As a Concept in the History of Architecture

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Article Architecture and Steel. Reﬂection and Analysis on the Use of Steel Structures (in Sight) as a Concept in the History of Architecture

Inês D. D. Campos 1,2,* and Luís F. A. Bernardo 3 1 Department of Civil Engineering and Architecture, University of Beira Interior, 6201-001 Covilhã, Portugal 2 CIAUD, Research Center in Architecture, Urbanism and Design, Faculty of Architecture, University of Lisbon, 1349-055 Lisbon, Portugal 3 Centre of Materials and Building Technologies (C-MADE), Department of Civil Engineering and Architecture, University of Beira Interior, 6201-001 Covilhã, Portugal; [email protected] * Correspondence: [email protected]

Received: 17 June 2020; Accepted: 29 July 2020; Published: 5 August 2020

Abstract: This is the first of two companion articles which aim to address the research on Architecture and Steel. In this article, some architectural projects are analyzed to show the potentiality to conjugate architectural conception and steel structures, as well as to show the contribution and influence from architectural history. This article also aims to contribute to the reflection of the knowledge and legacy left to us by several architects throughout the history of architecture in using aesthetic, visual and structurally safe profiled steel structures in architectural conception. The presented analysis and reflection are based on the characteristics and influences of the Industrial Revolution and, mainly, the Modern Movement, where the first housing projects came up with this constructive system, combined with the “simplistic” ways of living in architecture, highlighting the relationship with the place, cultural, spatial and typological references, the structural systems and associated materiality. In view of the diversity of alternatives allowed by the use of steel “Skeletons”, modular and standardized, combined with a huge variety of existing materials and constructive complexity, well combined and interconnected, it is possible to obtain a final product whose characteristics seduce by their beauty and elegance. Moreover, the practical and functional comfort which allows the safeguarding of the architectural integration of such product, with the necessary serenity in space and nature, in full environmental integration, is also emphasized.

Keywords: steel architecture; modern architecture; industrial revolution

1. Introduction With the Industrial Revolution, between the 18th and 19th century, “iron architecture” emerged from engineers who were in the art of building bridges, railway stations and pavilions for wide exhibitions, with magnificent drawings and economic solutions. In the 20th century, architects such as Mies van der Rohe, Philip Johnson, Richard Neutra and Rudolph Schindler marked the use of steel in architectural projects as a symbol of modernism. By assuming the steel structure in sight as an integral part of the architectural concept, this structural system allowed large glazed spans and open plans, with high freedom, functional and spatial flexibility, constituting the characteristics of a new architecture and a new way of living. Pierre Koenig was one of the architects who dedicated himself to develop projects with steel construction. He was known for participating in a program of innovative industrial houses, the Case Study Houses in Los Angeles. Together with Charles and Ray Eames, and Craig Ellwood, they defined such houses as poetic steel structures combining the strength and simplicity of this industrial system. They also proved that the mass production had the delicacy

Designs 2020, 4, 30; doi:10.3390/designs4030030 www.mdpi.com/journal/designs Designs 2020, 4, 30 2 of 13 for use on a domestic scale, where the form and function were prominent, and its relations with the external nature were present, as an extension of the interior space. Several examples built with this construction system exist. At the time, they were considered audacious and unlike everything that existed. The following and most emblematic works can be highlighted: the Crystal Palace in London, the Eiffel Tower in Paris, the Empire State Building and the Seagram Building both in New York, the buildings designated as 860–880 Lake Shore Drive Apartments in Chicago, the Golden Gate Bridge in San Francisco and the 25th Abril Bridge in Lisbon. Even with different architectural styles, these works remain timeless and with a delicate grandiosity which only steel can achieve. The relationship between the “architectural design for housing” and the use of the “modular system in steel structures” in the technological/scientific field has been partially addressed in chapters from architectural and engineering monographs, where independent projects are described in engineering Ph.D. theses, in articles published in periodic engineering journals on construction systems and, also, on projects developed by architects. For architects, conceptual projects are part of the research, even when they are not built. The creative process is the way that architecture evolves, based on the influences that come from history, culture and the experiences from each architect. It includes experiences carried out with or without success, the application and combination of new techniques and technologies and the materiality combined with the form and place. The biggest challenge for architects is to be able to combine and interconnect the creative and individual system (concept) with the constructive precision, rigor and standardization of industrial processes. For the success of this interconnection, it is important that the architect masters the knowledge on the construction system with steel structures for the architectural conception [1]. To help architects in this goal, this article is the first of two companion articles related to the research on Architecture and Steel. In this article, some architectural projects are analyzed to demonstrate the potentialities to combine architectural conception with the use of steel structures, showing the contribution from the history of architecture and its influences. In each case study, how the structure influences and defines the living space and the relationship of the project with its surroundings is studied. The aim is to try to demystify the use of this constructive system today, highlighting its advantages and disadvantages.

2. Contribution of History and Theory of Architecture In the early 20th century, mass production aimed to respond to the functional need to produce various components, to facilitate the daily lives of people and to increase the speed of construction of housing buildings. It is for this purpose that architects from the Modern Movement, such as Le Corbusier, associated the use of the “living machine” and mass production as a solution to solve the problem of the housing shortage at the time. They understood that objects produced in mass possess a geometric and ruled aesthetic which is pure, simple, organized and essential for modern individuals, who live in a new era, who are busier and with a fast pace and who appreciate and need order and simplicity [2]. For Le Corbusier, building houses in mass is related to inhabiting those houses, that is, building and living, as Heidegger thought. Thus, man inhabits the house which was built in mass. Here, Heidegger’s thinking vanishes because in this process the houses are built by technicians. Because of this, the relationship of living space with the inhabitant during the construction process does not exist, while in the popular housings, the inhabitants are part of the construction and inhabiting process [3]. One of the last built works designed by Le Corbusier is the “The Heidi Weber Museum” or the “Le Corbusier Center” (1961–1967) in Zurich (Figure1). This project was commissioned by a decorator, Heidi Weber, connected to the world of arts, and who wanted to honor the architect with a museum to publicize his work and thoughts. Le Corbusier chose a constructive system starting with the roof, made with a steel structure, which is disconnected from the building to constitute a shelter. The pavilion consists of prefabricated parts in steel, wood and colored enamel panels. This project Designs 2020, 4, x FOR PEER REVIEW 3 of 13 Designs 2020, 4, 30 3 of 13 with the roof, made with a steel structure, which is disconnected from the building to constitute a shelter. The pavilion consists of prefabricated parts in steel, wood and colored enamel panels. This marksproject amarks change a inchange the type in the of material type of usedmaterial by theused architect, by the inarchitect, which concrete in which and concrete stone previouslyand stone usedpreviously in his used architectural in his architectural poetics are poetics replaced are with repl otheraced with materials other suchmaterials as steel such and as glass,steel and leaving glass, a markleaving for a themark future for the [2]. future [2].

Figure 1. Le Corbusier Center, Zurich, 1961–1967 [[4].4].

At that same time, when Le Corbusier studied this new housing, other architects like Walter Gropius beganbegan to to explore explore constructive constructive systems systems allowing, allowing, within within uniformity, uniformity, to achieve to some achieve differences some indifferences the final objects. in the final During objects. this new During era of this industrialization new era of industrialization and, at the same and, time at as the Le Corbusier,same time Walter as Le GropiusCorbusier, developed Walter theGropius idea ofdeveloped producing the prefabricated idea of producing elements forprefabricated houses, which, elements when combinedfor houses, in diwhich,fferent when ways, combined gave architects in different several ways, possibilities gave architects for results. several possibilities for results. Gropius devoted himself to this topic because he believed that this type of housing freed people from most of the necessary work, providing more freefree time and a better quality of life. On the other hand, mass production allowed the product to be globalized more easily and would make it more economical. The The themes themes studied studied and and developed developed by by Gropius Gropius were were mobility, mobility, ease of transportation, adaptation to different different cultures and climates, the possibilitypossibility of creating several alternatives with the same building elements and their verticalvertical or horizontal expansion.expansion. In 1927, Walter GropiusGropius designeddesigned two fully prefabricatedprefabricated houses (houses 16 and 17) for the Werkbund ExhibitionExhibition in Stuttgart.Stuttgart. House 17 (Figur (Figuree 22)) hadhad aa rectangularrectangular shapeshape withwith aa squaredsquared gridgrid with 8080 cmcm spacing spacing which which allowed allowed a perfect a perfect modeling mode ofling the of spaces the spaces and all theand construction all the construction elements. Theelements. assembly The systemassembly consisted system of consisted a steel frame of a system, steel frame composed system, with composed an auxiliary with composite an auxiliary steel andcomposite wood structure,steel and and,wood for structure, insulation, and, cork for panels insula weretion, used.cork panels The exterior were ofused. the The house exterior was covered of the withhouse steel was sheet covered panels. with Thesteel external sheet panels. plate finishing The external was combinedplate finishing with thewas windows, combined both with with the standardwindows, sizes both as with a function standard of thesizes used as a plan function grid. Gropius’of the used investigations plan grid. Gropius’ and experiments investigations with suchand typeexperiments of system with allowed such a breakthroughtype of system in innovativeallowed a solutions breakthrough and represented in innovative an important solutions turning and pointrepresented at the time,an important which were turning important point at for the future time, architects which were [4]. important for future architects [4]. While Gropius developed his ideas, Buckminster Fuller created, as an inventor and designer, the book 4D Timelock in 1928. This book intended to solve the problem of economic housing for everyone and was based on Henry Ford’s mass production model. Fuller believed in the idea of producing economical houses like automobiles, with quality and modern materials to improve people’s lifestyles. For his projects, he used lightweight materials and regular forms, such as circles and hexagons, to distribute the loads uniformly per the whole area, as well as to facilitate transportation by land or air. This type of module allowed him to place materials on top of each other, to create a vertical connection element for the circulations [2].

Figure 2. Experimental house by Walter Gropius for the Werkbund Exhibition in Stuttgart (house 17), 1927 [5]. Designs 2020, 4, x FOR PEER REVIEW 3 of 13

with the roof, made with a steel structure, which is disconnected from the building to constitute a shelter. The pavilion consists of prefabricated parts in steel, wood and colored enamel panels. This project marks a change in the type of material used by the architect, in which concrete and stone previously used in his architectural poetics are replaced with other materials such as steel and glass, leaving a mark for the future [2].

Figure 1. Le Corbusier Center, Zurich, 1961–1967 [4].

At that same time, when Le Corbusier studied this new housing, other architects like Walter Gropius began to explore constructive systems allowing, within uniformity, to achieve some differences in the final objects. During this new era of industrialization and, at the same time as Le Corbusier, Walter Gropius developed the idea of producing prefabricated elements for houses, which, when combined in different ways, gave architects several possibilities for results. Gropius devoted himself to this topic because he believed that this type of housing freed people from most of the necessary work, providing more free time and a better quality of life. On the other hand, mass production allowed the product to be globalized more easily and would make it more economical. The themes studied and developed by Gropius were mobility, ease of transportation, adaptation to different cultures and climates, the possibility of creating several alternatives with the same building elements and their vertical or horizontal expansion. In 1927, Walter Gropius designed two fully prefabricated houses (houses 16 and 17) for the Werkbund Exhibition in Stuttgart. House 17 (Figure 2) had a rectangular shape with a squared grid with 80 cm spacing which allowed a perfect modeling of the spaces and all the construction elements. The assembly system consisted of a steel frame system, composed with an auxiliary composite steel and wood structure, and, for insulation, cork panels were used. The exterior of the house was covered with steel sheet panels. The external plate finishing was combined with the windows, both with standard sizes as a function of the used plan grid. Gropius’ investigations and Designsexperiments2020, 4, 30with such type of system allowed a breakthrough in innovative solutions4 ofand 13 represented an important turning point at the time, which were important for future architects [4].

Designs 2020, 4, x FOR PEER REVIEW 4 of 13

While Gropius developed his ideas, Buckminster Fuller created, as an inventor and designer, the book 4D Timelock in 1928. This book intended to solve the problem of economic housing for everyone and was based on Henry Ford’s mass production model. Fuller believed in the idea of producing economical houses like automobiles, with quality and modern materials to improve people’s lifestyles. For his projects, he used lightweight materials and regular forms, such as circles and hexagons, to distribute the loads uniformly per the whole area, as well as to facilitate transportationFigureFigure 2.2. ExperimentalExperimental by land or house air.house Th by byis Walter typeWalter Gropiusof Gropius module for for theallowed the Werkbund Werkbund him Exhibitionto Exhibitionplace materials in Stuttgart in Stuttgart on (house top (house 17),of each other,192717), to 1927create [5]. [5]. a vertical connection element for the circulations [2]. In the transition from the 40s and 50s of last century, Jean Prouvé as a designer, builder and engineer,In the also transition developed from prefabricated the 40s and systems 50s of last for century,houses. Prouvé Jean Prouv did énotas understand a designer, why builder houses and builtengineer, with alsoindustrial developed materials prefabricated continued systems to look fortraditional. houses. ProuvIt wasé essentialdid not understandfor him that whythe projects houses translatedbuilt with industrialnew ways materialsof living, continuedto meet the to new look daily traditional. habits of It each was person essential at forthe himtime. that In his the opinion, projects thetranslated projects new built ways with of living,industrial to meet materials the new could daily be habits aesthetically of each person interesting at the time.with simple In his opinion, forms, althoughthe projects imposing, built with allowing industrial the materials inhabitants could to be aestheticallyuse spaces but interesting to be harmonious with simple and forms, respond although to day-to-dayimposing, allowingactivities thewith inhabitants which they to could use spaces identify but themselves. to be harmonious and respond to day-to-day activitiesThe Meudon with which Houses they couldin 1949 identify by Prouvé themselves. were quite economical (Figure 3). They were built with steel Thestructures Meudon and Houses the walls in 1949 were by Prouvprefabricated,é were quite allowing economical them (Figureto be placed3). They inside were builtthe house with accordingsteel structures to the and spatial the walls needs were of prefabricated,the inhabitant. allowing People them characterized to be placed these inside houses the house as being according very modern,to the spatial fragile needs and of simple, the inhabitant. as they were People accustom characterizedated to these traditional houses buildings, as being very which modern, are massive fragile inand character simple, as[6]. they were accustomated to traditional buildings, which are massive in character [6].

Figure 3. MeudonMeudon Houses by Jean Prouvé, Prouvé, Paris, 1949 [7]. [7].

Charles Eames also developed the taste for steel. He developed projects in steel structures and used industrial industrial elements elements for for mass mass construction. construction. The The Eames Eames House House in 1949, in 1949, which which belongs belongs to the to Case the StudyCase Study House House Program Program in California, in California, designed designed by byEames Eames and and Eero Eero Saarinen, Saarinen, is is composed composed with with a modular steel structure, glass panelspanels and composite asbestos and cement panels. This structure was thought to recreate furniture andand symbolicsymbolic spacesspaces inin thethe interiorinterior habitable.habitable.

2.1. Potential Potential Use Use of of Steel Steel in Architectural Design—Structural Steel System as a Concept Mies Van der Rohe repeated the following sentence several times, which, directed directed for for teaching, teaching, represented thethe experienceexperience he he lived: lived: “Any “Any education education must must start start with with the the practical practical side side of life,of life, with with the thediscipline discipline path, path, going going from thefrom material, the material, through throug the function,h the function, to the creative to the work.” creative [8]. work.” He interpreted [8]. He interpretedarchitecture architecture as the unique as and the simple unique combination and simple of combination material, through of material, technology through and technology time, with form. and time, with form. This type of art, as a design concept, should be planned and built in detail and should be simple and pure. The synthesis of his works is the almost mystical stripping of forms and the nakedness of structures. His architectural ideas are based on the principle of construction which translates into absolute constructive clarity. In the Viollet-le-Duc’s architectural conceptions in the early 1860s, the aesthetic effect was not related to something fleeting, instead it was the result of a well-studied structure. For Mies Van der Rohe it was unthinkable to invent arbitrary forms, to copy historical motives and to create modern Designs 2020, 4, 30 5 of 13

This type of art, as a design concept, should be planned and built in detail and should be simple and pure. The synthesis of his works is the almost mystical stripping of forms and the nakedness of structures. His architectural ideas are based on the principle of construction which translates into absolute constructive clarity. In the Viollet-le-Duc’s architectural conceptions in the early 1860s, the aesthetic effect was not related to something fleeting, instead it was the result of a well-studied structure. For Mies Van der Designs 2020, 4, x FOR PEER REVIEW 5 of 13 Rohe it was unthinkable to invent arbitrary forms, to copy historical motives and to create modern formsforms thatthat werewere notnot motivated by by the the construction construction itse itselflf resulting resulting from from the the structure. structure. In Inhis his works, works, he heclearly clearly distinguished distinguished the the structural structural elements elements from from the the closing closing elements elements (w (wallsalls and and openings) openings) [4]. [4 ]. InIn the the German German Pavilion Pavilion for thefor Barcelonathe Barcelona International International Exhibition Exhibition in 1929 in (Figure 19294 ),(Figure with dividing 4), with panelsdividing freely panels arranged, freely arranged, Mies Van Mi deres RoheVan der combined Rohe combined the materials, the materials, the distribution the distribution and the and space the inspace a new in concept,a new concept, creating creating a spatial a spatial harmony harmony of great of attraction. great attraction. This building This building is seen is with seen great with admirationgreat admiration and contemplation and contemplation by people by people from allfrom areas all andareas knowledge and knowledge backgrounds backgrounds during during their constanttheir constant visits. visits. The building The building shows shows the fluidity the fluidity of its spaces of its spaces due to due the regularto the regular precision precision used by used the architect.by the architect. These qualitiesThese qualities can be can found be found in the teachingsin the teachings of the of rigorous the rigorous architecture architecture from thefrom past. the Thispast. project This project uses a uses system a system of columns of columns built with built equal withangle equal steel angle profiles steel profiles to support to support a flat roof. a flat It roof. will beIt will one be of theone startingof the starting points points for the for investigation the investigation of the of applied the applied modular modular system system developed developed in the in secondthe second companion companion article article from from the authors. the authors.

FigureFigure 4.4. GermanGerman PavilionPavilion byby MiesMies VanVan derder Rohe,Rohe, BarcelonaBarcelona International International Exhibition, Exhibition, 1929 1929 [ 9[9].].

MiesMies VanVan der der Rohe Rohe thought thought of architectureof architecture as something as something that isthat not is tied not to tied the to current the current and actual and moment,actual moment, nor to eternity, nor to eternity, but rather but adapted rather toadapted its time. to For its him,time. the For work him, that the expresseswork that his expresses time isthe his authentictime is the one. authentic The architectural one. The architectural vision of this vision architect of this is architect marked byis marked order and by sincerity,order and rigor sincerity, and beauty,rigor and formalizing beauty, formalizing a spatial harmony. a spatial harmony. It is difficult It is to difficult understand to understand at first sight at first the wholesight the process, whole eprocess,ffort and effort selflessness and selflessness necessary necessary for the result for the of his result crystalline of his crystalline and exemplary and exemplary works [8]. works [8]. TheThe structural structural steel steel system system as anas architecturalan architectural concept concept implies implies being being able to able combine to combine a set of factors,a set of suchfactors, as: interpretationsuch as: interpretation of the place, of program, the place, conceptual program, idea conceptual and, at the sameidea and, time, understandingat the same time, the potentialitiesunderstanding (positives the potentialities and negatives) (positives of this construction and negatives) material, of thethis advantages construction of rationalization, material, the abilityadvantages to plan of andrationalization, coordinate theability construction to plan and phases coordinate from on-site the construction production, phases allowing from elements on-site thoughtproduction, and designedallowing elements in a project thought so that and they designed can be produced in a project and so transported that they can to be the produced construction and sitetransported for final assembly.to the construction site for final assembly. InIn thethe projectproject coordination, coordination, thethe useuse of of this this steel steel construction construction systemsystem requiresrequires rigorous rigorous planning planning ofof thethe entireentire process,process, withwith aa millimetricmillimetric degreedegree ofof detaildetail ofof thethe structurestructure toto bebe built,built, soso thatthat thethe workwork assemblyassembly doesdoes notnot susufferffer unforeseenunforeseen circumstances.circumstances. TheThe processprocess beginsbegins withwith thethe “Previous”Previous Study”Study” phase,phase, presented presented in in the the form form of of sketches sketches and and diagrams, diagrams, with with the the definition definition of the of buildingthe building typology typology and theand construction the construction system system to be used,to be whichused, resultwhich from result a firstfrom approach a first approach with the client.with the This client. decision This mustdecision be mademust atbe thismade stage, at this since stage, the since application the application of steel structuresof steel structures opens the opens range the of range the project of the development,project development, because thebecause structure the madestructure with made industrial with steelindustrial can be steel used can in several be used ways. in several This system ways. allowsThis system for modular allows coordination for modular ascoordination a form of manufacturing as a form of manufacturing planning, transportation planning, andtransportation assembly, and assembly, oriented for a better use of the materials, less waste of effort and a cost reduction at the construction site [1].

2.2. Flexibility, Materiality and Context The flexibility of steel for housing construction allows for the easy mutation of spaces through mechanisms incorporated in the partition walls, so that their proportion and harmony do not change, but provide a differentiated experience of spaces according to the need at the time. In a modular system, this concept of flexibility allows the composition of differentiated spaces, depending on needs and functions. Designs 2020, 4, 30 6 of 13 oriented for a better use of the materials, less waste of eﬀort and a cost reduction at the construction site [1].

2.2. Flexibility, Materiality and Context The flexibility of steel for housing construction allows for the easy mutation of spaces through mechanisms incorporated in the partition walls, so that their proportion and harmony do not change, but provide a differentiated experience of spaces according to the need at the time. In a modular Designssystem, 2020 this, 4, conceptx FOR PEER of flexibilityREVIEW allows the composition of differentiated spaces, depending on needs6 of 13 and functions. In the housings, there are spaces that cannot be completely flexible, such as sanitary In the housings, there are spaces that cannot be completely flexible, such as sanitary installations installations because there is a need for privacy, and the kitchens because of the need to avoid smells because there is a need for privacy, and the kitchens because of the need to avoid smells and steam and steam throughout the house. For such spaces, there must exist the possibility to be hidden. The throughout the house. For such spaces, there must exist the possibility to be hidden. The separation of separation of these spaces can be made through fixed walls functioning as technical columns, where these spaces can be made through fixed walls functioning as technical columns, where all necessary all necessary pipes for waters and sewers can be located, in addition to other technical equipment, pipes for waters and sewers can be located, in addition to other technical equipment, such as such as electrical panels. electrical panels. Cedric Price, as one of the most visionary architects of the 20th century, influenced architecture Cedric Price, as one of the most visionary architects of the 20th century, influenced architecture with his flexible housing systems. In spite of his little built legacy, his interventions were based at a with his flexible housing systems. In spite of his little built legacy, his interventions were based at time of the housing revolution that influenced some contemporary architects. He considered that a time of the housing revolution that influenced some contemporary architects. He considered that housing should have a flexible structure: “The house is no longer acceptable as a pre-set ordering housing should have a flexible structure: “The house is no longer acceptable as a pre-set ordering mechanism for family life” [10]. The architect’s idea was to study people’s way of life and to mechanism for family life” [10]. The architect’s idea was to study people’s way of life and to organize organize spaces accordingly. spaces accordingly. The Steel Housing project in 1967 (Figure 5) is thought around the concept of flexibility of The Steel Housing project in 1967 (Figure5) is thought around the concept of flexibility of spaces, spaces, allowing them to be changed by moving the walls over time. This project can be allowing them to be changed by moving the walls over time. This project can be characterized as the characterized as the “living machine” where it is possible to control spaces as needed throughout the “living machine” where it is possible to control spaces as needed throughout the day. The structure is day. The structure is a modular system composed of frames with 2 × 7 m in plan. It used a steel a modular system composed of frames with 2 7 m in plan. It used a steel structure, composed of structure, composed of several frames, and ×organized as if it was a kit of pieces containing several frames, and organized as if it was a kit of pieces containing prefabricated walls, platforms, prefabricated walls, platforms, floors, stairs and ceilings, which could be assembled and floors, stairs and ceilings, which could be assembled and disassembled as needed. This entire structure disassembled as needed. This entire structure was versatile, allowing for a rapid and continuous was versatile, allowing for a rapid and continuous change of spaces. The objective of each module was change of spaces. The objective of each module was to respond to the coordination of the space of the to respond to the coordination of the space of the house according to needs. In this sense, the space was house according to needs. In this sense, the space was designed to be flexible and to allow all designed to be flexible and to allow all possible changes. The modules were combined horizontally possible changes. The modules were combined horizontally and vertically, with only two stories. and vertically, with only two stories. This proposal was never built but became important in the field This proposal was never built but became important in the field of research on changing people’s of research on changing people’s habits during the 24 h cycle [10]. habits during the 24 h cycle [10].

Figure 5. SteelSteel Housing Housing by Cedric Price, 1967: simple simple model, model, structure structure and connections [11]. [11].

Michael HopkinsHopkins builtbuilt his his own own house house in 1975in 1975 with with two stories,two stories, using using a structure a structure with steel with proﬁles steel profilesto form to cells, form which cells, were which enclosed were enclosed with steel with panels steel or panels glass or (Figure glass6 (Figure). The construction6). The construction system wassystem so simplewas so thatsimple it could that it be could assembled be assembled from elements from elements of an industrial of an industrial catalog, choosingcatalog, choosing piece by piecepiece. by This piece. house This started house with started a construction with a construc systemtion through system the through connections the connections of standard components,of standard components, which was based on a structure of three-dimensional modules assembled from the addition of linear elements. The base of the geometric grid was square aluminum tubes and a connection point to connect them orthogonally. The whole house was organized according to these interconnected modules, allowing a diversity in the creation of interior spaces according to the needs of the inhabitant [12]. Based on the same constructive conception, Richard Horden designed the Yacht house in 1984 (Figure 7). The house was developed on one single floor, starting from the squared tubular system, and composed of prefabricated floor panels, roof, facade and dividing walls. The courtyards of the house were empty modules, which connected the interior and exterior. The façade modules were composed of “semi-opaque” elements in slatted wood and glass panels. The main objective of this project was flexibility and the possibility to be adapted and increased over the years. The lightweight Designs 2020, 4, 30 7 of 13

Designs 2020, 4, x FOR PEER REVIEW 7 of 13 which was based on a structure of three-dimensional modules assembled from the addition of linear structureelements. allowed The base it of to the be geometric easily assembled grid was square in the aluminum construction tubes site. and The a connection structure pointand the to connect filling elementsthem orthogonally. were built Thefrom whole standardized house was components organized and according could tobe theseeasily interconnected placed together modules, in any module,allowing forming a diversity a lightweight in the creation and ofweather interior resistant spaces accordingstructure [13]. to the needs of the inhabitant [12].

Designs 2020, 4, x FOR PEER REVIEW 7 of 13 structure allowed it to be easily assembled in the construction site. The structure and the filling elements were built from standardized components and could be easily placed together in any module, forming a lightweight and weather resistant structure [13].

Figure 6. Michael and Patty Hopkins House, 1975–1976 [12]. [12].

Based on the same constructive conception, Richard Horden designed the Yacht house in 1984 (Figure7). The house was developed on one single floor, starting from the squared tubular system, and composed of prefabricated floor panels, roof, facade and dividing walls. The courtyards of the house were empty modules, which connected the interior and exterior. The façade modules were composed of “semi-opaque” elements in slatted wood and glass panels. The main objective of this project was flexibility and the possibility to be adapted and increased over the years. The lightweight structure allowed it to be easily assembled in the construction site. The structure and the filling elements were built from standardized components and could be easily placed together in any module, forming a lightweight and weather resistant structure [13]. Figure 6. Michael and Patty Hopkins House, 1975–1976 [12]. Figure 7. Yacht house by Richard Horden, New Forest, England, 1984 [13].

The previous two houses, although designed to be produced in mass, were used as models for other projects based on the modular system with steel structures, combined with the concept of simplicity, flexibility, lightness, speed and relationship with the place and integration.

3. Architectural References—Modern and Contemporary Movement With the Modern Movement, the house became the most “desired” object to experience ideas and to affirm concepts, after a time of industrialization in which steel technology, in its pure form, was rarely used in housing projects. Some architects showed interest to design single-family and collective housings,Figure in which7. YachtYacht the house structure by Richard is part Horden, of the Newdesign Forest, concept. England, The 1984 steel [[13].13 structure]. became a new challenge for the project conception, becoming part of the architectural space, and evidenced by the transmittedThe previous lightness two two houses, houses, [6]. although although designed designed to to be be produced produced in inmass, mass, were were used used as models as models for forother otherThe projects projectsfunctional based based characteristicon onthe the modular modular of thesystem system modern with with space, steel steel structures,according structures, tocombined combined Bruno Zeviwith with inthe the ”Saber concept Ver ofa Arquitecturasimplicity, ﬂexibility,flexibility, (Knowing lightness,lightness, See Architecture)”, speedspeed andand relationship relationship is based withon with the the the open place place plan, and and integration. integration.which should solve the problem of the house for the average family, with the new construction technique using steel and 3. Architectural References—Modern and Contemporary Movement reinforced3. Architectural concrete, References—Modern allowing light structuresand Contemporary and open Movement spaces. Bruno Zevi relates modern architectureWith the to ModernModern a Gothic Movement, dream in space, the house where became new techniques the most “desired” allow audacity object toand experienceexperience the creation ideas of spacesand to with aaffirmﬃrm large concepts, open spans,after a and time the of stained-glassindustrialization windows in in which become steel steel widetechnology, technology, glass walls, in its allowing pure form, an wasabsolute rarely contact usedused ininof housinghousinginterior/exterior. projects.projects. TheSome internal architects partitions showed no interest longer torespond design to single-family static functions, and theycollective are only housings, thin separation in which elements, the structure with is the part possibility of the design of acquiring concept. differentThe steel shapes structure and became moving a freely,new challenge giving the for possibility the project to conception, combine different becoming environments part of the architectural [14]. space, and evidenced by the transmittedThere are good lightness examples [[6].6]. in the history of architecture that show some of the advantages of usingThe this functional construction characteristic system for of housings. the modern For example,space, according in the 1950s, to Bruno the “CaseZevi inStudy ”Saber House” Ver a program,Arquitectura launched (Knowing by EntenzaSee Architecture)”, in 1945, was is aimebasedd aton promoting the open newplan, housings which should where solveaesthetic, the problem of the house for the average family, with the new construction technique using steel and reinforced concrete, allowing light structures and open spaces. Bruno Zevi relates modern architecture to a Gothic dream in space, where new techniques allow audacity and the creation of spaces with large open spans, and the stained-glass windows become wide glass walls, allowing an absolute contact of interior/exterior. The internal partitions no longer respond to static functions, they are only thin separation elements, with the possibility of acquiring different shapes and moving freely, giving the possibility to combine different environments [14]. There are good examples in the history of architecture that show some of the advantages of using this construction system for housings. For example, in the 1950s, the “Case Study House” program, launched by Entenza in 1945, was aimed at promoting new housings where aesthetic, Designs 2020, 4, 30 8 of 13

The functional characteristic of the modern space, according to Bruno Zevi in ”Saber Ver a Arquitectura (Knowing See Architecture)”, is based on the open plan, which should solve the problem of the house for the average family, with the new construction technique using steel and reinforced concrete, allowing light structures and open spaces. Bruno Zevi relates modern architecture to a Gothic dream in space, where new techniques allow audacity and the creation of spaces with large open spans, and the stained-glass windows become wide glass walls, allowing an absolute contact of interior/exterior. The internal partitions no longer respond to static functions, they are only thin separation elements, with the possibility of acquiring different shapes and moving freely, giving the possibility to combine different environments [14]. There are good examples in the history of architecture that show some of the advantages of using Designsthis construction 2020, 4, x FOR system PEER REVIEW for housings. For example, in the 1950s, the “Case Study House” program,8 of 13 launched by Entenza in 1945, was aimed at promoting new housings where aesthetic, social, cultural social, cultural and innovation ideals could be present. Nowadays, the competition “The Living Steel and innovation ideals could be present. Nowadays, the competition “The Living Steel International International Architecture” is another example, among other ones. Architecture” is another example, among other ones. Such programs paved the way for a new perspective on the future of sustainability in housing Such programs paved the way for a new perspective on the future of sustainability in housing architecture, new housing concepts, challenges and construction methods, leading to the fast architecture, new housing concepts, challenges and construction methods, leading to the fast development of urban areas. development of urban areas. Following this new ideology, and responding to the needs and difficulties architects faced by Following this new ideology, and responding to the needs and difficulties architects faced by taking advantage of the industrial development, John Entenza decided to create the “Case Study taking advantage of the industrial development, John Entenza decided to create the “Case Study House House Program”, where some architects at that time chose to design economical houses by applying Program”, where some architects at that time chose to design economical houses by applying concepts concepts with prefabricated materials and profiled steel structures at low costs. with prefabricated materials and profiled steel structures at low costs. Having the option of using these new concepts, Pierre Koenig had to rectify his initial project Having the option of using these new concepts, Pierre Koenig had to rectify his initial project for for the House Koenig #1 (Figure 8), as it was expensive. This made him realize the importance of the House Koenig #1 (Figure8), as it was expensive. This made him realize the importance of modular modular planning and the use of standardized materials to make viable this type of construction for planning and the use of standardized materials to make viable this type of construction for single-family single-family housing. The chosen modular system was the 3 m squared, which, when put together, housing. The chosen modular system was the 3 m squared, which, when put together, allowed him to allowed him to organize the closed common spaces in a 12 × 6 m structure and a 3 × 6 m L-shaped organize the closed common spaces in a 12 6 m structure and a 3 6 m L-shaped garage. garage. × ×

Figure 8. House Koenig #1, Los Encinos Avenue, Glendale, Califórnia, 1950 [15]. Figure 8. House Koenig #1, Los Encinos Avenue, Glendale, Califórnia, 1950 [15].

The Case Study House #8 (Figure 99),), EamesEames House,House, byby CharlesCharles andand RayRay EamesEames inin CaliforniaCalifornia (1945–1949), is a project where the architect combined concepts such as industrialization, cinema and Japanese minimalism.minimalism. InIn thisthis project,project, the the “new” ”new” technology technology and and steel steel were were applied applied in orderin order to serve to serve the thesociety, society, creating creating personalized personalized housings housings for each for individual each individual at a low at cost, a low where cost, the where modular the naturemodular of naturethe entire of the system entire allowed system the allowed management the management and coordination and coordination of the entire of project,the entire with project, the possibility with the possibilityto be expanded to be andexpanded reformulated, and reformulated, or to create otheror to create forms withother theforms same with components. the same components. It constitutes It a constitutesgood example a good of modular example housing, of modular with housing, fast and wi easyth productionfast and easy and production assembly, and that assembly, allows greater that allowsﬂexibility greater in changing flexibility spaces. in changing The construction spaces. The system construction demonstrated system the demonstrated possibilities the that possibilities technology thatat that technology time provided, at that such time as steel,provided, glass, such asbestos as st (recentlyeel, glass, removed asbestos from (recently the market) removed and “cemesto”from the market)plates. Most and “cemesto” of the exterior plates. is glazed,Most of transparentthe exterior is and glazed, translucent, transparent although and translucent, it is counteracted although with it is counteracted with areas covered with white painted coating panels and primary colors. The house consists of regular modules of 2.25 m in length and 6 m in depth, made of black steel industrial profiles, positioned horizontally like “Japanese shoji panels” [16]. Designs 2020, 4, 30 9 of 13 areas covered with white painted coating panels and primary colors. The house consists of regular modules of 2.25 m in length and 6 m in depth, made of black steel industrial proﬁles, positioned horizontallyDesigns 2020, 4, likex FOR “Japanese PEER REVIEW shoji panels” [16]. 9 of 13 Designs 2020, 4, x FOR PEER REVIEW 9 of 13

Figure 9. Case Study House #8 by Charles and Ray Eames, Eames House, Santa Mónica, Califórnia, Figure 9. Case Study House #8 by Charles and Ray Eames, Eames House, Santa Mónica, Califórnia, Figure1945–1949 9. Case [17]. Study House #8 by Charles and Ray Eames, Eames House, Santa Mónica, Califórnia, 1945–1949 [[17].17]. At the same time as the “CSH program”, in New York Philip Johnson designed the “Glass At thethe samesame time time as as the the “CSH “CSH program”, program”, in New in New York York Philip Philip Johnson Johnson designed designed the “Glass the House”“Glass House” in New Canaan in 1949 (Figure 10). This project is considered one of the slenderest examples inHouse” New in Canaan New Canaan in 1949 in (Figure 1949 (Figure 10). This 10). projectThis project is considered is considered one one of the of the slenderest slenderest examples examples of of American modernism, where the experience of space can be questioned because it is all in glass. Americanof American modernism, modernism, where where the the experience experience of of space space can can be be questionedquestioned becausebecause itit is all in glass. glass. The architect lived in it for 58 years. The architect himself refers to it as “the diary of an eccentric The architect lived in it forfor 5858 years.years. The architect hi himselfmself refers to it as “the diary of an eccentric architect”. In this project, Johnson had no concern with sustainability in architecture. The building architect”. In this project, Johnson had no concernconcern withwith sustainabilitysustainability inin architecture.architecture. The building consists of a “box” structured with black steel beams wrapped with glass from the floor to the consists ofof aa “box” “box” structured structured with with black black steel steel beams beams wrapped wrapped with with glass glass from thefrom ﬂoor the tofloor the ceiling.to the ceiling. The interior space was divided by low walnut cabinets and a brick cylinder containing the Theceiling. interior The spaceinterior was space divided was bydivided low walnut by low cabinets walnut andcabinets a brick and cylinder a brick containing cylinder containing the toilet andthe toilet and in which the fireplace is embedded. The purpose of this house was to obtain a space to intoilet which and the in which ﬁreplace the is fireplace embedded. is embedded. The purpose The of purpose this house of this was house to obtain was a to space obtain to protecta space the to protect the inhabitant, but also continuing to allow for a relationship and a better use of the natural protect the inhabitant, but also continuing to allow for a relationship and a better use of the natural inhabitant,space [18]. but also continuing to allow for a relationship and a better use of the natural space [18]. space [18].

Figure 10. Glass House by Philip Johnson, New Canaan, 1949 [19]. Figure 10. Glass House by Philip Johnson, New Canaan, 1949 [[19].19].

With the same concept, the ”Farnsworth “Farnsworth House” by by Mies Mies Van Van der Rohe in Plano (Figure 11),11), With the same concept, the ”Farnsworth House” by Mies Van der Rohe in Plano (Figure 11), Illinois, fromfrom 1950, 1950, is is seen seen as anas iconan icon of modern of mode architecturern architecture and one and of theone most of the recognized most recognized buildings Illinois, from 1950, is seen as an icon of modern architecture and one of the most recognized inbuildings the definition in the ofdefinition the architectural of the architectural language of language the 20th of century. the 20th For century. Mies, error For Mies, cannot error exist cannot in the buildings in the definition of the architectural language of the 20th century. For Mies, error cannot searchexist in for the perfection. search for Inperfection. this sense, In thethis choice sense, of th materiale choice (steel)of material and technologies(steel) and technologies for its application for its exist in the search for perfection. In this sense, the choice of material (steel) and technologies for its guaranteeapplication the guarantee rigor. As the in the rigor. previous As in example, the previous the main example, characteristics the main of characteristics this house are of transparency, this house application guarantee the rigor. As in the previous example, the main characteristics of this house fluidityare transparency, of spaces andfluidity the subtleof spaces diff erentiationand the subtle that differentiation is almost nonexistent that is almost between nonexistent public and between private. are transparency, fluidity of spaces and the subtle differentiation that is almost nonexistent between Thepublic place and of private. intervention The place for this of projectintervention is in the for middle this project of a forest is in withthe middle a lagoon of anda forest all the with picturesque a lagoon public and private. The place of intervention for this project is in the middle of a forest with a lagoon surroundings.and all the picturesque The construction surroundings. procedure The hasconstruc broughttion theprocedure latest ideas has ofbrought “standardization” the latest ideas to the of and all the picturesque surroundings. The construction procedure has brought the latest ideas of last“standardization” consequences, to strongly the last linking consequences, the interior strongly with linking the exterior, the interior providing with a the fluid, exterior, continuous providing and “standardization” to the last consequences, strongly linking the interior with the exterior, providing a fluid, continuous and flexible space. The architect chose to lift the house from the ground with a a fluid, continuous and flexible space. The architect chose to lift the house from the ground with a stilt system to avoid flooding problems. The design is composed of a rigorous layout using minimal stilt system to avoid flooding problems. The design is composed of a rigorous layout using minimal lines, promoting a language of illusion that it is “floating” on the ground, allowing it to be adapted lines, promoting a language of illusion that it is “floating” on the ground, allowing it to be adapted to all seasons which are very strict in winter with floods and snow [20]. to all seasons which are very strict in winter with floods and snow [20]. Designs 2020, 4, 30 10 of 13

flexible space. The architect chose to lift the house from the ground with a stilt system to avoid flooding problems. The design is composed of a rigorous layout using minimal lines, promoting a language of illusion that it is “floating” on the ground, allowing it to be adapted to all seasons which are very strict in winter with floods and snow [20]. Designs 2020, 4, x FOR PEER REVIEW 10 of 13 Designs 2020, 4, x FOR PEER REVIEW 10 of 13

Figure 11. Farnsworth House by Mies Vand der Rohe, Illinois, 1950 [21]. Figure 11. FarnsworthFarnsworth House House by by Mies Mies Vand der Rohe, Illinois, 1950 [[21].21].

The CHS#21CHS#21 (Figure (Figure 12 )12) by Pierreby Pierre Koenig’s Koenig’s (1958–1960) (1958–1960) represents represents the culmination the culmination of the architect’s of the The CHS#21 (Figure 12) by Pierre Koenig’s (1958–1960) represents the culmination of the architect’sresearch in research his interest in his in steelinterest construction in steel construc and thetion perfecting and the perfecting of constructive of constructive details. He details. designed He architect’s research in his interest in steel construction and the perfecting of constructive details. He designedan elegant an and elegant austere and pavilion austere for pavilion a childless for a couple, childless located couple, in anlocated elevated in an place elevated in Hollywood place in designed an elegant and austere pavilion for a childless couple, located in an elevated place in HollywoodHills. The concept Hills. The of this concept project of wasthis thatproject of the was “universal that of the house”, “universal which house”, would bewhich possible would to be Hollywood Hills. The concept of this project was that of the “universal house”, which would be producedpossible to in be mass. produced For this, in mass. the elements For this, designedthe elements for itsdesigned assembly for incorporatedits assembly incorporated only two types only of possible to be produced in mass. For this, the elements designed for its assembly incorporated only twodetails types for theof details columns, for allowing the columns, any element allowing to beany used element for various to be solutions.used for various It is a minimalist solutions. project, It is a two types of details for the columns, allowing any element to be used for various solutions. It is a withminimalist contained project, spaces with that contained open to spaces exterior that areas open designed to exterior with areas water designed mirrors with all around water mirrors the house. all minimalist project, with contained spaces that open to exterior areas designed with water mirrors all Thearound geometric the house. shape The of geometric the house shape is even of more the house evident is even with more its ﬂat evident roof, which with isits built flat roof, with which exposed is around the house. The geometric shape of the house is even more evident with its flat roof, which is builtribbed with steel exposed sheets. ribbed The house steel was sheets. designed The house in a steel was structure,designed consistingin a steel structure, of columns consisting and beams, of built with exposed ribbed steel sheets. The house was designed in a steel structure, consisting of columnsin modules and with beams, 10 by in 22 modules feet sections with (1 10 foot by= 2230.48 feet cm),sections under (1 whichfoot = glass30.48 walls cm), wereunder mounted which glass with columns and beams, in modules with 10 by 22 feet sections (1 foot = 30.48 cm), under which glass wallsalternated were claddingmounted steel with and alternated plaster panelscladding [22 steel]. and plaster panels [22]. walls were mounted with alternated cladding steel and plaster panels [22].

Figure 12. CSH#21 by Pierre Koenig, West Hollywood, 1958–1960 [23]. Figure 12. CSH#21CSH#21 by by Pierre Pierre Koenig, Koenig, West Hollywood, 1958–1960 [[23].23]. The way of living is changing. The economy requires that homes are increasingly smaller and The way of living is changing.changing. The economy requires that homes are increasingly smaller and lack quality in spaces. Could this type of housing be able to respond to the functional and cultural lack quality in spaces. Could Could this this type type of of housing be be able to respond to the functional and cultural needs of our current lifestyle? Could it be adapted to the different cultures in the world? needs of our current lifestyle? Could it be ad adaptedapted to the didifferentﬀerent culturescultures inin thethe world?world? In 2005, the World Steel Association launched the “Living Steel” program to show why steel is a In 2005, the World Steel Association launched thethe “Living Steel” program to show why steel is a good bet for the construction of preeminent housing, especially at a low sustainable cost. This good betbet forfor the the construction construction of preeminentof preeminent housing, hous especiallying, especially at a low at sustainablea low sustainable cost. This cost. program This program was developed with the main objective of becoming a forum for submitting proposals in wasprogram developed was developed with the mainwith objectivethe main ofobjective becoming of becoming a forum for a forum submitting for su proposalsbmitting inproposals which the in which the steel industry would be the protagonist of the project conception, from architects around whichsteel industry the steel would industry be thewould protagonist be the protagonist of the project of the conception, project conception, from architects from aroundarchitects the around world, the world, to respond to the needs of efficient and responsible housing. To make it work, all the the world, to respond to the needs of efficient and responsible housing. To make it work, all the teams had to demonstrate that steel was the distinctive building material for low-cost sustainable teams had to demonstrate that steel was the distinctive building material for low-cost sustainable housing [24]. housing [24]. The concept of the SymHouse proposal (Figure 13) is the biological symbiosis of the interaction The concept of the SymHouse proposal (Figure 13) is the biological symbiosis of the interaction between two living organisms, man and the living (house), in which, in the flexible interior, it is the between two living organisms, man and the living (house), in which, in the flexible interior, it is the inhabitant who controls. Stuart Piercy said that “there is a contrast between western-style houses inhabitant who controls. Stuart Piercy said that “there is a contrast between western-style houses which are in general closed with the permeability of subtropical architecture.” [22]. Here, the which are in general closed with the permeability of subtropical architecture.” [22]. Here, the architects used several layers that allowed forward or backward movement, seeking the essence of architects used several layers that allowed forward or backward movement, seeking the essence of Designs 2020, 4, 30 11 of 13

to respond to the needs of eﬃcient and responsible housing. To make it work, all the teams had to demonstrate that steel was the distinctive building material for low-cost sustainable housing [24]. The concept of the SymHouse proposal (Figure 13) is the biological symbiosis of the interaction between two living organisms, man and the living (house), in which, in the ﬂexible interior, it is the inhabitant who controls. Stuart Piercy said that “there is a contrast between western-style houses which are in general closed with the permeability of subtropical architecture.” [22]. Here, the architects Designs 2020, 4, x FOR PEER REVIEW 11 of 13 used several layers that allowed forward or backward movement, seeking the essence of Kolkata Kolkata(Calcutta) (Calcutta) in India. in The India. steel The doors steel were doors designed were based designed on the based Indo-Islamic on the culture,Indo-Islamic protecting culture, from protectingrain and sun,from creating rain and some sun, privacy creating as some the interior privacy doors as the are interior made of doors glass forare amade greater of amplitudeglass for a to greaterthe outside. amplitude to the outside.

FigureFigure 13. 13. SymHouseSymHouse by by Piercy Piercy Conner, Conner, United United Kingdom, Kingdom, Living Living Steel Steel International International Architecture, Architecture, India,India, 2005 2005 [24]. [24 ].

TheThe construction construction techniques techniques used used in in this this projec project,t, based based on on the the program program for for low-cost low-cost apartments, apartments, areare the the same asas thosethose used used in in the the construction construction of o ffiofces, offices, being being quickly quickly built in built the factory, in the andfactory, assembled and assembledon the construction on the construction site. The structure site. The is made structur of steele is andmade the of slabs steel are and made the of lightweightslabs are made concrete, of lightweightwith ribbed concrete, metal sheets with usedribbed as metal composite sheets slabs. usedThe as composite exteriors are slabs. covered The exteriors with perforated are covered metal withscreens perforated which, asmetal the sunscreens moves which, in the as sky,the createsun mo patternsves in the inside, sky, and, create at night,patterns provide inside, light and, plays at night,with theprovide internal light lights. plays The with shape the internal of the buildings lights. The maximizes shape of naturalthe buildings light and maximizes ventilation. natural At the light top andof theventilation. buildings, At there the aretop terraces of the withbuildings, gardens, there and are the terraces bedrooms with include gardens, “mezzanines” and the bedrooms over patios includeat the level“mezzanines” of the living over rooms, patios allowing at the forlevel a visualof the andliving real rooms, extension allowing of the spaces.for a visual and real extensionWith of the the usespaces. of steel in housing construction, it is possible to create lightweight, elegant and transparentWith the structures,use of steel with in housing the potential construction, for large it openings is possible and to spatial create flexibility.lightweight, This elegant minimalist and transparentsimplicity andstructures, structural with slenderness the potential allow for for large an interconnection openings and betweenspatial flexibility. the interior This and minimalist the exterior, simplicitymaking the and houses structural perfectly slenderness integrated allow in the for place. an interconnection between the interior and the exterior, making the houses perfectly integrated in the place. 4. Conclusions 4. ConclusionsWith the industrialization, new materials produced in mass were used, allowing the study and developmentWith the industrialization, of new ways of new living. materials One of produc the driversed in ofmass this were change used, was allowing Le Corbusier the study with and his developmentconcept of “living of new machine”. ways of Heliving. redefined One of the the existing drivers values of this and change introduced was Le new Corbusier concepts, with with his the conceptaim of improvingof “living machine”. the quality He of redefined life of people the exis in theting private values space. and introduced There was new a group concepts, of architects with thewho aim innovated of improving and implementedthe quality of the life construction of people in of the single-family private space. houses There with was steel a group structures. of architectsThe structures who innovated were left in and sight, implemented taking advantage the cons of thistruction rising of material, single-family which houses is currently with mostlysteel structures.used in large The architectural structures andwere industrial left in sight, works. taking The group advantage that participated of this rising in the material, “Case Study which House” is currentlyprogram mostly created used by John in large Entenza, architectural aimed to and create industrial economical works. and The unpretentious group that participated houses that in would the ”Caserespond Study to the House” needs ofprogram the inhabitants created and by that John would Entenza, be more aimed functional to create and simple, economical with a betterand unpretentiousorganization andhouses flexibility that would of living respond spaces to and the with needs larger of the usable inhabitants areas, using and prefabricated that would be materials. more functional and simple, with a better organization and flexibility of living spaces and with larger usable areas, using prefabricated materials. From that time, the concept of ”living” has been thought and rethought by several architects, using industrialized processes, and giving a quick response to the lack of housing that existed at the time due to the rural exodus. Currently, it responds to the changes in ways of living influenced by globalization and the interchange of cultures, and the need for constant changes imposed by these intercultural and socioeconomic changes. Many of the innovative solutions of modular systems, which were created throughout history, are interpreted as isolated objects that can be placed anywhere, but that do not belong anywhere; they are almost habitable sculptural works. In order to be characterized as architecture, it is Designs 2020, 4, 30 12 of 13

From that time, the concept of “living” has been thought and rethought by several architects, using industrialized processes, and giving a quick response to the lack of housing that existed at the time due to the rural exodus. Currently, it responds to the changes in ways of living influenced by globalization and the interchange of cultures, and the need for constant changes imposed by these intercultural and socioeconomic changes. Many of the innovative solutions of modular systems, which were created throughout history, are interpreted as isolated objects that can be placed anywhere, but that do not belong anywhere; they are almost habitable sculptural works. In order to be characterized as architecture, it is important to combine concepts that must be part of the creative conception of the architectural project, namely: the study of the living space, the relationship of housing with the place (the identity of the place), the structural system as a concept, the modular system and the time and space factors, and the flexibility, materiality and context of the combination of architecture with the steel structure in sight. The case studies analyzed in this article, being unique works and without repetition, allowed the understanding that it is fundamental to think about the project as a whole—structure and architecture. It is necessary to define the living spaces using the lines—the steel structure—as a network which in architectural design defines the spaces to inhabit. After the study of this type of architecture, several constructive and historical contributions can be pointed out, namely: the speed of construction, a work always being clean and precise and with minimum errors which can be masked with covers, the lightness conveyed by their framing, the perfect relationship with the surroundings, the permeability and flexibility of spaces which easily allows changes. This type of architecture is very suitable to the pandemic situation that we have been experiencing, which has given people an understanding that houses were not built to remain. After studying and analyzing this topic, the second companion article presents and discusses the development of an innovative prototype in a steel structure, where the acquired knowledge is applied. It consists of a modular system applied to single-family housing, in which steel remains part of the design concept, not only as a structural element, but also as an aesthetic element. The needs of contemporary “Living” are reinterpreted, with all the changes and cultural influences due to globalization, comparing it with the “Living” in Portuguese popular architecture, which has a simplistic character and minimal spaces, and referring it to a given place.

Author Contributions: I.D.D.C. investigated the topic and wrote the article. L.F.A.B. revised the article. All authors have read and agreed to the published version of the manuscript. Funding: This research received no external funding. Conﬂicts of Interest: The authors declare no conﬂict of interest.

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