Solar Decathlon Latin America and Caribbean: Comfort and the Balance between Passive and Active Design

sustainability Article Solar Decathlon Latin America and Caribbean: Comfort and the Balance between Passive and Active Design Rafael Herrera-Limones * , Ángel Luis León-Rodríguez and Álvaro López-Escamilla Instituto Universitario de Arquitectura y Ciencias de la Construcci ó n, Escuela T é cnica Superior de Arquitectura, Universidad de Sevilla, Av. Reina Mercedes 2, 41012 Seville, Spain *Correspondence: herr[email protected]; Tel.: +34-954-55-65-20 Received: 12 April 2019; Accepted: 21 June 2019; Published: 26 June 2019   Abstract: This article contains an overall analysis of the results obtained by the four highest scoring teams in the Solar Decathlon Latin America and Caribbean 2015 collegiate sustainable habitat competition. Considering that the prototypes developed were based on energy self-sufficiency when operational, it was considered necessary to propose this analysis based on the degree of suitability of each of these models based on their different performances from the perspective of comfort conditions. It was observed that the design of the prototypes did not manage to properly adjust the relationship between passive and active conditioning elements based on the location’s conditions. Accordingly, this article concludes that a balance of the two aforementioned conditioning modes recorded better results based on the measurements taken. Keywords: architecture; solar; prototype; competition; environmental; conditioning; active; passive; university 1. Introduction The building sector consumes too many natural resources and is responsible for enormous CO 2 emissions into the atmosphere [ 1 , 2 ]. Therefore, architectural styles must be found that minimize their environmental impact [3,4]. This article is based on a line of research aimed primarily at searching for construction models that minimize environmental impact based on an alignment with the Horizon 2020 (European Union Framework Program, the strategic objectives of which are aimed at scientific excellency and developing technologies), and the UNESCO and Sustainable Development Goals for 2030 (in particular, goal 11: Sustainable cities and communities). It is based on the premise that in the search for sustainable architectural models, competitions dedicated to generating ideas that are responsive to passive conditioning strategies, as well as maximizing efficiency and self-sufficiency, can and should be a primary research field when it comes to refining future building prototypes. The Solar Decathlon Competition is the most prestigious sustainable habitat competition on the planet. In collaboration with institutions and companies, universities from all over the world participate with the aim of designing, building, and putting into operation an exhibition pavilion in the form of a housing prototype, with the highest level of self-sufficiency and use of renewable energies. However, the final construction (which has the dual purpose of acting as both a pavilion that can be visited as well as a prototype that can be monitored) is not the sole purpose of the competition, but rather in the educational and research process, the prototypes undergo the following 10 contests (hence the name decathlon): Architecture, engineering, and construction; energy efficiency; electrical Sustainability 2019,11, 3498; doi:10.3390/su11133498 www.mdpi.com/journal/sustainability Sustainability 2019,11, 3498 2 of 17 balance; comfort conditions; sustainability; housing functionality; communications and marketing; urban design; and innovation. In this manner, the decathletes (recently graduated or final-year university students), mentored by teachers and researchers from different knowledge areas, comprise an inter-disciplinary team that takes on the competitive process as a tool for learning through problem solving, ultimately constituting an exceptional framework for exchanging information and an effective forum for transmitting knowledge gained in academia. The Solar Decathlon Latin America and Caribbean (hereinafter SDLAC) 2015, held in Cali (Colombia), was a pioneer in displaying a certain concern for regional relevance and social housing [ 5 ], unlike previous editions of the competition. This was the first edition of the contest held in Latin America: Due to the cultural and climatic context of the competition, it seems particularly suitable for an analysis of the confrontation between the active and the passive, as far as conditioning is concerned. The main objective of this article is to show which conditioning strategies are the most suitable for the general context of the Latin American Solar Decathlon Competition, in particular for Colombia (in the city of Santiago de Cali), since this is the specific location of the first competition of its type in the American subcontinent, SDLAC 2015. Accordingly, it follows that this article is appropriate for two reasons: Firstly, to consider (from a temporal perspective) the experience acquired in this competition; and secondly, to confirm that current research into sustainable habitats continues to take place. The latter is confirmed by the announcement of the upcoming SDLAC in December 2019 (also to be held in Colombia), which will be attended by the University of Seville, among others. Therefore, a second objective of this study is to show and analyze the results obtained in the 2015 edition of the competition so that this university experience can be used in the next edition, which will take place in the same city (Santiago de Cali) in December 2019, in which the University of Seville team will compete with a new proposal. Finally, to clarify the purpose of the research in this article, the possibility of transferring the most successful prototypes from the previous SDLAC15 competition, in terms of the proper balance between active and passive conditioning strategies, will be considered, this being understood as a clear indication of environmental innovation, which could even lead to real everyday models that could contribute to reducing environmental impact on a broad scale. In order to build on the above, the specific original methodology described below was used. 2. Methodology Considering that this is a complex problem that must be analyzed from a singular environmental context (tropical climate and social housing), a two-part methodology is proposed: The first part was based on analyzing the latest advances on the subject and the second focuses on the results obtained in the Solar Decathlon Latin America and Caribbean 2015 competition (SDLAC). These two stages of analysis are represented in Figure 1. In turn, the first stage of analysis was carried out in three stages: • Firstly, the latest advances in relation to the aim of the competition were analyzed, considering the current strategies/technologies for improving environmental and energy conditions in social housing. In order to do so, a literature review was conducted (mainly scientific articles). With the results from this, a database was developed that can be referenced with the aims and results of the SDLAC competition. • Secondly, the current legislation was analyzed with regard to design and environmental conditioning, both in the country where the competition takes place (Colombia) as well as in other reference countries (Spain). By doing so, the aim was to link the legislative conditions and environmental conditioning strategies (both passive and active) that are applicable to the construction of social housing in a tropical climate. Sustainability 2019,11, 3498 3 of 17 • Lastly, the rules and guidelines for the different editions of the Solar Decathlon competition were analyzed, displaying their scoring criteria. This information was connected to the literature and legislation of the previous sections in order to verify how far this competition can help to transfer beneficial results into society. The second stage contains a synthetic analysis of the results obtained by the top four teams in the SDLAC 2015 competition: 1. Casa Uruguaya/Universidad ORT (Uruguay); 2. Casa ALERO/Pontificia U. Javeriana and U. Icesi de Cali (Colombia); 3. AURA Prototype/Universidad de Sevilla (Spain) and U. Santiago de Cali (Colombia); and 4. unSOLAR/U. Nacional de Medell í n (Colombia). The four prototypes were compared to the context defined in the first stage and the capacity for transferring knowledge and solutions into society was analyzed, in the context of “social housing in a tropical climate.” Sustainability 2019, 11, x FOR PEER REVIEW 3 of 18 Figure 1. Diagram of the process. In turn, the first stage of analysis was carried out in three stages:  Firstly, the latest advances in relation to the aim of the competition were analyzed, considering the current strategies/technologies for improving environmental and energy conditions in social housing. In order to do so, a literature review was conducted (mainly scientific articles). With the results from this, a database was developed that can be referenced with the aims and results of the SDLAC competition.  Secondly, the current legislation was analyzed with regard to design and environmental conditioning, both in the country where the competition takes place (Colombia) as well as in other reference countries (Spain). By doing so, the aim was to link the legislative conditions and environmental conditioning strategies (both passive and active) that are applicable to the construction of social housing in a tropical climate.  Lastly, the rules and guidelines for the different editions of the Solar Decathlon competition were analyzed, displaying their scoring criteria. This information was connected to the literature and legislation of the previous sections in order to verify how far this competition can help to transfer beneficial results into society. The second stage contains a synthetic analysis of the results obtained by the top four teams in the SDLAC 2015 competition: 1. Casa Uruguaya/Universidad ORT (Uruguay); 2. Casa ALERO/Pontificia U. Javeriana and U. Icesi de Cali (Colombia); 3. AURA Prototype/Universidad de Sevilla (Spain) and U. Santiago de Cali (Colombia); and 4. unSOLAR/U. Nacional de Medellín (Colombia). The four prototypes were compared to the context defined in the first stage and the capacity for transferring knowledge and solutions into society was analyzed, in the context of “social housing in a tropical climate.” 3. Literature Review 3.1. History and Timeline of the Solar Decathlon The international Solar Decathlon competition, the most prestigious collegiate competition related to sustainable social habitat throughout the world, took place for the first time in Washington D.C. in 2002, organized by the US Department of Energy. Since then, it has been held every two years in various North American cities. However, from 2010, the competition has also taken place on other continents, with Spain being the first country to host this event outside of the United States. Subsequently, there were two more Figure 1. Diagram of the process. 3. Literature Review 3.1. History and Timeline of the Solar Decathlon The international Solar Decathlon competition, the most prestigious collegiate competition related to sustainable social habitat throughout the world, took place for the first time in Washington D.C. in 2002, organized by the US Department of Energy. Since then, it has been held every two years in various North American cities. However, from 2010, the competition has also taken place on other continents, with Spain being the first country to host this event outside of the United States. Subsequently, there were two more editions of the European version of the competition, with the fourth edition being in process (in Hungary) and a fifth edition planned for 2021. China, Africa, the Middle East, and Latin America are the other areas where this collegiate competition has been held (Table 1), although their histories are shorter as fewer editions have taken place in each of these settings. Although each of the six Solar Decathlon competitions has different rules, what never changes is the essence of the competition. These are 10 points-based contests on which each team is assessed. The winning team is the one that best combines excellency in design and the production of intelligent energy with innovation, market potential, efficiency, sustainability, and the water cycle, etc. Since it began in 2002, the competition has held (or is planning to hold or is even currently holding) the following versions in the following locations: Sustainability 2019,11, 3498 4 of 17 Table 1. Timeline of editions of the Solar Decathlon competition. SOLAR DECATHLON COUNTRY YEAR US Washington D.C. 2002 Washington D.C. 2005 Washington D.C. 2007 Washington D.C. 2009 Washington D.C. 2011 Irvine, California 2013 Irvine, California 2015 Denver, Colorado 2017 Africa Ben Guerir, Morocco 2019 China Datong 2013 Dezhou 2018 Europe Madrid, Spain 2010 Madrid, Spain 2012 Paris-Versailles, France 2014 Szentendre-Budapest, Hungary 2019 Wuppertal, Germany 2021 Latin America and Caribbean Santiago de Cali, Colombia 2015 Santiago de Cali, Colombia 2019 Middle East Dubai, United Arab Emirates 2018 Dubai, United Arab Emirates 2020 3.2. Conditioning Strategies, Legislation, and Competition Rules We started this literature review with a selective and synthetic study of the current zero-energy building strategies, which may be classified into passive energy saving systems, production technologies, and storage of renewable energies, on the one hand, and efficient energy service systems, on the other [6–8]. The last column of Table 2indicates the bibliographic references that justify the inclusion of the various technologies/strategies and procedures. The reference selection was based on databases with recognized scientific prestige and validity, thus obtaining an updated review of the technologies and strategies studied in this article. Regarding the above table, it is worth clarifying that the competition’s host country, Colombia, presents a wide variety of climates; however, given the specific location of the event (Santiago de Cali), it is the warm/tropical climate strategies that are the most interesting in this case. Sustainability 2019,11, 3498 5 of 17 Table 2. Technologies and strategies: cross-referenced with bibliographic references. PASSIVE ENERGY SAVING SYSTEMS ENCLOSURE Form Factor/Modulation:/Flexibility/Prefabrication [9,10] Solar shading [9,11,12] Ventilated façade [13,14] Thermal insulation [15] Low-emission openings (Low-E) [9,16] Active user [17] PASSIVE HEATING Solar roof [18,19] Trombe wall [18] Curtain wall [20] Greenhouse [9] PASSIVE COOLING Natural ventilation [4,9,11,21,22] Earth-air heat exchanger (EAHE) [23] Adiabatic cooling/Evaporative cooling [9,18] Green roof [24] Dehumidification [25] THERMAL ENERGY STORAGE Phase change materials (PCM) Thermal inertia [26–28] EFFICIENT ENERGY SERVICE SYSTEMS SOLAR ENERGY Photovoltaic panels Architectural integration Photovoltaic panels for façades [4,9,11,12,29–32] Hybrid photovoltaic/thermal systems [9,33] WIND POWER Wind turbines [34] GEOTHERMAL POWER Geothermal heat pump [35] BIOENERGY Biomass boiler [36,37] Biofuels [38] ENERGY STORAGE Batteries [39,40] HVAC (Heating, Ventilating and Conditioning systems) Evaporative cooling [41] Active thermal storage [42] Heat recovery [37,43,44] Radiative heating/cooling [45] Variable air volume (VAV)/variable coolant volume [46,47] DWH Solar water heating (SWH) - Flat plate collectors - Vacuum tube collectors [9,14,32,35,48] Solar heat pump system [37,49] Combined cooling/heating and power (CCHP) [37,50] LIGHTING Light-emitting diodes (LED) [51] Use of daylight [52] HOUSEHOLD EQUIPMENT Efficient appliances [9,32,53] Domotics/Monitoring/Automation [17,30,54] WATER CYCLE Greywater recycling [11,30] Use of rainwater [11] Sustainability 2019,11, 3498 6 of 17 After analyzing the regulations of the countries being studied (Colombia and Spain), it is clear that the implementation of a certain technology in the architectural process must pass through a legal and regulatory filter. It is for this reason that an updated review of the energy efficiency legislation and renewable energies regulations in both Colombia [ 55 ] and Spain [ 56 ] was carried out, these countries being the location of SDLAC15 and the field of work of the authors of the article, respectively, which could be assimilated to Latin America vs. Europe. Table 3shows that although it is true that in Colombia (and in other Latin American countries with similar levels of development) there is a high level of interest in the promotion of renewable energies, in order for this interest to take shape rather than remaining a desire, it is essential that regulations are developed that enable zero-energy building technologies to be implemented. Table 3. Colombian legislation on energy efficiency and renewable energies. LEGISLATIVE FRAMEWORK SPAIN (Europe) COLOMBIA (Latin America) General legislation -energy efficiency Current Energy Efficiency Directive 2012/27/EU, with regard to directives 2006/32/EC and 93/76/EEC Law 697 of 2001 on the rational and efficient use of energy Efficiency Agency Institute for the Diversification and Saving of Energy (IDAE) Does not exist Action plans Energy Saving and Efficiency Action Plan 2011–2020 Program for the Rational and Efficient Use of Energy and other Non-Conventional Energy Sources, PROURE BUILDINGS Energy performance requirements in buildings Technical Building Code (CTE)(RD 31472006 and 1371/2007) Does not exist. Only one proposal has been submitted for Regulation of Technical Energy Efficiency for Social Housing (RETEVIS). Energy certificate RD 235/2013, which approves the basic procedure for certifying the energy efficiency of buildings Does not exist Savings objective Technical Building Code—Basic Document HE on Energy Savings Does not exist Requirements for thermal installations Regulation of Thermal Installations in RITE Buildings (RD 1027/2007 and 1826/2009) Does not exist LIGHTING Energy performance requirement Technical Building Code—Basic Document HE.3 (Energy efficiency of lighting installations) and Regulation on Energy Efficiency in Outdoor Lighting Installations (RD 1890/2008) Technical Regulation on Lighting and Street Lighting RETILAP (Resolution 18 1331 of 2009 and modified by resolution 1805 40 of 2010 by which the requirements of light efficiency and other provisions are established) Removal of lamps Commission Regulation (EU) 2015/1428, amending Commission Regulation (EC) 244/2009 as regards ecodesign requirements for non-directional household lamps and Commission Regulation (EC) 245/2009 Decree 2331 of 2007, which establishes a measure aimed at the rational and efficient use of electricity. Compiled Decree 1073 of 2015 Labelling Regulation Regulation 874/2012/EU, which complements Directive 2010/30/EU of the European Parliament and of the Council regarding the energy labelling of electric lamps and lights Technical Labelling Regulation (RETIQ). Decree 1471 of 2014 APPLIANCES AND EQUIPMENT Energy performance requirement RD 187/2011, regarding the establishment of ecodesign requirements applicable to energy-related products Does not exist Energy labelling RD 1390/2011, which regulates the indication of energy consumption and other resources for energy-related products, through labelling and standardized information Technical Labelling Regulation (RETIQ). Decree 1471 of 2014 ENERGY SUPPLY Cogeneration RD 413/2014, which regulates the activity of producing electricity from renewable energy sources, cogeneration and waste. Supreme Court judgement BOE 245 of 10/10/2016 Law 1715 of 2014, which regulates the integration of non-conventional renewable energies into the national energy system ECONOMIC INSTRUMENTS Industrial and commercial sector Aid programs managed by the IDAE under the National Energy Efficiency Fund (FNEE) Fiscal measures limited to the indicative plans of PROURE Residential sector and individuals Program for Energy Refurbishment of Buildings (PAREER-CRECE) Does not exist Sustainability 2019,11, 3498 7 of 17 Current Colombian laws do not establish binding objectives and the available economic incentives are indirect [ 55 ]. An example of this is the construction sector, for both new buildings and refurbishments (Table 3, BUILDINGS section), which entirely lacks any legislative framework that imposes energy efficiency measures and strategies. Moving on to the analysis of the competition rules [ 2 ], we must point out that these are focused on a series of objectives that are part of the spirit of the competition (Table 4). Thus, based on the process of building sustainable housing cell prototypes, we seek to educate in terms of environmental awareness and serve as a training activity for the members of the participating teams. Table 4. Analysis of the 10 contests of the competition: summary table generated from the SDLAC15 Competition Rules, but with our own re-drafting. CONTEST DESCRIPTION SCORING JUDGING Architecture Evaluates spatial efficiency, the adequacy of the materials in relation to bioclimatic strategies for the future of social housing in the context of Latin America and the Caribbean. 100 Judges Engineering and construction Evaluates feasibility and adequate integration of the structural, electrical, plumbing, and solar design and that of the enclosure for low-cost social housing. 100 Judges Energy efficiency Evaluates suitable design of the dwelling’s systems to achieve a reduction in energy consumption. Energy efficiency 60 Monitoring Limiting energy consumption 40 Electrical balance Measures the level of electrical self-sufficiency of the dwelling through balancing electricity generation and consumption. Electrical balance 60 Monitoring Consumption peaks 40 Comfort conditions Measures interior conditions, such as temperature, humidity, acoustics, lighting, and air quality, to assess the sensation of interior comfort in each housing solution. Thermal comfort 50 Monitoring Relative humidity 20 Natural and artificial lighting 20 Acoustic performance 20 Sustainability Focused on reducing environmental impact in the long term. Evaluates strategies to properly manage the topics of architecture, engineering and construction, energy efficiency, urban design, and economic viability. 100 Judges Housing functionality Measures the efficiency and functionality of a set of applications to ensure normal functioning of the dwelling. Cooling 8 Test Freezer 8 Washing machine 12 Microwave 5 Blender 5 Kitchen 10 Appliances 7 Social activity 15 Minimizing water consumption 10 Hot running water 20 Communications and marketing Evaluates the effectiveness and efficiency of marketing and communications strategies to generate social awareness of the projects and the advantages of using sustainable buildings with a solar energy supply. 100 Judges Urban design and affordability Promotes research into urban design with a density applicable to the context of Latin America and the Caribbean to achieve an effective and innovative proposal based on low-cost housing. 100 Judges Innovation Evaluates the incorporation of creative solutions to improve conventional levels of habitability. 100 Judges However, the specific rules of the Latin American Solar Decathlon are excessively based on the rules of the competition’s previous editions (in North America or Europe), meaning they lack greater Sustainability 2019,11, 3498 8 of 17 suitability for the context, both in the contests presented and in the conditioning strategies that could be possible as a result. Alternatively, the fact of the competition organizers disallowing the storage of energy by means of batteries seems odd (in previous editions of the Solar Decathlon, this prohibition did not exist). This is especially true considering the Colombian electrical system is divided between the national interconnected system (SIN) and the ZNI, or geographic areas where the public electricity service is not available [ 57 ], and where the implementation of electric energy storage batteries could be an efficient alternative. 4. Comparative Analysis of the Winning Prototypes We will start this comparative analysis by studying the specific results of the SDLAC15 competition, in particular the four teams that finished with the highest scores after 15 days of competition, which are as follows: First Prize: Casa Uruguaya/Universidad ORT (Uruguay) This prototype consisted of a closed pavilion, very dependent on technology and active conditioning strategies (Figure 2). However, vertical solar shading was used through an outer layer on its perimeter, with the aim of generating a microclimate between the house and the exterior, thus protecting it from direct sunlight. Low impact materials, such as wood or glass wool, were used with the intention of obtaining low greenhouse gas emissions and generating a reduced ecological footprint. In addition, it was equipped with a system that enables rainwater to be reused for watering plants and hydroponic systems. Sustainability 2019, 11, x FOR PEER REVIEW 8 of 18 4. Comparative Analysis of the Winning Prototypes We will start this comparative analysis by studying the specific results of the SDLAC15 competition, in particular the four teams that finished with the highest scores after 15 days of competition, which are as follows:  First Prize: Casa Uruguaya/Universidad ORT (Uruguay) This prototype consisted of a closed pavilion, very dependent on technology and active conditioning strategies (Figure 2). However, vertical solar shading was used through an outer layer on its perimeter, with the aim of generating a microclimate between the house and the exterior, thus protecting it from direct sunlight. Low impact materials, such as wood or glass wool, were used with the intention of obtaining low greenhouse gas emissions and generating a reduced ecological footprint. In addition, it was equipped with a system that enables rainwater to be reused for watering plants and hydroponic systems. Furthermore, it should be noted that the dwelling was equipped with domotic energy control, enabling the occupant to be informed of the energy demand by the use of a mobile device in order to control the humidity and temperature, depending on atmospheric conditions, with the objective of adjusting the energy balance. Figure 2. North side of Casa Uruguaya.  Second Prize: Casa ALERO/Pontificia U. Javeriana and U. Icesi de Cali (Colombia) Unlike the previous example, this team presented a completely open prototype with comfort conditions that were based entirely on passive conditioning, which fluctuate depending on the external conditions (Figure 3). As a result, it was highly dependent on these factors during the final phase of the competition (which, on this occasion, were favorable since there were no rainfalls or excessive temperatures during the competition period). The operation of the model is based, fundamentally, on its roof, which was designed to provide solar shading at the latitude of Santiago de Cali, and was planted with vegetation to offset the effects of direct solar radiation. The proposal was complemented by a series of balconies that were completely permeable and collapsible, converting the entire house into a covered but open space, as an extension of the outdoor space. Figure 2. North side of Casa Uruguaya. Furthermore, it should be noted that the dwelling was equipped with domotic energy control, enabling the occupant to be informed of the energy demand by the use of a mobile device in order to control the humidity and temperature, depending on atmospheric conditions, with the objective of adjusting the energy balance. Second Prize: Casa ALERO/Pontificia U. Javeriana and U. Icesi de Cali (Colombia) Sustainability 2019,11, 3498 9 of 17 Unlike the previous example, this team presented a completely open prototype with comfort conditions that were based entirely on passive conditioning, which fluctuate depending on the external conditions (Figure 3). As a result, it was highly dependent on these factors during the final phase of the competition (which, on this occasion, were favorable since there were no rainfalls or excessive temperatures during the competition period). Sustainability 2019, 11, x FOR PEER REVIEW 9 of 18 Figure 3. South side of Casa ALERO.  Third Prize: AURA Prototype/U. de Sevilla (Spain) and U. Santiago de Cali (Colombia) Unlike the two previous prototypes, this prototype sought a balance, combining both passive and active conditioning strategies (Figure 4)., resulting in a completely open or closed house depending on the weather conditions at the time and adapted to the location where the competition was held. The theoretical residential building to which the housing cell or prototype would belong is longitudinal: The sides with a greater surface area face north–south, where the sun’s position is more vertical. This makes it easier to be protected from the sun. However, it did use solar shading strategies, such as a gallery to the north and a ventilated layer system to the south (constructed using a local bamboo variety called guadua). Thermal inertia was minimized and natural ventilation was enhanced, always resulting in a side with sunlight and another in shadow, thus generating air flow. The house also had a solar chimney, which is a duct that complements the effect of natural cross ventilation by extracting hot air using the Venturi effect. Figure 4. South side of the AURA Prototype. Figure 3. South side of Casa ALERO. The operation of the model is based, fundamentally, on its roof, which was designed to provide solar shading at the latitude of Santiago de Cali, and was planted with vegetation to offset the effects of direct solar radiation. The proposal was complemented by a series of balconies that were completely permeable and collapsible, converting the entire house into a covered but open space, as an extension of the outdoor space. Third Prize: AURA Prototype/U. de Sevilla (Spain) and U. Santiago de Cali (Colombia) Unlike the two previous prototypes, this prototype sought a balance, combining both passive and active conditioning strategies (Figure 4)., resulting in a completely open or closed house depending on the weather conditions at the time and adapted to the location where the competition was held. The theoretical residential building to which the housing cell or prototype would belong is longitudinal: The sides with a greater surface area face north–south, where the sun’s position is more vertical. This makes it easier to be protected from the sun. However, it did use solar shading strategies, such as a gallery to the north and a ventilated layer system to the south (constructed using a local bamboo variety called guadua). Thermal inertia was minimized and natural ventilation was enhanced, always resulting in a side with sunlight and another in shadow, thus generating air flow. 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