The Energy Consumption of Terraces in the Barcelona Public Space: Heating the Street

sustainability

Article The Energy Consumption of Terraces in the Barcelona Public Space: Heating the Street

Carlos Alonso-Montolio * , Gloria Serra-Coch, Antonio Isalgue and Helena Coch

Architecture & Energy,School of Architecture of Barcelona, Universitat Politècnica de Catalunya, 08034 Barcelona, Spain; [email protected] (G.S.-C.); [email protected] (A.I.); [email protected] (H.C.) * Correspondence: [email protected]; Tel.: +34-934-010-866

Abstract: Terraces, as outdoor extensions of food and beverage businesses located in the public realm, have very high potential to activate the streetscape, bring people together and improving urban experiences. Among the consequences of the current COVID-19 pandemic are the recommendations of maximizing outdoor environments when conducting human interactions. Therefore, outdoor eating has dramatically increased throughout the world, with terraces becoming a radical urban change in many streetscapes. The urgency of the situation, and rapid implementation of these changes, has revealed some aspects of this phenomenon that should be considered when adapting the regulations to this new reality. However, the research on their functioning and impact is limited. Additionally, although energy consumption in the architectural and urban field is considered fundamental, research has rarely addressed small business outdoor spaces, placing the focus instead on residential heating or public lighting. This study focuses on the intersection of these two gaps by analyzing a set of terraces in Barcelona and estimating the power installed in their outdoor heating devices. The goal is to determine the potential energy consumed, contrast it with other values more commonly used when researching architectural energy consumption and point out the lack of sustainability of these approaches to providing comfort. The calculations show that the installed power in Barcelona terraces is significant and, when estimating potential consumption, it presents values higher that Citation: Alonso-Montolio, C.; the average heating consumption of residential units in Spain. These results support two main Serra-Coch, G.; Isalgue, A.; Coch, H. conclusions: first, the relevance of addressing the means of providing comfort in outdoor urban The Energy Consumption of Terraces in the Barcelona Public Space: spaces due to the high magnitude of their potential energy consumption; second, the importance Heating the Street. Sustainability 2021, of adapting those systems to outdoor conditions, understanding the needs of the occupants and 13, 865. https://doi.org/10.3390/ the limitations of the environment in order to develop sustainable solutions that provide comfort su13020865 without attempting to heat the air of the street.

Received: 25 November 2020 Keywords: public space; energy consumption; urban terraces; COVID-19 pandemic Accepted: 13 January 2021 Published: 16 January 2021

Publisher’s Note: MDPI stays neutral 1. Introduction. Terraces and Public Space. The Case of Barcelona with regard to jurisdictional claims in There is a type of phenomenon in the urban public space that, although often disre- published maps and institutional affil- garded by urban planning professionals, is placed at the core of current political and social iations. discussions. Terraces located in the public realm have the potential of highly influencing the dynamics and performance of cities and, therefore, are in need of further analysis and study. The term “terrace” is generally used to describe architectural outdoor extensions of Copyright: © 2021 by the authors. indoor spaces. For instance, private terraces in residential buildings extend the living area Licensee MDPI, Basel, Switzerland. outdoors. In this article, we will focus on a particular case, using the word “terrace” to This article is an open access article define the outdoor extension of food and beverage businesses, generally restaurants and distributed under the terms and cafes (Figure1). Specifically, we focus on those that make use of the public space to provide conditions of the Creative Commons this extension [1]. Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).

Sustainability 2021, 13, 865. https://doi.org/10.3390/su13020865 https://www.mdpi.com/journal/sustainability Sustainability 2021, 13, 865 2 of 20 Sustainability 2021, 13, x FOR PEER REVIEW 2 of 21

Figure 1. Terrace in Enrique Granados Street, Barcelona. Figure 1. Terrace in Enrique Granados Street, Barcelona.

OurOur society society is is currently currently facing facing an an extraordinary extraordinary challenge challenge in thein the form form of the of the COVID-19 COVID- pandemic19 pandemic first first identified identified in December in December 2019 2019 and declaredand declared a pandemic a pandemic in March in March 2020 by2020 The by WorldThe World Health Health Organization Organization [2]. It has[2]. abruptlyIt has abru disruptedptly disrupted the way the of way living of across living the across entire the world.entire Theworld. events The that events we arethat experiencing we are experiencing demand demand a revision a ofrevision practices of practices and priorities and pri- in ourorities everyday in our life.everyday A wide life. range A wide of fields range and of fields disciplines and disciplines will have towill adapt have and to adapt re-think and there-think status the quo, status urban quo, planning urban beingplanning one being of the one most of significant the most significant [3]. [3]. TerracesTerraces can can become become key key elements elements in thisin this reflection reflection for twofor two main main reasons. reasons. First, First, current cur- quarantinerent quarantine and stay and at stay home at situations home situations have revealed have revealed the importance the importance of access toof outdooraccess to spaceoutdoor for space the well-being for the well-being of humans. of humans. Sun and Sun open and air open have air been have unmasked been unmasked not only not asonly privileges as privileges for the for few the butfew asbut needs as needs for generalfor general health health and and wellness. wellness. Secondly, Secondly, the the newnew standards standards that that will will need need to to be be put put in in place place moving moving forward forward will will demand demand inventive inventive solutions.solutions. LargerLarger spaces will will be be needed needed to to accommodate accommodate the the same same amount amount of people of people and andfulfill fulfill minimum minimum distance distance requirements. requirements. Terraces Terraces could could be important be important to be able to be to ableprovide to provideoutdoor outdoor experiences experiences and social and interaction social interaction with safer with distances. safer distances. Around the Around world, themu- world,nicipalities municipalities are already are tackling already the tackling challenge, the challenge, rapidly updating rapidly and updating adapting and regulations adapting regulationsto the new tosituation. the new situation. ThereThere are are multiple multiple conditions conditions that that allow allow the the existence existence of of this this type type of of terrace. terrace. The The most most basicbasic ones ones are are the the presence presence of of food food and and beverage beverage businesses, businesses, the the social social acceptance acceptance to eat to ineat publicin public and and the existencethe existence of the of conceptthe concept of public of public space space [4]. [4]. Traditionally,Traditionally, terraces terraces offered offered the the opportunity opportunity of of taking taking advantage advantage of of better better outdoor outdoor conditions,conditions, related related to to thermal thermal comfort, comfort, a sunny a sunny or airyor airy environment, environment, easier easier social social interaction interac- ortion better or better views views [5,6]. However,[5,6]. However, these characteristicsthese characteristics are often are lostoften in lost the in current the current situation. situ- Whenation. the When urban the environmenturban environment is not consideredis not consid asered positive as positive as desired, as desired, elements elements tend tend to beto incorporatedbe incorporated into into the the terrace terrace in orderin order to to protect protect the the client client from from the the outdoor outdoor public public surroundingssurroundings (Figure (Figure2). 2). These These elements elements can can have have different different aims, aims, such such as as protection protection from from thethe sun sun (sunshade/parasol), (sunshade/parasol), from from the the car car noise noise and and emissions emissions or windor wind (lateral (lateral divisions) divisions) or fromor from the coldthe cold (heating). (heating). In this In this article, article, the heatingthe heating elements elements incorporated incorporated in terraces in terraces are the are focusthe focus of the of investigation. the investigation. The high level of energy consumption that human activity is currently responsible for

is a pressing issue at multiple levels. The scarcity of fossil energy sources, the emissions produced by current energy generation systems, radioactivity pollution from nuclear sources, rise of global temperatures and climate change, lack of basic energy needs of vulnerable populations and limited resiliency in emergency situations. Cities, suburbs and other urban centers have been identiﬁed as a major focus of energy consumption, and great efforts have been devoted to reducing its use. Research, studies and policies [7,8] have attempted to address the issue through a wide range of actions, from reducing private transportation to incentivizing the implementation of renewable energy sources [9,10].

Sustainability 2021, 13, 865 3 of 20 Sustainability 2021, 13, x FOR PEER REVIEW 3 of 21

(a) (b)

Figure 2.2. ((aa)) HotelHotel Oriente’s Oriente’s terrace terrace on on Rambla Rambla dels dels Caputxins. Caputxins. Photography Photography by Jesusby Jesus Fraiz Fraiz Ord óOrdóñez.ñez. Barcelona, Barcelona, 1907–1908; 1907– (1908;b) terrace (b) terrace in Enrique in Enrique Granados Granad Streetos Street during during winter. winter.

InThe addition, high level recent of energy economic consumption crises have that magnified human seriousactivity existing is currently issues responsible related to energyfor is a pressing poverty. issueThese at events multiple have levels. raised The sustainability scarcity of fossil awareness energy [sources,11] and encouragedthe emissions a driveproduced for energy by current saving energy and an interestgeneration in energy systems, efficiency radioactivity rehabilitation pollution for buildings from nuclear [12,13]. Studiessources, have rise of shown global how temperatures the largest and energy climate consumption change, lack share of withinbasic energy a household needs of is thatvul- causednerable bypopulations heating and and cooling limited systems resiliency [14 ,in15 ].emergency situations. Consequently,Cities, suburbs significantand other urban efforts, centers both in have academia been identified and professional as a major practice, focus of have en- beenergy consumption, focused on the and development great efforts of strategieshave been that devoted tackle to the reducing building its environment use. Research, [16 stud-–18]. Throughies and policies multiple [7,8] studies, have heatingattempted and to cooling addres haves the beenissue identified through a as wide an important range of fractionactions, offrom energy reducing consumption, private transportation especially in to residential incentivizing buildings, the implementation and design strategies of renewable and policiesenergy sources have been [9,10]. focused on addressing this issue [19,20]. Open public space approaches haveIn been addition, generally recent focused economic on thecrises management have magnified of public serious lighting existing or issues the limiting related ofto certainenergy transportationpoverty. These means events [ 21have]. These raised measures sustainability have beenawareness established [11] and by governmentalencouraged a agenciesdrive for thatenergy have saving the tools and to an control interest these in energy elements efficiency of the public rehabilitation realm. for buildings [12,13].However, Studies otherhave importantshown how energy the larges consumingt energyactivities consumption are often share overlooked. within a house- The energyhold is that used caused to light, by heatheating or cooland cooling outdoor systems terraces [14,15]. is rarely accounted for in academic energy studies or governmental policies. This situation might be the consequence of Consequently, significant efforts, both in academia and professional practice, have three main factors: first, the difficulty to acquire data on energy consumption from all the been focused on the development of strategies that tackle the building environment [16– disaggregated businesses of a city in comparison with municipal infrastructure; second, the 18]. Through multiple studies, heating and cooling have been identified as an important challenges of separating the indoor and outdoor energy consumption of food and beverage fraction of energy consumption, especially in residential buildings, and design strategies businesses; finally, the variability regarding both the presence and heating use of terraces, and policies have been focused on addressing this issue [19,20]. Open public space ap- which are constantly changing due to business closures and openings, opening hours and proaches have been generally focused on the management of public lighting or the limit- occupancy, which create difficulties in developing a comprehensive database. Based on the ing of certain transportation means [21]. These measures have been established by gov- increasing presence of terrasses, a thorough analysis of their energy performance could be ernmental agencies that have the tools to control these elements of the public realm. key for urban sustainability. However, other important energy consuming activities are often overlooked. The en- In Barcelona, the number of terraces located in the public space has recently increased ergy used to light, heat or cool outdoor terraces is rarely accounted for in academic energy very rapidly, under the influence of multiple factors: mild climate, tourism growth, the implementationstudies or governmental of the anti-tobacco policies. This law situation [22], widening might be of sidewalks,the consequence prioritization of three ofmain the pedestrianfactors: first, realm the difficulty in the public to acquire space [data23,24 on], rise energy of rental consumption prices and from the numberall the disaggre- of food- relatedgated businesses businesses of and, a city more in comparison recently, COVID-19 with municipal restrictions. infrastructure; This increment second, has causedthe chal- a climatelenges of filled separating with discussions the indoor and and even outdoor conflicts energy regarding consumption this issue. of food and beverage businesses;This situation finally, hasthe pushedvariability municipal regarding authorities both the topresence commission and heating studies use [25] of that terraces, could supportwhich are the constantly drafting andchanging proposal due ofto newbusine regulationsss closures that and might openings, address opening the abovemen- hours and tionedoccupancy, challenges which [create26–28 ].difficulties Nevertheless, in de theseveloping studies a comprehensive or regulations database. fail to address Based theon energythe increasing consumption presence that of these terrasses, elements a thor canough potentially analysis cause. of their energy performance couldThe be key presence for urban of switched-on sustainability. heating systems in terraces during the daytime in a city withIn aMediterranean Barcelona, the number climate suchof terraces as Barcelona, located wherein the public the average space annualhas recently temperature increased is aroundvery rapidly, 18.4 ◦ Cunder (average the influence temperature of multiple of years factors: 2014–18) mild and climate, with temperatures tourism growth, between the 12.4implementation and 6.1 ◦C for of thethe coolestanti-tobacco month, law February, [22], wi isdening questionable of sidewalks, (Table 1prioritization). of the pedestrian realm in the public space [23,24], rise of rental prices and the number of food-

Sustainability 2021, 13, 865 4 of 20

Table 1. Temperatures in 2014–2018 of Can Bruixa Observatory in the city center of Barcelona, according to the National Meteorology Agency.

Year/ Average Average Maximum Average Minimum Extreme Maximum Extreme Minimum Month Temperature ◦C Temperature ◦C Temperature ◦C Temperature ◦C Temperature ◦C 2014 18.3 21.3 15.4 33.0 5.0 2015 18.4 21.5 15.4 34.7 2.1 2016 18.4 21.4 15.4 32.6 3.9 2017 18.4 21.5 15.3 34.2 1.6 2018 18.5 21.5 15.5 37.8 0.9 January 13.3 16.3 10.2 22.3 5.7 February 9.3 12.4 6.1 17.4 0.9 March 13.4 17.0 9.7 21.2 3.2 April 16.7 19.7 13.7 24.5 8.5 May 19.1 22.2 16.0 24.9 9.3 June 23.4 26.2 20.6 30.4 16.5 July 26.7 29.6 23.8 32.6 21.0 August 27.4 30.3 24.5 37.8 20.2 September 24.4 27.0 21.7 30.9 18.0 October 19.6 22.7 16.4 25.8 7.6 November 15.2 17.9 12.5 22.3 8.9 December 13.6 16.6 10.6 20.9 6.6

2. Analysis of the Terraces in Barcelona Although terraces located in public space seem central in the development of the city, literature addressing this subject is scarce. Terraces are mentioned in certain urbanism publications about public space, but they appear only brieﬂy and often are not directly mentioned. It seems that public space professionals, probably due to their private commercial character, have overlooked this phenomenon. However, terraces have a high impact on morphological and social attributes of the public space. On one hand, they occupy a large amount of pedestrian areas and modify their routes. On the other hand, they offer a meeting point for citizens, contributing a secure and convivial feeling to the neighborhood.

2.1. Selection of the Zones of Analysis In order to proceed with a further analysis of several terrace areas in Barcelona, the first step was conducting a selection of the most significant zones. This choice was based on a cartographic databased work developed by the Centre de Política del Sol i Valoracions (CPSV) and published in “Estudi de caracterització i avaluació de Terrasses en espai public” [25]. From this database, with the use of a Geographic Information System software, 6 zones with the greatest terrace concentrations and diverse urban morphology typologies were detected (Figure3). The objective was to be able to collect data from areas of the city with a significant presence of this phenomenon and common or diverse characteristics that present a contrasting panorama. The selected zones: (a) Enrique Granados Street; (b) Rambla del Poble Nou; (c) Plaça Reial and Les Rambles; (d) Mercat del Born; (e) Gaudí Avenue; (f) Paral·lel Avenue and Blai Street. The terraces studied have different occupancy patterns between office hours and after hours and/or weekends. Two of these areas are located in the urban fabric of the Eixample, but with a substantial difference. Enrique Granados St. (1) is located in an office building area, and during breakfast and midday it is busy with office workers and some tourists, whereas Gaudí Avenue (5), due to being close to Sagrada Familia, has a much higher flow Sustainability 2021, 13, 865 5 of 20

of tourists. The two zones in the city center (3 and 4) are occupied by tourists but have fairly different urban attributes. Plaça Reial (3) has terraces of a larger size and with more equipment than those in Mercat del Born (4), while both have an intense nighttime use. The Sustainability 2021, 13, x FOR PEER REVIEW 5 of 21 former ones are restaurants, and their customer stays are longer, while the latter ones in Born (4), an after-hour drinks spot, have shorter customer stays. Rambla del Poble Nou (2) is located around Villa Olimpica, close to the sea, and it is the area that displays the most importantware, 6 zones difference with the in occupationgreatest terrace between conc daytime,entrations with and a diverse large proportion urban morphology of locals, and ty- nighttime,pologies were with detected a large proportion(Figure 3). The of tourists. objective Blai was Street to be (6) able is a to narrow collect pedestrian data from streetareas closeof the to city the with entertainment a significant business presence area of Paral this ·phenomenonlel, and has its and largest common ﬂow of or people diverse during char- theacteristics nighttime, that withpresent both a contrasting locals and tourists. panorama.

(a) (b)

Figure 3. (a) Map of Barcelona’s restaurantrestaurant businessbusiness activityactivity [[25];25]; ((bb)) indicationindication ofof thethe analyzedanalyzed zones.zones.

(a) TheEnrique selected Granados zones: Street a) LocatedEnrique inGranados the district Street; of central Eixample, Enrique Granados is an example of a vertical axisb) inRambla the Barcelona del Poble grid, Nou; with a NW–SE orientation. It connects la Diagonal with Gran Via, twoc) majorPlaça metropolitanReial and Les Barcelona Rambles; avenues. The street has a constant width of 20 m, like all regulard) Mercat streets del of Born; l’Eixample grid, but with different section conﬁgurations. Although some partse) Gaudí of the Avenue; street are pedestrianized, the most common section holds 50% of the surface dedicatedf) Paral·lel to pedestrians, Avenue and organized Blai Street. in two wide lateral walkways, one direction car lane, a Sustainability 2021, 13, x FOR PEER REVIEWtwo-way bike lane and a central parking area, which alternates bicycles, motorcycles6 of 21 and The terraces studied have different occupancy patterns between office hours and af- cars (Figure4). ter hours and/or weekends. Two of these areas are located in the urban fabric of the Eix- ample, but with a substantial difference. Enrique Granados St. (1) is located in an office building area, and during breakfast and midday it is busy with office workers and some tourists, whereas Gaudí Avenue (5), due to being close to Sagrada Familia, has a much higher flow of tourists. The two zones in the city center (3 and 4) are occupied by tourists but have fairly different urban attributes. Plaça Reial (3) has terraces of a larger size and with more equipment than those in Mercat del Born (4), while both have an intense nighttime use. The former ones are restaurants, and their customer stays are longer, while the latter ones in Born (4), an after-hour drinks spot, have shorter customer stays. Rambla del Poble Nou (2) is located around Villa Olimpica, close to the sea, and it is the area that displays the most important difference in occupation between daytime, with a large proportion of locals, and nighttime, with a large proportion of tourists. Blai Street (6) is a narrow pedestrian street close to the entertainment business area Paral·lel, and has its largest flow of people during the nighttime, with both locals and tourists. (a) (b) a) Enrique Granados Street FigureFigure 4. (a 4.) Plan(a) Plan and and section section of Enrique of Enrique Granados Granados Street; Street; (b) (streetb) street view view of Enrique of Enrique Granados Granados Street. Street. Located in the district of central Eixample, Enrique Granados is an example of a vertical b) axisRambla in the del Barcelona Poble Nou grid, with a NW–SE orientation. It connects la Diagonal with Gran Via,This two boulevard major metropolitan is also located Barcelona in the district avenues. of Eixample.The street Ithas has a aconstant width of width 30 m offrom 20 m, Avingudalike all regularDiagonal streets to Carrer of l’Eixample de Pere IV,grid, and but a withwidth different of 20 m section for the configurations. most part of its Alt- length,hough between some parts Carrer of dethe Pere street IV are to Passeig pedestri deanized, Clavell, the with most 70% common of the totalsection surface holds used 50% of for thepedestrian surface dedicatedmovement, to consisting pedestrians, of lateralorgani zedwalkways in two smallerwide lateral than walkways,Enrique Granados one direc- andtion a central car lane, Rambla a two-way that acts bike as lane the andpedestrian a central core parking of the area, street. which It has alternates two car lanes,bicycles, markedmotorcycles as bicycle and priority cars (Figure lanes, 4). split by the Rambla with opposite directions. The width of the lateral sidewalks slightly changes along the street, but the structural elements of the section remain the same (Figures 5 and 6).

(a) (b)

Figure 5. (a) Plan and section of Rambla del Poble Nou, upper section; (b) street view of Rambla del Poble Nou, upper section.

(a) (b)

Figure 6. (a) Plan and section of Rambla del Poble Nou, lower section; (b) street view of Rambla del Poble Nou, lower section.

Sustainability 2021, 13, x FOR PEER REVIEW 6 of 21 Sustainability 2021, 13, x FOR PEER REVIEW 6 of 21

(a) (b) Sustainability 2021, 13, 865 (a) (b) 6 of 20 Figure 4. (a) Plan and section of Enrique Granados Street; (b) street view of Enrique Granados Street. Figure 4. (a) Plan and section of Enrique Granados Street; (b) street view of Enrique Granados Street. b) Rambla del Poble Nou (b)b) Rambla del Poble Nou This boulevard is also located in the district of Eixample. It has a width of 30 m from This boulevard is also located in the district of Eixample. It has a width of 30 m from This boulevardAvinguda isDiagonal also located to Carrer in the dedistrict Pere ofIV, Eixample. and a width It has of a 20width m for of 30the m most from part of its Avinguda Diagonal to Carrer de Pere IV, and a width of 20 m for the most part of its length, Avingudalength, Diagonal between to Carrer Carrer de de Pere Pere IV, IV and to Passeig a width de of Clavell, 20 m withfor the 70% most of the part total of surfaceits used between Carrer de Pere IV to Passeig de Clavell, with 70% of the total surface used for length, betweenfor pedestrian Carrer de movement, Pere IV to consistingPasseig de ofClavell, lateral with walkways 70% of smaller the total than surface Enrique used Granados pedestrian movement, consisting of lateral walkways smaller than Enrique Granados and for pedestrianand amovement, central Rambla consisting that actsof lateral as the walkways pedestrian smaller core of than the Enriquestreet. It Granados has two car lanes, a central Rambla that acts as the pedestrian core of the street. It has two car lanes, marked and a centralmarked Rambla as bicycle that acts priority as the lane pedestrians, split by core the Ramblaof the street. with oppositeIt has two directions. car lanes, The width as bicycle priority lanes, split by the Rambla with opposite directions. The width of the marked asof bicycle the lateral priority sidewalks lanes, splitslightly by thechanges Rambla along with the opposite street, but directions. the structural The width elements of the lateral sidewalks slightly changes along the street, but the structural elements of the section of the lateralsection sidewalks remain slightly the same changes (Figures along 5 and the 6).street, but the structural elements of the remainsection theremain same the (Figures same (Figures5 and6). 5 and 6).

(a) (b) (a) (b) Figure 5. (a) Plan and section of Rambla del Poble Nou, upper section; (b) street view of Rambla del Poble Nou, upper FigureFigure 5.5.( a(a)section.) Plan Plan and and section section of of Rambla Rambla del del Poble Poble Nou, Nou, upper upper section; section; (b) street (b) street view ofview Rambla of Rambla del Poble del Nou, Poble upper Nou, section. upper section.

(a) (b) (a) (b) Figure 6. (a) PlanFigure and section 6. (a) Plan of Rambla and section del Poble of Rambla Nou, del lower Poble section; Nou, lower(b) street section; view (b of) street Rambla view del of Poble Rambla Nou, del lower Figure 6. (a) Plan and section of Rambla del Poble Nou, lower section; (b) street view of Rambla del Poble Nou, lower section. Poble Nou, lower section. section. (c) Plaça Reial and les Rambles Plaça Reial is an important square in Barcelona located in the core of the medieval city, tangential to Les Rambles. Measuring 113 × 75 m, Plaça Reial presents the first regularized façades of the medieval city through arcades on the ground floor. It has several connections with lateral streets, the most important being Carrer Ferran, the first straight street of the city, and les Rambles. The zone studied in this case also includes several terraces located in Les Rambles. This avenue of Barcelona connects Plaça Catalunya with the sea. It was also formerly the limit between the walled city and the Raval neighborhood, the hors-murailles western extension, now the avenue that divides both neighborhoods and the most touristic axis in Barcelona (Figure7). Sustainability 2021, 13, x FOR PEER REVIEW 7 of 21

c) Plaça Reial and les Rambles Plaça Reial is an important square in Barcelona located in the core of the medieval city, tangential to Les Rambles. Measuring 113 × 75 m, Plaça Reial presents the first regularized façades of the medieval city through arcades on the ground floor. It has several connections with lateral streets, the most important being Carrer Ferran, the first straight street of the city, and les Rambles. The zone studied in this case also includes several terraces located in Les Rambles. This avenue of Barcelona connects Plaça Catalunya with the sea. It was also formerly the limit between the walled city and the Raval neighborhood, Sustainability 2021, 13, 865 the hors-murailles western extension, now the avenue that divides both neighborhoods7 of 20 and the most touristic axis in Barcelona (Figure 7).

(a)

(b)

Figure 7. (a) Plan and section of Plaça Reial; (b) street view of Plaça Reial.

(d)d) MercatMercat del del Born Born Pedestrian areaarea MercatMercat del del Born Born is is a formera former municipal municipal market market of Barcelona of Barcelona inaugurated inaugu- ratedin 1876 in and1876 located and located at the at end the of end Passeig of Passeig del Born. del Born. Since Since September September 2013, 2013, it has it been has usedbeen usedas a culturalas a cultural center center accommodating accommodating various various archaeological archaeological remains. remains. The The remodeling remodeling of ofthe the center center was was complemented complemented by anby urbanan urba plann plan that that pedestrianized pedestrianized the surrounding the surrounding area. × Sustainability 2021, 13, x FOR PEER REVIEWThearea. 30 The 7030 m× 70 square m square located located at its at front, its front, the 20the m 20 wide m wide Passeig Passeig del Born,del Born, along along with8 with of the 21

thetransformation transformation of the of neighborhood,the neighborhood, have have helped helped create create a leisure a leisure area commonly area commonly visited vis- by itedtourists by tourists and locals and and locals stimulate and stimulate the emergence the emergence of restaurant of restaurant businesses businesses (Figure8). (Figure 8).

(a)

(b)

Figure 8. ((aa)) Plan Plan and and section section of of Mercat Mercat del Born area; (b) street view of Mercat deldel BornBorn area.area.

e) Gaudi Avenue Gaudí Avenue is a 25 m wide street splitting the orthogonal grid of Eixample in a precise north–south diagonal that connects two landmarks, the Sagrada Familia and Hos- pital de Sant Pau. Originally, it was used as an important driveway, but in 1985, the avenue was remodeled, becoming more pedestrian friendly. Since then, the street has hosted a large number of restaurant businesses frequented by visitors to the Sagrada Familia. Its current layout has two car lanes separated by a 10 m wide pedestrian way and two other 4 m wide pedestrian ways adjacent to the building façades, resulting in a 75% of the section dedicated to pedestrians (Figure 9).

(a) (b)

Figure 9. (a) Plan and section of Gaudí Avenue; (b) street view of Gaudí Avenue.

f) Paral·lel Avenue and Blai Street. Traffic Focused Street (Paral·lel) vs. Pedestrian Street (Blai) Paral·lel Avenue is a 40 m wide street originated after the approval of Pla Cerdà in 1859 that connects Plaça Espanya to the old royal shipyards by the port. It also delimits the boroughs of Poble Sec and Raval. Its trace, following the same east–west direction as

Sustainability 2021, 13, x FOR PEER REVIEW 8 of 21

(a)

Sustainability 2021, 13, 865 (b) 8 of 20

Figure 8. (a) Plan and section of Mercat del Born area; (b) street view of Mercat del Born area.

e)(e) GaudiGaudi Avenue Avenue GaudíGaud Avenueí Avenue is isa a25 25 m mwide wide street street splitting splitting the the orthogonal orthogonal grid grid of Eixample of Eixample in a in precisea precise north–south north–south diagonal diagonal that connects that connects two landmarks, two landmarks, the Sagrada the Sagrada Familia Familia and Hos- and pitalHospital de Sant de Pau. Sant Originally, Pau. Originally, it was used it was as an used important as an important driveway, driveway, but in 1985, but the in ave- 1985, nuethe was avenue remodeled, was remodeled, becoming becomingmore pedestrian more pedestrianfriendly. Since friendly. then, the Since street then, has the hosted street a haslarge hosted number a large of restaurant number ofbusinesses restaurant freque businessesnted by frequented visitors to bythe visitors Sagrada to Familia. the Sagrada Its currentFamilia. layout Its current has two layout car lane hass two separated car lanes by separated a 10 m wide by apedestrian 10 m wide way pedestrian and two way other and 4 twom wide other pedestrian 4 m wide ways pedestrian adjacent ways to adjacentthe building to the façades, building resulting façades, in resulting a 75% of in the a 75% sec- of tionthe dedicated section dedicated to pedestrians to pedestrians (Figure 9). (Figure 9).

(a) (b)

FigureFigure 9. 9.(a)( aPlan) Plan and and section section of ofGaudí Gaud Avenue;í Avenue; (b ()b street) street view view of of Gaudí Gaud Avenue.í Avenue.

f)(f) Paral·lelParal·lel Avenue Avenue and and Blai Street. TrafficTraffic Focused Focused Street Street (Paral (Paral·lel)·lel) vs. Pedestrianvs. Pedestrian Street (Blai) Street (Blai) Paral·lel Avenue is a 40 m wide street originated after the approval of Pla Cerdà in 1859Paral·lel that connects Avenue Plaça is a 40 Espanya m wide to street the old originated royal shipyards after the by approval the port. of It Pla also Cerdà delimits in 1859the that boroughs connects of Poble Plaça Sec Espanya and Raval. to the Its old trace, royal following shipyards the by same the east–westport. It also direction delimits as thethe boroughs geographic of Poble parallel, Sec wasand Raval. established Its trace, over following the demolished the same medieval east–west city direction walls. Theas avenue constituted a leisure axis, especially nightlife businesses, from the last years of the 19th century until the 1970s. Nowadays, it still holds a good number of entertainment businesses, such as theatres, cinemas, concert halls. Its layout gives a total of 40% of its

width to pedestrian areas, arranged in two lateral walkways, two three-lane driveways and a central two-way bicycle lane. Blai Street is a 450 m long, 10 m wide street in the neighborhood of Poble Sec that has recently become very popular. Once unnoticed, this street, aided by its pedestrianization and a rebranding strategy, has become the center of the neighborhood life, ﬁlled with bars and terraces (Figures 10 and 11).

2.2. Data Collection of the Characteristic Elements of the Terraces The second step of the process was the creation of a database that assembled the characteristics of the studied terraces. Each spreadsheet includes 21 attributes organized in three sections: premises data, terrace elements and urban environment. It also contains graphical information: plan and section, an image of the terrace and an environment conceptual diagram describing the relationship with the surroundings (Figure 12). The first section, premises data, addresses the eight following fields: name and address, date and hour of observation, type of business, price of coffee, price of beer (33 cl), opening schedule and approximate tourist/local client percentage. The price of coffee and beer are used as proxies of the business economic level, as they tend to be sold at all types of terraces, be it restaurants, bars or cafes. Every zone is codified with an ID, from 1 to 6, and Sustainability 2021, 13, x FOR PEER REVIEW 9 of 21 Sustainability 2021, 13, x FOR PEER REVIEW 9 of 21

thethe geographicgeographic parallel,parallel, waswas establishedestablished overover thethe demolisheddemolished medievalmedieval citycity walls.walls. TheThe avenueavenue constituted constituted a a leisure leisure axis, axis, especially especially ni nightlifeghtlife businesses, businesses, from from the the last last years years of of the the 19th19th centurycentury untiluntil thethe 1970s.1970s. Nowadays,Nowadays, itit ststillill holdsholds aa goodgood numbernumber ofof entertainmententertainment businesses,businesses, suchsuch asas theatres,theatres, cinemas,cinemas, concertconcert halls.halls. ItsIts layoutlayout givesgives aa totaltotal ofof 40%40% ofof itsits Sustainability 2021, 13, 865 widthwidth toto pedestrianpedestrian areas,areas, arrangedarranged inin twtwoo laterallateral walkways,walkways, twotwo three-lanethree-lane drivewaysdriveways9 of 20 andand a a central central two-way two-way bicycle bicycle lane. lane. BlaiBlai Street Street is is a a 450 450 m m long, long, 10 10 m m wide wide street street in in the the neighborhood neighborhood of of Poble Poble Sec Sec that that has has recentlyrecently becomebecome veryvery popular.popular. OnceOnce unnoticed,unnoticed, thisthis street,street, aidedaided byby itsits pedestrianizationpedestrianization everyand a rebranding terrace has astrategy, number has of twobecome digits the preceded center of bythe the neighborhood ID of its zone life, (total filled of with 3 digits) bars and(Figure a rebranding 13). strategy, has become the center of the neighborhood life, filled with bars andand terraces terraces (Figures (Figures 10 10 and and 11). 11).

((aa))

((bb)) · · FigureFigure 10. 10. ( (aa)) Plan Plan and and section sectionsection of ofof Paral·lel ParalParal·lellel Avenue; Avenue; ( ((bbb))) street streetstreet view viewview of ofof Paral·lel ParalParal·lellel Avenue. Avenue.Avenue.

((aa)) ((bb)) Figure 11. (a) Plan and section of Blai Street; (b) street view of Blai Street. FigureFigure 11. 11. ((aa)) Plan Plan and and section section of of Blai Blai Street; Street; ( (bb)) street street view view of of Blai Blai Street. Street.

2.2.2.2. Data DataThe Collection Collection second section, of of the the Characteristic Characteristic terrace elements, Elements Elements describes of of the the Terraces Terraces the equipment of the terrace. This section is divided into four subsections: seats, tables, auxiliary elements and heating TheThe secondsecond stepstep ofof thethe processprocess waswas thethe creationcreation ofof aa databasedatabase thatthat assembledassembled thethe devices (Figure 14). The seats subsection has three ﬁelds: number of seats, number of characteristicscharacteristics of of the the studied studied terraces. terraces. people occupying these seats and the type of chair. The tables subsection includes two ﬁelds: number of tables and use or not of tablecloth (the presence of the meal). The last subsection describes the terrace through their auxiliary elements, in addition to tables and

chairs, such as umbrellas, planters, awning, platform, buffet, heating and artiﬁcial lighting. With the aim of synthesizing the diversity of terraces regarding equipment, eight modules of terrace are deﬁned, based on the previous work by Pia Giannoni [29]. The description of these modules ranges from a terrace with only tables and seats [M1] to a terrace that becomes a physical extension of its own indoor business [M8]. The last subsection, the Sustainability 2021, 13, x FOR PEER REVIEW 10 of 21

Each spreadsheet includes 21 attributes organized in three sections: premises data, terrace elements and urban environment. It also contains graphical information: plan and section, an image of the terrace and an environment conceptual diagram describing the relationship with the surroundings (Figure 12). Sustainability 2021, 13, x FOR PEER REVIEW 10 of 21 Sustainability 2021, 13, 865 10 of 20

Each spreadsheet includes 21 attributes organized in three sections: premises data, heating subsection, is the one that acts as the basis for the analysis of this research. This terrace elements and urban environment. It also contains graphical information: plan and part seeks to quantify the heating devices installed for every terrace. It contains 3 ﬁelds: section, an image of the terrace and an environment conceptual diagram describing the gas, electric and interior, which describe the type and number of heating devices. relationship with the surroundings (Figure 12).

Figure 12. Example of data sheet.

The first section, premises data, addresses the eight following fields: name and address, date and hour of observation, type of business, price of coffee, price of beer (33 cl), opening schedule and approximate tourist/local client percentage. The price of coffee and beer are used as proxies of the business economic level, as they tend to be sold at all types of terraces, be it restaurants, bars or cafes. Every zone is codified with an ID, from 1 to 6, and every terrace has a number of two digits preceded by the ID of its zone (total of 3 Figure 12. Example of data sheet. digits) (Figure 13). The first section, premises data, addresses the eight following fields: name and address, date and hour of observation, type of business, price of coffee, price of beer (33 cl), opening schedule and approximate tourist/local client percentage. The price of coffee and beer are used as proxies of the business economic level, as they tend to be sold at all types of terraces, be it restaurants, bars or cafes. Every zone is codified with an ID, from 1 to 6, and every terrace has a number of two digits preceded by the ID of its zone (total of 3 digits) (Figure 13). Figure 13. Part of the data sheet containing the premises data. Figure 13. Part of the data sheet containing the premises data.

TheFinally, second the urbansection, environment terrace elements, section describes focuses on the three equipment fields: the of terrace–premisesthe terrace. This sectionconnection, is divided the terrace–premises into four subsections: proportion seats, andtables, the auxiliary terrace–street elements relation and heating (Figure de-15). vicesThe terrace–premises (Figure 14). The seats connection subsection has fourhas thr possibleee fields: values: number “adhered” of seats, when number the of terrace people is occupyingin contact withthese the seats business; and the “close” type of when chair. it isThe located tables right subsection next to includes it, without two space fields: for numberpedestrians of tables to walk and in use between; or not of “separated” tablecloth (t whenhe presence there isof a the gap meal). between The thelast terracesubsection and describestheFigure premises 13. the Part enoughterrace of the datathrough for pedestrianssheet their containing auxiliary to walk the premises elements, by; and data. “far” in addition when the to terrace tables isand separated chairs, suchfrom as the umbrellas, premises planters, by, at least, awning, a car lane. platform, buffet, heating and artificial lighting. With the aimThe of second terrace–street synthesizing section, proportionthe terrace diversity elements, is of also terraces structured describes regarding inthe four equipment equipment, options: of “appendage”, eight the terrace. modules This “ex- of terracesectiontension”, areis divided “equivalent”defined, into based four and on subsections: “dispenser”.the previous seats, wo “appendage”rk tables, by Pia auxiliary Giannoni is when elements [29]. the The terrace and description heating surface de- of is thesevicessignificantly (Figuremodules smaller14). ranges The than seatsfrom the subsectiona terrace indoor with part has ofthronly theee tablesfields: food andand number beverageseats of [M1] seats, business. to numbera terrace “extension” of that people be- comesoccupyingwhen thea physical terrace, these extensionseats although and of stillthe its smallertype own of indoor thanchair. thebusiness The business, tables [M8]. subsection represents The last subsection, aincludes significant two the portion fields: heat- ingnumberofthe subsection, entire of tables establishment. is and the useone orthat not “equivalent” acts of tablecloth as the basis represents (the for presence the those analysis of terraces the of meal). this in which research.The last their subsection This surface part describesis approximately the terrace the samethrough as thetheir surface auxiliary of the elements, business. in Finally, addition “dispenser” to tables and represents chairs, suchthose as cases umbrellas, when theplanters, surface awning, of the terraceplatform, is significantlybuffet, heating larger and thanartificial the indoorlighting. part With of thethe aim business. of synthesizing the diversity of terraces regarding equipment, eight modules of terraceFinally, are defined, the last based subsection, on the the previous terrace–street work by relation, Pia Giannoni considers [29]. two The fields: description the side- of thesewalk widthmodules where ranges the from terrace a terrace is located, with and only the tables ratio and between seats sidewalk[M1] to a andterrace total that street be- comeswidth (consideringa physical extension sidewalks of its on own both indoor sides ofbusiness the street). [M8]. In The addition last subsection, to these variables, the heat- ingthis subsection, section takes is the into one account that acts the environmentas the basis for concept the analysis diagram. of this This research. diagram This aims part to present the influence of the terrace over its immediate environment and the reverse.

Sustainability 2021, 13, x FOR PEER REVIEW 11 of 21

seeks to quantify the heating devices installed for every terrace. It contains 3 fields: gas, electric and interior, which describe the type and number of heating devices.

Figure 14. Part of the data sheet containing the terrace elements.

Sustainability 2021, 13, x FOR PEER REVIEW 11 of 21 Finally, the urban environment section focuses on three fields: the terrace–premises connection, the terrace–premises proportion and the terrace–street relation (Figure 15). Sustainability 2021, 13, 865 The terrace–premises connection has four possible values: “adhered” when the terrace11 of 20is seeksin contact to quantify with the the business; heating “close”devices when installed it is forlocated every right terrace. next It to contains it, without 3 fields: space gas, for electricpedestrians and interior,to walk inwhich between; describe “separated” the type whenand number there is of a heatinggap between devices. the terrace and the premises enough for pedestrians to walk by; and “far” when the terrace is separated from the premises by, at least, a car lane. The terrace–street proportion is also structured in four options: “appendage”, “extension”, “equivalent” and “dispenser”. “appendage” is when the terrace surface is significantly smaller than the indoor part of the food and beverage business. “extension” when the terrace, although still smaller than the business, represents a significant portion of the entire establishment. “equivalent” represents those terraces in which their surface is approximately the same as the surface of the business. Finally, “dispenser” represents those cases when the surface of the terrace is significantly larger than the indoor part of the business. Finally, the last subsection, the terrace–street relation, considers two fields: the sidewalk width where the terrace is located, and the ratio between sidewalk and total street width (considering sidewalks on both sides of the street). In addition to these variables, Figurethis section 14. Part takes of the into data account sheet containing the environment the terrace conceptelements. diagram. This diagram aims to Figure 14. Part of the data sheet containing the terrace elements. present the influence of the terrace over its immediate environment and the reverse. Finally, the urban environment section focuses on three fields: the terrace–premises connection, the terrace–premises proportion and the terrace–street relation (Figure 15). The terrace–premises connection has four possible values: “adhered” when the terrace is in contact with the business; “close” when it is located right next to it, without space for pedestrians to walk in between; “separated” when there is a gap between the terrace and the premises enough for pedestrians to walk by; and “far” when the terrace is separated from the premises by, at least, a car lane. The terrace–street proportion is also structured in four options: “appendage”, “extension”, “equivalent” and “dispenser”. “appendage” is when the terrace surface is significantly smaller than the indoor part of the food and beverage business. “extension” Figure 15. Part of the data sheet containing the Urban environment section. Figurewhen 15. Partthe terrace, of the data although sheet containing still smaller the Urban than the environment business, section. represents a significant portion of the entire establishment. “equivalent” represents those terraces in which their surface The field ﬁeld work consisted in collecting collecting the the data data using using the the previously previously described described spread- spread- is approximately the same as the surface of the business. Finally, “dispenser” represents sheet in the six mentioned areas and processingprocessing itit withwith GeographicGeographic InformationInformation System those cases when the surface of the terrace is significantly larger than the indoor part of (GIS), using ArcMap 10.4 (Esri) as the main software. The data collection was carried out the business. in the winterwinter ofof 2017,2017, throughout throughout February February and and March, March, a perioda period which which will will be thebe the reference refer- Finally, the last subsection, the terrace–street relation, considers two fields: the side- encefor the for below the below comparisons comparisons with with other other representative representative values. values. The The sample sample collected collected for thefor walk width where the terrace is located, and the ratio between sidewalk and total street thepresent present investigation investigation comprises comprises a total a total of 268 of 268 terraces, terraces, which which are dividedare divided as follows: as follows: width (considering sidewalks on both sides of the street). In addition to these variables, this• sectionZ1_Enrique takes Granados:into account 49; the environment concept diagram. This diagram aims to present• Z2_Poble the influence Nou: 25; of the terrace over its immediate environment and the reverse. • Z3_Plaza Reial 44; • Z4_Mercat Born 50; • Z5_Av. Gaudí: 50; • Z6_Parallel: 50.

3. Results and Discussion From a total of 268 studied terraces, 120 (45%) have heating devices. From these 45%, 87 terraces have gas cylinder heaters, while 22 have electric heaters and 11 have both. When calculating the total installed power that these terraces represent (3100 kW),

gas cylinder heaters are responsible for 97% (3000 kW), while only the remaining 3% Figure(87 15. kW) Part is of due the todata the sheet 145 electriccontaining heaters. the Urban Due environment to the low percentage section. of terraces with electric heating devices, the energy analysis presented in the ﬁnal discussion only considered gas heatingThe values. field work consisted in collecting the data using the previously described spread- sheetThese in the terracessix mentioned have a areas total ofand 4018 processi seatsng and it occupywith Geographic a total area Information of approximately System (GIS),2878 m using2. Using ArcMap these 10.4 calculations, (Esri) as the the main average software. installed The power data collection per square was meter carried can out be inapproximated, the winter of resulting 2017, throughout in 997 W/m February2 (Table and2). March, a period which will be the reference for the below comparisons with other representative values. The sample collected for the present investigation comprises a total of 268 terraces, which are divided as follows:

Sustainability 2021, 13, 865 12 of 20

Table 2. Calculation of the average installed power per square meter, considering only terraces with gas.

Terraces Seats Installed Power (kW) Area (m2) W/m2 98 4018 2868 2878 997

In order to gain further insight into the use of heating devices in terraces, data retrieved were analyzed regarding two main factors: the installed power per square meter by zone (Table3) and the differences in heating type in terraces, by zone and by size.

Table 3. Total installed power and installed power per square meter by zone.

Zone Installed Power (kW) Installed Power Per m2 (W/m2) Z1 Enrique Granados 192 1931 Z2 Poblenou 228 1124 Z3 Plaça Reial 1392 822 Z4 Mercat del Born 672 1163 Z5 Avinguda Gaudí 204 1329 Z6 Paral·lel-Blai 180 1195

The following chart (Figure 16) analyzes the dimension of the terraces, estimated by Sustainability 2021, 13, thex FOR number PEER REVIEW of seats and divided by their heating type: gas (red dots), electric (yellow dots), 13 of 21

none (blue dots).

Figure 16.FigureTerraces 16. Terraces by number by number of seats of and seats heating and heating type, organized type, organized by zones. by zones.

When focusingWhen on focusing the percentage on the ofpercentage terraces without of terraces heating without devices, heatingAvinguda devices, Gaud Avingudaí Gaudí and Paral·lel/Blaiand Paral·lel/Blaihave a value have above a value 70%, above while zones70%, while such aszonesEnrique such Granados as Enrique, Poble Granados Nou , Poble Nou and Mercatand del Born Mercathave del approximately Born have approximately 50% and Plaça 50% Reial andunder Plaça Reial 20%. under In all the20%. zones, In all the zones, the percentagethe ofpercentage terraces with of terraces heating with is lower heating than is thelowe percentager than the ofpercentage terraces withoutof terraces it, without it, except for theexcept case for of Plaça the case Reial of. Plaça Reial. It can be observedIt can be that observedPlaça Reial thatis Plaça the areaReial with is the the area greatest with the percentage greatest ofpercentage terraces of terraces with heatingwith and heating also the and one also with the the one highest with totalthe highes installedt total power installed of all power the evaluated of all the evaluated zones. However,zones. as However, seen in the as previousseen in the table, previous the resulting table, the values resulting of installed values powerof installed per power per square metersquare are the meter lowest are ofthe all lowest the areas. of all Considering the areas. Considering that the terraces that the in thisterraces location in this location are also theare largest also ones,the largest it can ones, be concluded it can be thatconclude the dimensiond that the ofdimension the terraces of the greatly terraces greatly inﬂuences theinfluences installed the power installed per square power meterper square value. meter value. If the same dataIf the are same re-arranged data are re-arranged in descending in descen order byding dimension, order by dimension, given in number given in number of seats, otherof seats, observations other observations can be made can (Figure be made 17). (Figure 17).

Figure 17. Terraces by number of seats and heating type.

The highest number of terraces without any type of heating device is represented by the terraces with less than 24 seats. Above this limit, a significant number of terraces have heating devices. Furthermore, only two of the terraces with more than 48 seats do not have

Sustainability 2021, 13, x FOR PEER REVIEW 13 of 21

Figure 16. Terraces by number of seats and heating type, organized by zones.

When focusing on the percentage of terraces without heating devices, Avinguda Gaudí and Paral·lel/Blai have a value above 70%, while zones such as Enrique Granados, Poble Nou and Mercat del Born have approximately 50% and Plaça Reial under 20%. In all the zones, the percentage of terraces with heating is lower than the percentage of terraces without it, except for the case of Plaça Reial. It can be observed that Plaça Reial is the area with the greatest percentage of terraces with heating and also the one with the highest total installed power of all the evaluated zones. However, as seen in the previous table, the resulting values of installed power per square meter are the lowest of all the areas. Considering that the terraces in this location are also the largest ones, it can be concluded that the dimension of the terraces greatly Sustainability 2021, 13, 865 influences the installed power per square meter value. 13 of 20 If the same data are re-arranged in descending order by dimension, given in number of seats, other observations can be made (Figure 17).

FigureFigure 17.17. Terraces byby numbernumber ofof seatsseats andand heatingheating type.type.

The highest number of terraces without any typetype ofof heatingheating device is represented byby thethe terracesterraces withwith lessless thanthan 2424 seats.seats. AboveAbove thisthis limit,limit, aa signiﬁcantsignificant numbernumber ofof terracesterraces havehave heating devices.devices. Furthermore, onlyonly twotwo ofof thethe terracesterraces withwith moremore thanthan 4848 seatsseats dodo notnot havehave heating devices. Consequently, three main groups of terraces were identiﬁed regarding size that respond to heating criteria, from 0 to 24 seats, from 24 to 48 seats and above 48 seats. The following table (Table4) indicates the value of installed power per square meter

calculated for each of the three main groups (size in square meters calculated with the aforementioned 0.77 m2/seat value).

Table 4. Installed power per square meter in terraces by size group.

Seats Installed Power Per m2 (W/m2) Less than 24 seats 1535 W/m2 24–48 seats (extremes included) 1058 W/m2 Greater than 48 seats 918 W/m2

It can be observed that around 90% of large terraces (>48 seats) have heating devices. Municipal regulations set a heating load per square meter limit of 0.7 kW/m2 [26]. The installed power per square meter of large terraces (>48 seats) is close to the regulations. On the other hand, in the case of small terraces (<24 seats) which constitute only 20% of this group, the installed power per square meter tends to surpass the municipal regulations by approximately twice the limiting value (1.5 kW/m2).

4. Energy Considerations 4.1. Installed Power and Reference Values Heating devices could be classiﬁed into two main groups: gas cylinder heaters and electric ones. In order to analyze the installed power of every terrace, nominal power values for these gas and electric heaters were assigned. An average power of 12 kW was assigned to the gas cylinder heaters and an average power of 0.6 kW to the electric ones. These values represent the maximum power and were obtained from catalog speciﬁcations of most of the available heaters installed in these zones [30–32]. Sustainability 2021, 13, 865 14 of 20

In order to obtain a reference baseline to assist in comparing the results obtained regarding power installed in the terraces, five power values are considered and estimated as follows. (a) The average solar radiation flux (W/m2), referring to a 24 h period, received by a horizontal surface in Barcelona, with no obstructions, in an average day in March. The value used was obtained from the EPW climatic file of the DesignBuilder simula- tion, based on data from the Meteorology Station of El Prat de Llobregat, Barcelona, with a value of 200 W/m2 as global radiation for the simulated average day of March. It was cross-referenced with two additional values: Data from the AEMET Agencia Estatal de Meteorología (Spanish State Meteorology Agency) for the month of March 2015 in Barcelona display a global solar radiation of 4.11 kWh/m2 day, in terms of energy. This represents an average solar radiation flux received in a 24 h period of 171 W/m2. Solar radiation data from Catalonian Meteorology Service (MeteoCAT) given by the Station of El Prat de Llobregat, Barcelona, corresponding to 20 March 2017 give a value of 231 W/m2. The power of solar radiation received in a surface can be used to set up a first baseline value. The value of 200 W/m2 represents the average solar radiation received on a horizontal surface before any transformation process. It should be noted that during the 2 Sustainability 2021, 13, x FOR PEER sunREVIEW hours this value can reach around 800 W/m . It represents 1/5 of the installed power16 of 21

(1000 W/m2) or around 1/3.5 of that recommended by municipal regulations (700 W/m2). This means that terraces are equipped with heating devices that provide an average of ﬁve times the solar heating power, similar to being under peak hour sun radiation without Therefore, the comparison of the average installed power per square meter in terraces any protection. in Barcelona with the aforementioned values shows that it is, approximately, 180 times (b) The heating load of a mean terrace type, enclosed in a single glazed envelope the necessary power to heat a square meter of a residential building and also the average (Figure 18). heating energy consumption in residential buildings in Spain.

Figure 18. Installation of glazed gazebos at a restaurant’s terrace in Amsterdam motivated by the Figure 18. Installation of glazed gazebos at a restaurant’s terrace in Amsterdam motivated by the COVID-19 situation. Photography by Willem Velthoven for Mediamatic Amsterdam, Amsterdam, COVID-19 situation. Photography by Willem Velthoven for Mediamatic Amsterdam, Amsterdam, Netherlands, 2020. Netherlands, 2020. In order to show these results in a graphical way, two charts are needed. The first one The volume of the mean terrace type was calculated based on the average area of represents a comparison of the reference values mentioned in this section, in W/m2. The terraces with gas heating installed, and a height of 3 m, obtaining a value of 88 m3. The resultingsecond one envelope aims to surface properly considers display the all thelarge surfaces difference in contact between with the thereference exterior, values, except the withmunicipal the ground, regulation and resulted and the incurrent 94.4 m installed2. The transmittance power in terraces. value The estimated installed for power a single per glazedsquare curtain meter wallfor heating was 5 W/(min terraces2 K). has a high value, often over the value recommended by theThe municipal estimated regulations heating load (F considersigure 19b). transmission The regulations and ventilation of Barcelona losses. limit The the heating heating 2 loadload was by 0.7 estimated kW/m . by As the we Heating have seen, Degree while Day large (HDD) terraces (20 ◦often) method, show and values the per value square for Barcelonameter under was the used, regulatory obtained limit, from small the IDAE ones databasecan double [33 the]. Themunicipal air renovation maximum. load was estimated considering one Air Change per Hour (ACH). The estimated heating load resulted in 130 W/m2, 65% of the solar power.

(a) (b)

Figure 19. (a) Power (solar radiation flux and other heating reference values) in W/m2; (b) reference values vs. installed power in terraces and current municipal regulation.

Sustainability 2021, 13, 865 15 of 20

The installed power at the terraces is around eight times the power necessary to achieve comfort conditions in a glazed enclosure. (c) The heating load of a mean terrace type, enclosed in an insulated envelope. The heating load estimated in this case is similar to the previous one but considers a scenario with an insulated envelope. The same value of “mean terrace volume” and the same value of “envelope surface” were taken, but with a transmittance of 0.7 W/(m2 K). This value is recommended by the Codigo Técnico de la Edificación (CTE), the Spanish regulation for residential buildings [34]. The air renovation load also was estimated considering one Air Change per Hour (ACH). In this case, the result was 24.8 W/m2. A more efficient envelope characterized by a transmittance U-value of 0.7 W/(m2 K) in order to improve the performance yielded only 25 W/m2. This would reduce the necessary power down to 12.5% of the solar power and to only a small percentage (2.5%) of the installed power in terraces. Although (b) and (c) values are useful for first rough approximations, they do not reflect real life situations. The exterior surface (S) and the enclosed volume (V) have a relation where the repercussion of the transmittance value is too high. The estimate output of the calculation of heating power per occupied square meter does not reflect usual situations. This leads us to search for data from living spaces. The first result came from statistical data obtained from a high number of residential buildings used by people in Spain, and a second value was obtained through simulations with DesignBuilder. The aim was to compare the power installed in terraces per square meter with the power needed to heat a square meter of a home. For this reason, two additional values were used for comparison. (d) The average heating energy consumption in residential buildings in Spain. The data were extracted from Conama Foundation’s report [15], regarding the heating power consumption in residential buildings in Spain, and has a value of 49.3 kWh/m2 annum, which constitutes an average of 5.62 W/m2. This figure refers to an annual value, including winter and summer months without distinction, which makes it difficult to isolate the focus on the month of March in this study. In any case, it is an interesting value to include in the comparison because it offers an order of magnitude of heating power consumption. (e) The heating load of a simulated standard residential unit. Simulations with DesignBuilder were run on typical residential models, similar to the average considered in the aforementioned report [15]. The climate file used was that of Barcelona, with a global radiation value of 200 W/m2. The values considered regarding the thermal envelope were those recommended by the Spanish regulations [34]. Several comparisons between façades, adiabatic enveloping surfaces and/or those adjacent to the ground were made with respect to their energy exchange. In order to account for unfavorable scenarios, the dwelling models used were those with four or five out of the six enveloping surfaces in contact with the exterior, and only one or 2 adiabatic and/or adjacent to the ground. The results obtained range between 5 and 5.4 W/m2. Therefore, the comparison of the average installed power per square meter in terraces in Barcelona with the aforementioned values shows that it is, approximately, 180 times the necessary power to heat a square meter of a residential building and also the average heating energy consumption in residential buildings in Spain. In order to show these results in a graphical way, two charts are needed. The first one represents a comparison of the reference values mentioned in this section, in W/m2. The second one aims to properly display the large difference between the reference values, the municipal regulation and the current installed power in terraces. The installed power per square meter for heating in terraces has a high value, often over the value recommended by the municipal regulations (Figure 19b). The regulations of Barcelona limit the heating load by 0.7 kW/m2. As we have seen, while large terraces often show values per square meter under the regulatory limit, small ones can double the municipal maximum. Sustainability 2021, 13, x FOR PEER REVIEW 16 of 21

Therefore, the comparison of the average installed power per square meter in terraces in Barcelona with the aforementioned values shows that it is, approximately, 180 times the necessary power to heat a square meter of a residential building and also the average heating energy consumption in residential buildings in Spain.

Figure 18. Installation of glazed gazebos at a restaurant’s terrace in Amsterdam motivated by the COVID-19 situation. Photography by Willem Velthoven for Mediamatic Amsterdam, Amsterdam, Netherlands, 2020.

In order to show these results in a graphical way, two charts are needed. The first one represents a comparison of the reference values mentioned in this section, in W/m2. The second one aims to properly display the large difference between the reference values, the municipal regulation and the current installed power in terraces. The installed power per square meter for heating in terraces has a high value, often over the value recommended by the municipal regulations (Figure 19b). The regulations of Barcelona limit the heating load by 0.7 kW/m2. As we have seen, while large terraces often show values per square Sustainability 2021, 13, 865 meter under the regulatory limit, small ones can double the municipal maximum. 16 of 20

(a) (b)

FigureFigure 19. 19. ((aa)) Power Power (solar (solar radiation radiation flux ﬂux and and ot otherher heating reference values) in W/m 2;2 ;((bb) )reference reference values values vs. vs. installed installed powerpower in in terraces terraces and and current current municipal municipal regulation. regulation.

The fact that regulations set a limit to the installed power per square meter can distort the overall consumption results, as terraces with less installed power in absolute terms might be surpassing the municipal regulations, while terraces with more installed power might not reach the limits. From the data collected in this survey as well as the samples chosen, it can be stated that the installed power in a terrace is related to the size and number of seats. Urban morphology, microclimatic zone and situation in the city also present certain trends. Terraces in squares, near the sea or in a touristic zone present characteristic features, but a more extended monitoring should be performed to support these points. If all the available heating devices were turned on, the power consumption could be almost forty times the power needed to keep the interior conditions within regulations (CTE) [34] and 180 times the power needed to maintain the interior conditions of a square meter of an average terrace. Therefore, if the number of terraces continues to increase at the current rate, the impact on power consumption could acquire great signiﬁcance.

4.2. Estimated Energy Consumption The energy consumed was estimated using different scenarios based on the following variables: opening hours, percentage of installed power used and outdoor air temperature. Opening hours were set from 8:00 h to 24:00 h, based on the regulations of the “Ordenanza de Terrazas de Barcelona” [26]. During weekends and exceptional occasions, terraces can be open two additional hours at night. We did not take into consideration these singular occasions for the calculations, rendering 5840 annual open hours of a total of 8760, with 496 h in March. The percentage of switched-on heating devices was set either at 100% or 60%, based on direct observation and surveys to restaurant owners. Three values (14, 16 and 18 ◦C) were set based on existing literature on outdoor comfort [35–37]. The number of hours below set temperatures were calculated during the terrace opening hours (Figure 20). Sustainability 2021, 13, x FOR PEER REVIEW 17 of 21

4.2. Estimated Energy Consumption The energy consumed was estimated using different scenarios based on the following variables: opening hours, percentage of installed power used and outdoor air temperature. Opening hours were set from 8:00 h to 24:00 h, based on the regulations of the “Or- denanza de Terrazas de Barcelona” [26]. During weekends and exceptional occasions, terraces can be open two additional hours at night. We did not take into consideration these singular occasions for the calculations, rendering 5840 annual open hours of a total of 8760, with 496 h in March. The percentage of switched-on heating devices was set either at 100% or 60%, based on direct observation and surveys to restaurant owners. Sustainability 2021, 13, 865 Three values (14, 16 and 18 °C) were set based on existing literature on outdoor17 com- of 20 fort [35–37]. The number of hours below set temperatures were calculated during the terrace opening hours (Figure 20).

FigureFigure 20.20. NumberNumber ofof hourshours belowbelow setset temperaturestemperatures duringduring thethe terraceterrace openingopening hourshours inin aaweek. week.

ToTo deﬁnedefine thethe temperaturestemperatures inin Barcelona,Barcelona, climaticclimatic datadata fromfrom thethe simulationsimulation softwaresoftware DesignBuilderDesignBuilder werewere used,used, alsoalso comparedcompared withwith thethe locallocal meteorologicalmeteorological StationStation CanCan BruixaBruixa (Table(Table5 ).5).

TableTable 5.5.Scenarios Scenarios andand estimatedestimated energyenergy consumptionconsumption for for studied studied terraces. terraces.

Hours under Estimated 100% Estimated 60% Estimated 100% Estimated 60% Outdoor HoursHours under un- Set HoursSet Temp. underEnergy Estimated Consumption 100% EnergyEstimated Consumption 60% EstimatedEnergy Consumption 100% EnergyEstimated Consumption 60% AirOutdoor Temp. Temp.der (March) Set (Annual)Set Temp. Energy(Annual) Consump- Energy(Annual) Consump- Energy(March) Consump- Energy(March) Consump- Air<14 Temp.◦C 2165 h 6209 MWh 3725 MWhTemp. 271 h 777 MWh 466 MWh <16 ◦C(Annual) 2716 h tion 7789 MWh(Annual) tion 4673 MWh (Annual) 352 htion 1009 (March) MWh tion 605 (March) MWh <18 ◦C 3285 h 9421 MWh 5653 MWh(March) 421 h 1207 MWh 724 MWh

The study was conducted on 268 terraces, with 36.5% having heating devices. The total number of terraces of the municipal census in June 2020 was 5650, not accounting for those exceptionally authorized due to COVID-19 [38].

5. Conclusions This study is centered on terraces of food and beverage businesses located in the public realm, with a particular focus on the energy use of heating devices installed during the winter months. We analyzed a set of case studies that were used as a reference to calculate installed power values for heating devices and, through different scenarios, estimated the potential energy consumed. These values were compared with a set of baselines to give an indication of the importance of considering this outdoor dining from an energy consumption angle. While residential buildings might be the focus of current energy concerns, this study points out that activities performed outdoors, such as consuming food or drinks in a terrace while socializing, could be the cause for the radical increase in the overall power consumption of an individual’s daily activity [39]. In addition, the current COVID-19 pandemic has added more urgency to the study of this practice, as the presence of outdoor dining is dramatically increasing everywhere. The biggest challenge is found in cities where the outdoor climate conditions will require heating devices for a long period of time in the year. In order to guarantee an overall sustainable trajectory in our ways of living, it is important to anticipate and monitor new practices that could become a challenge to our environmental objectives. Therefore, appropriate regulations are needed in order to ensure that the comfort of the user in terraces is not provided at the expense of unnecessary energy consumption. This study also aims to highlight how current regulations tend to be limited in their approach. There is a clear difference between regulations that set up a limit value of installed power and regulations that specify features that would guarantee the creation of Sustainability 2021, 13, 865 18 of 20

certain environmental conditions. The Codigo Técnico de la Edificación (CTE) [34] is the latter type of regulations, while the Ordenança de terrasses, current municipal regulations on terraces [26], is the former type. A possible improvement could be basing the regulations on outdoor air temperature instead of only relying on values weighted by square meter [40]. Although the consumption would still be high, turning heaters off in the middle of the day, when the temperature rises, would be a feasible strategy to reduce it. The best option, however, would be to base the entire approach to providing comfort on the environmental conditions at hand and the needs of users, considering using radiant solutions, instead of heating the air of the street. When efforts are directed toward achieving higher sustainability and responsible use of energy, it is important to control spaces that, even though privately owned, are in the public space. This work aims to open this pathway by showing the significance of the energy consumption in terraces and pointing out following research directions that should be taken in order to achieve a comprehensive understanding of the topic. With more means and by involving more researchers and institutions, we aim start finding the answers to the questions we have highlighted. Is this extensive use of heating devices sustainable in outdoor terraces in Barcelona? Is the real objective of these devices to improve the thermal conditions of the users, or is there an underlying commercial interest, expressed through a warm visual image projected to the public? If the goal is an improvement of the thermal conditions, would it not be better to use radiant systems that modify the radiant temperature instead of the air temperature? If the main objective is psychological, could we use other visual effects with a similar “warm” image but much lower consumption? Terraces have been and will continue to be key elements of the public realm, with the capacity of bringing people together or activating the streetscape. More recently, the focus has shifted in allowing social interactions with access to open air and with safety and health measures. In any case, terraces remain an element that can be strategically used to benefit the public realm and urban experience. Therefore, it is important that we study how to improve them at many different levels, from social justice to wellness. Energy consumption and human comfort should be at the center of focus, and the fact that scarce resources are directed towards “heating the street” should be a major concern.

Author Contributions: The different knowledge and experience of each author have equally con- tributed to the development and final version of this article. All authors collectively designed the methodology, performed the data collection, analyzed the data and wrote the paper with equal responsibility. All authors have read and agreed to the published version of the manuscript. Funding: This work was supported by the Spanish Government under the project code BIA2016-77675-R. Institutional Review Board Statement: Not applicable. Informed Consent Statement: Meaning is retained. Data Availability Statement: Not applicable. Acknowledgments: The support of J. Torres-Quezada and Arch. J. Rotger-Vinent is gratefully acknowledged. Part of the field work was carried out by the students of the master’s degree in Advanced Studies at Architecture Barcelona, line of specialization, Architecture, Energy and Environment, 2016–17 edition: Luis Miguel Armendáriz, María Benalcázar, Luana Boiani, Diana Cruz, Javier Fonzo, Joanna Kiedrowska, Aleix Llorach, Lourdes Ruiz, Oriol Roig, Sergio Rojas, Francisco Torres, Catalina Valderrama, Patricia Valdez and Pamela Villegas. Conflicts of Interest: The authors declare no conflict of interest. Sustainability 2021, 13, 865 19 of 20

References 1. Sahito, N.; Han, H.; Nguyen, T.V.T.; Kim, I.; Hwang, J.; Jameel, A. Examining the Quasi-Public Spaces in Commercial Complexes. Sustainability 2020, 12, 1830. [CrossRef] 2. Rothan, H.A.; Byrareddy, S.N. The epidemiology and pathogenesis of coronavirus disease (COVID-19) outbreak. J. Autoimmun. 2020, 109, 102433. [CrossRef][PubMed] 3. Serra-Coch, G.; Chastel, C.; Campos-Sánchez, F.-S.; Roura, H.C. Graphical approach to assess urban quality: Mapping walkability based on the TOD-standard. Cities 2018, 76, 58–71. [CrossRef] 4. Espinàs, J.M.; Vilá, E.; Joan, V. Quinze Anys de Cafès de Barcelona, 1959–1974; DOPESA: Barcelona, Spain, 1975. 5. Chen, L.; Wen, Y.; Zhang, L.; Xiang, W.-N. Studies of thermal comfort and space use in an urban park square in cool and cold seasons in Shanghai. Build. Environ. 2015, 94, 644–653. [CrossRef] 6. Zacharias, J.; Stathopoulos, T.; Wu, H. Spatial Behavior in San Francisco’s Plazas: The Effects of Microclimate, Other People, and Environmental Design. Environ. Behav. 2004, 36, 638–658. [CrossRef] 7. Santamouris, M.; Cartalis, C.; Synnefa, A.; Kolokotsa, D. On the impact of urban heat island and global warming on the power demand and electricity consumption of buildings—A review. Energy Build. 2015, 98, 119–124. [CrossRef] 8. Haarstad, H. Where are urban energy transitions governed? Conceptualizing the complex governance arrangements for low-carbon mobility in Europe. Cities 2016, 54, 4–10. [CrossRef] 9. Poggi, F.; Firmino, A.; Amado, M. Assessing energy performances: A step toward energy efficiency at the municipal level. Sustain. Cities Soc. 2017, 33, 57–69. [CrossRef] 10. Pereira, I.M.; De Assis, E.S. Urban energy consumption mapping for energy management. Energy Policy 2013, 59, 257–269. [CrossRef] 11. Holden, E.; Norland, I.T. Three Challenges for the Compact City as a Sustainable Urban Form: Household Consumption of Energy and Transport in Eight Residential Areas in the Greater Oslo Region. Urban Stud. 2005, 42, 2145–2166. [CrossRef] 12. Blanco, N. 5.1 Millones de Personas no Pueden Calentar sus Hogares en ESPAÑA, Diario16. Available online: http://diario16. com/51-millones-de-familias-no-pueden-calentar-sus-hogares-en-espana (accessed on 2 September 2016). 13. Foster, D. Why is one older person dying every seven minutes during the winter? The Guardian. Available online: https: //www.theguardian.com/society/2016/jan/20/older-person-dying-winter-fuel-poverty (accessed on 13 September 2016). 14. Departamento de Planificación y Estudios, Gobierno de España, Secretaria General. Proyecto SECH-SPAHOUSEC, Análisis del Consumo Energético del Sector Residencial en España—Informe Final; IDAE (Instituto para la Diversificación y Ahorro de la Energía): Madrid, Spain, 2011. 15. Cuchí, A.; Arcas-Abella, J.; Pagès-Ramon, A. Estudio de la Distribución del Consumo Energético Residencial Para Calefacción en España. Subdirección General de Urbanismo, Ministerio de Fomento. [Green Building Council España 2017]. 2017. Avail- able online: https://www.fomento.gob.es/NR/rdonlyres/53E31468-1B09-4123-A05B-0FBEB86B858E/149686/201804_Estudio_ distribucion_consumo_energetico_res.pdf (accessed on 30 November 2017). 16. Salvati, A.; Monti, P.; Roura, H.C.; Cecere, C. Climatic performance of urban textures: Analysis tools for a Mediterranean urban context. Energy Build. 2019, 185, 162–179. [CrossRef] 17. Carpino, C.; Bruno, R.; Arcuri, N. Social housing refurbishment for the improvement of city sustainability: Identification of targeted interventions based on a disaggregated cost-optimal approach. Sustain. Cities Soc. 2020, 60, 102223. [CrossRef] 18. Lucchi, E.; Delera, A.C. Enhancing the Historic Public Social Housing through a User-Centered Design-Driven Approach. Buildings 2020, 10, 159. [CrossRef] 19. Pérez, J.; Lázaro, S.; Lumbreras, J.; Rodríguez, E. A methodology for the development of urban energy balances: Ten years of application to the city of Madrid. Cities 2019, 91, 126–136. [CrossRef] 20. Salvati, A.; Coch Roura, H.; Cecere, C. Assessing the urban heat island and its energy impact on residential buildings in Mediterranean climate: Barcelona case study. Energy Build. 2017, 146, 38–54. [CrossRef] 21. Fichera, A.; Inturri, G.; La Greca, P.; Palermo, V. A model for mapping the energy consumption of buildings, transport and outdoor lighting of neighbourhoods. Cities 2016, 55, 49–60. [CrossRef] 22. B.O.E. Jefatura del Estado, Gobierno de España Ley 42/2010, de 30 de Diciembre, Boletín Oficial del Estado n.318. 2010. Available online: https://www.boe.es/eli/es/l/2010/12/30/42/con/ (accessed on 30 November 2017). 23. Ajuntament de Barcelona. Se Aprueba Inicialmente la Mejora y Ampliación de Aceras de la Via Laietana. Available online: https://www.barcelona.cat/mobilitat/es/actualidad-y-recursos/noticias/se-aprueba-inicialmente-la-mejora-y-ampliacion- de-aceras-en-la-via-laietana_643293 (accessed on 17 April 2018). 24. Ajuntament de Barcelona. La Nueva Rambla, una Transformación al Servicio de las Personas. Available online: https:// ajuntament.barcelona.cat/lesrambles/es/noticia/la-nueva-rambla-una-transformacion-al-servicio-de-las-personas_729668 (accessed on 2 November 2018). 25. García-Almirall, P. Estudi de Caracterització i Avaluació de Terrasses en Espai Públic, Modificació de les Ordenances de Taxes Fiscals de les Terrasses, CPSV (Centre de Política del Sol i Valoracions). 2016. Available online: http://hdl.handle.net/2117/97548 (accessed on 1 March 2017). 26. BOPB. Ordenança de Terrasses, Butlletí Oficial de la Provincia de Barcelona, Barcelona. 2014. Available online: https:// ajuntament.barcelona.cat/eixample/es/ordenanzas-de-terrazas (accessed on 30 September 2020). Sustainability 2021, 13, 865 20 of 20

27. Castán, P. Restauradores Plantean Acuerdo Para Acabar la Guerra de las Terrazas, elPeriódico. Available online: http://www.elperiodico.com/es/barcelona/20170712/los-restauradores-plantean-acuerdo-minimos-para-acabar-guerra- terrazas-barcelona-6164509 (accessed on 7 July 2017). 28. Cugat, R. Las Claves de la Regulación de las Terrazas en BCN, elPeriódico. 2017. Available online: http://www.elperiodico.com/ es/sociedad/20150716/claves-regulacion-terrazas-bcn-4361228/ (accessed on 15 September 2017). 29. Giannoni, P. Terrazas, en el Espacio Público. Master´s Thesis, Polytecnic University of Catalonia, Barcelona, Spain, 2015. Available online: https://etsab.upc.edu/ca/escola/qualitat/vsma-titulacions/acreditacio2018/ex-mbarch/tfm-l5-notable-gp. pdf (accessed on 30 September 2017). 30. Home Depot. Patio Heaters [Online]. 2017. Available online: https://buenosybaratos.es/hogar-y-cocina/estufa-de-gas/la- mejor-estufa-de-gas-exterior/ (accessed on 15 June 2020). 31. Forcali Seta. ¿Cuáles son las Mejores Estufas de Gas Exterior? [Online]. 2017. Available online: https://buenosybaratos.es/hogar- y-cocina/estufa-de-gas/la-mejor-estufa-de-gas-exterior/ (accessed on 15 June 2020). 32. Media Market. Estufa Eléctrica de Baño Orbegozo BB4000 750W, 1 Barra de Cuarzo [Online]. 2017. Available online: https: //tiendas.mediamarkt.es/p/estufa-electrica-de-bano-orbegozo-bb-4-1178399 (accessed on 15 June 2020). 33. IDAE (Instituto para la Diversificación y Ahorro de la Energía). Ahorro y Eficiencia Energética en Climatización: Guía Técnica Condiciones Climáticas Exteriores de Proyecto. 2010. Available online: https://www.idae.es/tecnologias/eficiencia-energetica/ edificacion/reglamento-de-instalaciones-termicas-de-los-0/ (accessed on 30 September 2017). 34. Código Técnico de la Edificación, CTE. Ley 38/1999 de 5 de Noviembre, de ORDENACIÓN de la Edificación (LOE). Gobierno de España. 2006. Available online: https://www.codigotecnico.org (accessed on 31 December 2019). 35. Nakano, J.; Tanabe, S.-I. Thermal Adaptation and Comfort Zones in Urban Semi-Outdoor Environments. Front. Built Environ. 2020, 6.[CrossRef] 36. American Society of Heating, Refrigerating, and Air-Conditioning Engineers [ASHRAE]. ANSI/ASHRAE Standard 55-2017: Thermal Environmental Conditions for Human Occupancy; American Society: Peachtree Corners, GA, USA, 2017. 37. Nikolopoulou, M.; Lykoudis, S. Thermal comfort in outdoor urban spaces: Analysis across different European countries. Build. Environ. 2006, 41, 1455–1470. [CrossRef] 38. Open Data BCN. Available online: https://opendata-ajuntament.barcelona.cat/data/es/dataset/terrasses-comercos-vigents/ resource/cc7963b4-e3c9-461d-88a3-0f7ba0b0f46f (accessed on 31 December 2020). 39. Karakounos, I.; Dimoudi, A.; Zoras, S. The influence of bioclimatic urban redevelopment on outdoor thermal comfort. Energy Build. 2018, 158, 1266–1274. [CrossRef] 40. Spagnolo, J.; De Dear, R. A field study of thermal comfort in outdoor and semi-outdoor environments in subtropical Sydney Australia. Build. Environ. 2003, 38, 721–738. [CrossRef]