The naturalisation of architecture

Sustainability is gaining a firm presence within the discipline of architecture in spite of the number of obstacles with which it has been challenged: either confronting detractors, sceptics, and the discredit resulting from the abusive use of the term as a marketing tactic, or dealing with the actual practicalities inherent to its implementation. This heightened environmental consciousness increasingly engrained within the profession is solidly supported by a growing social, political and media interest, which has impelled new regulations and the involvement of new experts like physicists, engineers, and ecologists in the design process. This phenomenon is transforming architectural practice and design techniques, moving the focus from a mechanical perspective of architecture (tectonics, construction, materiality, structure) to a biotechnical approach which attempts to equip the architect with instruments to regard buildings as living structures permanently exchanging energy with their environment. Using the environment as a creative generator for design has prompted the emergence of new aesthetic models in current architectural design. The access to new tools, together with new concerns and ways of thinking, have opened new lines of intervention that seem to affect the profession in a more fundamental way. The focus of this paper is to provide an account of these cultural constructs as experimental aesthetic systems, with the intention of not only clarifying their principles and objectives, but also reflecting on the design techniques associated to them. Ultimately, this paper provides a reflection on the role of aesthetics in sustainable design, and on the critical question: is sustainability finally becoming an intrinsic part of architecture?

positions. For example, some architects claim that there is very little relationship between the notion of sustainability and the interests of contemporary architecture. Others use the term sustainability in an ambiguous way. Even clear advocates of sustainable architecture rarely talk in terms of the 'style' or 'aesthetics' of their buildings. Some controversial statements about how sustainability is all about ethics rather than aesthetics have recently nurtured substantial discussions in the media. Cesar Pelli alleged: 'most architects will keep giving the highest value to the looks of the building -that's how we know most buildings -and the sustainability doesn't necessarily photograph'. 2 Wolf Prix, co-founder of Coop Himmelb(l)au, declared: 'sustainability belies signification -and it is therefore not possible to generate "aesthetics" from the term sustainability'. 3 Lastly, Peter Eisenman asserted: '"Green" and sustainability have nothing to do with architecture. Some of the worst buildings I have seen are done by sustainable architects. They may optimise ecological constraints today but they don't do anything for the culture in terms of the excess required for architecture. '4 While sustainable architecture calls for austerity in the use of resources and the greatest possible reduction of any waste, aesthetics seems linked to the sensuality, enjoyment, and luxury experienced in a space with certain proportions, materials, and ornamental style. The truth is that for a large sector of the profession sustainability, by definition, cannot be framed within an aesthetic proposal. Aesthetics is regarded as the antithesis of any value close to the extreme functionality and efficiency demanded by energy savings.
However, based strictly on biological evidence, some theoretical positions welcome that 'excess' of energy that Eisenman mentioned as an indispensable contribution to cultural values. Some scholars postulate that it is precisely in energy's nature that it be expended; that waste is a fundamental part of the natural process. As Henri Lefevbre argued in L'Architectonique Spatiale: 'the idea that the principle of economy is biologically inadequate goes back to Spinoza and can be traced through Schiller, Goethe, Marx and Nietzsche'. 5 Living organisms capture energy from their vicinity, use part of it for their basic needs (nutrition, respiration, heat, etc.), and stock a surplus. This surplus is what distinguishes life from survival; what allows the organism to take initiatives. That stocked energy must find opportunities to be expended, otherwise the organism degenerates, and as in any release of energy, when expended it will have an impact on the environment: as Lefevbre says, 'waste, play, struggle, art, festival -in short Eros -are themselves a necessity'. 6 We are trying to learn how to control energy by observing and emulating natural phenomena and processes, but are we approaching energy's dynamic condition correctly? It is in energy's nature to be ephemeral, vibrant, mutant, boundless, and ungraspable, but we are trying to contain, define, and stock it at our discretion. If architecture is considered a 'living organism' in a constant exchange of energy with its surroundings, we not only need to manage energy to achieve balance, but also use this excess in favour of that leeway for creativity.
The aesthetics of sustainable technology has been ruled mostly by the maxim of invisibility, trying to make the technical 'prosthesis' as unnoticed as possible. If sustainability is the framework from which a future architecture must germinate, we should determinedly question if we must keep making its components invisible, or if architectural sensuality and beauty can be truly sustainable.
For some theorists and architects this is not only so but is absolutely essential. Architecture always materialises somehow and, consequently, the architecture of sustainability is to be characterised by a convincing conceptual expression: it must develop its own formal vocabulary with which to build its own aesthetic semantic field. In 1994, Ezio Manzini drew our attention to this issue: not only is there no contradiction between ethics and aesthetics, but also aesthetics should be taken seriously and not as a 'secondary' dimension, since idea is not new. The influence of biological analogies on architecture can be traced to about 1750, and the meaning of 'organic' that we use in architecture today was established at the beginning of the nineteenth century. 11 The findings from studies on form growth, the relationship between form and function or the effect of the environment and climate on the natural elements, was soon extrapolated to design, which became more evident at the start of the twentieth century. From the 1920s' theories on natural formative processes (R. H. Francé, F. J. Kiesler, and S. Ebeling), to the sensorised and intelligent skins of the 1980s and 1990s (M. Davies), 12 design has attempted to emulate different aspects of the natural environment which, in Detlef Mertins' words, showed our continuous 'aspirations for ecologically benign technologies that enable buildings to perform as if they were alive'. 13 This article identifies and speculates on some of the latest trends which, continuing this way of thinking, are trying to erase the boundary between culture and nature. In the production of this common ground, what are the aesthetic implications of a naturalisation of architecture?

Respect for nature
The subtlest propositions pursue an architecture that is receptive to the heterogeneous sensory qualities of the natural context. This feature is present, to a greater or lesser extent, in any vernacular architecture, and particularly present in Japan. Kengo Kuma explains that it is through the careful incorporation of colour, light, smell, sound, seasonal dynamics, and variations in the natural landscape that nature is manifested in Japanese architecture.
14 It is about starting the house from the garden following the gardener's practice: absorbing the rhythms of nature, instead of creating a limit, a shield with which to block it or a shelter from it. Junichiro Tanizaki 15 aesthetics represents 'the way a historical period and the values it contains take shape', 'a way of expressing a synthetic, and therefore intelligible form, the complexity of a proposal'. 7 For architects to be engaged and recognise their role, it is critical to regard the notion of sustainability as a form of aesthetic thinking that is fundamentally implicit to the discipline. For that to happen, architects should operate ontologically from within both sustainability and technology to develop their own practices, as opposed to leaving their application to the new class of experts, who will tackle it as an addition to whatever the architect is designing.
The end of the 1990s brought a new paradigm to approach this issue. During the design process of the London City Hall (1997)(1998)(1999)(2000)(2001)(2002), Foster + Partners and Arup jointly produced a new strategic framework in which they reversed their traditional modus operandi, strongly supported by technical solutions. They proposed a triangular diagram where architectural form, passive systems, and active systems were ordered in ascending progression 8 [1]. This inverted hierarchical approach committed them to an environmental strategy firmly supported by designoriented operations. In the same period, three other leaders of high-tech also proposed a new relationship with technology: Helmut Jahn, Werner Sobek, and Matthias Schuler coined the term Archi-neering, following the same inclination towards producing a common discourse for low-tech and high-tech responses to sustainability. However, how can this unified design method be put into operation? The image of sustainability is still mostly regarded as either one of two extremes: as technological add-ons implemented in existing aesthetic trends (high-tech, sophisticated and expensive, active design), or as new versions of the North American counterculture environmentalism of the 1960s and 1970s (back-to-land, low-tech, social, inexpensive, passive design).
Recent approaches address this problem by focusing on the dialogue between natural and artificial environments, displacing the typical discourses between passive versus active design and moving towards a deeper interrelation between these two concepts, which now are envisioned as part of the same complex ecosystem: the super-ecological. 9 The distance between outside and inside, between the objective and the subjective, is challenged. 10  design, without losing sight of simple, traditional methods. Iñaki Abalos, in his analysis of this question, suggested that sustainable architecture will probably come up with a 'technical and aesthetic hybrid model' where both approaches are combined -'addition sustainability (more layers more complex) and subtraction sustainability, useful in the first and third world' -but that undoubtedly must give primacy to the architectural form.

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He refers to these forms as 'massive systems, almost archaic', 'a vision yet to come', 20 but that would have some connections with proposals taking landscape as the project's driver.

Adaptation, integration, imitation of nature
Organisational landscapes: megaforms In this endeavour to create a dialogue with the natural context, many architects try to find a basis for action in the 'methods and tectonics of landscape'. In this approach the building's envelope is no longer just a sensitive mediator that exchanges inputs/outputs with the exterior world, but rather the building is designed as an extension of the natural landscape, using landscape design techniques to arrange the spatial configuration of architecture. It is therefore important to understand what these techniques are, the elements that make up landscapes, and what implicit and explicit qualities they bring to the new architectural space. The dialogue that a building establishes physically with its site depends on a number of factors: passively, with its topography, geometry and space; actively, with its ecological, climatological, and functional processes. The concept of megaform 21 proposes an aesthetic sustainable model in this direction: as a structure capable of modulating the landscape, establishing itself as a continuum with the surrounding topology. Kenneth Frampton discusses the megaform model as a very pertinent vehicle towards 'sustainable and environmentally responsible design that is both culturally stimulating and aesthetically expressive'. 22 In his discourse, sustainability should be defined by the durability and adaptability of buildings, where the topographic dimension must take precedence as the factor that links the architectural intervention to a specific context, emphasising its 'locality' as opposed to a sculptural and universal character. This design practice focuses on 'folding' the architectural components to be incorporated into the landscape's tectonics, rather than on using technology. However, although visually there is a unification of language, mere topological adaptation presupposes no efficiency in the use of natural resources. Despite topography taking a prominent role for form generation and the spatial relationships that should articulate the building use between inside and outside, Frampton is aware of the need for a symbiotic conception at all levels: the built environment should participate in ecological, geological and hydrological processes; that is, it should interact with the dynamic forces present in any environmental context.
It is infinitely preferable to suggest rather than to show, veiling all of the space with diffuse shadows, allowing the house's limit to be barely discerned from the inside, generating the internal spaces from a matrix of elements that screen the external light. Every point in the sequential structure of the Japanese house always allows a diagonal view to the garden's natural landscape, as one of the levels in the gradation of environments. The Japanese house is not insulated, so it relies on material use, passive energy strategies, and user habits to minimise its ecological impact. Nature is not only visually present: the house uses natural, light, permeating, low processed or completely untreated materials -wood, bamboo, straw, willow, paper, rope -which age, breathe, and expel their scent according to each season. This is clearly found in traditional examples, like in the Yoshijima Heritage House in Takayama (1890s) [2], and contemporary projects, such as the Suntory Museum of Art in Tokyo (2007).
Kuma identifies environmental design with this sensitive and emotional design that permits the house to be adaptable and permeable to the outside, and not with the artificial climate of the environmental engineers. 16 His discourse does not find poetical or architectural value in the building services, but nevertheless contemporary Japanese architectural practice is making good use of artificial environmental systems and, in well-known cases, it does not even disdain the use of high-performance, sophisticated technology in combination with poetic dialogue with the exterior environment. 17 More committed positions try to find an appropriate role for technology in contemporary topographical this intervention may be. The overheating suffered by the occupants serves as an example, due to the fact that the design team did not consider the wind in the area when they designed the external blinds to protect the glass envelope (which were persistently retracted, otherwise they would blow away, break or produce noise incompatible with the educational activities taking place inside the building). 23 Patterns of nature The building should reflect the immediate landscape, but it must also consider the forces that natural phenomena exert on form. Natural forces shape natural landscapes, and the reproduction of the local topography per se addresses this issue only superficially. Some architects are studying these phenomena to propose architectures that reveal the conditions of their environment, just as these forces are reflected in the growth and patterns of nature: the adaptation patterns of life. Landscape differentiation and diversification is related to how the different organisms have adapted to resist strong winds, extreme temperatures and solar radiation, or particular water conditions.
Buildings are subjected to the same natural forces that have caused differentiation in nature, thus their built form should evidence these influences. This theory, headed by Ralph Knowles since 1962, 24 (2011), despite generating an artificial landscape in synergy with the existing topography, do not participate in the energy exchange processes of the ecosystems in which they are inserted [3,4]. This design methodology shares with vernacular architecture skilful integration within the landscape, but still does not embrace important sustainable indicators, such as the provision of materials in a way in which their renewal and constant supply is guaranteed, or the creation of an architecture that is not only sensitive to climate, but also effective in regulating phenomena and energy exchange in a passive way. Although claiming a deep relationship between architecture and landscape in all its layers, this mimicry is only visual and does not constitute integration in the energy balance. At the least, it seems too naive to assert that the Rolex Learning Centre is a sustainable building, however   The naturalisation of architecture Rosa Urbano Gutiérrez appropriation of its natural elements. There is no doubt that our tendency towards a biophilic society 26 must have also contributed to this way of operating. Our society is increasingly aware of the benefits that result from human interaction with dynamic natural environments that are sensorially stimulating, and how they help to promote our wellness in physical, psychological, and health terms.

Biomimetic architecture
One line of action in this direction investigates biologically-inspired designs. The biomimetic model is based on the processes of natural selection, evolution and optimisation, and therefore intends to generate design through working with the parameters that allow an organism to adapt its physiology over time. Using generative systems that meet parametric or environmental conditions, this design methodology pursues the generation of form as a direct translation of function [6]. 27 As opposed to the above-referred mimetic process that literally replicated a natural product, the new approach is based rather on understanding the intrinsic relationships with which natural phenomena are deployed, and how 'we position ourselves and establish an intimate relationship with the biological environment'.

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To put this into practice, it is not only necessary to identify the principles but also to set the metrics with which to assess ecosystems, so as to be able to make built habitats work in the same way that natural habitats do. The critical question of this procedure is to gauge whether natural factors can effectively be extrapolated to the artificial environment, and which are the factors that define ecological integrity in a natural ecosystem. According to the ecologists, the and rhythms that make clear the diversity and richness of forms that exist in nature. Form is not determined a priori; instead the design process generates adaptable forms to each natural phenomenon. For instance, in maximising light distribution, form will emerge from the adaptation of the building to the solar path. Optimising the use of solar light will affect the form of the building's mass, the relationship between the building and its surroundings (that is, avoiding obstacles), the type and size of openings, the inclination of walls, and the creation of light wells, courtyards, galleries, atria, conservatories, cornices, overhangs or shading devices [5].
In a similar but more technical approach, some design propositions attempt to literally integrate natural adaptation patterns, in the majority of cases through the reproduction of natural biological performances by mechanical means which are then applied to specific areas of the building. We can find a typical example of this strategy in the envelope designed by Nicholas Grimshaw's practice for the Las Palmas Water Theatre: by taking inspiration from the Namibian fog-basking beetle, the envelope generates fresh water for the building.
Whether shaping the building through topographical or environmental forces, both design approaches refer to a form-generating methodology that leads to a very diverse range of results. Yet the definition of aesthetics responds to a recognisable set of stylistic features. If there is no single image associated with a concept, but it rather refers to a process resulting in a variety of expressions, can we still recognise an aesthetic pattern of sustainability?
Actually, if we are to take nature as a reference, this problem reverts to a previous question: considering the vast diversity of elements, shapes and relationships that occur in natural ecosystems, what are the aesthetics of nature? What are the qualities that we automatically recognise in nature, that make us categorise items as belonging to the natural? And then, what is the level of subjectivity in our conception or perception of nature?

Appropriation of nature
The prominence that health as a global theme has recently taken in all research settings, along with a new understanding of comfort and wellbeing as part of the definition of sustainability, might have led to another negotiation with nature -through the  [8]. In this mixed tectonics, plants and animals donate their image to the architectural object, and the technology that enables the reproduction of the energy processes is concealed within the living matter. In these proposals, the delineation of the form and its limit still does not rely on clear determinants: the processes are consistent with the context, but the natural only wraps an architectural mass that is unrelated to the driving concept, which actually, in many cases, uses orthogonal boxes. We can find the same disconnect between envelope and building form in the new initiatives to incorporate photobioreactors or aquaponic systems, such as the integrity of an ecosystem is defined as 'the ability to perform nature's services, evaluated in terms of biodiversity, stability, resilience, sustainability and naturalness'. 30 If we accept this definition, then the issue is how to transfer these five indicators into the 'built habitat'. As common denominators in all ecosystems, we can agree on the existence of: an organic dynamic condition of nature that includes the ability to adapt to change; fractal and complex geometries; energy balanced relationships; time and weather based cyclical processes; overall harmony; and synergetic and symbiotic relationships among their constituents. Design methods derived from digital design using natural algorithms aim to recreate these parameters. However, we are still far from achieving the wealth present in nature due to our limitations in modelling the infinite possible occurrence of accidents and contingencies that lead to adaptation and diversity, and this takes us to simplistic geometrical configurations. To be truly part of the ecosystem, a rather critical aspect is to allow the inert elements to interact with the natural ones, thus creating symbiotic relationships with the natural system, instead of subjugating it.
Living architecture Some proposals of artificial ecosystems have proposed the idea of putting natural processes and living things into play, integrating fauna and flora into the architectural components. The basis for this argument is to imagine that the non-natural environment will be less artificial if it is mixed, as much as possible, with life: moving the natural ecosystem to the actual building fabric, using living matter as a building material. If living, natural elements were only the content of greenhouses, zoos or gardens, now these elements can come out of their enclosures and interwoven with inert materials to become the container -the inclusion of the external 7a,b environment arq . vol 20 . no 3 . 2016 263 The naturalisation of architecture Rosa Urbano Gutiérrez microalgae facade developed for the BIQ building in Hamburg by Splitterwerk and Arup (2013) [9], originally conceived as sun-tracking louvres, or the prototype for a Vertical Farm developed at ENEA for EXPO 2015 [10].
On a theoretical level, concepts like synthetic lifeforms and vibrant matter also investigate new kinds of living architectures. The former examines how emergent biological developments could be embedded in the building fabric at molecular scale to allow life-related performances: from stimulusresponsive biomembranes (energy exchange interior-exterior) to the creation of synthetic metabolisms (provision of energy) and homeostatic processes (regulation of internal environment). 32 The latter attempts to design alongside the 'many parallel realities that intersect with our architectural interventions at different scales': from molecular forces to grime, viruses, or pigeons. 33 This expanded vision of matter as a non-inert element opens prospective new lines of design investigation, further discussed in the next section.  Rosa Urbano Gutiérrez The naturalisation of architecture this respect: 'sustainability has kept us locked in talks on efficiency, preconceived notions of comfort levels, and the discourse on the 'atmospheric'. Instead, we should investigate the material energies as something generative and exploratory beyond cosmetic effects: sound out how these materialities can take more responsibility in the architectural design, acting as organisational systems'.

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Some artists deal with this proposition in their installations, bringing the materiality of environmental phenomena to solid state. Laurie Anderson, in her piece 'From the Air', intensified an area of the room through a precise delimitation of light and sound. When the entrance to the space is crossed, deep darkness and silence is perceived, disturbed only by a spatial reference, a circle of light on the floor. The island of light represents a unique spot, selected from the total space. First that differentiation is evident by the contrast of light but as we approach it another sense comes into play: the ear. Only between the limits of the circle of light can we hear the singing of birds. Without positioning oneself at the edge of the circle of light, curious about its auditory limits (which ultimately is to test the accuracy and scope of the technology behind the directional speakers), there is no discourse. What qualifies that space is the individual wandering around the solid light. Other artists work with similar concepts. Anthony McCall's work also uses light and dark, time and space, and the viewer to construct his narrative. McCall's investigation of solid light as sculptural form requires the spectator to move inside and outside the light-form, not only to comprehend its changing geometry, but also to contribute to its infinite, instantaneous materialisations by slicing the light projection with their passing bodies [11]. In all these cases, the surrounding darkness serves to focus attention on the illuminated area, but also avoids the need to define the container's form and limit. 36 James Turrell uses light to modify our perception of the space, challenging the spectator to experience disconcerting phenomena, such as loss of depth, and illusions of spatial components (walls, corners, veils). Swiss architect Philippe Rahm, apologist of

Energy as a design agent Material energy manifestations
The building envelope has benefitted from a status of sustainable responsibility that other areas have not enjoyed, being the place to exhibit technological sophistication. This is largely due to its strategic position between the inside and the outside, but also because of our need to link the performative to a material substrate accountable to generate morphology and tectonics.
We are used to conceiving architectural space as defined by material limits. But if that is not the case, if the building enclosure vanishes, what spectrum of materiality can be expected in a future architecture synergistic with energy phenomena? This was the critical question posited by the 2009 issue of AD titled Energies. New Material Boundaries. 34 What if energy takes a more 'solid' presence? What if the variations in temperature, air velocity, light spectra, or electricity solidify and become more visible? We are urged to reflect on the ability of energy-related phenomena to create spatial boundaries or distribute programmes. Indeed, some design initiatives are looking at nature's modeller agent to effectively provide a methodology to aesthetically define our architecture: the quantitative and qualitative components of energy. Images as impressive as those of Nikola Tesla in his laboratory in Colorado Springs, with eighteen-meters-long electricity sparks crossing the space above his head, give an idea of how electricity, a form of energy normally invisible, can take other spatial corporeality that is in effect appreciable. Still we do not know much about the manifestations that energy can incarnate, but it is important to start considering the potential that these energy manifestations can offer beyond producing effects or providing a certain character to the environment. Since the Industrial Revolution, these potentials have been explored in association with a material surface, but they have been little explored in a state freed from the substrate material. Energy has been one of the protagonists that has influenced our architecture, but it has not yet determined its design. Architect Sean Lally argues in 11a,b environment arq . vol 20 . no 3 . 2016 265 The naturalisation of architecture Rosa Urbano Gutiérrez them with rigour. In order to characterise architectural space through climatic modulation as a tactic to create new programmes for spatial distribution, we must first comprehend the climatic effects and their benefits on our health, emotional and psychological wellbeing.
The problem is to recognise the great variety and complexity of phenomena, and to discern individuality within the atmosphere. For this task we will need to borrow advanced pattern recognition techniques from other fields. In his seminal text Air/ Condition, Peter Sloterdijk emphasises how very little we are aware of the manipulation of the air to which we are subjected, and suggests that we let the disciplines where atmospheric description is more developed guide us, such as climatology and meteorology, in order to understand air and climate events that are important both culturally and for the welfare of people. 39 Firstly, we have to apprehend the different phenomena. Secondly, we need to get familiar with the categorisations and visualisations used by the experts in these fields. And lastly, we need to design space planning in synergy with them, to take advantage of the natural energy flows. The active incorporation of these environmental references in our spatial cognition is becoming indispensable. Normally attached to land, these expanded references have long been obvious determinants when we move through other media such as air or water. The artist James Turrell, a supporter of this theory, describes the importance of incorporating, in his art, his experiences as a pilotas a navigator in a medium that exerts its spatial impositions with a different perspective: […] There are many moments in flying that are a world apart. Well, it's a world within our world, but it is something to pay attention to, just as in orienting to the concept of atmospheric gradient as the articulator of architectural space, has analogously implemented his theories as art installations within galleries or museums (thus using existing structures), or as formalisations of modernist architectures [12]. 37 Similarly, the exploration of either deceptive or 'intensified' atmospheres tends to ignore the spatial confines. Whether as a physical manifestation or as a comfort condition, it still seems very difficult to generate building form out of environmental gradients without using a delimiting mediating envelope. The latest facade environmental research appears to incline towards the revision of familiar themes, such as thermal insulation. Michelle Addington criticises the still-present ghost of the need for a sealed envelope, 'the famous "Build Tight, Ventilate Right" as a paradigm of environmental control'. 38  The naturalisation of architecture Rosa Urbano Gutiérrez as extensions of the agents that generated the phenomenon. In performance-oriented architecture, the design process is not driven by the architectural elements (defining form, function, etc. of that element), but architectural conditions: the relationships of the element with its ecosystem. 43 The increasing miniaturisation, fragmentation, and complexity of contemporary envelopes at the material level coincide with a trend towards a heterogeneous conception of space at a comprehensive scale. With the new operations for the generation of algorithmic spaces, surfaces become deep, organic and full of cavities. This spatial complexity not only accommodates a new sense of ornament or the hardware required by active systems to control the environment, but also hosts and generates those virtual spaces [14]. In the geometrical investigations experienced by both surfaces and volumes, light patterns (being the most obvious), and other surrounding environmental parameters will arise accompanying these new spatial compositions.
Of special interest in Menges and Hensel's article, is the reference to the detail of the filigree carved inside the vaults of the Music Chamber in the Ali Qapu Palace in Isfahan. Through this geometric richness the vault becomes an acoustic agent. According to popular belief, one can still listen to the music in the room even after the musicians finish their performance, through sound reverberation. The chamber's spatial proportions together with its sculpted surfaces are finely calibrated to become an extension of the musical instruments. This relationship between matter, energy, and form connects with recent discourses on New Materialism: 44,45 moving away from 'an Aristotelian view on matter as an inert receptacle of form' to envision the generation of material form as 'driven from within by immanent patterns', 'by matter's own tendencies and capacities'. 46 It is this potential of architectural form as a generator of a stimulating and sustainable environment that is substantially attractive about this theory.

Conclusions
Traditionally, the aesthetic evaluation of architecture discusses the design values, concerns, and interests originated within a period's technological, political, economic, ethical, and sociocultural context. The origination of distinct aesthetic and stylistic expressions entails a physical formalisation, which is usually assessed upon inspection of compositional aspects, such as order, geometry, form, proportion, organisational axes, ornament, function, materiality, tectonics, construction, structure, context, etc. Compositions based on aesthetic styles or standards have been applied and practiced since ancient times to impart properties such as beauty, splendour, spirituality, or power in buildings and cities. Our contemporary context demands new negotiations between the aesthetics of architecture and the natural environment, generating an effective synergy between the use of technology, architecture of the 1950s and 60s. This concept of selective barriers offers a very inspiring path to study other environmental parameters in combination with applied knowledge from other disciplines and computational tools.
Going back to our triangular diagram, this is, in my opinion, the most consistent way to design technological sustainability departing from architectural form: either there is no limit at all and architecture is configured as an open space in continuation with the natural context, as in the topographies proposed by Weathers or the open architecture proposed by Addington, or these thresholds are the most concrete points of departure for a connection between form and energy. But once again, does this lead to a generation of aesthetics?
In natural ecosystems, there are a variety of forms among their components, and there is no unifying structure acting as a referential formal system. Except in specific examples, living beings do not adopt literal contextual forms to work in harmony with nature. Exchanges between components occur at different levels, some are very subtle, and many are invisible or not directly related to form at all. The consensus with the existing is established at an energy level regarding gravity, climate-seasons, life cycles, etc. That is what, in a variety of forms and programmes, all living beings have in common. There are many ways to serve in the chain of elements that build up the balance in an ecosystem, without defining a list of physical features that can be extrapolated as the determinants that characterise the aesthetics of nature. 47 Reflections on the design strategies presented reveal exploratory design trends where new aesthetic metrics have to be considered: those related to the integral principles of nature. Ultimately, this article has attempted to reveal that for now, our role on the aesthetics of sustainability is not about defining style and envisioning specific visualisations of a naturalised architecture, but about assimilating new operational methodologies that include techniques imported from scientific disciplines, like biology, biochemistry, or climatology. None of the analysed lines of action on their own seem to provide a holistic approach, but represent a promising first step forward. energy and environmental resources, and the production of space to develop our needs. A fundamental issue is to propose design methodologies that identify crucial design parameters in order to achieve such a synergy. The design problem therefore revolves around a new approach to architectural composition, where dynamic processes like energy exchange, the optimisation of resources, or biodiversity are critical design factors.
Among the aesthetic realities reviewed in this article, those that consider the constructed habitat as a natural one, present a more innovative and challenging approach to the fusing of ecology and design. On the other hand, the distinct biodiversity inherent in each ecosystem raises some questions as an aesthetic model. In aesthetic terms, biodiversity implies that the system's image is constructed from a set of different elements. Individually, the integration of the building in the system assumes its generation from a process of adaptation. As a methodology for sustainability, this procedure is consistent for all buildings, each in its own ecosystem. But when brought together it will lead to a series of aesthetically separate buildings, in the same way that ecosystems are formally independent from each other. Again we could ask how an aesthetic of sustainability is then generated? Does the set of rules for the adaptation to a particular microclimate and ecosystem generate recognisable aesthetic standards in all ecosystems? Can we find aesthetic connections between sustainable buildings set in very different climatic, cultural, and economic regions?
In a similar way, research on environmental control and the creation of atmospheres seems to still have work ahead to identify, classify, and assimilate the vast diversity of energy patterns within our design language. For now, what we mostly have at hand is the notion of the environmental gradients in combination with material thresholds. These porous boundaries have been explored more as acoustic and luminous experiences, historically exemplified in the ceilings developed by Alvar Aalto, Gustave Lyon, Jean Nouvel or Hans Scharoun for their auditoria; and of course, in the very diverse brise-soleil structures that gave character to the