applied sciences

Article Environmental Comfort as a Sustainable Strategy for Housing Integration: The AURA 1.0 Prototype for Social Housing

Álvaro López-Escamilla 1 , Rafael Herrera-Limones 1,* , Ángel Luis León-Rodríguez 1 and Miguel Torres-García 2

1 Instituto Universitario de Arquitectura y Ciencias de la Construcción, Escuela Técnica Superior de Arquitectura, Universidad de Sevilla, Av. Reina Mercedes 2, 41012 Seville, Spain; [email protected] (Á.L.-E.); [email protected] (Á.L.L.-R.) 2 Departamento de Ingeniería Energética. E.T.S. de Ingeniería, Universidad de Sevilla, Camino de los Descubrimientos, s/n, 41092 Seville, Spain; [email protected] * Correspondence: [email protected]; Tel.: +34-954-55-98-93



Received: 21 September 2020; Accepted: 29 October 2020; Published: 31 October 2020


Abstract: The AURA 1.0 prototype is a sustainable social housing proposal, designed by the University of Seville and built for the first Latin American edition of the prestigious Solar Decathlon competition. Different conditioning strategies were integrated into this prototype, optimized for a tropical climate, and focused on contributing positively to the health of the most humble people in society. In this moment, in which a large part of the world population is confined to their homes due to the Covid-19 pandemic, we have the opportunity (and the obligation) to reconsider the relationship between architecture and medicine or in other words, between the daily human habitat and health. For this reason, this analysis of aspects derived from the interior conditioning of the homes is carried out. The main objective of the Aura proposal is to be able to extract data through a housing monitoring system, which allows us to transfer some design strategies to the society to which is a case study, in order to promote environmental comfort and, therefore, people’s health. The AURA 1.0 prototype develops flexible and adaptable living spaces, with a high environmental quality, in order to maintain the variables of temperature, relative humidity and natural lighting within a range of comfort required by the rules of the event. To achieve this end, the prototype develops an architectural proposal that combines passive and active conditioning strategies, using construction qualities and typical costs of social housing. These strategies allowed the project to achieve the first prize in the Comfort Conditions test. So, this paper presents an appropriate and tested solution that can satisfy comfortability and health of residents who live in social housing while maintaining low energy consumption.

Keywords: architecture; sustainability; solar decathlon; comfort; health; environment; prototype; indoor conditioning; daylight factor; monitoring; building

1. Introduction The Solar Decathlon Competition is the most prestigious international university competition on sustainable habitat, originally sponsored by the U.S. Department of Energy. Universities from all over the world participate in it, in collaboration with institutions and private companies, with the aim of designing, building, and monitoring a prototype of a housing cell with the highest level of self-sufficiency and use of renewable energies. This prototype will fulfill its double function: on the one hand, it will be a pavilion that can be visited, and on the other, a cell that can be monitored and technically measured [1].

Appl. Sci. 2020, 10, 7734; doi:10.3390/app10217734 www.mdpi.com/journal/applsci Appl. Sci. 2020, 10, 7734 2 of 21

However, this is not the only purpose of the competition. Throughout the entire process, students (undergraduate, master or PhD), tutored by teachers and researchers [2–5], develop ten tests—hence the name decathlon—apparently as diverse as: Sustainability, Innovation, Communication, Housing Operation, Social Relevance, Architecture, Engineering and Construction, Energy Balance, Comfort Conditions, Energy Efficiency [6,7]. The main stage of the competition takes place in the two weeks that make up the final phase, when different prototypes are evaluated in the “Solar City”, the venue proposed by the Organization. However, what is really relevant is the learning process through the resolution of a project (urban and social) from which, finally, the aforementioned archetype of sustainable habitat is extracted, in order to be tested with scientific and humanistic parameters. The version of the competition, Solar Decathlon Latin America and Caribbean 2015 (Cali, Colombia), to which the prototype presented in this article was submitted, unlike previous editions [8–13], was given a social approach, which allowed researching on other architectural typologies and sustainable-healthy construction solutions, where the transfer to society of the environmental strategies implemented in these prototypes gained special relevance. The objective was no longer to present a housing cell where excellent comfort conditions and minimum energy consumption were achieved on the basis of technology decontextualized socioeconomically from the society where the competition was held [14]. The time had come to design a prototype of low-energy consumption housing for vulnerable society sectors, focused, therefore, on working under the concept of energy poverty [15], which is in many cases responsible for not allowing to achieve minimum conditions of comfort and healthiness of domestic space [16]. Although comfort conditions in the human environment (temperature, humidity, lighting, air quality, etc.) do not always have a direct impact on the health of the user [17], it is usually understood that optimum comfort conditions in buildings do have direct consequences on human health [18–20]. For this reason, in this article, the monitoring strategy [21–23] used in the prototype is considered a fundamental part of the project and aimed at collecting data on the indicators that, traditionally, scientifically constitutes the comfort parameters [24,25]: temperature, humidity, and lighting [26]. Because these data are considered indicative needed to assess the environmental quality of the prototype [27–29] and to indicate where to direct efforts in future versions it improved in subsequent investigations [30,31]. Therefore, considering a space-temporal context, this article belongs to the Solar Decathlon edition that was held in Santiago de Cali (Colombia) in December 2015, in which many Latin American and European universities participated, in addition to the local ones (Table1). The Solar City is open to the teams 10 days before the start of the competition, so the prototypes have to be assembled during this period, and is undoubtedly one of the challenges of the competition [32]. Each team will have to design the construction process of its prototype, so that it can be assembled in the estimated time, we are talking about prefabricated architecture (Figure1).

Table 1. Teams participating in first Solar Decathlon in Latin America.

Project University Country La CasaUruguaya ORT University Uruguay Casa ALERO Pontifical Javerian University of Cali and ICESI University Colombia AURA University of Seville and University of Santiago de Cali Spain + Colombia unSOLAR National University of Colombia - Medellin Campus Colombia SMART Technology University of Panama and Western New England University Panama + USA KUXTAL Monterrey Institute of Technology and Higher Studies, Queretaro Campus Mexico MIHOUSE San Buenaventura University and Autonomous Occident University Colombia AYNI National University of Engineering of Peru Peru HABITEC La Salle University and University of Applied Sciences East Westphalia-Lippe Colombia-Germany +HUERTO +CASA University of the Andes Colombia VRISSA Seine Valley of the Cauca Colombia PEI Pontifical Javerian University of Bogotá Colombia YARUMO Pontifical Bolivarian University - Medellín Colombia SOL_ID London Metropolitan University UK Appl. Sci. 2020, 10, x 3 of 22

+HUERTO University of the Andes Colombia +CASA VRISSA Seine Valley of the Cauca Colombia PEI Pontifical Javerian University of Bogotá Colombia YARUMO Pontifical Bolivarian University - Medellín Colombia SOL_ID London Metropolitan University UK

The Solar City is open to the teams 10 days before the start of the competition, so the prototypes have to be assembled during this period, and is undoubtedly one of the challenges of the competition

Appl.[32]. Sci.Each2020 team, 10, 7734 will have to design the construction process of its prototype, so that it can3 of be 21 assembled in the estimated time, we are talking about prefabricated architecture (Figure 1).

Figure 1. ImageImage of of the the prototyp prototypee assembly process.

In this edition, the first first one held in Latin America, the objective was to propose a social housing model that would be the result of a previous urban project with a high buildi buildingng density. As indicated above, all the prototypes submitted to the competitio competitionn and built at a 1:1 scale in the Solar City were evaluated based based on on 10 10 tests tests (Table (Table 22).). As As it it can can be be seen, seen, some some were were evaluated evaluated by by a ajury jury of of experts experts in thein the field field and and others, others, from from data data obtained obtained from from monitoring monitoring environmental environmental and and energy energy conditions: temperature, background noisenoise level,level, illuminance,illuminance, electricity,electricity, waterwater consumption,consumption, etc.etc. The team led by the University of Seville, which presented the AURA 1.0 prototype, was the winner of theTable “Comfort 2. Analysis Conditions” of the 10 contests test [33 ].of Thethe Competitio main purposen: summary of this table article generated is, therefore, from the to SDLAC15 explain what conditioningCompetition strategies Rules, but were with implemented our own re-drafting. in this prototype, attempting to overcome the atmospheric conditions typical of the tropical climate that prevails in Santiago de Cali in December, in order to achieveCONTEST optimum interior comfort conditions,DESCRIPTION taking into account the parameters thatJUDGING influence the Measures interior conditions such as temperature, humidity, healthComfort of the inhabitant of the dwelling. The research focuses specifically on the Latin American acoustics, lighting and air quality to assess the sensation of Monitorig context,conditions in which the special geo-social conditions cause the criteria of passive solar architecture and use of “natural” resources to beinterior more important, comfort in due each to housing the high solution. rates of energy poverty present in most of these countries.Evaluates To achieve spatial this efficiency, end, the prototype the adequacy develops of the anmaterials architectural in proposal that combinesArchitecture passive andrelation active conditioningto bioclimatic strategies, strategies usingfor the construction future of social qualities housing and typicalJudges costs of social housing. in the context of Latin America and the Caribbean. Engineering Evaluates feasibility and adequate integration of the structural, Tableand 2. Analysiselectrical, of the 10 contestsplumbing of the and Competition: solar design summary and that table of the generated enclosure from for the SDLAC15Judges constructionCompetition Rules, but with our own re-drafting.low-cost social housing. Energy Evaluates suitable design of the dwelling’s systems to achieve a CONTEST DESCRIPTION JUDGINGMonitorig efficiency Measuresreduction interior conditions in energy such as consumption. temperature, humidity, acoustics, ElectricalComfort conditions Measureslighting the andlevel air qualityof electrical to assess theself-sufficiency sensation of interior of comfort the dwelling in each Monitorig housing solution. Monitorig balance throughEvaluates balancing spatial eelectricityfficiency, the adequacygeneration of the materialsand consumption. in relation to Architecture bioclimatic strategies for the future of social housing in the context of Latin Judges America and the Caribbean. Evaluates feasibility and adequate integration of the structural, electrical, Engineering and construction plumbing and solar design and that of the enclosure for low-cost social Judges housing. Evaluates suitable design of the dwelling’s systems to achieve a reduction in Energy efficiency Monitorig energy consumption. Measures the level of electrical self-sufficiency of the dwelling through Electrical balance Monitorig balancing electricity generation and consumption. Focused on reducing environmental impact in the long term. Evaluates Sustainability strategies to properly manage the topics of architecture, engineering and Judges construction, energy efficiency, urban design, and economic viability. Measures the efficiency and functionality of a set of applications to ensure Housing functionality Test normal functioning of the dwelling. Appl. Sci. 2020, 10, x 4 of 22

Focused on reducing environmental impact in the long term. Evaluates strategies to properly manage the topics of Sustainability Judges architecture, engineering and construction, energy efficiency, urban design, and economic viability. Housing Measures the efficiency and functionality of a set of applications Test functionality to ensure normal functioning of the dwelling. Evaluates the effectiveness and efficiency of marketing and Communicatio communications strategies to generate social awareness of the ns and Judges projects and the advantages of using sustainable buildings with a marketing solar energy supply. Urban design Promotes research into urban design with a density applicable to and the context of Latin America and the Caribbean to achieve an Judges affordability effective and innovative proposal based on low-cost housing. Evaluates the incorporation of creative solutions to improve Innovation Judges conventional levels of habitability.

The team led by the University of Seville, which presented the AURA 1.0 prototype, was the winnerAppl. Sci. of2020 the, 10 “Comfort, 7734 Conditions” test [33]. The main purpose of this article is, therefore, to explain4 of 21 what conditioning strategies were implemented in this prototype, attempting to overcome the atmospheric conditions typical of the tropical climate that prevails in Santiago de Cali in December, Table 2. Cont. in order to achieve optimum interior comfort conditions, taking into account the parameters that influence theCONTEST health of the inhabitant of the dwellin DESCRIPTIONg. The research focuses specifically JUDGINGon the Latin American context, in whichEvaluates the special the effectiveness geo-social and effi ciencyconditions of marketing cause and communications the criteria of passive solar Communications and marketing strategies to generate social awareness of the projects and the advantages of Judges architecture and use of “natural” resourcesusing sustainable to be buildings more with important, a solar energy due supply. to the high rates of energy Promotes research into urban design with a density applicable to the context povertyUrban designpresent and affinordability most ofof these Latin America countries. and the CaribbeanTo achieve to achieve this an e ffectiveend, andthe innovative prototype developsJudges an architectural proposal that combines passiveproposal and based active on low-cost conditioning housing. strategies, using construction Evaluates the incorporation of creative solutions to improve conventional Innovation Judges qualities and typical costs of social housing. levels of habitability.

2.2. Starting Starting Conditions Conditions InIn order order to to understand understand the conditioning strategiesstrategies implementedimplemented in in the the AURA AURA 1.0 1.0 prototype, prototype, first first of ofall, all, it isit necessary is necessary to analyze to analyze what thewhat comfort the comfort conditions conditions are and underare and what under ranges what the competitionranges the competitionscored the test scored [34], the so thattest we[34], can so understandthat we can atun whatderstand times at of what the daytimes and of underthe day what and strategiesunder what the strategies the prototype was scoring well and when it was not. prototype was scoring well and when it was not. However, on the other hand, it is necessary to analyze under which atmospheric conditions the However, on the other hand, it is necessary to analyze under which atmospheric conditions competition was being held, in order to put into context which were the external hygrothermal the competition was being held, in order to put into context which were the external hygrothermal variables that had to be overcome in order to keep the internal hygrothermal conditions in the optimal variables that had to be overcome in order to keep the internal hygrothermal conditions in the optimal scoring ranges (Figure 2). scoring ranges (Figure2).

Figure 2. Diagram of the used methodology. Figure 2. Diagram of the used methodology. 2.1. Comfort Condition Test in SD2015 2.1. Comfort Condition Test in SD2015 The comfort conditions test, a case study in this article, had a maximum score of 100 points, which were divided into 4 categories (Table3):

Table 3. Score of the “Comfort Conditions” test, taken from the competition rules.

Test Score Sub-Categories Score Description The interior temperature of the house was collected Temperature 50 continuously through 2 sensors. Relative During the days of competition, the relative humidity of the Comfort 20 100 Humidity different points of the prototype was recorded with 3 sensors Conditions Natural This parameter could be known through 1 lighting sensor 20 lighting strategically placed by the competition organization The organization carried out an acoustic test in isolation and at Acoustics 10 night, with the venue closed to the public.

Temperature: To obtain the maximum score, the interior temperature of the prototype must be kept within a range of 24 ◦C and 28 ◦C. However, reduced points can be obtained up to a tolerance of 2 ◦C above and below the established range (Table4). These reduced points were given on a proportional and linear basis between the highest and lowest scoring value. Appl. Sci. 2020, 10, 7734 5 of 21

Table 4. Sub-category score range.

Full Points T Temperature Tmax min ≤ ≤ Temperature Tmin 2 Temperature Tmax Tmin = 24 ◦C Reduced Points − ≤ ≤ T = 28 C T Temperature Tmax + 2 max ◦ min ≤ ≤ No Points Tmax + 2 Temperature T 2 ≤ ≤ min − Full Points Relative humidity 60% ≤ Relative Humidity Reduced points 60% < Relative humidity < 70% No points Relative humidity 70% ≥ Full Points 4% < Daylight Factor Natural lighting Reduced points 2.5% < Daylight Factor < 4% No points Daylight Factor < 2.5%

Relative humidity: To obtain the maximum score, the relative humidity of the prototype must always be kept below 60%. However, reduced points can be obtained if this humidity is between 60% and 70%. Natural lighting: To measure this parameter, a light sensor is placed in the living room, which must be at a height of 0.90 m and at least 2 m away from any window. All the points are obtained if the Daylight Factor is higher than 4%, and a reduced score is obtained if the Daylight Factor is between 4% and 2.5%. Below 2.5% no score is obtained. The reduced points, in the same way, were given in a proportional and linear way between the highest and lowest scoring value. Acoustic behavior: This subcategory is scored on the basic of two parameters, the acoustic insulation to the outside and the reverberation time in the living room (Table5). However, this sub-category would be illogical in the face of very open-to-the-outside architectures submitted to this edition of the competition, which were adjusted to tropical climate conditions.

Table 5. Score for the subcategory “Acoustic behavior”.

Full Points Acoustic value 42 dB ≥ Acoustic Value Reduced Points 30 dB < Acoustic value < 42 dB No Points Acoustic value < 30 dB Full Points Reverberation time 0.8 s ≤ Reverberation Time Reduced Points 0.8 s < Reverberation time < 1.2 s No Points Reverberation time > 1.2 s

2.2. Climatic Conditions of the Competition Location: Santiago de Cali (Colombia) The entire territory of Colombia has a tropical climate modified by altitude. This means that there are no great differences between the different seasons, the summers or winters are differentiated by the amount of received solar radiation. The city of Santiago de Cali is located in southwestern Colombia, in the valley between the western and central branches of the Colombian Andes, an area known as Valle del Cauca. The coordinates of Cali are latitude 3◦2700 N and longitude 76◦3200 W and it is 995 m above sea level (Figure3). In the humid tropical climate (also known as savanna climate according to the Koppen Climate Classification), the weather factors change suddenly. In comparison to temperate climates, the influence of direct radiation decreases while diffuse radiation increases. Rainfall is a very important element to take into account, as well as relative humidity, which is considered very high. Consequently, buildings need to be prepared to deal with diffuse light, as well as effective covers against rain and abundant solar radiation (Figure4). Appl.Appl. Sci. Sci. 2020 2020, ,10 10, ,x x 66 of of 22 22

TableTable 5. 5. Score Score for for the the subcategory subcategory “Acoustic “Acoustic behavior”. behavior”.

FullFull Points Points AcousticAcoustic value value ≥ ≥ 42 42 dB dB AcousticAcoustic Value Value ReducedReduced Points Points 3030 dB dB < < Acoustic Acoustic value value <42 <42 dB dB NoNo Points Points AcousticAcoustic value value <30 <30 dB dB FullFull Points Points ReverberationReverberation time time ≤ ≤ 0.8 0.8 s s ReverberationReverberation Time Time ReducedReduced Points Points 0.80.8 s s < < Reverberation Reverberation time time < < 1.2 1.2 s s NoNo Points Points ReverberationReverberation time time >1.2 >1.2 s s

2.2.2.2. Climatic Climatic Conditions Conditions of of the the Competit Competitionion Location: Location: Santiago Santiago de de Cali Cali (Colombia) (Colombia) TheThe entireentire territoryterritory ofof ColombiaColombia hashas aa tropicaltropical climateclimate modifiedmodified byby altitude.altitude. ThisThis meansmeans thatthat therethere areare nono greatgreat differencesdifferences betweenbetween thethe didifferentfferent seasons,seasons, thethe summerssummers oror winterswinters areare differentiateddifferentiated by by the the amount amount of of received received solar solar radiation. radiation. TheThe citycity ofof SantiagoSantiago dede CaliCali isis locatedlocated inin southwesternsouthwestern Colombia,Colombia, inin thethe valleyvalley betweenbetween thethe westernwestern andand centralcentral branchesbranches ofof thethe ColombianColombian Andes,Andes, anan areaarea knownknown asas ValleValle deldel Cauca.Cauca. TheThe coordinatescoordinates ofof CaliCali areare latitudelatitude 3°3° 27”27” NN andand longitudelongitude 76°76° 32”32” WW andand itit isis 995995 mm aboveabove seasea levellevel (Figure(Figure 3). 3). InIn the the humid humid tropical tropical climate climate (also (also known known as as savanna savanna climate climate according according to to the the Koppen Koppen Climate Climate Classification),Classification), thethe weatherweather factorsfactors changechange suddenly.suddenly. InIn comparisoncomparison toto temperatetemperate climates,climates, thethe influenceinfluence of of direct direct radiation radiation decreases decreases while while diffuse diffuse radiation radiation increases. increases. Rainfall Rainfall is is a a very very important important elementelement toto taketake intointo account,account, asas wellwell asas relarelativetive humidity,humidity, whichwhich isis consideredconsidered veryvery high.high. Consequently,Appl.Consequently, Sci. 2020, 10, buildings 7734buildings need need to to be be prepared prepared to to deal deal with with diffuse diffuse light, light, as as well well as as effective effective covers covers6 of 21 againstagainst rain rain and and abundant abundant solar solar radiation radiation (Figure (Figure 4). 4).

Figure 3. Location map of Santiago de Cali. FigureFigure 3. 3. LocationLocation map map of of Santiago Santiago de de Cali. Cali.

Figure 4. Average climatic values of Santiago de Cali. FigureFigure 4. 4. Average Average climatic climatic values values of of Santiago Santiago de de Cali. Cali. In this article, special importance is given to the atmospheric conditions which occurred during InIn this this article, article, special special importance importance is is given given to to the the atmospheric atmospheric conditions conditions which which occurred occurred during during the competition period, 4 15 December (Figures5 and6), and had to be counteracted in order to thethe competitioncompetition period,period, 44−−−1515 DecemberDecember (Figures(Figures 55 andand 6),6), andand hadhad toto bebe counteractedcounteracted inin orderorder toto achieve the comfort ranges imposed by the event’s organization. On the other hand, it is worth noting achieveachieve the the comfort comfort ranges ranges imposed imposed by by the the event’s event’s or organization.ganization. On On the the other other ha hand,nd, it it is is worth worth noting noting the absence of rainfall during these days. Dates are obtained by the network of measurement sensors thethe absence absence of of rainfall rainfall during during th theseese days. days. Dates Dates are are obtained obtained by by the the network network of of measurement measurement sensors sensors thatAppl. staSci. ff2020of, the10, x Solar Decathlon installed in outdoor spaces where the event was held. 7 of 22 thatthat staff staff of of the the Solar Solar Decathlon Decathlon installed installed in in outdoor outdoor spaces spaces where where the the event event was was held. held.

Figure 5. Hygrothermal data in Santiago de Cali, 4–15 December. Source: Solar Decathlon staff. staff.

Figure 6. Lighting data in Santiago de Cali, December 4−15. Source: Solar Decathlon staff.

3. Case Study: AURA Project The development of AURA Project [35] aims to unite both ends of the Latin American reality: the American and the Southern European. They are both sides of the same coin, not only in architecture but also in lifestyle; they both inhabit what could be called the “architecture of warm countries” [36]. Social housing generally has two weaknesses: Firstly, when it is built as a low-cost house, frequently the comfort conditions do not reach the minimum levels, this is due to a low quality design where there is a reduction of the spaces, or by the use of low quality materials, by the bad quality of the carpentry, little efficient isolations, etc. However, we have to add that the inhabitants of these houses are people and families in a situation of economic vulnerability, so that in most cases they cannot use air conditioning equipment to alleviate the bad conditions of comfort because they cannot face the economic outlay that this implies, we are talking about energy poverty. Therefore, when we talk about sustainable social housing, we refer to an architecture where the maximum comfort of the inhabitants is sought with the least possible energy consumption, that is, that the house itself is placed as much as possible within the comfort range, which is what we have quantified in this publication. When this is not possible, it is necessary to make use of air conditioning technology. Therefore, this paper argues that air conditioning equipment should be an integrated part of social housing, always focused on the energy self-supply of the home and aimed at alleviating peak atmospheric situations where passive strategies are not able to generate minimum comfort conditions. Appl. Sci. 2020, 10, x 7 of 22

Appl. Sci. 2020, 10, 7734 7 of 21 Figure 5. Hygrothermal data in Santiago de Cali, 4–15 December. Source: Solar Decathlon staff.

Figure 6. LightingLighting data data in in Santiago Santiago de de Cali, Cali, December December 4 −15.15. Source: Source: Solar Solar Decathlon Decathlon staff. staff . − 3.3. Case Case Study: Study: AURA AURA Project Project TheThe development development of of AURA AURA Project Project [35] [35] aims aims to to un uniteite both both ends ends of of the the Latin Latin American American reality: reality: thethe AmericanAmerican andand the the Southern Southern European. European. They They are both are sidesboth ofsides the sameof the coin, same not onlycoin, in not architecture only in architecturebut also in lifestyle; but also they in lifestyle; both inhabit they whatboth couldinhabit be what called could the “architecture be called the of “architecture warm countries” of warm [36]. countries”Social [36]. housing generally has two weaknesses: Firstly, when it is built as a low-cost house, frequentlySocial thehousing comfort generally conditions has do two not weaknesses: reach the minimum Firstly, levels,when thisit is is built due toas a a low low-cost quality house, design frequentlywhere there the is comfort a reduction conditions of the spaces, do not or reach by the the use minimum of low quality levels, materials,this is due by to thea low bad quality quality design of the wherecarpentry, there little is a ereductionfficient isolations, of the spaces, etc. However, or by the weuse have of low to addquality that materials, the inhabitants by the ofbad these quality houses of theare carpentry, people and little families efficient in a situationisolations, of etc. economic Howeve vulnerability,r, we have soto thatadd inthat most the casesinhabitants they cannot of these use housesair conditioning are people equipment and families to alleviatein a situation the bad of conditionseconomic vulnerability, of comfort because so that they in most cannot cases face they the cannoteconomic use outlayair conditioning that this implies, equipment we are to alleviate talking about the bad energy conditions poverty. of comfort because they cannot face theTherefore, economic when outlay we that talk this about imp sustainablelies, we are social talking housing, about energy we refer poverty. to an architecture where the maximumTherefore, comfort when of we the talk inhabitants about sustainable is sought social with thehousing, least possiblewe refer energyto an architecture consumption, where that the is, maximumthat the house comfort itself of is the placed inhabitants as much is as sought possible with within the least the comfortpossible range,energy which consumption, is what we that have is, thatquantified the house in this itself publication. is placed as much as possible within the comfort range, which is what we have quantifiedWhen in this this is publication. not possible, it is necessary to make use of air conditioning technology. Therefore, thisWhen paper this argues is not that possible, air conditioning it is necessary equipment to make should use of beair anconditioning integrated technology. part of social Therefore, housing, thisalways paper focused argues on that the air energy conditioning self-supply equipment of the home should and be aimed an integrated at alleviating part of peak social atmospheric housing, alwayssituations focused where on passive the energy strategies self-supply are not ableof the to home generate and minimum aimed at comfortalleviating conditions. peak atmospheric situationsTheAURA where 1.0passive prototype strate isgies an are appropriate not able to and generate tested solutionminimum that comfort can satisfy conditions. comfortability and health of residents who lives in social housing while maintaining low energy consumption.

3.1. Territorial Scale and Urban Scale—Master Plan The Project has to be explained from the three-dimensional mesh that holds all the services that the user needs to inhabit. This three-dimensional mesh is developed from the scale of the city, reaching the scale of the prototype/housing cell. At a territorial and urban level, a Master Plan is drawn up (Figure7) which, starting from the territorial scale (the city itself), ends up landing in the most optimum area of urban expansion and configuring an eco-neighborhood, made up of facilities, equipment, open areas, and residential buildings designed with passive solar parameters. Appl. Sci. 2020, 10, x 8 of 22

The AURA 1.0 prototype is an appropriate and tested solution that can satisfy comfortability and health of residents who lives in social housing while maintaining low energy consumption.

3.1. Territorial Scale and Urban Scale—Master Plan The Project has to be explained from the three-dimensional mesh that holds all the services that the user needs to inhabit. This three-dimensional mesh is developed from the scale of the city, reaching the scale of the prototype/housing cell. At a territorial and urban level, a Master Plan is drawn up (Figure 7) which, starting from the territorial scale (the city itself), ends up landing in the most optimum area of urban expansion and configuringAppl. Sci. 2020, 10an, 7734eco-neighborhood, made up of facilities, equipment, open areas, and residential8 of 21 buildings designed with passive solar parameters.

FigureFigure 7. 7. MasterMaster Plan. Plan.

InIn this this way, way, the the housing proposal proposal ends ends up up being being materialized materialized in in social social housing housing buildings, buildings, adaptedadapted to to the the climatic climatic conditions conditions of tropical climate.

3.2.3.2. Building Building Scale Scale FromFrom the researchresearch onon the the rehabilitation rehabilitation of of obsolete obsolete structures structures existing existing in Spain in Spain after after the real the estate real estatecrisis thatcrisis resulted that resulted in a large in a number large number of unfinished of unfinished buildings buildings throughout throughout the Spanish the Spanish territory, territory, the idea theof a idea three-dimensional of a three-dimensional mesh or network mesh or arises. network To this arises. end, To from this an end, urban from approach an urban to inhabit approach the city, to inhabitthe proposal the city, envisages the proposal the construction envisages of the this construc mesh astion a way of ofthis organizing mesh as thea way territory of organizing and its scales the territory(from the and general: its scales Master (from Plan; the to general: the particular: Master prototypePlan; to the built particular: in the Solar prototype City); and built it accumulatesin the Solar City);all the and technical, it accumulates service, andall the basic technical, structural service, aspects and for basic the exercise structural ofinhabiting. aspects for Itthe goes exercise from theof territory to the housing, passing through the neighborhood and the building. Thus, the main concept behind the building-scale project refers on its development in two phases, based on a system of progressive occupation from the mentioned main three-dimensional network (Figure8):

Phase 0 (initial): in this phase the community part of the building is configured. The three-dimensional • structural mesh that distributes the communications and the facilities throughout building. The entire structural and functional system is configured in this phase, forming a spatial grid, in which the communications are distributed horizontally and the installations vertically. This mesh will be the container of the habitable volumes, dimensions 9 9 x 3 m, where different homes will be installed. × Appl. Sci. 2020, 10, x 9 of 22

inhabiting. It goes from the territory to the housing, passing through the neighborhood and the building. Thus, the main concept behind the building-scale project refers on its development in two phases, based on a system of progressive occupation from the mentioned main three-dimensional network (Figure 8): • Phase 0 (initial): in this phase the community part of the building is configured. The three- dimensional structural mesh that distributes the communications and the facilities throughout building. The entire structural and functional system is configured in this phase, forming a Appl. Sci.spatial2020, 10grid,, 7734 in which the communications are distributed horizontally and the installations9 of 21 vertically. This mesh will be the container of the habitable volumes, dimensions 9 × 9 x 3 m, Phasewhere 1different (occupation): homes Self-construction, will be installed. simple construction systems are proposed, which can •• bePhase developed 1 (occupation): by the inhabitantsSelf-construction, of the simple building construction themselves, systems under are technical proposed, bases which previously can be defineddeveloped by architectsby the inhabitants and under of their the supervision. building themselves, under technical bases previously defined by architects and under their supervision.

Figure 8. Decantation process from the collective buildingbuilding to the prototypeprototype inin thethe SolarSolar City.City.

AA systemsystem of of porticoes porticoes is formedis formed by panelsby panels that actthat as act prefabricated as prefabricated reinforced reinforced concrete concrete load-bearing load- walls,bearing to walls, avoid to seismic avoid loads seismic on loads the building, on the building, this being this braced being with braced plates with made plates of themade same of the material same tomaterial form the to form floor the slabfloor ofthe the slab diff oferent the floors.different This floors. main This network main network is complemented is complemented by a vertical by a communicationvertical communication system, system, which includeswhich includes facilities facili andties communication and communication cores, cores, in order in order to obtain to obtain the highestthe highest possible possible level level of accessibility of accessibility in height. in height. AsAs forfor thethe facilities,facilities, itit isis expectedexpected thatthat theythey willwill bebe integratedintegrated intointo thethe three-dimensionalthree-dimensional mesh, soso thethe di differentfferent networks networks will will be be led led to theto pointsthe points of attachment of attachment in the in access the access to the house.to the house. It is a system, It is a therefore,system, therefore, where all where its parts all areits configuredparts are configured from industrialized from industrialized elements, providingelements, providing quality assurance quality toassurance the technique to the oftechnique self-construction, of self-construction, so deeply rooted so deeply in the rooted humblest in the strata humb oflest Santiago strata de of Cali.Santiago de Cali.This is due to the fact that industrialization is a rational and automated production process, whichThis involves is due advancedto the fact designs that industrialization of production, is manufacturing, a rational and andautomated management production technologies, process, wherewhich materials,involves transport,advanced anddesigns mechanized of production techniques, manufacturing, are used in series and with management the aim of achievingtechnologies, the highestwhere materials, possible productivity transport, and [37 mechanized–40]. techniques are used in series with the aim of achieving the highestThe industrial possible manufacturing productivity [37–40]. process generates higher quality end products, shorter delivery times,The more industrial flexibility, manufacturing safer working process conditions, generates waste higher minimization, quality moreend products, possibilities shorter for reuse delivery and, consequently,times, more flexibility, greater respect safer forworking the environment conditions, [ 41waste,42]. minimization, more possibilities for reuse and, consequently, greater respect for the environment [41,42]. 3.3. Housing Scale—Architectural Concept 3.3. HousingThe housing Scale—Architectural cell was formed Concept based on a set of architectural concepts that arise from the need to respond to a social housing solution in a Latin American context: The housing cell was formed based on a set of architectural concepts that arise from the need to respondDwelling to a decompactionsocial housing solution in a Latin American context: • • DwellingIt is understood decompaction that the concept of traditional compact housing must be fragmented, thus appearing the transition spaces between the different functional pieces (Figure9). The relevance of these spaces becomes clear to the extent that they create new uses not foreseen in the home or that they give rise to situations that help promote the functional flexibility of the dwelling. This contributes to the following concept: perfectibility. Appl. Sci. 2020, 10, x 10 of 22

It is understood that the concept of traditional compact housing must be fragmented, thus appearing the transition spaces between the different functional pieces (Figure 9). The relevance of these spaces becomes clear to the extent that they create new uses not foreseen in the home or that Appl.they Sci.Appl.give2020 Sci. rise,202010, , 7734 10to, x situations that help promote the functional flexibility of the dwelling.10 of 2210 This of 21 contributes to the following concept: perfectibility. It is understood that the concept of traditional compact housing must be fragmented, thus appearing the transition spaces between the different functional pieces (Figure 9). The relevance of these spaces becomes clear to the extent that they create new uses not foreseen in the home or that they give rise to situations that help promote the functional flexibility of the dwelling. This contributes to the following concept: perfectibility.

Figure 9. Scheme adaptable spaces that make housing: 1.Access, 2.Hallway, 3.Living room, 4.Kitchen, Figure 9. Scheme adaptable spaces that make housing: 1.Access, 2.Hallway, 3.Living room, 4.Kitchen, 5.Use nº1, 6.Use nº2, 7.Bathroom, 8.Use8.Use nº3.nº3. Figure 9. Scheme adaptable spaces that make housing: 1.Access, 2.Hallway, 3.Living room, 4.Kitchen, 5.Use nº1, 6.Use nº2, 7.Bathroom, 8.Use nº3. • ProgressivityProgressivity and and adaptability adaptability • •By understanding,Progressivity and inadaptability the social context in which this project is located, the difficulty difficulty of a family to completelyBy understanding, occupy one in of the the social housing context volumes in which that this make project up is thelocated, collective the difficulty building, of a afamily process of progressiveto completely occupationoccupation occupy ofof one thisthis of spacespacethe housing isis programmedprogrammed volumes that (Figure(Figure make up 1010). ).the collective building, a process of progressiveOnce the occupation house is completed,of this space isyou programmed will have (Figure the 10). option to improveimprove/perfect/perfect it with the implementationOnce the of house active is air completed, conditioningconditioning you elementswill have that the contributeoption to toimprove/perfect maintain an optimaloptimalit with the thermalthermal comfort,implementation or others in of order active to air give conditioning a better answer elements to that the contributeproblems tothat maintain every family an optimal faces. thermal Therefore, Therefore, the housingcomfort, or is others progressively in order to improved give a better over answer time to and the problemsthe family that could could every increase increasefamily faces. its its Therefore,“social “social status” status” the housing is progressively improved over time and the family could increase its “social status” without being forcedforced toto move.move. without being forced to move.

FigureFigure 10. 10.Diagram Diagram ofof housing space space occupation occupation phases. phases. Figure 10. Diagram of housing space occupation phases. Equipped furniture • Following the concept of the disintegration of the house, it shapes its different interior spaces based on the layout of the furniture, which will mutate its position and shape depending on the Appl. Sci. 2020, 10, x 11 of 22

Appl. Sci.• 2020Equipped, 10, 7734 furniture 11 of 21 Following the concept of the disintegration of the house, it shapes its different interior spaces differentbased needs on the that layout arise of inthe the furniture, house which throughout will mutate the day.its position On the and other shape hand, depending it will on also the have the functiondifferent ofneeds providing that arise di infferent the house services throughout to the house:the day. conditioningOn the other hand, installations, it will also solar have chimney, the function of providing different services to the house: conditioning installations, solar chimney, electrical installation, etc. (Figure 11).Therefore, a new level of flexibility is provided within the home electrical installation, etc. (Figure 11).Therefore, a new level of flexibility is provided within the home accordingaccording to the to needsthe needs of itsof its inhabitants. inhabitants.

FigureFigure 11. 11.Interior Interior photos photos of of the the prototype: prototype: mobile mobile furniture furniture and and folding folding bed. bed.

• Hallway Hallway • AURA 1.0 Project introduces a new element to social housing with the aim of providing AURAadditional 1.0 values Project to introduces the minimu am new housing element module to social (Figure housing 12): with the aim of providing additional values to the minimum housing module (Figure 12): a. Ventilation: The “hallway” module works as a bioclimatic dumper between homes, which a. Ventilation:guarantees cross The ventilation “hallway” in modulethe home, workstaking advantage as a bioclimatic of the benefits dumper of the between city climate, homes, whichwhich guarantees provides a pleasant cross ventilation breeze every in day the at home, sunset. taking This air advantage movement ofcontributes the benefits to increase of the city climate,the feeling which of providesthermal comfort a pleasant in the breeze house. every day at sunset. This air movement contributes to b.increase Lighting: the It feeling works ofas thermal a transition comfort space in between the house. the exterior and the interior of the house, obtaining a graduated light from the gallery of collective access to the interior of the house. The b. Lighting: It works as a transition space between the exterior and the interior of the house, “hallway” module, provided with openings to the outside, allows the light to be filtered and obtainingdimmed, a contributing graduated to light obtaining from quality the gallery and comf of collectiveortable lighting access in tothe the interior interior spaces of for the the house. Thedevelopment “hallway” module,of the different provided domestic with activities openings (Figure to the 13). outside, allows the light to be filtered and c.dimmed, Noise: contributingThis element toworks obtaining as an quality acoustic and damper comfortable between lighting adjoining in the houses. interior Due spaces to its for the developmentconfiguration, of this the dispacefferent allows domestic each home activities to have (Figure four exterior 13). facades, which improves the c. Noise:acoustic This behavior element of each works one asof them. an acoustic damper between adjoining houses. Due to its d.configuration, Health: This is this the spaceorgan on allows which each the rest home of th toe haveconditioning four exterior strategies facades, are based, which contributing, improves the acousticon the behaviorone hand, of to eachthe physical one of them.health of the inhabitant by achieving optimum hygrothermal and lighting values; and on the other, to mental health, integrating “the street”, urbanity and d. Health: This is the organ on which the rest of the conditioning strategies are based, contributing, territory inside the home. We are facing a society very used to interacting with the environment, onso the that one suppressing hand, to the this physical component health of the of hous theing inhabitant cell would by cause achieving a sense optimum of bewilderment hygrothermal of andthe lighting individual values; that could andon lead the to other,pathology. to mental It is an health, extension integrating of the house, “the a street”,kind of a urbanity covered and territorybut open inside space the that home. allows We the are promotion facing a society of neig veryhborhood used relations, to interacting losing with its border the environment, status sobetween that suppressing the public thisand componentthe private, the of theindividual housing and cell the would collective. cause a sense of bewilderment of the individual that could lead to pathology. It is an extension of the house, a kind of a covered but open space that allows the promotion of neighborhood relations, losing its border status between the public and the private, the individual and the collective. Appl. Sci. 2020, 10, x 12 of 22

FigureFigure 12. Photo12. Photo of of the the hallway hallway as seen seen from from inside inside the theprototype. prototype.

Figure 13. Photo of the entrance hall and access to the prototype.

3.4. Housing Scale—Conditioning Strategies Having analyzed the climate of Santiago de Cali, characterized by high temperatures in certain times of the day, high humidity, torrential rain likelihood, and a breeze at sunset, the team responsible for carrying out the AURA 1.0 Project understood that in order to reach the comfort levels that the event organizers had set as a target, both passive and active conditioning strategies would have to be implemented [43]. It was understood that the inclusion of an air conditioning in the design, fed with the energy generated by the house through the photovoltaic solar installation on the roof of the prototype, would be necessary to counteract both the maximum temperature peaks and the high relative humidity of the place (Figure 14). In addition, two ceiling fans were installed to encourage air movement inside the house. It is therefore important to emphasize that among the minimum equipment required to provide social housing, in this case in a tropical climate, with minimum living conditions, there are the air conditioning. Most of the regulations on social housing in different countries detail minimum construction qualities or the size of the spaces. However, in order to guarantee the health of the inhabitant, it is necessary to provide the housing with active air conditioning systems wherever the climatic conditions do not allow maintaining optimum comfort conditions continuously over time. Appl. Sci. 2020, 10, x 12 of 22

Appl. Sci. 2020, 10, 7734 12 of 21 Figure 12. Photo of the hallway as seen from inside the prototype.

Figure 13. Photo of the entrance hall an andd access to the prototype.

3.4. Housing Scale—Conditioning Strategies Having analyzed the climate of Santiago de Cali, characterized by high temperatures in certain times ofof the the day, day, high high humidity, humidity, torrential torrential rain likelihood,rain likelihood, and abreeze and a at breeze sunset, at the sunset, team responsible the team forresponsible carrying for out carrying the AURA out the 1.0 ProjectAURA 1.0 understood Project unde thatrstood in order that to in reach order the to reach comfort the levelscomfort that levels the eventthat the organizers event organizers had set as had a target, set as botha target, passive both and passive active and conditioning active conditioning strategies wouldstrategies have would to be implementedhave to be implemented [43]. [43]. It was understood that the inclusion of an air conditioning in the design, fed with the energy generated byby thethe househouse throughthrough the the photovoltaic photovoltaic solar solar installation installation on on the the roof roof of of the the prototype, prototype, would would be necessarybe necessary to to counteract counteract both both the the maximum maximum temperature temperature peaks peaks and and the the highhigh relativerelative humidityhumidity of the place (Figure 1414).). In addition, two ceiling fans were installed to encourage air movement inside Appl.the Sci. house. 2020, 10, x 13 of 22 It is therefore important to emphasize that among the minimum equipment required to provide social housing, in this case in a tropical climate, with minimum living conditions, there are the air conditioning. Most of the regulations on social housing in different countries detail minimum construction qualities or the size of the spaces. However, in order to guarantee the health of the inhabitant, it is necessary to provide the housing with active air conditioning systems wherever the climatic conditions do not allow maintaining optimum comfort conditions continuously over time.

FigureFigure 14. 14. SchemeScheme about about generation generation and and energy energy consumption. consumption.

OnIt isthe therefore other hand, important a series to of emphasize passive conditio that amongning the strategies minimum are equipment implemented, required which to would provide contributesocial housing, both to inhygrothermal this case in comfort a tropical and climate, a reduction with in minimum energy consumption living conditions, by the refrigeration there are the equipment:air conditioning. Most of the regulations on social housing in different countries detail minimum construction qualities or the size of the spaces. However, in order to guarantee the health of the • inhabitant,Ventilated it facade—South is necessary to elevation provide the housing with active air conditioning systems wherever the climaticAn outer conditions skin was do designed not allow for maintaining the south optimumelevation comfortof the collective conditions building, continuously so that over it would time. contribute to unifying the image of the proposal and guarantee the safety of the users-inhabitants during the self-construction phase in which not all the plots of the three-dimensional mesh (collective building) would be occupied at the same time. This would provide a certain guarantee of safety, playing the role of a skin on the building, so that the common areas can be used effectively and guaranteeing the safe self-construction of each home (Figure 15). This outer skin is light and permeable, designed with wild cane framed (Arundodonax) in a wooden perimeter, it works as a filter absorbing direct sunlight, but allowing air to pass through, besides being an answer to the important problem of dust in the city breeze. The orientation of the wild cane is horizontal and the exterior carpentry elements are integrated into the established modulation. This envelope is supported by a modulated and visible metal structure of metal profiles, which form both the ventilated facade and the roof of the building. These profiles of the envelope generate an asymmetric sloping roof, which provides the necessary slope to drain the water in episodes of heavy rain (Figure 16).

Figure 15. Photo of the south-east facade. Appl. Sci. 2020, 10, x 13 of 22

Figure 14. Scheme about generation and energy consumption.

On the other hand, a series of passive conditioning strategies are implemented, which would contribute both to hygrothermal comfort and a reduction in energy consumption by the refrigeration equipment: • Ventilated facade—South elevation An outer skin was designed for the south elevation of the collective building, so that it would Appl. Sci. 2020, 10, 7734 13 of 21 contribute to unifying the image of the proposal and guarantee the safety of the users-inhabitants during the self-construction phase in which not all the plots of the three-dimensional mesh (collective building)On the would other be hand, occupied a series at ofthe passive same time. conditioning This would strategies provide are a implemented,certain guarantee which of wouldsafety, playingcontribute the bothrole of to a hygrothermalskin on the building, comfort so andthat athe reduction common areas in energy can be consumption used effectively by and the guaranteeingrefrigeration equipment:the safe self-construction of each home (Figure 15). This outer skin is light and permeable, designed with wild cane framed (Arundodonax) in a Ventilated facade—South elevation wooden• perimeter, it works as a filter absorbing direct sunlight, but allowing air to pass through, besidesAn being outer an skin answer was designed to the important for the south problem elevation of dust of in the the collective city breeze. building, The orientation so that itwould of the wildcontribute cane tois unifyinghorizontal the imageand the of theexterior proposal carpen andtry guarantee elements the are safety integrated of the users-inhabitants into the established during modulation.the self-construction phase in which not all the plots of the three-dimensional mesh (collective building) wouldThis be occupiedenvelope atis thesupported same time. by a This modulated would provideand visible a certain metal guarantee structure ofof safety, metal playingprofiles, the which role formof a skin both on the the ventilated building, facade so that and the commonthe roof of areas the building. can be used These effectively profiles and of the guaranteeing envelope generate the safe anself-construction asymmetric sloping of each roof, home which (Figure provides 15). the necessary slope to drain the water in episodes of heavy rain (Figure 16).

Figure 15. Photo of the south-east facade.

This outer skin is light and permeable, designed with wild cane framed (Arundodonax) in a wooden perimeter, it works as a filter absorbing direct sunlight, but allowing air to pass through, besides being an answer to the important problem of dust in the city breeze. The orientation of the wild cane is horizontal and the exterior carpentry elements are integrated into the established modulation. This envelope is supported by a modulated and visible metal structure of metal profiles, which form both the ventilated facade and the roof of the building. These profiles of the envelope generate an asymmetric sloping roof, which provides the necessary slope to drain the water in episodes of heavy rainAppl. (FigureSci. 2020, 1610,). x 14 of 22

Figure 16.16. Photo of the north-east facade.

• EnclosuresEnclosures with with low low thermal thermal inertia inertia • Given the climate of Santiago de Cali, the absenceabsence of thermal inertia in the enclosure panels was chosen, since it was understood that this would be counterproductive in maintaining optimal thermal conditions insideinside thethe prototypeprototype (Figure(Figure 1717).).

Figure 17. Exterior facade without thermal inertia.

• Solar chimney Taking advantage of the solar radiation of the place where the event was held, a solar chimney was installed, which helped to evacuate the warmer air from inside the house, thus favoring both air movement and air renewal. • Sunlight Reflector Using a solar reflector, included in the structure of the ventilated facade, the sunlight is directed towards the interior of the house, bouncing it off the roof and thus achieving optimum diffused lighting. The warm colors used in the ceiling and interior walls also contribute to this (Figure 18). Appl. Sci. 2020, 10, x 14 of 22

Figure 16. Photo of the north-east facade.

• Enclosures with low thermal inertia Given the climate of Santiago de Cali, the absence of thermal inertia in the enclosure panels was Appl.chosen, Sci. 2020since, 10 it, 7734was understood that this would be counterproductive in maintaining optimal thermal14 of 21 conditions inside the prototype (Figure 17).

FigureFigure 17.17. Exterior facade withoutwithout thermal inertia.inertia.

• Solar chimney Solar chimney • Taking advantage of the solar radiation of the place where the event was held, a solar chimney Taking advantage of the solar radiation of the place where the event was held, a solar chimney was installed, which helped to evacuate the warmer air from inside the house, thus favoring both air was installed, which helped to evacuate the warmer air from inside the house, thus favoring both air movement and air renewal. movement and air renewal. • Sunlight Reflector Sunlight Reflector • Using a solar reflector, included in the structure of the ventilated facade, the sunlight is directed Using a solar reflector, included in the structure of the ventilated facade, the sunlight is directed towards the interior of the house, bouncing it off the roof and thus achieving optimum diffused towards the interior of the house, bouncing it off the roof and thus achieving optimum diffused lighting. lighting. The warm colors used in the ceiling and interior walls also contribute to this (Figure 18). TheAppl. warmSci. 2020 colors, 10, x used in the ceiling and interior walls also contribute to this (Figure 18). 15 of 22

Figure 18. Image of one of the solar reflectors. Figure 18. Image of one of the solar reflectors.

4. Environmental Behavior of the Prototype Although the AURA 1.0 Project won 3rd prize in the overall classification (adding up 10 tests) of the competition, in the specific “Comfort Conditions” test it managed to be the prototype that obtained the best results, thanks to the combination of active and passive conditioning strategies (Figure 19).

Figure 19. Graph of results by teams of the “Comfort Conditions” test.

To evaluate the comfort conditions in each prototype, the judges installed several Printed Circuit Boards (PCB) in different rooms of each prototype (Figure 20). Those PCB contained the components to obtain the temperature, relative humidity, and lighting data. Each prototype that participated in the competition was monitored uninterruptedly for 10 days [44,45], 2 sensors were placed in each of them from which temperature data were obtained, 1 sensor where data was collected exclusively on relative humidity, and 1 sensor that provided the levels of natural lighting inside the house. Appl. Sci. 2020, 10, x 15 of 22

Appl. Sci. 2020, 10, 7734 Figure 18. Image of one of the solar reflectors. 15 of 21

4. Environmental Behavior of the Prototype 4. Environmental Behavior of the Prototype Although the AURA 1.0 Project won 3rd prize in the overall classification (adding up 10 tests) of theAlthough competition, the AURA in the 1.0 specific Project “Comfort won 3rd prizeCond initions” the overall test it classificationmanaged to (addingbe the prototype up 10 tests) that of theobtained competition, the best in results, the specific thanks “Comfort to the Conditions”combination test of itactive managed and topassive be the prototypeconditioning that strategies obtained the(Figure best 19). results, thanks to the combination of active and passive conditioning strategies (Figure 19).

Figure 19. Graph of results by teams of the “Comfort Conditions” test.

To evaluateevaluate thethe comfort conditions inin each prototype, the judges installed several Printed Circuit Boards (PCB) in didifferentfferent roomsrooms ofof eacheach prototypeprototype (Figure(Figure 2020).). Those PCB contained the components to obtainobtain thethe temperature,temperature, relativerelative humidity,humidity, andand lightinglighting data.data. Each prototype prototype that that participated participated in the in compet the competitionition was monitored was monitored uninterruptedly uninterruptedly for 10 days for 10[44,45], days 2[44 sensors,45], 2 sensorswere placed were in placed each of in them each offrom them which from temperature which temperature data were data obtained, were obtained, 1 sensor 1where sensor data where was data collected was collectedexclusively exclusively on relative on hu relativemidity, humidity, and 1 sensor and 1that sensor provided that provided the levels the of levelsnatural of lighting natural inside lighting the inside house. the house. These sensors were placed on the same criteria in all homes: the sensor for the measurement of natural lighting must be located more than 2 m from any window, two combined sensors (temperature + humidity) were placed in the living room and a bedroom; and finally, a sensor inAppl. the Sci. kitchen 2020, 10 is, x responsible for measuring relative humidity in this area of the housing. 16 of 22

Figure 20. Sensors for monitoring housing.

FocusingThese sensors on the were AURA placed 1.0 prototype,on the same Figure criteria 21 inshow all homes: the location the sensor of this for PCB: the measurement of natural lighting must be located more than 2 m from any window, two combined sensors (temperature + humidity) were placed in the living room and a bedroom; and finally, a sensor in the kitchen is responsible for measuring relative humidity in this area of the housing. Focusing on the AURA 1.0 prototype, Figure 21 show the location of this PCB:

Figure 21. Prototype plant and measurement points.

4.1. Hygrothermal Data The hygrothermal data extracted from the monitoring of the prototype (Figure 22) show us that in relation to relative humidity, the results were very good, with the graph being below 60% most of the time. Appl. Sci. 2020, 10, x 16 of 22

Figure 20. Sensors for monitoring housing.

These sensors were placed on the same criteria in all homes: the sensor for the measurement of natural lighting must be located more than 2 m from any window, two combined sensors (temperature + humidity) were placed in the living room and a bedroom; and finally, a sensor in the kitchen is responsible for measuring relative humidity in this area of the housing. Appl. Sci. 2020, 10, 7734 16 of 21 Focusing on the AURA 1.0 prototype, Figure 21 show the location of this PCB:

FigureFigure 21. 21.Prototype Prototype plantplant andand measurement points. points.

4.1.4.1. Hygrothermal Hygrothermal Data Data TheThe hygrothermal hygrothermal data data extracted extracted from from the the monitoringmonitoring of the prototype prototype (Figure (Figure 22) 22 show) show us us that that in relationin relation to to relative relative humidity, humidity, the the results results were were very very good,good, with the graph graph being being below below 60% 60% most most of of thethe time. time. The temperature graph shows an average line of 25 ◦C, except for peaks during the hottest hours of the day. It should be noted that temperature and relative humidity measurements were not taken 24 h a day, but alternated with public opening hours, so that the public did not have a negative impact on the measurements (Table6). From these data we can confirm that, in a large percentage of the scoring hours, the prototype was in the maximum score range, and that practically 100% of the time it was obtaining at least a reduced score. In other words, the percentage of the time when the prototype was getting no points was practically negligible. In this sense, the greatest achievement of this model is to maintain a relative air humidity in a range suitable for health. This takes on special relevance in a climate like that of Santiago de Cali, where high humidity is one of its characteristic parameters. This prototype managed to keep the humidity below 65% during 91% of the time, and it never went up from 70%, so living in the AURA house means avoiding respiratory diseases related to the presence of mold, which is sometimes a consequence of the high environmental humidity. Appl. Sci. 2020, 10, x 17 of 22

Appl. Sci.The2020 temperature, 10, 7734 graph shows an average line of 25 °C, except for peaks during the hottest 17hours of 21 of the day.

Figure 22. GraphGraph of of hygrothermal hygrothermal behavior. behavior. Table 6. Percentage of Hours (in scoring hours) in Comfort Range. It should be noted that temperature and relative humidity measurements were not taken 24 h a day, but alternated with public opening hours, TEMP.so that the public did not have a negative HUM. impact REL. on the measurementsMAX. SCORE (Table Comfort 6). range >24–<28 68% Comfort range <60%. 42%

Comfort range 1 ◦C 14% Comfort range <65%–>60 49% LOW SCORE Table 6. Percentage± of Hours (in scoring hours) in Comfort Range. Comfort range 2 C 11% Comfort range <70%–>65 9% ± ◦ NO SCORING Out of confort rangeTEMP. 7% Out of confort rangeHUM. 0% REL. MAX. SCORE Comfort range >24–<28 68% Comfort range <60%. 42% Comfort range ±1 °C 14% Comfort range <65%–>60 49% 4.2. LightingLOW SCORE Data Comfort range ±2 °C 11% Comfort range <70%–>65 9% NOThe SCORING objective was Out to achieve of confort lighting range values 7% above 4% Out of the of Naturalconfort range Lighting Factor 0% or, at least, that their value should never be less than 2.5% of the latter (Figure 23). Thus, analyzing the behavior of FigureFrom 23, wethese confirm data thatwe can the confirm line of interior that, in lighting a large is percentage above the 2.5%of the most scoring of the hours, time, alsothe prototype exceeding wasthe 4% in linethe bymaximum a large percentage, score range, so and it is consideredthat practically that, in100% this of sense, the thetime prototype it was obtaining behaved optimallyat least a reducedin relation score. to this In sectionother words, (Table 7the). percentage of the time when the prototype was getting no points was practicallyThese values, negligible. which refer to natural lighting, have a positive influence on the well-being of the individual,In this sense, as the well greatest as positively achievement influencing of this the mo cognitivedel is to maintain function ofa relative the brain air and humidity helping in toa rangestrengthen suitable its immunefor health. system, This thustakes improving on special therelevance quality in of lifea climate of the peoplelike that living of Santiago in this dwellingde Cali, where(Table8 high). humidity is one of its characteristic parameters. This prototype managed to keep the humidity below 65% during 91% of the time, and it never went up from 70%, so living in the AURA Table 7. Percentage of Hours (in scoring hours) in Lighting Range. house means avoiding respiratory diseases related to the presence of mold, which is sometimes a consequence of the high environmental humidity. ILLUM. MAXIMUM SCORE Daylight Factor > 4% 52% 4.2. Lighting Data Daylight Factor > 3% 76% LOW SCORE The objective was to achieve lighting valuesDaylight above Factor 4%> of2.5% the Natural 91% Lighting Factor or, at least, that their value should never be less than 2.5% of the latter (Figure 23). Thus, analyzing the behavior NO SCORING Out of comfort range 9% of Figure 23, we confirm that the line of interior lighting is above the 2.5% most of the time, also exceeding the 4% line by a large percentage, so it is considered that, in this sense, the prototype behaved optimally in relation to this section (Table 7). Appl. Sci. 2020, 10, 7734 18 of 21

Appl. Sci. 2020, 10, x 18 of 22

FigureFigure 23.23. Graph of of lighting lighting behavior. behavior. Table 8. Nomenclature table with units. Table 7. Percentage of Hours (in scoring hours) in Lighting Range.

Variable Units ILLUM.

MAXIMUM SCORETemperature Daylight Factor◦C >4% 52% Daylight Factor >3% 76% LOW SCOREHumidity % Daylight Factor >2.5% 91% Illuminance Lux NO SCORING Out of comfort range 9% Daylight Factor % These values, which refer to natural lighting, have a positive influence on the well-being of the 5. Discussionindividual, andas well Conclusions as positively influencing the cognitive function of the brain and helping to strengthen its immune system, thus improving the quality of life of the people living in this dwelling (TableTaking 8). into consideration this analysis, the AURA proposal for sustainable social housing for a tropical climate, presented by the team from the University of Seville at the first Latin American edition of the Solar Decathlon, held in SantiagoTable 8. deNomenclature Cali (Colombia), table with proved units. its high performance in terms of all three analyzed comfort parameters whichVariable contribute Units to improving the quality of life, and therefore, the health of the inhabitants: temperature,Temperature relative humidity, °C and lighting. The proposal achieved an adequateHumidity balance in the% implementation and combination of active and passive conditioning strategies, showingIlluminance that in orderLux to guarantee adequate conditions in social housing, it is necessary to contemplateDaylight active Factor conditioning % systems. This combination of systems, by combating the adverse climatic conditions typical of tropical climates characterized by a combination of high5. Discussion temperature and and Conclusions relative humidity, appears to be a basic tool for the inhabited spaces to avoid health problems,Taking into especially consideration among this the analysis, most vulnerablethe AURA proposal population. for sustainable social housing for a tropicalIt is in theclimate, poorest presented classes by of the society team (population from the University with fewer of Seville resources, at the inhabitants first Latin ofAmerican the so-called “socialedition housing”) of the Solar where Decathlon, the most casesheld in of Santiago people sudeff Caliering (Colombia), from the deficientproved its comfort high performance conditions in of their domesticterms habitatof all three are analyzed registered. comfort These parameters deficiencies which are contribute due to the to lack improving of equipment the quality to air-condition of life, and the therefore, the health of the inhabitants: temperature, relative humidity, and lighting. spaces and the difficulty these people have to pay for the necessary energy expenditure, and therefore, The proposal achieved an adequate balance in the implementation and combination of active to produceand passive energy. conditioning strategies, showing that in order to guarantee adequate conditions in social housing,It is precisely it is necessary in this to area contemplate that passive active environmentalconditioning systems. techniques This combination and energy of systems, self-su ffibyciency becomecombating critical: theon adverse the one climatic hand, conditions passive typical conditioning of tropical strategies climates characterized will make an by impact a combination in less time than using air-conditioning systems, which will make it possible to obtain more energy-efficient living spaces with optimum bioclimatic design during a large percentage of the hours of the day; on the other hand, when the use of this technology becomes necessary, energy self-sufficiency will allow people with fewer resources to maintain their homes in optimal ranges for their health and comfort, without this Appl. Sci. 2020, 10, 7734 19 of 21 having repercussions on their socio-economic situation. Furthermore, in this Latin American context, in which there are high rates of energy poverty in most of these countries, all the above explained is especially appropriate from the point of view of economic sustainability, in addition to seeking optimal levels of comfort to the user, which will ultimately affect their health conditions. In conclusion, as far as sustainable social architecture is concerned, the AURA 1.0 prototype constitutes an adapted and tested sample, with excellent results in a tropical climate, which strategies are perfectly viable and transferable to the society of the Colombian region where it is located. Although the concept of comfort is very broad and its impact on people’s health depends on various factors, this project has achieved certain improvements in conditions related to both hygrometric and lighting conditions in domestic spaces. Although this project is developed for a tropical climate and the conditioning strategies are specific to that climate, the sociological strategies used can be applied to other climatic zones. Therefore, we must understand that social housing needs to be adapted to the socio-economic context of the place, and architects must think about an economic sustainability of housing without reducing the user’s comfort and health levels.

Author Contributions: Conceptualization, Á.L.-E., R.H.-L., Á.L.L.-R. and M.T.-G.; Formal analysis, Á.L.-E., R.H.-L., Á.L.L.-R. and M.T.-G.; Investigation, Á.L.-E., R.H.-L., Á.L.L.-R. and M.T.-G.; Methodology, Á.L.-E., R.H.-L., Á.L.L.-R. and M.T.-G.; Writing—original draft, Á.L.-E., R.H.-L., Á.L.L.-R. and M.T.-G.; Writing—review & editing, Á.L.-E., R.H.-L., Á.L.L.-R. and M.T.-G. All authors have read and agreed to the published version of the manuscript. Funding: This research received no external funding. Acknowledgments: The Authors would like to thank Aura Team (Universidad de Sevilla, Spain) who participated in the 2015 edition of the Solar Decathlon Latin America and Caribbean, held in Santiago de Cali (Colombia), for all the data provided for this article. Conflicts of Interest: The authors declare no conflict of interest.

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