Le Bourget-du-Lac, France
Le Bourget-du-Lac, France
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Andrieux F.,CSTB | Thorel M.,CSTB | Buhe C.,LOCIE
eWork and eBusiness in Architecture, Engineering and Construction - Proceedings of the European Conference on Product and Process Modelling 2012, ECPPM 2012 | Year: 2012

Refurbishment of existing buildings is a major challenge to reach the French objective to divide by 4 the greenhouse gas emissions by 2050. Methods and tools for decision support are needed, to convince householders, through estimated potential energy savings, to undertake retrofit operations, and mainly, to give professionals the keys to identify potential impacts linked to the implementation of specific refurbishment solutions. To meet these requirements, a seven steps approach is engaged. This approach concerns: (i) users requirements collection and analysis, (ii) typological studies of existing buildings, (iii) database to characterize the holistic performance of renovation solutions, (iv) toolbox to be used for a global building's diagnosis, (v) knowledge base to gather expertise on solutions impacts (expert system), (vi) analysis method for multicriteria decision support, (vii) and tool creation. A state-of-the-art has been carried out on all these steps. © 2012 Taylor & Francis Group.

Lallemand A.,rue de Cropet | Luo L.,LOCIE | Gicquel R.,MINES ParisTech
UPB Scientific Bulletin, Series C: Electrical Engineering | Year: 2010

Considering Carnot cycles, it is shown that reducing the power of a thermal power plant to produce cogeneration or using this difference in power to run heat pumps is equivalent in terms of overall performance. Practically, this is however not the same. This conclusion is put in evidence when considering an actual 280 MW power cycle and Rl34a, R600 and R717 heat pumps. It is shown that depending on the operating temperatures of the heat pumps and the heating network transmission losses, the overall cogeneration performance can be higher than the use of heat pumps in many configurations.

Fouquet M.,Joseph Fourier University | Levasseur A.,Ecole Polytechnique de Montréal | Margni M.,Ecole Polytechnique de Montréal | Lebert A.,Joseph Fourier University | And 4 more authors.
Building and Environment | Year: 2015

In Europe, low energy buildings become common for new constructions and life cycle assessment (LCA) is increasingly used to assess their environmental performance. The overall objective of this study is to investigate known challenges related to buildings LCA such as biogenic carbon accounting and dynamic and prospective aspects, and to discuss how they affect LCA results for low energy buildings and what developments are still needed. Three single family houses built respectively with timber frame, concrete blocks cavity wall, and cast concrete are used as a case study, focusing on the global warming impact category.When biogenic carbon is addressed, the timber house is the less impacting choice, whether it is landfilled or burned at the end-of-life. The cavity wall house is the second most favourable option, and the cast concrete house is the worst one. In the case of landfilling for the timber house, the biogenic carbon balance is not neutral and worth to be considered. When a dynamic approach and specific prospective scenarios are considered, the ranking between houses stays the same, but the gaps between options vary e.g. the gap between the landfilled timber house and the cast concrete house vary from 40 % to 60 % when optimistic changes in the electricity mix are considered.Dynamic LCA allows for a more consistent analysis of emissions flows and global warming impacts over time. Prospective LCA could provide more relevant LCA results but increases uncertainty and could be used as sensitivity analysis for long life span buildings. © 2015 Elsevier Ltd.

Labat M.,INSA Lyon | Labat M.,French Scientific and Technical Center for Building | Woloszyn M.,LOCIE | Garnier G.,French Scientific and Technical Center for Building | Roux J.J.,INSA Lyon
Building and Environment | Year: 2013

Under natural conditions, air change rates are very sensitive to specific building elements and to climate conditions, even more so in the case of airtight buildings. Consequently, applying general correlations to such cases may lead to inaccurate predicted air change rates. Still, this approach remains valuable because of its simplicity compared to other methods such as wind tunnelling and CFD simulations. In this paper, the tracer gas concentration decay technique was selected to contribute additional information to classical air-tightness measurements. The measurements were used to fit the coefficients of a general single-node pressure model. Simulation results were found to be consistent with tracer gas measurements most of the time. However, the closeness of the fit is strongly related to the average pressure coefficients from the literature, which were estimated more precisely using the other techniques mentioned above. From a general point of view however, it would seem promising to extend this method to other buildings. © 2012 Elsevier Ltd.

Labat M.,INSA Lyon | Labat M.,French Scientific and Technical Center for Building | Labat M.,CNRS Materials and Construction Durability Laboratory | Woloszyn M.,LOCIE | And 2 more authors.
Building and Environment | Year: 2015

An experimental wooden-frame house was designed, instrumented and tested to provide measurements suitable for the study of coupled vapour and heat transfer under real climate conditions. In this paper, six different wall assemblies were tested under complex temperature and humidity boundary conditions over more than 3 years. The main objective is to take advantage of the strong outdoor and indoor stresses to emphasise the dynamic coupling between vapour and heat transfer for different wall assemblies. Measurements showed that the heat flux crossing the vertical walls was significantly influenced when a vapour flow crossed insulating materials with high hygroscopic inertia. To further explain this result, a classical numerical model was selected. It was designed to compute coupled transfer at the building scale. A good agreement was obtained for temperature measurements, while higher differences were observed with humidity measurement. An uncertainty analysis was achieved on both experimental and numerical results. It appeared that the uncertainty of the simulation results was one order of magnitude lower than the experimental uncertainty. Finally, the numerical model was used to break down the coupling of vapour and heat transfers. The latent heat effect occurred as the most sizeable effect, which was consistent with the experimental observations. © 2015 Elsevier Ltd.

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