Sensitivity analysis of visual and thermal parameters for energy savings: climatic variations

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.

Numerical modeling and neural networks to identify model parameters from piezocone tests: I. FEM analysis of penetration in two-phase continuum

Rafal Filip Obrzud, Andrzej Truty, Laurent Vulliet

This study presents a numerical approach designed for material parameter identification for the coupled hydro-mechanical boundary value problem (BVP) of the piezocone test (CPTU) in normally and lightly overconsolidated clayey soils. The study is presented in two related papers and it explores the possibility of using neural networks (NNs) to solve the complex inverse problem of the penetration test, including partially drained conditions. It has been demonstrated that the development of NN-based inverse models can be based on training data sets that consist of pseudo-experimental measurements derived from numerical simulations of the piezocone test. The first paper presents the development of the FE model of the studied problem, which can be used to generate a training data population corresponding to typical piezocone measurements that are obtained for clayey soils. The paper contains a detailed description of the numerical model with a sensitivity analysis with respect to different model parameters including the effect of partial drainage. The analysis also includes the model verification by means of a comparative analysis with numerical models of penetration proposed in the literature, as well as experimental evidence. Finally, owing to the loss of accuracy observed when applying a 'rough' frictional interface in the Updated Lagrangian formulation, an equivalent semi-numerical model for the piezocone test is proposed, taking into account a possible occurrence of partial drainage during penetration. Copyright (C) 2010 John Wiley & Sons, Ltd.

Wiley-Blackwell2011

Modelling the Urban Microclimate and its Influence on Building Energy Demands of an Urban Neighbourhood

Jérôme Henri Kämpf

In the past decades the portion of the population living in urban areas has continuously increased. Due to the high building density, the microclimate in urban areas changed significantly compared to rural areas. The temperatures measured in urban areas are, due to the urban heat island (UHI) effect, higher compared to the rural temperatures. The UHI intensities are increasing with higher building densities and growing cities. Space cooling and heating demands of buildings are strongly affected by the local microclimate at the building sites. Due to the climate change and the limited energy resources, energy saving and sustainability are nowadays important issues. A significant part of the global energy consumption is used for space cooling and space heating of buildings. Thus its minimization for buildings in urban areas has great energy saving potential. Most building energy simulation (BES) models were developed for stand-alone buildings and therefore do not consider effects of the urban microclimate. This can lead to inaccurate predictions of the space cooling and heating demands for buildings in urban areas. The aim of this paper is to investigate the urban microclimate and its potential influence on the energy demand of buildings in an urban context by conducting detailed flow, radiation and building energy simulations at the urban neighborhood scale. CitySim is used for the radiation and building energy simulations. In CitySim detailed radiation models for solar and longwave radiation are implemented that can account for the radiation exchange between neighbouring buildings. The flow around the buildings is modelled by running CFD (computational fluid dynamics) simulations using OpenFOAM. As a result it is shown, how the temperatures and wind speeds can strongly differ within different urban areas. Further an approach is presented, to consider the local microclimate in the building energy simulation tool CitySim.

EPFL Solar Energy and Building Physics Laboratory (LESO-PB)2013

Toward an Integrated Platform for Energy Efficient Lighting Control of Non-Residential Buildings

Laurent Deschamps, Ali Motamed, Jean-Louis Scartezzini

Net energy import of Switzerland corresponds to about 13 BCHF (petroleum, uranium, etc.) each year. According to the energy perspective 2035 defined by Swiss Federal Office Energy, the energy import should be reduced to 7.3 BCHF. Meeting the goals defined by this perspective can be envisaged by mitigating the energy demand of buildings since the built environment consumes 40% of the total primary energy. In Switzerland; 20 % of the buildings’ energy consumption is moreover related to electric lighting. Therein, integrated building automation technologies, such as automatic regulation of sun shadings and electric lighting can play an important role in reducing lighting energy demand while maintaining user comfort. For this purpose, a rapid, reliable, accurate evaluation of the lighting conditions in a building is essential. In this paper, a control platform installed in two offices of the LESO experimental building on the EPFL campus in Lausanne, Switzerland is presented. This data acquisition and actuation platform hosts two motorized sun shadings per office, a dimmable lighting system, a presence detector, energy meters, ceiling mounted luminance-meters and two novel High Dynamic Range (HDR) vision sensors. A sample controller is implemented in the platform to evaluate its robustness and performance. This platform is currently ready for integrating novel controllers for testing several energy efficient control scenarios/algorithms.

vdf Hochschulverlag AG ETH Zurich2016

Modelling the Urban Microclimate and its Influence on Building Energy Demands of an Urban Neighbourhood

Jérôme Henri Kämpf

EPFL Solar Energy and Building Physics Laboratory (LESO-PB)2013