Human settlements and sustainability: a crucial and open issue

The human habitation of the surface of the planet has led, especially since the mid-twentieth century, to an enormous increase in the built up area. This phenomenon concerns both the oldest industrialised countries, such as European Union and the United States, and the so-called emerging countries in Asia, Africa and Latin America.The urbanised built area has increased in different ways, but has led everywhere to the destruction of large portions of virgin soil, the loss of biodiversity in the number and type of species in fauna and flora, and often the total or partial impairment of ecosystem functions of enormous environmental value (such as the evapotransportive mechanisms of soil and vegetation). Although the curve of global population growth is slowing, the growth of urban areas continues to expand, even in countries which have long been industrialised, where the spread of building has given rise to cities dispersed over a territory so that there is no longer a recognisable clear division between the city and the countryside. In fact, contemporary cities are the main consumers of all environmental resources, from water to food, including energy and environmental stressors, and are responsible for 80% of CO2 emissions into the atmosphere. The ecosystem surface required to sustain a large city on the planet today canbe about 200 times larger than its physical size. The urban civilisation of the 21st century, which at a superficial glance may appear as a symbol of the human capacity to radically adapt and transform the natural habitat toits own needs, is also a witness to the unsustainability of the human footprint on earth. Radically rethinking cities and human settlements entails an equally radical rethinking of our economic and development model, but it is a necessary and strategic task if we really want to face the challenge of sustainability with appropriate
instruments.


Phenomena of urban growth
Five years after the first Sciece ad the Future cferece the prbes ccerig the reatiship betwee hua setteets ad sustaiabiity despite the fact that iteratia debate has itesified ad expaded appear t be uresved The grwth tred f urba areas i sie ad uber at the gba eve aready highighted by studies ad the prectis f the Uited atis i the past decade is cfired Tday 55% f the wrd's ppuati ives i cities ad whie y 30% f the wrd's ppuati ived i cities i 1950 abut haf f the ppuati resided i urba areas by 2007 The curret grwth tred i the absece f crrective easures suggests that 66% f the wrd's ppuati wi ive i urba areas i 2050 1 Currety the st urbaised regis  the paet are rth Aerica with 82% f the ppuati ivig i urba areas ati Aerica ad the Caribbea with 81% f the ppuati beig urbaised ad Eurpe with 74% The eve f urbaisati i Asia cutries is abut 50% ad i Africa y 43% f the ppuati ives i urba areas (WUP2018) Prectis idicate that Chia Idia ad igeria were the cutries with the highest urba ppuati grwth i the perid 20182050 (abut 35%) Uder these cditis the chaege f sustaiabiity is csey ied t the ecic scia ad evireta devepet f urba areas It has bee destrated that a cutry's ecic grwth depeds heaviy  the ecy f its cities with 80% f gba GDP prduced i urba areas 2 It therefre sees cear that the grwth pheea f urbaised areas are csey reated t the cyces f gba ad ca ecic devepet The sae gbaisati f arets etais the trasfrati f cities it privieged catis fr the cati f fiacia ad advaced tertiary cpaies the ai abratries f ivati ad experietati f prducts ad prcesses The gba aret fids its fudaeta spatia structure i the city f the third ieiu ie a pheea f paetary ecic gbaisati the dyaics f urbaisati are hwever ctradictry  the e had cities ca be csidered the ai geeratrs f ecic devepet ad grwth but  the ther had their ipact  the eviret is very high Eve fr a scia pit f view csts are fte very high with egative csequeces such as vercrwdig ac f adequate ifrastructure ad especiay i eergig cutries precarius husig (re tha 1 bii pepe ive i sus r i cditis f scia ad spatia segregati  U 2016 data) As far as the Eurpea ad Itaia ctext is ccered the grwth i the sie ad uber f urba areas is cfired eve i the absece f degraphic grwth This phee the scaed urba spraw which ivves a the cutries f the dest urbaisati is characterised by a disrdery ad uctred expasi twards the periphera areas ad by a decrease i ppuati desity 3 The ai ipacts f this type f urba grwth fr a evireta pit f view are the csupti f free r agricutura ad the csequet ss f bidiversity (e f the st iprtat idicatrs fr sustaiabiity) the ss f idetity f paces i the absece f ay urba quaity referece the ac f a recgisabe budary betwee city ad cutry the eed fr rad trasprt resutig i greater use f private vehices re traffic ad puti ad raisig pubic spedig  the prvisi f services ad eergy Accrdig t Istat 2017 data urba spraw cvers abut 7% f the Itaia surface but this spraw eas that at east a quarter f the territry is ivved i urba uses

The situation of urban areas in Italy
The ai Itaia urba ad tgether ccupy a area f abut 27000 square  88% f the atia surface The argest area is Re with 13% f the territry fwed by Turi Bga ad Cagiari (abut 08%) ad ia (abut 06%) The grup f ediusied cities represets abut a quarter f the tta urbaised area whie the rest f the atia territry (arud 65%) begs t sa setteets The data cected by Istat idicates that fr 2001 t 2015 the grwth f urba cstructi ctiued withut iterrupti ad i particuar ag the 21 st iprtat urba cetres f the peisua the average grwth f buidig was arud 8% f which Turi grew by 116% The ihabitats f the ai urba areas i Itay accut fr 363% f the etire atia ppuati The fur ai systes Re ia Turi ad apes ae accut fr ast 20% f the etire Itaia ppuati The average ppuati desity f the 21 st iprtat urba cetres at atia eve is 828 ihabitats per square ietre cpared t 201 fr the rest f the atia territry e f the st iprtat csequeces f the grwth f urbaised areas is the csupti f free r agricutura ad which is repaced by a artificia surface cver ied t the dyaics f athrpic setteets (ad Cver Directive 20072EC) Sice gd quaity si hsts a arge part f the bisphere ad is abe t carry ut uerus ecsyste fuctis ad sice the thicess f the si preset  the earth's crust is iited ad taes a very g tie t refr (abut 200 years per 1  f thicess) it sees evidet that it ust be csidered a very iprtat reewabe evireta resurce Artificia grud cver fr the cstructi f buidigs r rads geeray ivves si seaig with the csequet serius ipairet f ecsyste services that the free grud ray perfrs ad is therefre a very sigificat evireta cst (Eurpea Cissi 2013) The ss f pereabiity i particuar is e f the ai causes f si degradati at a gba eve icreasig the ris f fdig ctributig t ciate chage ad threateig bidiversity ad adscape quaity Fr these reass i 2015 the Uited atis Gba Ageda fr Sustaiabe Devepet set a strategic bective fr Sustaiabe Devepet (SDGs U Suit 2015) by 2030 that was t be itegrated it atia picies si prtecti thrugh csupti t exceedig ppuati grwth esurig icusive access t gree spaces ad areas achievig the ga f a eutra ad degradati wrdwide Despite the urget eed t tae acti t prtect the si  the Eurpea ctiet se 1000 square ietres per year have bee st sice the ate 1990s 4 The gegraphica ad rphgica pecuiarities f Itay ae it eve re urget t ipeet picies ad strategic actis t prtect the si ad the adscape I ie with what happeed i ther idustriaised cutries csidated urba buidig i the ai urba areas icreased fr 153% t 193% i Itay i the twety years fr 19912011 with a average icrease f % 5 ad csupti appears t ivve bth cetra high ppuati desity areas ad arge sprawig periphera areas The areas st affected by these pheea are the P Vaey (Turi hiterad ia curbati Berga Brescia axis) the Veetia Eiia pai the casta systes fr rth t suth the etrpita systes f Re ad apes thse f rther Tuscay ad the areas arud the ai cities i the suth such as Bari ad Paer Cataia ad essia f thse Itaia cities i which the csupti f ad i reati t the tta surface area f the urba area is re sigificat we highight ia with abut 40% f buidigs ad apes with abut 44% Cataia fws with 29% Padua with 285% ad Re with abut 21% Turi i 2011 was abut 17% I geera ters the data prvided by the SPA (Sistea aiae per a Prteie de'Abiete  atia Syste fr the Prtecti f the Eviret) cartgraphy shws that at a atia eve we have ge fr a artificia si area f 27% i 1950 t 775% i 2017 (a grwth f 180%) which eas that 23063 square  f Itaia territry has bee irreparaby cprised with a greater icidece i the areas f the P Vaey ag the Tusca axis betwee Frece ad Pisa the pai areas f ai Capaia ad Saet ad ag the casta strips bardy had the highest ad csupti i 2017 6 (310000 hectares f artificia territry) fwed by Veet Eiia Raga ad Piedt The regis with the west ad csupti i 2017 were iguria Vae d'Asta Basiicata ad ise with icreases f ess tha 40 hectares The dyaics f ad csupti icreases ad percetages ted t cfir their crreati with the ecic dyaics f the territries i the presece f ecic recvery ad i the absece f striget reguatry crrectis ad csupti icreases I the absece f a fraewr reguatry istruet at atia eve ad i the presece f reativey hetergeeus regia rues the scearis currety peig up fr ad use i Itay (ISPRA bservatry) cud have very differet csequeces If the bective f achievig a er icrease i et ad use i 2050 was pursued with cvicti this wud ea 818  2 f ew ad st betwee 2017 ad 2050 If  the ther had the tred bserved i 2017 i cditis f w ecic grwth is cfired 1772  2 per year wud be st I cditis f strg ecic recvery withut strict reguati ad csupti vaues i the cig decades cud ctiue ad reach the 8073 square ieters f ad st i 2050

The energy impact of the Building sector
The grwth f urba areas t y ivves the ss f free si ad urba dispersi r ccetrati but is ievitaby accpaied by a grwth i the vue ad surface area f buidigs i buitup areas f truy ipressive prprtis ver the ast decade i fact re tha 50 bii square etres f ew ccrete have bee buit gbay a tred that is t diiishig as urba grwth frecasts fr the ext 40 years icude 230 bii square etres f ew buidigs equivaet t the cstructi f a city the sie f Paris every wee The buidig sectr 7 accuts fr 36% f fia eergy csupti gbay the arity f this csupti (82%) is sti et by the use f fssi fues Accrdig t data fr the GABC Dssier 2016 buidigs ad cstructis are respsibe fr 39% f tta C2 eissis T eet the bectives f the Paris Ciate Agreeets f 2015 ad ctai the icrease i gba warig t 2C i the cetury the eergy efficiecy f buidigs eed t iprve by 30% cpared t 2015 eves by 2030 This eas that fr w  ad i the ext decade ereissi ad earer eergy buidigs shud bece the gba stadard The dssier highights the rapid grwth f cstructi  a gba scae withut crrective easures the surface area f buidigs i the wrd wi dube by 2060 Athugh the efficiecy f the eergy sectr has iprved i recet years it is sti t sufficiet t reduce the icrease i eergy dead C2 eissis have ctiued t grw by 1% per year sice 2010 ad re tha fur ii deaths per year are attributabe t diseases caused by puti fr buidigs High eergy perfrace buidig ad prfudy upgradig existig buidigs cud save abut 91000 TWh (330 exaues) uti 2060 (re tha the fia eergy csupti f a the G20 cutries i 2015) ad usig highefficiecy heatig ad cig techgies wud as cut eergy csupti by a further 180 TWh (660 exaues) i ters f gba eergy dead which is equivaet t Chia's fia eergy csupti i the ast te years

City cause and solution of the problem.
Rethink the city, rethink the development model.
As we have see buidig stc is aiy ccetrated i the cities ad tday it represets a huge cst fr a eergy ad evireta pit f view but it ca as be csidered a extrardiary resurce t y fr a stricty cstructi pit f view but i reati t the eed t prtect the agricutura si ad the adscape Uderstadig this ctradicti ad vercig it is e f the ai techica (but as cutura ad ecic) chaeges that awaits us i this cetury If a ecsyste is a uit that icudes a the rgaiss that ive tgether i a give area ad iteract with the physica eviret frig a stabe bitic structure withi a csed cyce f atter ad eergy 8 9 the the city ca be csidered a pe therdyaic syste depedig  the eviret i which it is iserted ad where the eergy ces aiy fr fssi fues Curret etrpita areas are characterised by a ctiuus fw f uidirectia eergy iwards whse ctiuus icrease aes the urba de structuray ustabe ad vuerabe I rder fr the urba rgais t icrease its resiiece it is ecessary fr it t estabish a "sustaiabe" reatiship with its territry that reduces the iput (ateria ad eergy) ad utput (etrpy ad waste) fws ad i cpiace with the tie required fr the expitati f sar eergy ad atura cyce This ipies a trasfrati f the urba etabis fr iear t circuar The cse reatiship betwee cities ad eergy csupti has histricay cditied the evuti r decie f iprtat histrica cities ad has strgy affected their differet spatia cfiguratis I recet decades experietati via pit prgraes i severa cities at Eurpea ad iteratia eves has shw the eed t idetify geera idicatrs fr the bective evauati f the quaity f setteets The difficuty ies i uderstadig urba dyaics which are by their ature cpex with disaggregated ad partia idicatrs

Buildings and energy consumption, reducing them is possible
There are ay bstaces  the path t eergy efficiecy i buidigs the first beig a ac f stadards ad c aguage A uifrity f aguage is absutey ecessary i rder fr the cstructi idustry t grw ad respd t the ciate chaege ther sectrs have deveped ad use c aguages such as ICT cuicati prtcs ad this is their stregth Ast 70% f the wrd's buidig csupti is t currety cvered by adatry cdes ad stadards Tw thirds f cutries d t have eergy stadards fr the cstructi f ew buidigs This eas that i the ext 40 years 100 bii cubic etres f ew buidigs (f the 235 paed) wi t have ay id f adatry eergy cde t cpy with I Eurpe a ew buidigs fr 2021 wi have t have eergy csupti "cse t er" they wi have t be buit as 10 ties ess eergyitesive tha the average f the buidigs i which we ive tday A Itaia study  residetia eergy csupti i the perid 1970 2005 10 has shw that whie average csupti per he has decreased (as a resut f tax exepti picies) vera residetia eergy csupti has icreased with a average aua icrease f 13% It ca be deduced that i rder t achieve sigificat eergy savigs it is ecessary t g beyd the scae f the sige husig uit ad the sige buidig t csider a the buidigs the urba ayut ad the st efficiet techgica sutis  the urba scae Sice cities are sty ade up f buidigs buit i the secd haf f the twetieth cetury hwever ad are iadequate ad iefficiet fr a eergy pit f view the redevepet f the existig husig stc which ust be csistet with the Eurpea bective that prvide fr a 80% reducti by 2050 i carb dixide eissis is e f the st iprtat issues fr the pit f view f sustaiabiity I additi t the ciate bectives this shud icrease the eergy security f ur ctiet (Deep revati f buidigs Reprt Ecfys 2014) Currety a area equa t 1% f the tta buidig is redeveped each year with eergy iprveets f 1525% geeray i idividua apartets This is a psitive resut but it is cpetey iadequate i reati t the EU's decarbisati bectives The ew phase hwever requires a acceerati f bth the uber f itervetis which wi re tha dube ad their ipact idividua easures (widws bier isuati etc) wi have t chage t "deep revati" the upgradig f etire buidigs with savigs i the rder f 6080% ew cstructi ethds the use f highperfrace techgies ad aterias ad the itrducti f specific fiacig ethds cud create a eviret that ffers uexpected pprtuities Give the deep crisis i the cstructi sectr this devepet cud be a great pprtuity fr its reauch As the utiities have de the cstructi wrd wi have t rethi itsef Cpaies that are the first t d s wi be abe t estabish theseves  the aret We ust therefre tae a quaitative eap frward The revati f idividua apartets i utistrey buidigs ust be reduced ad icetives fr the redevepet f etire buidigs r eighburhds ust be icreased A iterestig exape is the etherads where i recet years a abitius eergy requaificati prgrae (Patfr 31) has bee deveped usig easiy istaabe idustriaised prefabricated eeets that aw wr t be carried ut  23 strey buidigs i ust fiftee days 11 A thusad revatis are uderway as part f a extesive gveret prgrae t upgrade 111000 apartets i scia husig The refieet f these ethds f iterveti has eabed a 40% reducti i csts i three years ad a chage fr havig csupti t the ccept f "et er eergy" which is btaied by cuttig the dead fr air cditiig by 70% ad eetig the reaiig dead with reewabes

Conclusions
Give the ipact f urbaisati  a gba ad ca eve the evireta ad eergy requaificati f cities shud be csidered e f the ai strategic actis t achieve ur def sustaiabe devepet fr bth a resurce perspective (evireta ad eergy) ad a scia perspective (equity ad icusiveess) Sustaiabiity  a urba scae shud be pursued abve a thrugh itervetis aied at reuitig periphera ad argia areas thrugh redesificati actis that favur a typgica ad fuctia ix ad cective biity ad the recvery f disused areas ipeetig urba greeery accrdig t the pricipes f urba ecgy I ters f eergy  the ther had the curret picies f tax exepti fr easures t iprve the eergy perfrace f buidigs are t eugh t achieve a effective reducti i csupti ad t reduce greehuse gas eissis ad it is ecessary t idetify the st efficiet techgica sutis at the urba buidig scae Eergy ad evireta actis ad strategies are eeded t prte urba sefsufficiecy reducig the fw f aterias ad eergy i ad ut ad f eissis ad wastewater brigig the fuctiig f the urba etabis cser t that f atura ecsystes The itegrati ad use f reewabe eergy surces ust be ecuraged by prtig the creati f sart grids i cse reati t the specific fuctia eeds ad the differet evireta cditis f the city (sart cities) It is as ecessary t itegrate the psitive ideas cig fr participatry ad "btt up" cperative experieces f chagig ifestyes i reati t re sustaiabe husig ad urba des it gba ad ca picies The chaege f sustaiabiity ipies a radica rethiig f ur devepet de ad ifestye as aready ceary idetified i the first "iits t Grwth" reprt f 1972 the assuptis  which they are based thse f uiited grwth are cceptuay ad scietificay wrg atura resurces are t iterchageabe ad are iited T achieve sustaiabe devepet it is t eugh t estiate the vaue f atura resurces etariy ad t iteraise the evireta csts ad beefits i ecic accuts Sustaiabiity requires a ew paradig f ecy ad devepet based  the iits f the bisphere bud t the Secd Pricipe f Therdyaics iits that are ever cser ad cat be circuveted