Windows and renovation: The case of 19th century ordinary housing in Switzerland

Ordinary residential buildings dating from late nineteenth century and early twentieth century are an essential part of the European urban built environment. Today, it is important to address the comfort of residents through renovations improving the buildings’ energy performance. Nevertheless, strategies aiming for a drastic reduction of energy consumption – such as outside insulation currently applied to new buildings – are often incompatible with their original architectural character. Considering the absence of systematic protection measures, that could sometimes be too restrictive, ordinary buildings are often at risk of being completely disfigured, namely through interventions concerning the windows. This contribution examines the original features and renovation strategies for windows of ordinary residential buildings in French-speaking Switzerland. The aim is to compare the energy performance of different interventions, as well as assessing their architectural impact. We first identify four types of windows. The joinery techniques used are examined by looking at building manuals of the time and by conducting metric surveys in situ. Secondly, three types of intervention strategies are compared: adapting windows with single glazing to insulated glazing; replacing existing windows for some types of new windows; adding a second window with insulated glazing in front or behind the original window. The interventions are examined in collaboration with joiners to observe the construction processes. For each type of intervention, the architectural and thermal insulation impact are compared using the same criteria, drawings at the same scale and by calculating heat transfer coefficients. The aim is to show that an apparently simple procedure such as window renovation can induce important changes to buildings. Not only are the aspects to consider often contradictory, but the multiple intervention strategies are often little known. It is therefore essential to contribute to research concerning historic windows and to make public alternative solutions to their replacement.

Densité et logement collectif

Nicolas Bassand

As a measurement, built density (coefficient of land surface to be built and total floor space) has been the object of numerous researches on urban morphology and architectural forms during the twentieth century. However, for the last ten years, its sensory and qualitative dimension seems to be particularly valued: the perceived density. In multi-unit housing, dense, innovating and compact forms show a significant change of architectural and urban conception. In fact, project practices seem to have been marked by three major changes. Firstly, the importance of the precept of sustainable development, attempting at reducing urban sprawl. Secondly, the increased interest in urban values and the idea of "building a city within a city". Lastly, the current asserted need to redefine density: on one hand, new means are being researched to control it, on the other hand there is a widening of its definition due to the main impulse of architects and researchers. Within this framework, it is illuminating to reconsider the multiple disciplines using this term, as well as the distinct spatial scales tackled in this notion and changes in its use through time. However, focusing only on built density, the present research concentrates on the architectural and urban framework, also known as physical density. It is measured by a density figure but is also qualified by the perception of density. We propose as preliminary approach, an examination of this perceived density in fields where it is more frequently used, such as literature, painting and music. Another important notion of this research requires definition: architectural and urban innovation. Standing out from pure invention, this type of innovation consists essentially in a reinterpretation of previous architectural and urban productions worth naming "retro-innovation". Despite a housing program dependent on past models reluctant to rapid and important changes, radical innovations do occur, though more seldomly. Several ''moments'' of the collective housing architectural history allow for an updating of the different stakes manifested in the density – innovation relationship. Density perception plays a large role in a particular problem emerging from these two notions in contemporary Switzerland. The issue is how encouraging people coming back to the urban centers by proposing larger apartments with more square meters and urban architecture composed of numerous and various spaces, but protecting them at the same time from too close a proximity between neighboring housing and from environmental nuisances. The state of the art brings to light the enormous influence of the researcher and anthropologist Amos Rapoport on perceived density starting with his article, "Towards a Redefinition of Density", published in 1975. For more than thirty years now, architects, psychologists, city planners and geographers refer to this work when defining this notion in their respective fields. As a consequence, it nourishes several reflections in this research. Following these various observations, we propose the analysis of fourteen contemporary multi-unit buildings. They represent the current urban stakes at play and show the architectural and urban conception facing the double requirement of density: to insure a high enough floor area ratio (measured density) and to qualify the housing density (perceived density). In parallel, this research determines if this conception, unique to dense multi-unit housing, tends to modify architectural practice. In the first phase, we examine seven rectangular housing units, in which the width of the building is significant, and seven courtyard buildings in order to examine the exterior spaces contained by the building's volumes. In the second phase, we focus our attention on the wall expression of the fourteen buildings. In this way, these distinct analyses offer three new definitions of the perceived density expressing conception aspects particularly significant for understanding the architecture and urbanity of these dense multi-unit buildings. As a fundamental knowledge, it is shown that density, within the corpus, orientates the architects project's mode. The frequent reinterpretation of paradigmatic dense lodgings is one of the most striking proof of this conceptual change searching for innovations in the register of collective housing. So, in the density of depth, introversion and anonymity on the exterior seems to encourage distinct individualized space within the building as common domestic spheres only opened towards the inside of the apartment. In several cases, the usual urban and public spaces are integrated into the private interior of the apartments as if to domesticate a certain urbanity. In the density of the void, the proposed introversion of semi-public courtyards seems to help maintaining a larger sense of community in these multi-unit buildings. Altogether, it demonstrates a particular capacity to produce small cities within the city, at the same time independent and linked to the city. Finally, through the analysis of wall density, the exterior materiality and expression, dynamic or static, monumental at times, present a decidedly urban architecture enhancing a compact city in quest of new inhabitants.

EPFL2009

Concevoir à grande échelle

Mathieu Louis Pierre Mercuriali

Large-scale design - Mobility interface models and urban transformation strategies This research project is based on the hypothesis that the urban transformations generated by mobility interfaces constitute a key component of successful sustainable urban development. Effectively visioning and understanding these multimodal interchange hubs must therefore become a major strategic objective, in order to conceive an urban model that is compact - and networked and intelligent. With this aim in mind, this research aims to propose innovative strategies for transforming these communication interfaces into central reference points within the contemporary metropolitan landscape. Projects of this kind have already been designed and realised in most major European cities during the second half of the 20th century. These designs, characterised by their complexity and scale, formed the starting point of the major railway stations in today's cities, incorporating different forms of mobility over the course of time. Today they appear not just detached from their urban contexts - the very contexts in which they are embedded - but also unable to meet the current demand for functional mixity and communication effectively. They are undergoing obsolescence and finding it difficult to adapt to the paradigm shifts that have intervened - socially, economically and spatially. At a time when the city can no longer be conceived exclusively in terms of ex-nihilo construction, but must be viewed in terms of transforming an existing built fabric, what future can be proposed for these existing transport interfaces? What strategies can be developed to anchor them in their surrounding urban context? What capacity do they have for hosting new activities, new public and private spaces? Finally, what forms is it possible to imagine for this kind of design? Three hypotheses emerge: the development of mobility interfaces has generated specific architectural and urban forms correlating to the evolution of mobility forms themselves; the transformation and obsolescence phases of mobility interfaces offer potentials for metropolitan regeneration; and the process of producing a complex design calls for articulation and interrelation between different architectural and urban scales. To verify these hypotheses, the first part of this thesis is focused on the comprehension and analysis of these multimodal hubs, based on a review of architectural and urban theories that address the issue of how major urban projects relate to transport infrastructures. This is followed by close analysis of a series of relevant case studies within the Paris metropolitan area. The second part of the thesis proposes design tools to generate new urban and architectural design processes, derived from a process of design-based research. The final part of the thesis aims to demonstrate that this type of intervention is a design project with its own specific scale and complexity: between large building and urban fragment.

EPFL2015

Reconsidering traditional timber joinery for sustainable structures

Jan Friedrich Georg Brütting, Corentin Jean Dominique Fivet

Timber construction plays an important role in architectural history, in modern construction methods and in sustainable design, for which wood-only joinery techniques have been used for centuries. Traditional joinery typologies are the product of successive, empirical improvements over generations of artisans [1]. However, over the industrialization era, many traditional wood-only construction techniques were abandoned in favor of more profitable connections with mechanical fasteners [2]. This shift of practice lead to the development of connections with quantifiable capacity but neglecting the intrinsic anisotropic properties of natural timber. Specialized knowledge of carpenters and typical building traditions were lost. Yet, examples of historic timber buildings with a life span of multiple centuries have demonstrated many advantages of interlocking timber joints, e.g. in severe loading cases as in the case of earthquakes [2]. New technologies and recent developments in digital fabrication allow the custom and automated manufacturing of traditional wood-only connections for new buildings [3]. A big potential of such contact-only connections is their fast assembly and non-destructive disassembly. Remarkable examples include the Japanese Ise-Shrines, which are rebuilt in a 20-year frequency for the past 1300 years. Traditional joinery techniques allow for sustainable solutions through the replacement, long-term maintenance and repair of structural elements [4]. They also ease recycling and energy-recovery. In times of global environmental problems where the building sector is highly responsible for resource depletion, greenhouse-gas emissions and waste pollution, these advantages will become even more important for regenerative architecture or transformable building design. Buildings need to become more adaptable to frequent changes in ownership or use to avoid superfluous demolition. For example in Japan in the past, entire cities made from timber were constructed for disassembly and transport in order to accommodate for recurrently changing administrative centers [3]. Some joint typologies were designed to allow the later vertical or horizontal extension of buildings [2]. In Japan also, contemporary buildings are not understood as permanent edifices but as structures made to be replaced or removed. This could only be achieved through highly developed timber joinery techniques. A combination of traditional joinery with contemporary post and beam construction and CNC prefabrication is already well established in Japan in the construction of residential buildings [3]. However, a straightforward application of traditional joinery techniques in today’s construction is not always possible. In the past, the structural integrity of traditional joinery techniques was proven mainly through in-situ, de-facto testing. Today, building codes include little-to-no information about the application of wood-only carpentry connections in comparison to those with mechanical fasteners [2]. Research on interlocking joints concentrates on a very precise analysis of few different joint typologies. There are limitations in literature in terms of analyzing a variety, or a library of ancient interlocking wood joints to develop an extensive relative comparison between them. As a first step, the present research initiates a FEM campaign to catalog a library of Asian joints. To align traditional techniques with modern construction and typically used North American timber, solid Douglas fir was considered as the material. The goal of the analysis is to extract the relative capacity and stiffness of different joints to understand their mechanical behavior. This comparative record, which should be extended to additional Asian and European joint types, will allow academics and designers to push the capabilities of these ancient techniques while benefitting from modern materials, construction techniques and fabrication tools. Other research will also address the optimization of joint geometries to customize demanded capacity or stiffening. In addition, Life Cycle Assessment of constructions with conventional and advanced traditional joinery technology will be carried out to quantify potential environmental savings.

2018