s calculated through the HED Model fnal energy consumpton for space coolng s calculated through coeffcent of performance ndex whch s also set by the user as well as potental future mprovements. Ea Qc / COP (10) Where: Ea -fnal energy consumpton for space coolng (PJ), performance ndex COP - coeffcent of Ths way user can calculate how future technology mprovement would nfluence on fnal energy demand for space coolng Hot water Hot water demand s calculated based on the EN [22] norm that gves calculaton process for calculatng energy demand for hot water n households. Norm states specfc consumpton per a square meter whch s ncorporated nto the model as an nput data. In ths case only energy demand s calculated whle fnal energy demand s calculated based on dfferent technologes and ther effcences. Fuel mxng s descrbed n a more detaled way n the followng paragraphs Cookng Fnal energy demand for cookng s calculated based on the same methodology used for electrcal applances wth the dfference of fuel mx whch s here calculated separately. Intal data for fnal energy consumpton for cookng s nformaton receved based on poll nformaton. Ths poll nformaton s tested through the base year and t turned out to be vald and correct nformaton. Regardng fuel consumpton n ths category prmary mx s combned from electrcty and gas. Methodology for the fuel mxng s descrbed n the fuel mx chapter.

7 3.6. Fuel mxes HED Model has a separate fuel mx module whch combnes energy effcency of a certan technology and share rato of a certan fuel type n the fnal fuel dstrbuton of a certan subcategory. Ths module s necessary for calculatng fnal energy demand for heatng, hot water and cookng. Through ths module user can combne dfferent technologes and fuel types n a scenaro approach n order to compare dfferent strateges regardng future energy demand plannng. Startng energy mxes are calculated based n the nput data for the base year. User can set the paste of effcency and fuel raton change for every year tll year Wth effcency and fuel rato for every technology and fuel type fnal energy demand for prevously mentoned categores s calculated. F n 1 fd ee r Where: F - fnal energy demand (PJ), r - share rato of a certan fuel type ndex fd - energy demand (PJ), (11) ee - energy effcency ndex, As already mentoned ths methodology s used for calculatng fnal energy demand for heatng, hot water and cookng. 4. RESULTS One of the man ntentons for ths paper was to see the nfluence of future energy regulatons regardng refurbshments and buldng ero energy buldngs at a certan year n the future. On Fg. 1 heat demand of reference scenaro s presented wth refurbshment rate of 1% yearly and ntroducton of all new buldng enterng the system as ero-energy buldngs after year All buldng refurbshed after 2026 are also consdered as ero energy buldngs. Ths of course means they stll consume energy but that energy has to be produced locally from renewable energy source; ths s presented by marked surface n Fg. 1).

8 Fgure 1 Heat demand for the reference scenaro Other vtal ssue s the refurbshment paste whch also drectly nfluences future heat demand. On Fg. 2 dfferent heat demands are presented dependng on the appled refurbshment yearly paste. Fgure 2 Total heat demand dependng on dfferent refurbshment yearly rates Results connected to heat demand are presented because space heatng s the hghest energy consumer of Croatan households sector wth 57% [18]. On Fg. 3 reference scenaro wth fnal energy demand of all sub-categores s presented. Reference scenaro s modelled based on current buldng codes and wth the presumpton that people are complyng wth current

9 buldng codes strctly. Reference scenaro on Fg. 3 presents fnal energy demands together wth new and refurbshed ero energy buldngs energy demand. Fgure 3 Fnal energy demand - Reference scenaro As already mentoned n the ntroducton ths paper presents the comparson of offcal Croatan natonal energy demand projectons wth the results of HED Model. On Fg. 4 Natonal demand projectons are compared wth the HED Model reference scenaro [20]. Fgure 4 Fnal energy demand projectons comparson

10 When testng HED Model three future energy demand scenaros are made for the purposes of ths paper: bomass opton, dstrct heatng opton and heat pumps opton. These optons are appled to space heatng secton whle other sub-categores are set to reference scenaro values. On Fg. 5 bomass scenaro s presented regardng energy demand whle Fg. 6 gves share ratos of dfferent fuels of the same scenaro. Fgure 5 Fnal energy demand - bomass optons Fgure 6 Fuel share for bomass opton

11 Smlar stuaton happens wth dstrct heatng opton regardng fnal energy demand (Fg. 7) whle fuel shares changes n favour for dstrct heatng (Fg. 8). Fgure 7 Fnal energy demand dstrct heatng opton Fgure 8 Fuel share for dstrct heatng opton

12 As seen from the results (Fg. 9) hgh penetraton of heat pumps for space heatng leads to sgnfcant decrease of fnal energy consumpton n the households sector. Fgure 9 Fnal energy demand heat pumps opton Fgure 10 Fuel share for heat pumps opton

13 Hgh penetraton of heat pumps also leads to an ncrease of electrcal energy consumpton n the future perod but ths s electrcty that could also be produced locally and from renewable energy sources. It s clear that future buldng stock tendng to be passve or ero energy wll have a hard tme achevng ths wthout heat pumps. 5. CONCLUSION As seen from the results households sector presents a bg opportunty for energy savngs and penetraton of renewable sources n the future. One of the key elements s enforcng current buldng codes for all buldngs that are beng bult or refurbshed. Applyng these codes strctly would lead to sgnfcant energy savngs. One of the key elements regardng energy consumpton n the households sector would be ntroducng new regulatons that would requre new and refurbshed buldng to produce ther energy locally, or to be ero energy houses. For Croatan households sector, turnng heavly to bomass, heat pumps and dstrct heatng seems the most logcal choce for the future. One of the conclusons drawn from the presented results s the fact that Croatan natonal energy demand scenaros regardng households sector needs to be consdered wth a certan reserve snce bottom up modellng shows a certan room for energy savngs mprovements. 6. NOMENCLATURE A - total avalable surface n a certan county (m 2 ) P - populaton of a certan county M - specfc avalable surface (m 2 /person) - year for whch the calculaton s made N - new avalable surface n certan county (m 2 ) D - demolshed surface n certan county (m 2 ) R - renovated avalable surface n a certan county (m 2 ) S- renovaton paste ndex Q - total heat demand (PJ) Qt - heat transfer due to transmsson (PJ) Qv - heat transfer due to ventlaton (PJ) Qs - solar heat gans (PJ) Q - nternal heat gans (PJ) h - share of heated space Ae - avalable envelope surface (m 2 ) U - thermal transmttance (kw/m 2 K) T - temperature dfference between outsde monthly average temperature and nsde temperature (K) t - duraton of calculaton step (h) - ar densty (kg/m 3 ) cp - ar heat capacty (J/kgK) q - arflow (m 3 /h)

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