Establishing building environmental targets to implement a low carbon objective at the district level: methodology and case study

To face climate change, greenhouse gas (GHG) emission targets are specified into national policies. In France, the objective is to divide by 4 (Factor 4) the GHG emissions by 2050 comparing to 1990. The built environment, as a main contributor, is targeted by these policies: the future 2020 French regulation will set up GHG emissions targets for the building life cycle. However, the implementation of this regulation and its labels into real-estate development is challenging because it is uncorrelated to factor 4, architectural and technical constraints due to these labels are yet unknown and targets are defined at building scale and not at the district scale. This paper offers some answers to this challenges based on a case study from a real estate developer who wanted to implement a 2025 objective to a new district in Lyon, France. It was done thanks to a review on Factor 4 and labels' history, on calculation of GHG emissions from 1990s building and objectives for 2050 and illustration of labels' constraints. Finally, objectives were allocated at building scale to meet the overall district ambition

Étude des transferts de chaleur dans un canal vertical differentiellement chauffé (application aux enveloppes photovoltaïques thermiques)

Ce travail traite de l intégration des modules photovoltaïques (PV) au bâti. Leur rendement est fortement dépendant du niveau de température d où une intégration par adjonction d une lame d air permettant un rafraîchissement passif. La configuration étudiée est une double-peau photovoltaïque-thermique où l écoulement de convection naturelle se développe sous l effet d une répartition périodique des sollicitations thermiques imposées en flux sur les deux parois du canal. La réalisation d une cellule expérimentale permet d étudier l effet d un chauffage alterné sur les transferts de chaleur. Les mesures de température pariétale et l évaluation des échanges convectifs montrent que la périodicité des sources permet de réduire leur échauffement par rapport à une intégration continue. Ces résultats, confirmés par l étude numérique menée à l aide d un code RANS, conduisent à des tendances intéressantes mais restant à approfondir sur la disposition de composants PV en façade des double-peauxThis work involves the integration of photovoltaic modules within the building frame. The efficiency of PV panels is strongly dependent on their temperature level, which leads to an integration by addition of an air blade allowing their passive cooling. The line-up of the study is a double skin photovoltaic-thermics, where the natural convection develops in the air blade under periodic thermal disturbance imposed on both sides of the channel. The experimental cell made allowing the observation of the effects of an alternate (or continuous) heating on heat transfers. The temperature measurements on the wall and the evaluation of the heat transfer coefficients show that the periodic sources distribution makes it possible to reduce their temperature level compared to the case of a continuous distribution. These results, which are confirmed by a numerical study carried out using a RANS code, lead to interesting tendencies for the integration of PV components that remain to be deepenedLYON1-BU.Sciences (692662101) / SudocSudocFranceF

Numerical predictions of the fluid flow in a photovoltaic double skin facade

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