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Urban morphology, including building typology and layout, has a significant influence on the built environment’s access to the sun, which impacts its energy exchange with the environment. This energy exchange is a strong factor in determining the comfort levels of occupants in buildings and the energy consumed to reach comfort. The influence of urban form has been quantified in previous studies for certain building typologies and programs for specific climates (i.e. location-specific case studies). We are interested in taking this further to assess the variation, due to climate, of the influence of different urban forms on the urban energy balance. This is part of a larger project to study the interaction between form and climate vis-à-vis energy and comfort in buildings. In this paper, we explore this issue through simulation, in various climates, of 3D neighbourhood models. These models consist of a series of parametrically generated variations on building typologies like block, L-shaped, and courtyard block. Each neighbourhood alternative is described through a set of geometrical parameters including the form factor, window-to-floor and plot ratio. We used an extensive database of heating and cooling uses generated by simulating each variant in a representative set of climates to assess the sensitivity of energy use to the geometrical descriptors and climate types. This is done using a regression equation whose input parameters are easily calculable, e.g. form factor, and whose output is an estimate of simulated energy use. The aim of exploring this relationship is to use it to assess the suitability of different urban forms in a given climatic context. Moreover, it provides a promising route to avoid the necessity of detailed energy simulations in comparing the performance of different early urban design alternatives.

Le potentiel solaire a une importance primordiale dans la performance énergétique des bâtiments, car le soleil est normalement la principale source d’énergie renouvelable à disposition en milieu urbain. Pourtant, le potentiel solaire n’a pas une définition univoque. Comme nous l’avons déjà vu dans les précédents ouvrages de cette série, il est possible d’opérer une première distinction entre potentiel solaire actif et passif. Le premier se décline en potentiel solaire actif pour systèmes thermiques (production d’eau chaude) et pour systèmes photovoltaïques (production d’électricité). Dans le deuxième, on peut distinguer le potentiel solaire passif pour le chauffage de l’espace intérieur à travers les gains solaires, et l’éclairage à travers la lumière naturelle. Dans la présente étude, nous allons examiner l’irradiation annuelle sur les surfaces des bâtiments, que l’on peut considérer comme un premier indicateur du potentiel solaire actif, sans compter les pertes dues à la transformation en chaleur ou en électricité. Une évaluation du potentiel solaire dès les premières phases du projet, c’est-à-dire lorsque l’on aborde la question de la forme urbaine, permet une intégration plus efficace des critères de performance énergétique. En effet, très souvent, ces questions ne sont abordées que dans les phases avancées du projet, lorsqu’il est plus difficile d’effectuer des changements significatifs sur le projet. Cette étude s’inscrit donc dans une démarche d’évaluation précoce du potentiel solaire de différentes formes urbaines. Les visions urbaines développées par les étudiants de l’atelier du Prof. Emmanuel Rey pour le site de Crissier et présentées dans cet ouvrage se prêtent particulièrement bien à cet exercice d’analyse comparative, car elles présentent des formes urbaines très différenciées. Nous allons donc essayer de vérifier si certaines d’entre elles ont une meilleure exposition au soleil.

The aim of this paper is to provide a systematic understanding, through simulation-based assessment, of how contemporary urban planning affects the bioclimatic features of existing historic architecture. An emblematic early 20th century Brazilian building, the Casa das Rosas in São Paulo, has been chosen as a case study to see how the deep transformation of its surroundings has altered its indoor conditions. Taking into account both the original and the current urban and environmental conditions, a two-step assessment is conducted by moving between two levels of simulation: the urban- and building-scales. The urban-scale simulations characterize the microclimate parameters (temperature, humidity, and wind speed) that will represent the boundary conditions for the building-scale simulation. EnergyPlus and DIVA-for-Rhino were used to assess the bioclimatic features in terms of indoor thermal and visual comfort levels respectively. Despite the revival of passive design solutions derived from historic architecture, studies of the influence of contemporary urban settlements on their comfort behavior are still quite limited. Outcomes from our simulations show that urban planning can have a significant impact on the indoor light levels of historic buildings, but that the average temperature conditions are not significantly affected. We expect that the results would show a bigger difference if anthropogenic heat sources were taken into account, especially for outdoor comfort conditions.

Despite recent developments, the need for adequate guidance and support in the early decision-making process of urban planners, designers, and architects has recurrently been recognized. Traditional performance assessment methods, which are often based on partial and independent dynamic simulations evaluating individual metrics, are better suited for detailed design and are particularly complex and time-consuming at the urban scale. They typically follow a linear design-and-test approach, limiting the user-guidance features. Taking a different approach, this paper proposes a multi-criteria decision-support workflow that evaluates the daylight and passive and active solar potential of early-stage neighborhood designs. The performance evaluation is done through a predictive mathematical function for the passive solar and daylight potential, requiring little information from the user. The implemented workflow is introduced, and the development of the underlying performance assessment engine is summarized, along with the results from a proof-of-concept study to probe the validity boundaries of the predictive functions. Results show the proposed workflow to be promising as an interactive and real-time performance-based design support.

Substantial numbers of existing and new buildings are expected to survive long enough to experience perceptible shifts in climate ‘normals’ (averages). To predict a building's response to changes in typical weather, two inputs are required: weather data representing this change, and suitable metrics to compare building performance across different climate normals. This paper presents initial work on a proposed method for assessing the sensitivity of new or existing buildings to climate change. This method begins with a selection of weather files to represent climate change, then quantities a building's passive performance in those climates using an enthalpy-based metric, and ends with a graphical analysis of the performance of the building in different climates to assess its robustness. In this paper, we propose an objective performance metric based on the extent to which a building creates indoor conditions passively, i.e. without auxiliary systems. Initial work suggests that the performance assessment carried out here is reproducible and applicable for indoor environment design and evaluation in different ranges of climate change. This approach enables a comparison of building performance without the bias introduced by inherent differences in climatic conditions.

Although the integration of PV systems in the building envelope (BIPV) is an important factor for the acceptability of such installations, current urban-scale solar potential metrics only partially consider this aspect. As part of the definition of BIPV-suitable surfaces, we argue that a geometric-regularity criterion can help predict the possible disposition of solar panels already in the early assessment of BIPV potential in urban contexts. To address this need, we developed an algorithm for the geometric sampling of the parts of the building envelope achieving a minimum irradiation threshold, with the aim of defining uniformly-covered active solar surfaces. The proposed methodology is implemented in a flexible parametric design platform and tested in a case study in Neuchâtel (Switzerland). We show that integrating geometric regularity in the assessment of BIPV potential can have a significant influence in the calculation of the solar energy production and discuss the value of such information in urban planning practices.

The need for sustainable architecture and urban design and planning has long been acknowledged, along with the necessity for adequate, early-phase guiding instruments. This paper aims at exploring the effectiveness and usability of a novel decision-support workflow for neighbourhood-scale projects, developed to provide practitioners with early-stage design alternatives in an interactive and iterative sequence. The prototype includes a performance assessment engine, which quickly computes an estimate of the daylight and passive and active solar potential for each design alternative. To assess the added value for design and the educational features offered by the workflow, workshops were organized with architects and urban planners. Participants were asked to work on a realistic micro-urban design project by means of two different approaches: making use of their conventional tools and methods, and then using the prototype. In addition to these design phases, the workshop included ranking design alternatives with respect to their performance before and after using the prototype, and filling pre- and post-workshop questionnaires to gather the participants’ level of experience and their feedback. The main outcomes from these tasks show that the prototype yields a strong potential in terms of design guidance, despite mixed results in the level of success in the before and after ranking phases. Results also highlight the necessity to pursue the development and adoption of energy-oriented early-stage design instruments.

This paper describes the preliminary findings of a post-occupancy evaluation campaign conducted on contemporary and energy-efficient office buildings with different façades treatments. The aim is to investigate occupants’ comfort and perceived productivity and to observe to what extent the space appearance and the façade design play a role in the ultimate user’s satisfaction and overall comfort. Two Swiss office buildings with different vertical enclosures are considered for this preliminary study: one has regular-shaped windows and regular blinds while the other presents a double-skin façade with a coloured silk-printed pattern partially covering the external pane and semi-transparent internal roller blinds. The results reported in this paper relate to an on-line extensive survey distributed among the buildings occupants to provide a global estimation of the comfort and perception they experience in their office. Findings suggest that in case of high dissatisfaction with some environmental factors, these influence strongly people’s overall comfort evaluation but not the self-rated productivity. However, when comfort ratings are less critical –though not optimal-, overall comfort as well as perceived productivity are more strongly correlated to the pleasantness of the space than to the environmental factors. Nevertheless, in the case of patterned glazing, the façade design has a low influence on comfort perception. The study suggests that further research should be conducted, especially to look at façade designs that play a greater role in determining the appearance and/or a certain level of personal environmental control in a workspace.

Through the example of the VELUXBelgium building, this paper presents a real case application of a new methodology that is being developed to favor an interactive and intuitive approach of daylighting in buildings in the schematic design phase. The Lightsolve method, under development, is based on an interactive goal-oriented approach, and provides visual representations of annual, climate-based data that rely on a combination of sky distributions using the ASRC-CIE model. This paper focuses on the use of graphical representation of climate-based daylight performance metrics (illuminance and glare metrics) combined with luminance renderings for evaluating the design options occurring during the pre-design stage of the building.

The Cradle to Cradle (C2C) paradigm is emerging as an important regenerative design approach. C2C is aiming to create a positive footprint of the built environment, beyond carbon neutrality. However, there are very few studies that address the application of the C2C concept in building design. More importantly, there is hardly any documentation processes on methods or tools currently being used to design and evaluate C2C buildings. Therefore, the purpose of this paper is to design, model and assess a C2C building prototype with a focus on energy and materials. The research methodology is based on literature review, case study design and performance (energy/materials) evaluation (DesignBuilder/SimaPro). The paper articulates the values, principles and goals of the C2C paradigm and translates them through the prototype design in the Swiss context. The results of the prototype design point to a 74% independence from non-renewable energy resources, compensating the operating and embodied energy during the building’s life. On the other hand only 8% of the building materials were totally recyclable according to the C2C principles. The design process delivers insights on the application of the C2C concept in the built environment reporting on the limitation and means of improvement.

Conventionally, building energy performance is evaluated through energy simulations using a single input weather file referring to present weather conditions. However, the analysis shown in this study demonstrates the high sensitivity of calculated energy consumption to weather files chosen for simulation. Thus, we propose that multiple present and future weather files must be incorporated as random instances of an unknown population, i.e. the climate. This paper describes a methodology to assess the robustness of different energy efficient refurbishments over possible climate projections, by taking into account uncertainties in weather files. The innovation consists in the discussion of energy outcomes in terms of ranges instead of single values.

The assessment of the solar potential in urban areas relies on a geometrical model that can be defined at different levels of detail (LOD). In this work we compare the solar irradiation simulated on the surfaces of four sample buildings, which were modeled at three different LODs as defined by the CityGML standard. Results indicate a general overestimation of the solar irradiation when using LOD1 and LOD2 models, if we consider LOD3 (i.e. the finer model) as the ground truth. However, results show also that the error varies significantly between the analyzed buildings and the considered minimum irradiation thresholds and, if we take into account only rooftops, the effect of added elements might result either in an overestimation or an underestimation of the annual total irradiation. We conclude by discussing how such findings should influence current practices in the assessment of the solar potential at the urban scale.

In order to meet the requirements of the Energy Strategy 2050, there is the need for a large-scale energy retrofit of the current building stock combined with the use of solar active systems, in particular BIPV. However, existing tools to assess the potential solar energy yield, such as solar cadasters, present some limits. For instance, they calculate solar irradiation only on rooftops, neglecting hence the potential for façade-applied systems. Moreover, inter-reflections are usually not considered, although their contribution might be significant in dense urban areas. To overcome some of these limits, we present here a simulation-based workflow for the assessment of the BIPV potential in urban areas, applying advanced solar radiation and PV-modeling tools to detailed 3D city models. We use 3D geodata, including buildings with their actual roof shape and overhangs, terrain and vegetation, that are (or will be soon) available for all of Switzerland. In our workflow, all building surfaces are first regularly subdivided according to a given PV module size. For each sub-surface, the POA irradiance is then calculated using weather data from Metonorm and the software CitySim, whose radiation model includes direct, diffuse and reflected components. We finally apply the Sandia cell temperature model and the De Soto “Five Parameter” module model to calculate the DC power of the system. We here show the application of the workflow for some sample buildings in the city of Neuchâtel, while discussing its suitability for urban-scale assessments.

Building-integrated photovoltaics (BIPV) are photovoltaic devices that are meant to replace conventional building components normally used in the building envelope. Different BIPV options are nowadays available on the market. Despite the lower nominal efficiency, 3rd generation cells, such as the Dye-sensitized Solar Cells (DSCs) are showing great potential in terms of architectural integration because of their light weight, higher sensibility in non-oriented position, availability in different colors and transparency. The main objective of the project is to assess the implication of DSC application on the thermal and visual indoor environment and on the energy performance of the Solar Decathlon pavilion designed by the Swiss team.

The aim of this project is to investigate the benefit of thermally active building or home automation as well as the combination of various settings for visual and thermal parameters. While guarantying the users’ thermal comfort and his expectations in terms of illuminance, we will study the interactions between those parameters and how they could impact the final energy consumption. The innovation brought here lies in the integration of all environmental controls on the opposite of standards that set targeted values based on the influence of each parameter individually. Exploring current legislation, the varying parameters and their respective range will be discussed. A comparison between two heating systems is conducted.

The objective of this research is to study the potential energy savings due to changes in thermal and visual set-points, by means of computer simulations and sensitivity analyses. The first part of the project consists in the creation of a computer model of a "shoebox" office as close as to the reality (i.e., an existing climate chamber on EPFL campus). The second part of the project involves computer simulations in terms of final energy consumption by varying thermal and visual parameters with the integration of two computer simulation softwares. The obtained data are treated by means of a sensitive analysis. This part of the study has in particular made it possible to define the importance of the parameters as regards their influence on the energy consumption of the building. The analysis is run for two different cities and climates: Madrid and Geneva.

Since the second half of the XX century, the way new urban areas have risen next to the ancient/traditional parts of cities has been vastly unsystematic, often altering the original natural landscape and/or urban morphology significantly. This has sometimes generated a mixture of architectural languages and technologies without any regard for the connectivity of a community as a whole. Despite the revival in current design practice of passive design solutions, studies on the influence of contemporary urban settlements on the thermal behavior of traditional buildings are still very limited. The aim of this study is to investigate, through simulation-based assessments, how contemporary urban settlements and buildings affect the bioclimatic features of existing historic architecture. The analysis considers some case studies located in different countries and climates and moves from a micro-urban to a building scale.