Dimitri Bigot

A Simplified Model for Radiative Transfer in Building Enclosures With Low Emissivity Walls: Development and Application to Radiant Barrier Insulation

This paper deals with a simplified model of radiative heat transfer in building enclosures with low emissivity walls. The approach is based on an existing simplified model, well known and used in building multizone simulation codes, for the long wave exchanges in building enclosures. This method is simply extended to the case of a cavity including a very low emissivity wall, and it is shown that the obtained formalism is similar to the one used in the case of the based model, convenient for enclosures with only black walls (blackbody assumption). The proposed model has been integrated into a building simulation code and is based on simple examples; it is shown that intermediate results between the imprecise initial simple model and the more precise detailed model, the net-radiosity method, can be obtained. Finally, an application of the model is made for an existing experimental test cell including a radiant barrier insulation product, well used in Reunion Island for thermal insulation of roofs. With an efficacy based on the very low emissivity of their surfaces and the consequent decrease in radiative heat transfer through the wall in which they are included, the proposed simplified model leads to results very close to those of the reference method, the net-radiosity method.

A Sensitivity Analysis of a Thermal Model of Photovoltaic Panel

This paper deals with a sensitivity analysis of a thermal model. An integrated thermal modelling of photovoltaic panels (PV panels) has been built. In the case studied in this paper, the PV panel is considered like a solar protection of the building. The modelling has been run for Reunion Island climate, which has a strong solar radiation as encountered in tropical and humid conditions. The thermal model studied here has already been presented in a precedent work. In this work, the model has been validated, for comparing the results predicted and that measures showed significant differences. A sensitivity analysis seemed necessary to highlight the parameters that have the most influence on the thermal model. This will see which parameters to focus on during a future optimization of the model.

Heating or Cooling Buildings with PV Walls in Reunion Island

In Reunion Island, many buildings have been equipped with PV panels on their roofs in order to produce electricity. These PV systems were built to increase the penetration of renewable energies in the public electricity grid and so reduce greenhouse effect gases emissions. This type of installation was designed just in order to produce electricity but many works have shown that PV systems integrated to walls can also cool or heat the buildings. This paper presents how PV systems integrated to building can be used to help meeting energy needs in two microclimates of the island by cooling or heating the building where it is installed. To show this, a building simulation code able to model BIPV buildings is used.

Heat transfer in buildings : application to air solar heating and Trombe wall design

The aim of this paper is to briefly recall heat transfer modes and explain their integration within a software dedicated to building simulation (CODYRUN). Detailed elements of the validation of this software are presented and two applications are finally discussed. One concerns the modeling of a flat plate air collector and the second focuses on the modeling of Trombe solar walls. In each case, detailed modeling of heat transfer allows precise understanding of thermal and energetic behavior of the studied structures. Recent decades have seen a proliferation of tools for building thermal simulation. These applications cover a wide spectrum from very simplified steady state models to dynamic simulation ones, including computational fluid dynamics modules (Clarke, 2001). These tools are widely available in design offices and engineering firms. They are often used for the design of HVAC systems and still subject to detailed research, particularly with respect to the integration of new fields (specific insulation materials, lighting, pollutants transport, etc.). Available from: http://www.intechopen.com/books/evaporation-condensation-and-heat-transfer/heat-transfer-in-buildings-application-to-solar-air-collector-and-trombe-wall-design