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This work addresses issues related to daylight in urban canyons in predominantly sunny climates. Reflected sunlight from obstructions and ground is a major contribution to the illumination of buildings in orientations and at times when the sun is behind the building. Physical measurements collected in an urban canyon in Lisbon showed a linear relationship between the global horizontal illuminance and the total vertical illuminance when the facade is not receiving direct sunlight . Further studies carried out with computer simulations with RADIANCE as well as analytical calculations confirmed this relationship, which is shown to be relatively stable throughout the year, with latitude and orientations and time of day 'when sunlight is reflected off obstructions and ground. Moreover, the slope of this linear relationship is relatively similar for different floor heights and canyon ratios. Thus, the equation is representative of the whole year condition and fairly robust for individual parameters. It may therefore be used for quick calculations in the initial design stages of the project . Daylight calculations are commonly based on the daylight factor method regardless of prevailing weather conditions. While this method may be used for overcast sky conditions, it can be argued that it is not appropriate for clear skies. A relationship emerged which forms the basis for the average total daylight factor calculation in an urban canyon, taking into consideration reflected sunlight. In a similar way to the average daylight factor it may be used as an indicator of how well lit the indoor environment is and allows for the sizing of windows under predominantly sunny climates. All the above gave the basis to the definition of guidelines for daylight and urban planning in Europe. Two different set of criteria are presented. They apply to predominantly overcast and clear sky conditions. Both, individually or combined, allow for daylight design in European climates.

Daylight was the main source of lighting in vernacular architecture, and building design accordingly responded to its strategic limitations. Needs for new types of buildings in conjunction with the great development of electric lamp led to the ascendancy of electric lighting. However, a return to the interest in natural lighting emerged with the energy crises in the 1970s. In order to meet the new requirements, new optical materials and technologies have been combined to produce innovative daylighting systems able to deliver daylight long distances into buildings. There is a need to maximize the utilization of daylight, to optimize the integration between davlighting and electric lighting systems so as to increase the potential application of daYlig~ing system. The development of the hybrid lighting systems (HLS) aims to satisfy these desires. / HLS seek to maximize the utilization of daylight by tracking sunrays, and in most cases they are concentrated to minimize the light guidance size, which eases the installation and in turn increases the potential application of HLS. Prior to delivery of daylight, electric lighting source is added to instantly top up any possible shortage of daylight. A control system works to regulate this process to minimize the energy consumption. The one output device for both sources used in the HLS made it possible to no longer need for two distinct lighting systems to be installed in one space. Investigations in this work have measured HLS performance in terms of light delivery, light quality, energy saving and economic performance. Potential applications of HLS in different buildings types and across a wide geographical region have been investigated. An overall evaluation of HLS has been carried out. Furthermore, methods to estimate illuminance data, where measured data is unavailable, have been developed to help investigating systems performance over different geographical locations. Illuminance data produced using the developed methods showed superiority over that produced using other available methods, with the additional advantages of simplicity and universal application. HLS performance and potential application are influenced by many variables including system characteristics, building types, and location features. The research showed that the most important variable is the concentration ratio of the light collector. This determines HLS ability to collect daylight, and thus its applicability in different geographical locations. It also stipulates light collector and guidance size, and thus HLS applicability in different building type, influences the delivered light quality, and thus occupants' perception of daylight, and influences HLS initial and running costs. Delivered light by HLS may not be perceived as daylight due to the absence of the outside view, the likely change in daylight colour because of the mixing with electric light, the fade awareness of the seasonal and diurnal changes in daylight colour and intensity because of the instant and continuous top up. The challenges of cost, light quality and integration in building design are the most serious barriers confronting HLS ability to penetrate the market and to be used widely. This work makes suggestions to overcome these problems.

La lumière naturelle éclaire l'espace architectural créant les conditions nécessaires pour accueillir des activités humaines. La fonction d'éclairage de la lumière naturelle est associée à une autre dimension plus sensible attribuant une identité et une singularité à l'espace conçu. La maîtrise du comportement lumineux est une activité complexe qui fait appel à une multiplicité de facteurs dont la caractérisation est confrontée à l'incertitude et l'imprécision des informations disponibles durant les phases conceptuelles du projet. L'objectif de notre recherche est de proposer une méthode d'assistance qui prend en considération les propriétés des phases amont de conception pour aider le concepteur à intégrer ses intentions d'ambiance de lumière naturelle. Nous proposons une méthode d'assistance structurée selon un processus déclaratif permettant au concepteur d'expliciter ses intentions d'effets de lumière naturelle et de les traduire en solutions architecturales potentielles qu'il peut intégrer dans son projet. Cette méthode considère les intentions d'ambiance de lumière naturelle comme une information source à utiliser pour proposer une aide à la conception pendant les phases préliminaires du projet où elles constituent les seules informations disponibles. Cette méthode offre des fonctionnalités capables de gérer l'incertitude qui caractérise les phases de recherche et de formalisation d'idées. Notre méthode d'assistance a été implémentée dans un prototype d'outil dont l'apport cognitif et la capacité d'accompagnement des activités de conception ont été évalués et analysés dans un cadre expérimental de conception de projet / The daylight illuminates the architectural space and creates the necessary conditions to accommodate human activities. The illuminating function of daylight is joined to another sensitive dimension that attributes a distinctive identity to the designed space. The control of daylight in architectural environment needs some detailed and precise characteristics about aperture and walls features. The multiplicity of these characteristics is faced with the inaccuracy and the uncertainty of the design information available during the early steps. Our research aims to propose a design support method that takes into account the early design step features and helps designers to integrate there daylight atmosphere intentions in project. We propose a design support method structured as a declarative modelling process. The declarative process helps the designer to declare his daylight intentions and to translate them to potential solutions that could be integrated in his project. This method considers the designer intentions as the main design information used to help designer during the early design steps. The proposed method provides functionalities that could operate the inaccuracy and the uncertainty of the ideas research and formalisation steps. Our design support method was implemented in a prototype design support tool. The cognitive contribution and the ability to support the design activities of the proposed tool was evaluated and analysed in an experimental design context

La lumière naturelle est une préoccupation forte dans la conception du projet architectural. Elle a une grande influence sur le confort visuel et la qualité architecturale des espaces intérieurs. Plusieurs méthodes et outils ont été développés pour assister les architectes dans la conception des ambiances lumineuses. L’analyse de ces différentes méthodes et outils montre qu’ils sont peu adaptés à l’activité de formulation des intentions des concepteurs durant les premières phases de conception.Dans le cadre de cette thèse, notre objectif est d’améliorer ces premières phases de conception en apportant aux concepteurs une aide pour la formalisation de leurs intentions d’ambiances lumineuses. L’objectif poursuivi étant de faire de la lumière naturelle un fil conducteur dans le développement du projet architectural.L’étude de la pratique des concepteurs durant les premières phases de conception fait apparaître qu’ils font fréquemment appel à des références jouant le rôle de dispositifs heuristiques. L’analyse des caractéristiques de ces références et de leur évocation montre que les images comme formes de référence favorisent l’expression des désirs, des souhaits et des intentions du concepteur. L’assistance à l’activité de référenciation par les images serait donc une aide précieuse dans la formalisation des intentions pour la prise en compte de la lumière naturelle dans la conception de projet.Nous développons une méthode fondée sur la constitution d’une base d’images références représentatives des ambiances lumineuses et sur un environnement de manipulation et exploration particulière de cette base. Pour ce faire, nous considérons d’une part le rôle de l’image-référence comme élément actif du raisonnement visuel et d’autre part, les aspects du processus de référenciation notamment dans un mode de raisonnement analogique.Cette méthode a été implémentée dans un outil prototype dénommé « day@mbiance ». Cet outil propose une base d’images composée de photographies illustrant des espaces intérieurs en éclairage naturel. Ces dernières sont indexées à partir d’un thésaurus original dédié aux « ambiances lumineuses ». L’outil, par ailleurs, expérimente différents modes de navigation par l’image qui sont définis de manière à stimuler les différentes activités cognitives dans chacune des phases du processus de référenciation.Enfin, la méthode développée a été testée lors d’une phase expérimentale qui a validé les éléments méthodologiques développés / The natural light is a strong concern in the design of an architectural project. It has a great influence on visual comfort and architectural quality of interior spaces. Several methods and tools have been developed to assist architects in the design of bright atmospheres. Analysis of these different methods and tools showed that they are not well adapted to the designers activity during the early stages of design. In this thesis, our objective is to enhance the early stages of design by providing designers with a support for the formalization of their intentions of bright atmospheres. The aim is to make natural light a thread in the development of the architectural project. The study of the practice of designers during the early stages of design has shown that they frequently use references acting as heuristic devices. Analysis of the characteristics of these references and their evocation showed that images, as type of references, promote the expression of desires, wishes and intentions of the designer. Assistance to the activity of referring by the images would be a valuable aid in the formalization of intentions to include the natural light into the project design. We developed a method based on developping an image database of representative references of bright atmosphere and supported with a handling environment and exploration of this particular base. To achieve this, we consider, in the one hand, the role of the reference-image as the active item of visual reasoning and, on the other hand, aspects of referring process, specially, in a mode of analogical reasoning. This method has been implemented in a prototype tool called « day@mbiance ». This tool provides an image database composed of photographs of interior spaces with natural lighting. These images are indexed using an original thesaurus dedicated to « bright atmosphere ». The tool also experiments different modes of navigation through images that are defined in order to stimulate different cognitive activities in each stage of the referring process