The Laboratory of Integrated Performance in Design (LIPID) engages in questions of energy, health, comfort and perception and their interactions in the design of the built environment, with an overall strategic goal of fulfilling building occupant needs and a core focus area on daylighting strategies. Our work involves different perspectives and methods, ranging from the human scale to the building and even urban scale, based on both simulations and experimental work. LIPID aims to bring new models, methods, metrics, decision support platforms and physical demonstrators, to enrich the designer’s toolset and adopt a holistic and integrated approach in architecture.
Subjective and physiological responses to façade and sunlight pattern geometry in virtual reality
Building and Environment. 2019-01-08.
DOI : 10.1016/j.buildenv.2019.01.009.
This study investigates the joint impact of façade geometry and associated sunlight patterns on occupant subjective perception and physiological responses through a novel experimental method coupling physically-based simulations shown in virtual reality with a wearable biometric device. A total of 72 subjects participated in a study combining three façade configurations of an equal aperture ratio with different scenarios of space use (a social or working context). The façade variations –a non-uniform distribution of openings (“Irregular”), a uniform distribution of openings (“Regular”) and venetian blinds (“Blinds”)– were applied to an interior scene with clear sky and direct sun penetration. Subjective evaluations (how pleasant, interesting, and exciting the space was perceived) and physiological responses (heart rate and skin conductance) were collected during exposure to façade variations, while a neutral scene was used to record baseline physiological responses. Results revealed that façade and sunlight pattern geometry significantly influenced subjective responses for both context scenarios, while subsequent analyses showed differences mostly between the Irregular and Regular conditions, with the former being evaluated more positively. Façade and sunlight pattern geometry affected heart rate responses, but not skin conductance responses. In particular, participants showed a larger decrease in heart rate while exposed to the Irregular condition compared to the Blinds. Context scenarios influenced evaluations of interest and excitement. Findings are particularly relevant for applications in architecture and lighting, demonstrating that façade elements and their interaction with light can influence occupant subjective and physiological responses, and showcasing the potential of the presented method for investigating human perception.
Urban planning support based on the photovoltaic potential of buildings: a multi-scenario ranking system
Lausanne, EPFL, 2019. p. 289.
DOI : 10.5075/epfl-thesis-9051.
An increased use of renewable energy and of energy efficiency measures in buildings is needed to face the urgency of climate change. Buildings are in fact among the highest worldwide consumers of primary energy, mostly of fossil fuel origin, while still making insufficient use of in-situ renewable energy sources. To find a solution to this situation, many municipalities have promoted the use of solar cadastres mapping the solar energy potential of the existing building stock. However, their implementation has limits from different points of view including assessment accuracy, representation methods, and decision-support. To overcome these limits, this thesis proposes a planning-support system based on the photovoltaic (PV) potential of buildings. The goal is to provide decision-makers and stakeholders with a robust method to assess the potential of photovoltaic electricity generation of existing buildings under uncertain environmental conditions. The developed methodology is based on an urban-scale modeling workflow that includes the simulation of the photovoltaic electricity production and a simplified estimation of the building energy retrofit potential. Existing state-of-the-art models for solar radiation, building energy and PV performance are coupled in the workflow, which relies on a vector 3D city model featuring an accurate representation of buildings, terrain, and vegetation. The proposed modeling workflow also includes an innovative approach for simulating the arrangement of PV modules on the building envelope, which influences both the energy yield and the acceptability of the system. The modeling workflow is in turn integrated into a planning-support system that provides a robust assessment of the photovoltaic potential through risk-averse scenarios. We consider here two crucial yet underestimated uncertainty factors: weather and vegetation. The results are aggregated at different scales and, for each scale, the spatial locations are ranked through pairwise comparisons according to relevant energy indicators. The results are finally displayed in a 3D-mapping tool featuring false-color overlays at the considered aggregation scales to address different objectives and inform decision-makers. We conducted sensitivity analyses towards different input data resolutions and modeling scenarios so as to achieve a good trade-off between accuracy and computational cost and define confidence intervals for the calculated values. The simulated PV yield was also compared against measured data from an existing PV installation. The proposed modeling workflow and planning-support system were tested in an urban district within the city of Neuchâtel (Switzerland). The analysis highlighted areas with the highest potential and provided a priority list of interventions. It also showed the impact of vegetation on absolute results and especially on the ranking of the spatial locations evaluated by their energy potential.
Assessing the photovoltaic potential of flat roofs: Insights from the analysis of optimised array arrangements
Proceedings of the 34th International Conference on Passive and Low Energy Architecture. 2018-12-10. PLEA 2018: Smart and Healthy Within the Two-Degree Limit , Hong-Kong, China , December 10-12, 2018. p. 1032-1033.
PV installations on flat roofs offer a wide range of design options, which are usually neglected in urban-scale assessments as these typically assume horizontal or other fixed arrangements. In this study, we analyse the influence of common design parameters (tilt and inter-row distance) in evaluating the potential of PV arrays installed on flat roofs, using three different performance indicators. By comparing optimised arrangements to horizontal ones, we show that the latter could be misleading, unless building- and indicator-specific correction coefficients are applied.