Gas-filled panels for building applications: A state-of-the-art review

With their thermal conductivity down to 10 mW/m K, gas-filled panels (GFPs) are regarded as possible high performance thermal insulating solutions for building applications. However, thermal conductivities of respectively 46 and 40 mW/m K have so far been achieved for prototype air-filled and argon-filled panels, values slightly higher than currently traditional building insulation materials. Compared to other high performance thermal insulation materials and solutions, e.g. vacuum insulation panels (VIPs), the future of GFPs may therefore be questioned. Nevertheless, the application of a low-conductive gas and reflective barriers may have a potential in the development of new high performance thermal insulation materials. Within this work, a state-of-the-art review is given on the knowledge of GFPs for building applications today.     

Aerogel insulation for building applications: A state-of-the-art review

Aerogels are regarded as one of the most promising high performance thermal insulation materials for building applications today. With a thermal conductivity down to 13 mW/(m K) for commercial products they show remarkable characteristics compared to traditional thermal insulation materials. Also the possibility of high transmittances in the solar spectrum is of high interest for the construction sector. With the proper knowledge they give both the architect and engineer the opportunity of re-inventing architectural solutions. Within this work, a review is given on the knowledge of aerogel insulation in general and for building applications in particular.     

Phase change materials for building applications: A state-of-the-art review

Phase change materials (PCMs) are regarded as a possible solution for reducing the energy consumption of buildings. By storing and releasing heat within a certain temperature range, it raises the building inertia and stabilizes indoor climate. Within this work, a state-of-the-art review is given on the knowledge of PCMs today for building applications.     

A nodal thermal model for photovoltaic systems: Impact on building temperature fields and elements of validation for tropical and humid climatic conditions

This article deals with both an experimental study and a numerical model of the thermal behaviour of a building whose roof is equipped with photovoltaic panels (PV panels). The aim of this study is to show the impact of the PV panels in terms of level of insulation or solar protection for the building. Contrary to existing models, the one presented here will allow us to determine both the temperature field of the building and the electric production of the PV array. Moreover, an experimental study has been conducted in La Reunion Island, where the climate is tropical and humid, with a strong solar radiation. In such conditions, it is important to minimise the thermal load through the roof of the building. The thermal model is integrated in a building simulation code and is able to predict the thermal impact of PV panels installed on buildings in several configurations and also their production of electricity. Basically, the PV panel is considered as a complex wall within which coupled heat transfer occurs. Conduction, convection and radiation heat transfer equations are solved simultaneously to simulate the global thermal behaviour of the building envelope including the PV panels; this is an approach we call ‘integrated modelling’ of PV panels. The experimental study is used to give elements of validation for the numerical model and a sensitivity analysis has been run to put in evidence the governing parameters. It has been shown that the radiative properties of the PV panel have a great impact on the temperature field of the tested building and the determination of these parameters has to be taken with care.     

New concepts and approach for developing energy efficient buildings: Ideal specific heat for building internal thermal mass

The shortcomings or limitations of the traditional approach to developing energy efficient buildings are that they can not determine: (1) the ideal thermophysical properties of building envelope material, where “ideal” means that such material can use ambient air temperature variation and/or solar radiation efficiently to keep the indoor air temperature in the thermal comfort range with no additional space heating or cooling; (2) the best natural ventilation strategy; (3) the minimal additional energy consumption for space heating in winter or air-conditioning in summer. To overcome these problems, some new concepts for developing energy efficient buildings are put forward in this paper. They are the ideal thermophysical properties of the building envelope material, the ideal natural ventilation rate, and a minimal additional space heating or cooling energy consumption. A new approach for determining these properties is also developed. In contrast to the traditional approach (the thermophysical properties of building envelope material are known and constant so that the relating equations describing the indoor air temperature tend to be linear differential equations), the new approach solves the inverse problem (thermophysical properties, etc. of a buildings are unknown), whose solution can be a function instead of a value. As a first step, the ideal specific heat of the building envelope material for internal thermal mass is analyzed for buildings located in various cities in different climatic regions of China, such as Beijing, Shanghai, Harbin, Urumchi, Lhasa, Kunming and Guangzhou. We found that the ideal specific heat is composed of a basic value and an excessive one which is of δ function for the cases studied. Some limitations that would need further study are introduced in the end of the paper.     

Application of CFD plug-ins integrated into urban and building design platforms for performance simulations: A literature review

The transformation of urban and building design into green development is conducive to alleviating resource and environmental problems. Building design largely determines pollutant emissions and energy consumption throughout the building life cycle. Full consideration of the impact of urban geometries on the microclimate will help construct livable and healthy cities. Computational fluid dynamics (CFD) simulations significantly improve the efficiency of assessing the microclimate and the performance of design schemes. The integration of CFD into design platforms by plug-ins marks a landmark development for the interaction of computer-aided design (CAD) and CFD, allowing architects to perform CFD simulations in their familiar design environments. This review provides a systematic overview of the classification and comprehensive comparison of CFD plug-ins in Autodesk Revit, Rhinoceros/Grasshopper, and SketchUp. The applications of CFD plug-ins in urban and building design are reviewed according to three types: single-objective, multi-objective, and coupling simulations. Two primary roles of CFD plug-ins integrated into the design process, including providing various micro-scale numerical simulations and optimizing the original design via feedback results, are analyzed. The issues of mesh generation, boundary conditions, turbulence models, and simulation accuracy during CFD plug-in applications are discussed. Finally, the limitations and future possibilities of CFD plug-ins are proposed.