Eco-generative Design for Early Stages of Architecture - Xavier Marsault - ebook

Eco-generative Design for Early Stages of Architecture ebook

Xavier Marsault

599,99 zł


This book can be first considered as a complete synthesis of the EcCoGen ANR project (2011-2012), involving researchers from different French labs (including MAP) and domains, breaking major difficulties of the real-time generative design in the early stages of a pre-architectural project. Then the scope becomes larger, and the authors introduce major prospects following recent advances on natural and artificial evolution.

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Table of Contents





1 Context

1.1. The environmental context

1.2. The energy context

1.3. The technological context

1.4. The economic and social context

1.5. The professional context

1.6. The instrumental context

1.7. The programmatic context

1.8. The cognitive, ergonomic and sensory contexts

2 Eco-design

2.1. Eco-design of the built environment

2.2. Eco-design: a continually developing process

2.3. Life-cycle analysis (LCA)

2.4. Eco-design and BIM

2.5. Eco-design and efficient morphologies

2.6. Examples of software environments adapted to generative eco-design

3 Morphogenetics

3.1. Scientific formalisms of natural morphogenesis

3.2. Generation of forms for architecture

3.3. The specific case of the voxels approach

3.4. Optimization through genetic algorithms

3.5. Detailed presentation of a genetic algorithm

3.6. Interactive evolutionary algorithms (IEA)

4 Assessment Models and Meta-models

4.1. The concept of a model

4.2. Models and tools suited to the advanced phases of building design

4.3. Simplified modeling: difficulties and examples

4.4. Meta-modeling

4.5. Some prospects with major scientific obstacles

5 The EcoGen Software Program

5.1. Genesis of the project

5.2. General principles of EcoGen

5.3. A generative and modular tool

5.4. Urban, morphological and programmatic contexts

5.5. Bioclimatic optimization of the generated solutions

5.6. EcoGen2 assessment criteria

5.7. Interface and interactivity

5.8. Assessment of “high-efficiency” solutions and calculations

5.9. Short-term prospects

5.10. Experiments, results, development

6 Bio-inspired Perspectives

6.1. Biomimicry issues in architecture

6.2. A return to the theories of evolution

6.3. New morphogenetic approaches

6.4. Assisted creativity, coevolution and design of learning systems




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List of Tables

1 Context

Table 1.1. Parameters and options for an architecture project in the sketching phase

List of Illustrations

1 Context

Figure 1.1. The various design phases of a project

2 Eco-design

Figure 2.1. Online éco.mod software

Figure 2.2. Parallel coordinates visualization technology applied to the parameters of the building (upper line). On the right, a range of target values is selected, with references that correspond only to the pre-established objectives (e.g. “2,000 W society type”) underlined in dark grey

3 Morphogenetics

Figure 3.1. Bemis’s cubical modular concept [HOU 53]

Figure 3.2. LAVA VOxEL extension for the architectural school in Stuttgart, 2009. Three diagrams (left) show the generative principles: 1) attribution of functions; 2) cell stacking and 3) distribution of the program. For a color version of the figure, see

Figure 3.3. “Habitat 67”, modular architecture, brutalist style (Moshe Safdie). For a color version of the figure, see

Figure 3.4. “Palestinian housing” incremental architecture (Weston Williamson). For a color version of the figure, see

Figure 3.5. Some of Grannadeiro’s architectones

Figure 3.6. Simplified plan of an interactive genetic algorithm

Figure 3.7. Variation operators (crossover, mutation, swapping)

Figure 3.8. Pareto front of a maximization problem with two objectives

Figure 3.9. Organizational chart of an iteration of EcoGen2’s genetic algorithm. For a color version of the figure, see

4 Assessment Models and Meta-models

Figure 4.1. Simplified example of division of the walls and roofs of a “building and project” set into targets (in red: those not involved in the calculation). For a color version of the figure, see

Figure 4.2. Dialux simulations of interior light of a parallelepipedic volume including a maximum of four openings. For a color version of the figure, see

Figure 4.3. Precision of the adjustment model of the DF calculation

5 The EcoGen Software Program

Figure 5.1. The workings of EcoGen-N under Rhinocéros/Grasshopper. For a color version of the figure, see

Figure 5.2. EcoGen1 block diagram

Figure 5.3. Execution of the EcoGen2 assessment module (extracts)

Figure 5.4. 3D view of the (fairly small) urban site in Lyon and a typical capable volume

Figure 5.5. In green: a capable surface of 7 × 4 voxels, 12 × 12 × 3 m, set back from the east and west roads. In pink: non-buildable areas. For a color version of the figure, see

Figure 5.6. EcoGen I: automatic assessment of the fitnesses of an analogon in the Rhinocéros/Grasshopper calculation environment. For a color version of the figure, see

Figure 5.7. View of the whole EcoGen2 interface, with display of elites and impulse choices (©MAP-Aria, Renato Saleri). For a color version of the figure, see

Figure 5.8. Interface: the four main zones of the incubator. For a color version of the figure, see

Figure 5.9. Current status and evolution (colored bubbles) of the EcoGen2 software program. For a color version of the figure, see

Figure 5.10. Perspective view in EcoGen2, construction project of 12,080 m


over at most 16 floors (for the structure colors, see the caption of Figure 5.8). For a color version of the figure, see

Figure 5.11. Perspective view in EcoGen2, construction project of 22,800 m


over at most 20 floors, with acceptable overhang. The hollow space that emerges at the center promotes solar courtesy (for the structure colors, see the caption of Figure 5.8). For a color version of the figure, see

Figure 5.12. Example of exploration of a Pareto front: construction program of 8,040 m


on at least 10 floors, 17 optimized, fairly diversified individuals (for the structure colors, see the caption of Figure 5.8). For a color version of the figure, see

Figure 5.13. Objects expressing reworked proposals. Experiments of April 2012: a) sketch from an annotated perspective, b) objects expressing a reworked proposal with Sketchup software. For a color version of the figure, see

Figure 5.14. Objects expressing a reinterpretation of a solution proposed by EcoGen. Experiments of May 2014: a) rough sketch, b) arranged sketch

Figure 5.15. Collaborative work on EcoGen1 in 2012

6 Bio-inspired Perspectives

Figure 6.1. Synthesis of a self-similar urban fabric via an IFS

Figure 6.2. Classic and proteomic genetic approaches (adapted from Lefort-Mathivet [LEF 07]). For a color version of the figure, see



Table of Contents

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Architecture and Computer Science Set

coordinated byThierry Ciblac

Volume 1

Eco-generative Design for Early Stages of Architecture

Xavier Marsault

First published 2018 in Great Britain and the United States by ISTE Ltd and John Wiley & Sons, Inc.

Apart from any fair dealing for the purposes of research or private study, or criticism or review, as permitted under the Copyright, Designs and Patents Act 1988, this publication may only be reproduced, stored or transmitted, in any form or by any means, with the prior permission in writing of the publishers, or in the case of reprographic reproduction in accordance with the terms and licenses issued by the CLA. Enquiries concerning reproduction outside these terms should be sent to the publishers at the undermentioned address:


27-37 St George’s Road

London SW19 4EU


John Wiley & Sons, Inc.

111 River Street

Hoboken, NJ 07030


© ISTE Ltd 2018

The rights of Xavier Marsault to be identified as the author of this work have been asserted by him in accordance with the Copyright, Designs and Patents Act 1988.

Library of Congress Control Number: 2017957897

British Library Cataloguing-in-Publication Data

A CIP record for this book is available from the British Library

ISBN 978-1-78630-180-2


This book deals with “architectural eco-design”, a subject that is topical and fascinating, but difficult, because “in the drafting phase”, the designer has a wide range of options in front of him, but also a schedule, a certain number of constraints and rules that must be respected – and a barrage of uncertainties. This is why we have chosen to take “the generative approach” to help forge dynamic paths in these creative and promising spaces. In doing so, we address neither eco-construction nor eco-innovation, although they are closely connected to eco-design.

Architecture focuses just as much on the approach (the design process) as on the subject (analysis, study, construction, monitoring over time). Its subject of study is the structure, covering form, material, use and appropriate sustainability, all of which must come together to produce a building that is eco-efficient and pleasant to be in. It is discussed as the result of a project process based on the subtle balance between often contradictory decision-making criteria.

Elected representatives, managers, town planners, contracting authorities, architects and users navigate a constantly expanding universe of knowledge, often without the resources they need to understand its complexity and guide or explain their rationales, which are often a source of conflict. The fact that a large amount of knowledge is scattered and inaccessible to the people who have been affecting the environment through their choices for decades shows how urgent it is to produce tools that enable them to assess the impact of their decisions in a reasonable time frame.

A number of studies have questioned the conceptual, creative and innovative research phases of architecture and construction engineering. Most of these aim to define methods and develop tools that help with design and are likely to assist in the creation and production of more intelligently designed buildings. Digital instrumentation and support now have a vital role in this, and are the subject of regular studies and computing developments.

To meet the challenges of more environmentally responsible architectural production, for around 15 years, research has been enabling architects to access knowledge and tools from energy, environmental and constructive engineering, notably by means of digital simulation, a real interface between the engineer and the architect. Of course, we must acknowledge that specific tools for assisting with the design of efficient structures in the upstream project phase are only just starting to find applications outside laboratories. However, research strives to go further, proposing design support software environments that are better suited to the usual working methods of architects, attempting to preserve their autonomy and creativity.

The concept of efficiency, which is central to eco-design, runs through all the chapters. However, it is always “tricky to define efficiency in architecture, because it takes into account not only the objective and measurable qualities of an object, but also its relationship with its built or social environment, and the use to which it is put by users” [LAG 13]. Hensel proposes a redefinition of the concept of efficiency in architectural design, based on an analogy with biology [HEN 10]. We will return to this in the final chapter. This specific approach is different from previous ones, which either focused on questions of representation and meaning, or considered efficiency a synonym of function. According to current developments, efficiency is merely a level of requirement that must be reached retrospectively: energy efficiency, for example. But it could also be argued that the efficiencies that should be prioritized are those that have the greatest impact on the form and materiality of the structure.

In what follows, the four designations, namely criterion, objective, efficiency and fitness, denote one reality, seen, according to the case, from a qualitative or quantitative point of view.

What aspects should be prioritized in the upstream design phases? Which choices may be decisive, and what impact do they have on other aspects (formal, technical) that may influence the overall outcome of a structure?

We are going to examine the issues, possibilities and methods of eco-design, based largely on research and developments conducted within the French ANR EcCoGen project, which produced the EcoGen software program. Tackling the major difficulties of generative design head on in the interactive first stages of an architectural project (where the choices are the most decisive in terms of the overall and future efficiencies of the structure), EcoGen is interested in the behavior of structures in their constructed environment, through a generative and multi-criteria approach (morphological, energetic, atmospheric, functional, constructive) of eco-efficient design.

This book can therefore be considered partly as a summary of this project, which involved researchers from different laboratories, mainly the French CNRS’s UMR MAP 3495 (Models and simulations for Architecture, town planning and Heritage). Several texts from the final project report1 are cited to support and illustrate our arguments.

Finally, we will end with a discussion of the ambitious prospects combining some advances in the understanding of natural evolution with the desire to produce a truly bio-inspired theory of architectural morphogenesis. On this topic, the accounts provided in Chapter 3 should be linked to some of the bio-inspired prospects of Chapter 6.

I would particularly like to thank the following people for their contributions and thoughts: Philippe Marin, Renato Saleri, Hervé Lequay, Lazaros Mavromatidis, Florent Torres, Lara Schmitt, Nicolas Grégori, Jean-Claude Bignon, Gilles Halin, Estelle Cruz, Violette Abergel, Ronan Lagadec, Anaelle Quillet, Aymeric Broyet and Florian Mignot. I am also grateful to my “more distant” researcher colleagues: Grégoire Carpentier, Tibériu Catalina, Brian Mc Ginley and Thomas Jusselme, with whom I have had some valuable discussions.

This morning, arriving at his office, Paul knows that a new stage of his life as an architect is about to begin. Yesterday, he received the new tactile creative tool from Microsoft, “Surface studio”, equipped with a digital pen and control knob. He is one of the few in his profession to have this kind of equipment, although it is very affordable. His reason for turning to this modern solution, which encourages fluid design with tools that imitate freehand drawing, is called Minos. With this brand new software program, based on the integration of better technologies for designers, he knows that his ideas and creativity will transfer to the digital world like never before.

Minos registers Paul’s tiniest line, slightest curve or smallest volume sketch in real time. Little by little, it comes to understand the ideas behind his project by comparing them with local and cloud-based databases, and then delivers the results of multiple calculations by means of a voice assistant, along with graphics that support decision-making. It can therefore quickly give Paul advice, direct him to eco-efficient choices, suggest that he alters lighting, structural elements or openings, etc. However, in addition to supporting the project with this active intelligence, from the sketching phase onwards, Minos is constantly learning from the user and familiarizing itself with his ways of drawing and designing. After a certain amount of learning, it will be able to suggest innovative shapes to Paul, without jeopardizing his creativity. As Minos is subtle and knows how to be discreet, AI is a winner! It can even share this knowledge with other online users, if Paul authorizes it. It’s a real marvel!

Of course, just like the mythological hero after whom it is named, this software does not exist, or not yet. But are we very far from this kind of architectural design aid?




“Sustainable development is based on three complex, related pillars: economic, ecological and social aspects, with the aim of moving towards practices, lifestyles and ways of functioning that protect the environment and the availability of the resources needed to ensure the survival of present and future societies. A good environmental approach will always seek a compromise between economic, social and environmental issues” (Olivier Coutard, in [COU 10]).

1.1. The environmental context

1.1.1.Ecology: an ancient concept

“Ecology is an idea of the house, of the home – oikos in Greek means both ecology and economy. These two concepts have been combined from the beginning: oikonomia in Ancient Greek is the administration of a household, while oikologos, literally ‘the study of the house’, is initially defined as ‘the science of the relationships between organisms and the world around them, i.e. in a broad sense, the science of the conditions of life’ (Ernst Haeckel, 1866). Don’t many of our current problems come precisely from the divorce between the two notions, the first constantly trying to free itself from the social requirements of the second?” [BÈS 14].

The concept of economics in the home is therefore not new. In the 17th Century, there were already simple solutions for coping with energy scarcity and the difficulty of keeping warm. From the end of the 19th Century onwards, in a period of industrial expansion, engineers tried to use only the amount of material that was needed to produce objects, and thereby to reduce production costs. The past – even the distant past – is full of eco-oriented solutions that have often been wrongly abandoned by modernism [COU 10]. In addition, rural areas, which have fewer resources than large cities, have always demonstrated imagination and inventiveness in coping with adversity.

The so-called environmental approach is, however, more recent, especially with the joint increase in our technical resources for action in the world and their repercussions for a human population of more than seven billion. Eco-design appeared in the 1990s in northern European countries, following a three-fold realization: damage to increasingly weakened human populations and the environment, the gradual disappearance of fossil fuels and anthropogenic climate change. It became essential in the installation of energy transition [TIS 13], the responsible development of production and service activities, and resource savings at the heart of reflections on the built environment, also aiming to improve its efficiency.

1.1.2.The Anthropocene and urban concentration

During the period of history in which human activity has had the greatest impact on the environment (from 1850 to today), three major trends have emerged: a major increase in polluting industrial development, excessive consumption of material and energy resources by highly developed countries and the development of strong urban concentrations.

Due to the concentration of humans and their activities, urban environments are among the greatest drivers of past, present and future climate and environmental changes, and are also the social spaces that are most vulnerable to the consequences of these changes. “In 2007, for the first time in history, the number of people living in towns exceeded 50%. It is likely to reach 60% in 2025, causing profound changes in large conurbations, because the urban explosion is accompanied by severe human and environmental problems, and is synonymous with precarious housing and increased poverty: one billion people were already living in slums in 2005” (Nathalie Blanc, in [COU 10], Chapter 10, p. 171).

The Earth’s resilience threshold was reached between 1960 and 1970, but the intensification of greenhouse gas emissions is likely to peak around 2020. They have accumulated in vast quantities for over half a century, and their effects will last for a long time, even after emissions have been dramatically reduced. “We are beginning to depend on things that depend on the acts that we undertake, kindled, unleashed, in any case born out of our actions, like a new nature” [SER 01]. Thus, we have entered the Anthropocene Era – a term coined in 2000 by the American geologist and biologist Eugène Stoermer and the Dutch geochemist Paul Crutzen. This neologism denotes a period in which human activities are having a real impact on the geophysics of the planet and climates, with the considerable risk of unbalancing them irreversibly. Let us partially conclude with Sabine Barles: “experts say that we cannot return to former urban densities and morphologies. But we must start really thinking about how we organize and develop spaces so that their life and development are less harmful to ecosystems and the biosphere” [COU 10].

1.1.3.The increase in the Earth’s temperature

The International Energy Agency (IEA) confirms that by 2030, renewable energies will represent more than 50% of global electricity production, and annual greenhouse gas emissions should begin to stabilize, reaching 34.8 billion metric tons a year. In this period, corresponding to a phase of massive investment in the energy sector, the old thermal power plants will barely begin to disappear. If further efforts are not made after this date, global temperatures may increase by 2.6°C by the start of the next century [MIN 13], a figure much higher than the limit of 2°C beyond which the scientific community fears runaway climate change.

1.1.4.Architecture and environmental thinking

“At the end of the 19th century, architecture divided gradually into two schools of thought: the ‘modern’ school, which focused on the industrialization and globalization of architecture, and the ‘traditional’ school, which followed on from reflections on the qualities of regional practices. The modern school became dominant during the second half of the 20th Century, as post-war society dealt with an increased need for housing. This style began with the Bauhaus movement and developed from there, notably thanks to the architects Adolf Loos, Auguste Perret, Ludwig Mies Van der Rohe and Oscar Niemeyer. It was characterized by a return to minimalist decor, geometric and functional lines, and the use of new techniques. This movement was based on the idea that, in an increasingly industrialized society, architecture and design are functional elements. This movement had a lasting influence on architectural thought and made its mark on the entire century.

However, a second school, differing from the modern one, continued to follow vernacular architecture. More traditional and rural, this school was deemed outdated by society at the time. It had interesting values from an environmental point of view (use of local resources, consideration of context, etc.). It adapted to technological progress without reducing the existing regional qualities of the vernacular architecture. It is this school that inspired the concept of eco-design in architecture today” [GHO 11].

1.2. The energy context

Energy consumption has only been a major issue in the production and functioning of the built environment since the oil crisis in the 1970s.

1.2.1.The energy crisis

The energy crisis, which has received more and more attention since the last decade of the 20th Century, refers to the gradual disappearance of non-renewable primary energy sources, which still represent 78% of the global supply. Their consumption has doubled in 40 years, and, due to the inertia of the systems that we have put in place, the debts incurred for equipment, and our insufficient desire to change our behavior, the quantity of greenhouse gases emitted each year worldwide is not decreasing substantially [ADE 11]. However, to counteract the effects of the CO2 emitted since the beginning of the industrial era, it should already have diminished by at least 25%.

Furthermore, the ecological imprint of all human activities on a global scale means that our use of resources is 35% above the Earth’s capacities. Environmental issues are therefore playing an increasingly central role in architectural eco-design strategies and reflections on the built environment, with the aim of improving the efficiency of buildings in the upstream project phase, by integrating sustainable development parameters and constraints and taking legal and ethical imperatives into account. The 3x20 rule, fixed by a European Energy Efficiency Directive, aims to achieve the following by 2020: a 20% reduction in energy consumption, a 20% reduction in greenhouse gas emissions and a 20% share of renewable energies in the countries’ final consumption. There are various methods and labels in Europe to structure and support the approaches and objectives that need to be reached (section 2.2 in Chapter 2).

1.2.2.Energy consumption in houses

Over the last 30 years, housing in industrialized countries has become much more energy efficient. However, living standards and the need for comfort are reflected in the fact that living areas have increased from an average of 25–38 m2 per resident, thus significantly decreasing the savings made by their energy efficiency per square meter. The comfort temperature in well-insulated homes has also increased (above that fixed at 19° in France) since the introduction of the BBC (low-energy house) label, as has the tendency to open windows more readily in cold weather, to benefit from more ventilation. These effects, caused by comfort and reinforced insulation, have therefore led to an increase in energy consumption that sometimes reaches 30%, jeopardizing the commendable efforts that have enabled savings to be made (ultimately, only a 13% gain in homes between 1973 and 2006!). Finally, although there have been improvements in energy consumption and comfort, a new phenomenon has appeared: the steady growth in the use of electricity for specific uses other than those cited previously (consumption has increased from 13 kWh/m2/year in 1973 to 30 kWh/m2/year in 2010, although technical advances have greatly decreased the consumption of devices during the same period). Overall, it is easy to see why the building sector continues to consume massive amounts of energy and emit CO2 into the atmosphere. We are far from reaching “factor 4”.

1.2.3.Strong measures

The Rio Agreements (1992) and the Kyoto Protocol (1997) set objectives for limiting greenhouse gases, and France has committed to reducing the energy consumption of its buildings, which currently contribute 44% of the ultimate energy consumption (half of which is used for heating, ventilation and air conditioning) and 25% of greenhouse gas production. In light of this, France established two “Grenelle” laws in 2007 and 2010. These defined objectives and measures, notably for reinforcing thermal regulations, encouraging innovations and mobilizing society to save energy. Thermal regulation (TR) can be considered the cutting edge of energy control in new buildings in France. Requirements in this area are being gradually reinforced: average energy consumption of less than 110 kWh.EP/m2/year in 2008, and a low-energy building (BBC) label corresponding to less than 50 kWh.EP/m2/year in 2010 for public and commercial buildings, extended to all buildings in 2012, awaiting the positive energy building (BEPOS) label in 2018. Furthermore, in France, the Grenelle objectives were to make 38% savings in the sector of existing buildings from 2007 until 2020, based on 2005, and reduce greenhouse gas emissions by 75% in 2050, compared with 1990. In the wake of the Conference of the Parties COP2*, the latest energy transition law provides for a 40% drop in greenhouse gas emissions by 2030, compared with 1990, a 30% drop in fossil fuel consumption by 2030, compared with 2012, and a 50% reduction in ultimate energy consumption by 2050, compared with 2012.

1.2.4.“Smart city” versus energetic city

Optimizing electricity production and distribution depending on consumption and facilitating the network of local energy sources are at the heart of the current questions about energy saving. “Centralized electricity production plants far from consumption sites are recognized as one of the main causes of global warming, due to major losses in transport” [COU 10].

With this in mind, the smart grid, an energy component of the smart city, represents an intelligent approach of empowerment with the aim of managing local renewable resources better and, at the same time, promoting more restrained consumption. The general principle is to undertake urban transformations – technological, organizational and societal – with the main aim of developing optimized production, transport, mutualization and, potentially, energy storage services, while improving the everyday experience of inhabitants.

In practice, a smart grid is managed on an urban or territorial level through computing and control systems, with the aim of actively ensuring the functioning of each of its units in the face of fluctuations due to production sources and highly variable demand levels.

We will end with a distinction made by Christian Pierret, a former French Deputy Minister of Industry: “energy production is not the only thing that transforms our environment – lifestyles and consumption patterns (transport, housing, food, etc.) do too. The realization is universal and affects both the rural farmer and the urban consumer, the least advanced countries and the major industrial powers”.

1.3. The technological context

In the construction sector, the progress that has been made, particularly in terms of insulation, ventilation management and regulation, implementation of efficient materials, and local energy production and mutualization, means that we are heading towards little if any heating in new constructions by 2018–2020. Excellent insulation is no longer hard to find. Taking inertia into account is more difficult, and is a fairly new aspect of the calculations. Detailed data and models are required to take thermal bridges into account.

Ventilation (even if it is natural) is much more subtle, just like all posts requiring active control. Regulation has become difficult but essential, and poor management of it can cancel out all the benefits of optimizing insulation, for example. Good regulation is based on complex outlines and activation models of technical mechanisms (including some that are highly empirical). The building therefore tends to become a highly technological object.

Dynamic thermal simulation requires knowledge of the precise occupancy patterns of each room. It is impossible to implement in the upstream phase, but some approximate models use it for simulation plans (Chapter 4).

Lighting is also a tricky aspect: we are gradually moving from a quantitative approach (lux, daylight factor, norm) to a qualitative approach (comfort, perception, dynamic lighting), using more and more technology.

Indeed, technical mechanisms can now be optimized, but this involves spending much more time working on software, which does not always facilitate the customer-centered approach. As for on-site implementation, this is essential and can also reduce great conceptual efforts to nothing.

1.4. The economic and social context

The architectural design process is notably characterized by precise phasing, regulated by the 1985 MOP law (relating to public building procurement and its relationship to private building procurement), which conducts conceptual research until the built structures have been accepted. Even if design and resolution work is carried out continuously, it is accepted that the initial sketching phases define the fundamental guidelines of the project. The choices made during this creative exploration are decisive, and reconsidering them later can be difficult and costly, and sometimes impossible. Furthermore, innovation, which is vital in the building sector, is generally reflected in an increase from 5 to 15%.

On the social level, energy insecurity is currently affecting 10 million people in France. Moreover, in old buildings, the investment costs for renovation are often too high for households with limited or non-existent financial capacities. The same is true for a large number of communities that are in a lot of debt.

A few positive points should be noted, however: ecological transition is a considerable technical and economic challenge for energy production, management and consumption lines, the development of which will create jobs, particularly when it involves taking advantage of local resources (biomass, geothermal energy, wind, water, agriculture, waste) and energy renovation works. Finally, we can hope that inhabitants will gradually gain awareness and take responsibility for managing their energy consumption, particularly in terms of more intelligent energy management and a circular, sustainable and more restrained economy.

1.5. The professional context

1.5.1.The roles of the architect today

Architecture must contribute to human well-being. Architects are tasked with making an enlightened contribution to improving living environments, by designing efficient, sustainable structures, mindful of their immediate and distant environment. By planning the shapes, spaces and atmospheres that make up an environment, as much through built structures as by the empty spaces that surround them, they promote architectural and urban quality, which is an essential ingredient of a sustainable environment.

The role of the architect within a project is both complex and varied. First and foremost, he is the original designer, the person who comes up with the concept or guides the design work. He is also the project management representative, which is probably the trickiest role to take on. Indeed, it is important to remember the context of cooperation: “architectural quality is not the accumulated quality of all disciplines associated with design; what counts is the assertion of a global and consistent intention. In a sector in which each person tends to limit his responsibility and his intervention, the architect sometimes seems to be the only player who wants to reach this objective” [MAL 01].

The architect must therefore make decisions and resolve disputes while respecting the legislation in force, the constraints of the site and those outlined by the Project Manager. His role goes beyond that of a negotiator within a network of players. He has the central role in the design, but also summarizes, coordinates, negotiates and moderates in order to keep everyone focused on the target: producing a coherent project. Appropriate software tools should facilitate the consolidation of choices from the first design phases, given that simultaneous consideration of multiple efficiency criteria increases the complexity of a construction or rehabilitation operation, necessarily requiring a systemic approach.

Furthermore, architects work in an environment driven by the digital transition taking place in a socio-economic sector that is already subject to the pressure of considerable changes: urban densification, increasing awareness of environmental and energy issues, social and economic crises, and a fiercely competitive industrial environment. In this context, designing sustainable buildings forces architecture and engineering agencies to respond to constantly increasing levels of technical requirements (proliferation of rules and standards) today, with increasingly fast decision-making processes.

Figure 1.1.The various design phases of a project

Architects must therefore ensure that their buildings meet a certain level of efficiency, but they lack tools to help them design eco-efficient buildings from the first sketching phase, when formal and technical choices are decisive. The vast majority do not assess efficiency in the upstream phase, but in the detailed pre-project stage (Figure 1.1), when precise data has been sufficiently specified, resorting to specialized design offices, which increases the study costs and greatly limits the amount of back and forth and the number of variants. The problem is different for very large architecture agencies, which have internal engineering teams and their own software programs adapted to calculate more numerous variants (e.g. Gehry Technologies1). However, unlike in industrial design environments, the generative project approaches are fairly rare.

1.5.2.Architectural design and the numerous constraints