La Haie-Fouassière, France
La Haie-Fouassière, France

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Schwager J.,Cerema Direction Territoriale Est | Irles A.,Cerema Direction Territoriale Est | Thiriat J.,Cerema Direction Territoriale Est | Claverie R.,Gemcea | And 2 more authors.
Techniques - Sciences - Methodes | Year: 2014

The French market for vegetative roofs is continuing to develop rapidly and more than one million square meters were built in 2011. If these structures can offer various functions, not all green roofs have the same advantages and preliminary thinking is required to conceive a suitable system. The CETE de l'Est -LRPC de Nancy has launched a research project on vegetative roofs in autumn 2010 to establish guidelines for the construction of vegetative roofs with optimized abilities to retain pollutants, enhance biodiversity and improve thermal insulation. This article is dedicated to these first two functions. It describes the approach for the structures' conception and presents in situ and in laboratory results. These results allow identification of first tracks for the selection of materials with optimized ability to improve water quality. The introduction of local plant species has also shown a good implantation and development during these first two years. In addition, information allowing the actors of this sector to take into account these elements in a vegetative roof project is signaled. It could help the building owners to focus their choice toward a vegetative roof suited to the functions that they are expecting.

Leconte F.,British Petroleum | Bouyer J.,CEREMA Direction Territoriale Est | Claverie R.,CEREMA Direction Territoriale Est | Petrissans M.,British Petroleum
Theoretical and Applied Climatology | Year: 2016

The urban heat island phenomenon is generally defined as an air temperature difference between a city center and the non-urbanized rural areas nearby. However, this description does not encompass the intra-urban temperature differences that exist between neighborhoods in a city. This study investigates the air temperature dynamics of neighborhoods for meteorological conditions that lead to important urban heat island amplitude. Local climate zones (LCZs) have been determined in Nancy, France, and mobile screen-height air temperature measurements are performed using an instrumented vehicle. Initially, hourly measurements are performed within four different LCZs. These results show that air temperature within LCZ demonstrates a nocturnal cooling in two phases, i.e., a first phase between 1 to 3 h before sunset and 3 to 5 h after sunset, and a second phase from 3 to 5 h after sunset to sunrise. During phase 1, neighborhoods exhibit different cooling rate values and air temperature gaps develop between districts, while during phase 2, cooling rates tend to be analogous. Then, a larger meteorological data set is used to investigate these two phases for a selection of 13 LCZs. Normalized cooling rates are calculated between daytime measures and nighttime measures in order to quantify the air temperature dynamics of the studied areas during phase 1. Considering this indicator, three groups are emerging: LCZ compact midrise and open midrise with mean normalized cooling rate values of 0.09 h −1LCZ large lowrise and open lowrise/sparsely built with mean normalized cooling rate values of 0.011 h −1LCZ low plants with mean normalized cooling rate values of 0.014 h −1Results indicate that the relative position of LCZ within the conurbation does not drive air temperature dynamics during phase 1. In addition, measures performed during phase 2 tend to illustrate that cooling rates are similar to all LCZ during this period. © 2016 Springer-Verlag Wien

Leconte F.,ADEME | Leconte F.,British Petroleum | Bouyer J.,CEREMA Direction Territoriale Est | Claverie R.,CEREMA Direction Territoriale Est | Petrissans M.,British Petroleum
Building and Environment | Year: 2015

In the context of expansion of cities and raise of climate change awareness, urban planers are looking for methods and tools in order to take into account the urban heat island phenomenon. This study analyzes the way urban fabric modifies urban climate through the utilization of a climate scheme called Local Climate Zone (LCZ). This classification has been applied in Nancy (France). Urban indicators have been calculated so as to build 13 LCZ in the Great Nancy Area. The screen-height air temperature distribution has been investigated inside these LCZ via mobile measurements. Air temperature amplitude has mainly demonstrated lower values at nighttime than in daytime in urbanized LCZ types. Recurrent microscale hotspots and coldspots have been located in LCZ presenting heterogeneous urban fabric. Two Control Sites (CS) have been built in each LCZ. The CS average temperature has revealed good likeness with the spatially averaged air temperature. Average nocturnal air temperature differences between pairs of LCZ types have been obtained. These differences vary from less than 1°°C for close LCZ types to more than 4°°C for dissimilar LCZ types. © 2014 Elsevier Ltd.

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