arXiv subjects

Harry Boyer

Publications and source records attributed to Harry Boyer.

At least 19 recordsLinked to original sources

arXiv2015

Empirical Validation of a Thermal Model of a Complex Roof Including Phase Change Materials

This paper deals with the empirical validation of a building thermal model using a phase change material (PCM) in a complex roof. A mathematical model dedicated to phase change materials based on the heat apparent capacity method was implemented in a multi-zone building simulation code, the aim being to increase understanding of the thermal behavior of the whole building with PCM technologies. To empirically validate the model, the methodology is based both on numerical and experimental studies. A parametric sensitivity analysis was performed and a set of parameters of the thermal model have been identified for optimization. The use of a generic optimization program called GenOpt coupled to the building simulation code enabled to determine the set of adequate parameters. We first present the empirical validation methodology and main results of previous work. We then give an overview of GenOpt and its coupling with the building simulation code. Finally, once the optimization results are obtained, comparisons of thermal model of PCM with measurements are found to be acceptable and are presented.

physics.class-ph↗

arXiv2015

Elements of Validation of Artificial Lighting through the Software CODYRUN: Application to a Test Case of the International Commission on Illumination (CIE)

CODYRUN is a software for computational aeraulic and thermal simulation in buildings developed by the Laboratory of Building Physics and Systems (L.P.B.S). Numerical simulation codes of artificial lighting have been introduced to extend the tool capacity. These calculation codes are able to predict the amount of light received by any point of a given working plane and from one or more sources installed on the ceiling of the room. The model used for these calculations is original and semi-detailed (simplified). The test case references of the task-3 TC-33 International Commission on Illumination (CIE) were applied to the software to ensure reliability to properly handle this photometric aspect. This allowed having a precise idea about the reliability of the results of numerical simulations.

cs.GR↗

arXiv2014

Numerical evaluation of the thermal performances of roof-mounted radiant barriers

This paper deals with the thermal performances of roof-mounted radiant barriers. Using dynamic simulations of a mathematical model of a whole test cell including a radiant barrier installed between the roof top and the ceiling, the thermal performance of the roof is calculated. The mean method is more particularly used to assess the thermal resistance of the building component and lead to a value which is compared to the one obtained for a mass insulation product such as polyurethane foam. On a further stage, the thermal mathematical model is replaced by a thermo-aeraulic model which is used to evaluate the thermal resistance of the roof as a function of the airflow rate. The results shows a better performance of the roof in this new configuration, which is widely used in practice. Finally, the mathematical relation between the thermal resistance and the airflow rate is proposed.

physics.ins-det↗

arXiv2014

Weather data analysis based on typical weather sequence analysis. Application: energy building simulation

In building studies dealing about energy efficiency and comfort, simulation software need relevant weather files with optimal time steps. Few tools generate extreme and mean values of simultaneous hourly data including correlation between the climatic parameters. This paper presents the C++ Runeole software based on typical weather sequences analysis. It runs an analysis process of a stochastic continuous multivariable phenomenon with frequencies properties applied to a climatic database. The database analysis associates basic statistics, PCA (Principal Component Analysis) and automatic classifications. Different ways of applying these methods will be presented. All the results are stored in the Runeole internal database that allows an easy selection of weather sequences. The extreme sequences are used for system and building sizing and the mean sequences are used for the determination of the annual cooling loads as proposed by Audrier-Cros (Audrier-Cros, 1984). This weather analysis was tested with the database of the French weather forecast utility Meteo France. Reunion Island experiences a lot of different micro-climates due to the high altitude (3069m), specific relief, and geographic situation (Tropic of Capricorn). Furthermore Reunion Island has the densest meteorological network in France and is an ideal place to validate the methodology with different climates. To test the efficiency of such analysis, simulations using the resulting weather sequences were carried out with the building simulation software CODYRUN. This analysis is the first step of a more global research concerning weather data generation. Future work will permit whole hourly typical meteorological year generation using neural networks.

physics.comp-ph↗

arXiv2014

Impact of the atmospheric boundary layer profile on the ventilation of a cubic building with two large opposite openings

The aim of this paper is to show the influence of the atmospheric boundary layer profile on the distribution of velocity in a building having two large openings. The knowledge of the flow form inside a building is useful to define a thermal environment favourable with thermal comfort and good air quality. In computational fluid dynamics, several profiles of atmospheric boundary layer can be used like logarithmic profiles or power profiles. This paper shows the impact of these profiles on the indoor airflow. Non-ventilated or ventilated parts of room are found. They show respectively ineffective ventilation and effective ventilation. A qualitative and global approach allows to observe the flows in a cubic building and to show the influence of each profile according to the external ground roughness and the incidence angle of the wind. Some zones, where occupants move, are named volumes of life. Ventilation is there observed using traditional tools in order to analyze quantitatively the ventilation of these zones.

physics.flu-dyn↗

arXiv2013

Simulation of a typical house in the region of Antananarivo, Madagascar. Determination of passive solutions using local materials

This paper deals with new proposals for the design of passive solutions adapted to the climate of the highlands of Madagascar. While the strongest population density is located in the central highlands, the problem of thermal comfort in buildings occurs mainly during winter time. Currently, people use raw wood to warm the poorly designed houses. This leads to a large scale deforestation of the areas and causes erosion and environmental problems. The methodology used consisted of the identification of a typical building and of a typical meteorological year. Simulations were carried out using a thermal and airflow software (CODYRUN) to improve each building component (roof, walls, windows, and soil) in such a way as to estimate the influence of some technical solutions on each component in terms of thermal comfort. The proposed solutions also took into account the use of local materials and the standard of living of the country.

cs.CE↗

arXiv2013

Bringing simulation to implementation: Presentation of a global approach in the design of passive solar buildings under humid tropical climates

In early 1995, a DSM pilot initiative has been launched in the French islands of Guadeloupe and Reunion through a partnership between several public and private partners (the French Public Utility EDF, the University of Reunion Island, low cost housing companies, architects, energy consultants, etc...) to set up standards to improve thermal design of new residential buildings in tropical climates. This partnership led to defining optimized bio-climatic urban planning and architectural designs featuring the use of passive cooling architectural principles (solar shading, natural ventilation) and components, as well as energy efficient systems and technologies. The design and sizing of each architectural component on internal thermal comfort in building has been assessed with a validated thermal and airflow building simulation software (CODYRUN). These technical specifications have been edited in a reference document which has been used to build over 300 new pilot dwellings through the years 1996-1998 in Reunion Island and in Guadeloupe. An experimental monitoring has been made in these first ECODOM dwellings in 1998 and 1999. It will result in experimental validation of impact of the passive cooling strategies on thermal comfort of occupants leading to modify specifications if necessary. The paper present all the methodology used for the elaboration of ECODOM, from the simulations to the experimental results. This follow up is important, as the setting up of the ECODOM standard will be the first step towards the setting up of thermal regulations in the French overseas territories, by the year 2002.

cs.CE↗

arXiv2013

Optimization of thermal comfort in building through envelope design

Due to the current environmental situation, energy saving has become the leading drive in modern research. Although the residential houses in tropical climate do not use air conditioning to maintain thermal comfort in order to avoid use of electricity. As the thermal comfort is maintained by adequate envelope composition and natural ventilation, this paper shows that it is possible to determine the thickness of envelope layers for which the best thermal comfort is obtained. The building is modeled in EnergyPlus software and HookeJeves optimization methodology. The investigated house is a typical residential house one-storey high with five thermal zones located at Reunion Island, France. Three optimizations are performed such as the optimization of the thickness of the concrete block layer, of the wood layer, and that of the thermal insulation layer. The results show optimal thickness of thermal envelope layers that yield the maximum TC according to Fanger predicted mean vote.

cs.CE↗

arXiv2013

Performances of Low Temperature Radiant Heating Systems

Low temperature heating panel systems offer distinctive advantages in terms of thermal comfort and energy consumption, allowing work with low exergy sources. The purpose of this paper is to compare floor, wall, ceiling, and floor-ceiling panel heating systems in terms of energy, exergy and CO2 emissions. Simulation results for each of the analyzed panel system are given by its energy (the consumption of gas for heating, electricity for pumps and primary energy) and exergy consumption, the price of heating, and its carbon dioxide emission. Then, the values of the air temperatures of rooms are investigated and that of the surrounding walls and floors. It is found that the floor-ceiling heating system has the lowest energy, exergy, CO2 emissions, operating costs, and uses boiler of the lowest power. The worst system by all these parameters is the classical ceiling heating

cs.CE↗

arXiv2012

Low energy architecture in the tropics: from design to building construction

This paper presents a realization of passive construction in Reunion, French Department in the Indian Ocean (southern hemisphere) submitted to a wet tropical climate. Aspects of passive construction were integrated at the design stage and this house does not present additional costs towards classical ones. This project was awarded a prize for architecture climate.

physics.gen-ph↗

arXiv2012

Weather sequences for predicting HVAC system behaviour in residential units located in tropical climates

The purpose of our research deals with the description of a methodology for the definition of specific weather sequences and their influence on the energy needs of HVAC system. We'll apply the method on the tropical Reunion Island. The methodological approach based on a detailed analysis of weather sequences leads to a classification of climatic situations that can be applied to the site. These sequences have been used to simulate buildings and air handling systems thanks to a thermal simulation code, CODYRUN. Results bring to the light how necessary it is to have coherent meteorological data for this kind of simulation.

cs.CE↗

arXiv2012

Multiple model approach and experimental validation of a residential air-to-air heat pump

The beginning of this work is the achievement of a design tool, which is a multiple model software called " CODYRUN ", suitable for professionnals and usable by researchers. The original aspect of this software is that the designer has at his disposal a wide panel of choices between different heat transfer models More precisely, it consists in a multizone software integrating both natural ventilation and moisture tranfers . This software is developed on PC micro computer and gets advantage of the Microsoft WINDOWS front-end. Most of time, HVAC systems and specially domestic air conditioners, are taken into account in a very simplified way, or in a elaborated one. On one side,they are just supposed to supply the demand of cooling loads with an ideal control loop (no delay between the sollicitations and the time response of the system), The available outputs are initially the hourly cooling and heating consumptions without integrating the real caracteristics of the HVAC system This paper is also following the same multiple model approach than for the building modelling by defining different modelling levels for the air conditionning systems, from a very simplified one to a detailled one. An experimental validation is achieved in order to compare the sensitivity of each defined model and to point out the interaction between the thermal behaviour of the envelop and the electrical system consumption. For validation purposes, we will describe the data acquisition system. and the used real size test cell located in the University of Reunion island, Indian Ocean.

cs.CE↗

arXiv2012

Multiple model software for airflow and thermal building simulation. A case study under tropical humid climate, in Réunion Island

The first purpose of our work has been to allow -as far as heat transfer modes, airflow calculation and meteorological data reconstitution are concerned- the integration of diverse interchangeable physical models in a single software tool for professional use, CODYRUN. The designer's objectives, precision requested and calculation time consideration, lead us to design a structure accepting selective use of models, taking into account multizone description and airflow patterns. With a building case study in Reunion Island, we first analyse the sensibility of the thermal model to diffuse radiation reconstitution on tilted surfaces. Then, a realistic balance between precision required and calculation time leads us to select detailed models for the zone of main interest, but to choose simplified models for the other zones.

cs.CE↗

arXiv2012

Time-variant Linear reduction model approximation : application to thermal and airflow building simulation

Considering the natural ventilation, the thermal behavior of buildings can be described by a linear time varying model. In this paper, we describe an implementation of model reduction of linear time varying systems. We show the consequences of the model reduction on computing time and accuracy. Finally, we compare experimental measures and simulation results using the initial model or the reduced model. The reduced model shows negligible difference in accuracy, and the computing time shortens.

cs.CE↗

arXiv2012

Black box modelling of HVAC system : improving the performances of neural networks

This paper deals with neural networks modelling of HVAC systems. In order to increase the neural networks performances, a method based on sensitivity analysis is applied. The same technique is also used to compute the relevance of each input. To avoid the prediction errors in dry coil conditions, a metamodel for each capacity is derived from the neural networks. The regression coefficients of the polynomial forms are identified through the use of spectral analysis. These methods based on sensitivity and spectral analysis lead to an optimized neural network model, as regard to its architecture and predictions.

cs.NE↗

arXiv2012

Elaboration of a new tool for weather data sequences generation

This paper deals about the presentation of a new software RUNEOLE used to provide weather data in buildings physics. RUNEOLE associates three modules leading to the description, the modelling and the generation of weather data. The first module is dedicated to the description of each climatic variable included in the database. Graphic representation is possible (with histograms for example). Mathematical tools used to compare statistical distributions, determine daily characteristic evolutions, find typical days, and the correlations between the different climatic variables have been elaborated in the second module. Artificial weather datafiles adapted to different simulation codes are available at the issue of the third module. This tool can then be used in HVAC system evaluation, or in the study of thermal comfort. The studied buildings can then be tested under different thermal, aeraulic, and radiative solicitations, leading to a best understanding of their behaviour for example in humid climates.

cs.CE↗

arXiv2012

Building design in tropical climates. Elaboration of the ECODOM standard in the french tropical islands

This paper deals with the elaboration of global quality standards for natural and low energy cooling in french tropical island buildings. Electric load profiles of tropical islands in developed countries are characterised by morning, midday and evening peaks arising from all year round high power demand in the commercial and residential sectors, mostly due to air conditioning appliances and bad thermal conception of the building. In early 1995, a DSM pilot initiative has been launched in the french islands of Guadeloupe and Reunion through a partnership between the French Public Utility EDF, institutions involved in energy conservation, environment preservation (ADEME) and construction quality improvment, the University of Reunion Island and several other public and private partners (low cost housing institutions, architects, energy consultant, etc...) to set up a standard in the thermal conception of buildings in tropical climates. This has led to definition of optimized bioclimatic urban planning and architectural design, the use of passive cooling architectural components, natural ventilation and energy efficient systems. The impact of each technical solution on the thermal comfort within the building was evaluated with an airflow and thermal building simulation software (CODYRUN). These technical solutions have been edited in a pedagogical reference document and have been implemented in 300 new pilot dwelling projects through the year 1996 in Reunion Island and in Guadeloupe island. An experimental follow up is still in process in the first ECODOM dwellings for an experimental validation of the impact of the passive cooling solutions on the comfort of the occupants and to modify them if necessary.

cs.OH↗

arXiv2012

A simple evaluation of global and diffuse luminous efficacy for all sky conditions in tropical and humid climate

This paper presents initial values of global and diffuse luminous efficacy at Saint-Pierre (Reunion Island). Firstly, data used were measured for a period of 6 months, from February to June 2008. During this period, all defined day-types have been studied (clear, cloudy and intermediate). Generally, the meteorological database of Reunion does not contain information for illuminance values. On the other hand, the local meteorological center has a 60-years-old database for solar irradiance (W.m-2). So it is important to determine Luminous Efficacy in order to find illuminance from solar irradiance (or luminance from solar radiance). The measured data were analyzed, and empirical constant models were developed and presented in this paper in order to determine luminous efficacy under different sky conditions. A comparison between these empirical constants (models) and existing models has been made. The method used to define sky conditions (overcast, intermediate and clear) and day-types characterization as well as classification will be presented in this work.

physics.ao-ph↗