Thermal performance of outer and inner multi-layered walls in buildings (original) (raw)
Related papers
Correlations Between Structure Dependent and Dynamic Thermal Characteristics of Building Walls
Journal of Thermal Envelope and Building Science, 1999
The effect of the internal thermal structure of building walls and roofs on their frequency responses, of period of 24 h, is examined. The notion of the thermal structure factors of a wall is introduced. Correlation between the fre quency dependent and structure dependent thermal characteristics is analyzed for the representative sets of building walls and roofs from ASHRAE Handbook 1989: Fundamentals. Most evident is the correlation between the decrement factor and the structure dependent time constant, between the admittance response amplitude and the appropriate thermal mass factor, and between the time lag and its estimated value, and also thickness of a wall.
Thermal Behaviour Studies on Building Walls based on Type and Composition of the Materials
IOP Conference Series: Materials Science and Engineering, 2019
Controlling the thermal behaviour of buildings is very important because it affects the energy use in the buildings and impacts the thermal environment of the area. Thermal behaviour of the building is determined by the type and composition of the building material. This paper shows the thermal behaviour of several types and composition of commonly used building wall materials, i.e. brick, aerated concrete, laminated wood with glass wool insulation, and gypsum with glass wool insulation. For the thermal behaviour measurements, we used wall models exposed to halogen lamps of 2000 watts for 4 hours heating and 4 hours for cooling with a measurement interval of 5-15 minutes. Data retrieval using 8 thermocouples mounted on the surface and inserted inside the wall. The observed thermal behaviour phenomena are the heat flow on the walls, the time delay, and the heat capacity. The results show different maps of the thermal behaviour on the walls and indicating the need for additional therm...
On the Parameters Characterizing the Thermal Transient Behavior of the External Walls of Buildings
In the last few years the behavior, under unsteady conditions, of opaque elements within the building envelope has become of outstanding importance, also from the European and National rules point of view, to reduce the energy demand for the summer air-conditioning of buildings in the light of the European Directive 2002/91/CE (EPBD). Assuming the indoor air temperature to be constant, the thermal transient behavior of a building envelope's opaque wall, stressed by external temperature sinusoidal oscillations, is characterized by the following para-meters: the decrement factor f, the wall inner surface decrement factor , the time lag and the dynamic thermal transmittance U D . Such parameters depending on the wall thermal resistance and thermal capacity, on the period of the external thermal stress and on the stratigraphy of the wall, have been studied by several authors and can be found within the European technical standards (e.g. EN ISO 13786/2007) and Italian national and lo...
Communications - Scientific letters of the University of Zilina, 2017
It appears that the walls, insulated according to the new requirements for thermal resistance, can contribute to thermal stability. This is advantageous not only for the thermal comfort during the summer but in the cases of the intermittent heating, or overheating, as well. This article evaluates some alternatives of insulated and uninsulated external walls. The phase time shift of the indoor surface temperature with respect to the outdoor surface, together with the periodic penetration depth of indoor surface temperature, are considered in this analysis. Analyzing subsurface temperature courses we evaluate the ability of construction to accumulate heat gains, which can arise during the day.
Building Simulation, 2009
There is a wide variety of thermal analyses that can be used to characterize the thermal behavior of a wall under certain outdoor conditions. The selection of a particular wall configuration for a building project involves not only the outdoor climate, but also the whole building characteristics, orientation, percentage of glazed areas, occupation periods, lifestyles, etc. In this paper we apply common available methods for wall thermal analysis to two particular wall types, a massive brick wall and an insulated brick wall, in order to compare the information given by each method and to evaluate how these methods can help in the selection of a certain type of wall. The studied methods include the estimation of the wall time lag and decrement factor, the harmonically heated slab model, the Athanassouli's method, and numerical simulations. The study was performed for the walls of a residence for university students and it was built in La Pampa (Argentina). Once the building was finished, the transient thermal behavior of two walls was monitored during one summer week. The experimental results are presented and the fitting with the thermal behavior predicted by each method is discussed. The thermal comfort indicators PMV (predicted mean vote) and PPD (predicted percentage of dissatisfied) were calculated for two flats, at ground floor and first floor respectively.
Calculation of the Thermal Dynamic Performance of the Residential Buildings’ Walls
Quality Production Improvement-QPI, 2019
Calculation of the thermal dynamic properties of the multi-layer wall isolation of residential buildings is presented in this paper. Taking into account that the final objective is to create a building with the highest energy efficiency ratio, i.e. with the lowest energy consumption, both for heating and cooling, it is necessary to realize the good thermal characteristics of the multi-layer wall. To obtain the optimal solution for the wall's structure, various wall structures with different thicknesses of the individual layers, were analyzed. Based on results, presented in this paper, one can conclude that for walls with the same total thickness, but various thicknesses of the individual layers, that constitute the complete wall structure, the differences appear in the delay of the change of the walls outside temperature. In that way, by varying those individual layers' thicknesses, one can obtain the optimal solution for the wall structure with the highest savings of energy.
2014
In this work a numerical study of the thermal behavior of a multilayer building wall (3 and 5 layers) is presented. The external side of the wall is subjected to the local atmospheric conditions of Algeria. The finite differences method is used to solve the transient heat transfer equations through the building wall, which is submitted to a solar heat flux, and a convective heat transfer with the environment. A sinusoidal forms of the external temperature and the solar flux were used to approach the measured data of Ouargla city (Algeria) (attitude 31°57' N, longitude: 5° 20'E, altitude 123-315 m), during the summer and winter seasons. An economic study is presented and a solution for a good thermal insulation at a lower cost is proposed.
Journal of Renewable Energies
The two-dimensional transient heat conduction through a multilayers wall made of different materials and thicknesses was numerically resolved. The equations system resolution was carried out by Alternating direction implicit method (ADI). The outdoor and indoor temperatures and the convective coefficients used as boundary conditions in the developed Fortran program were from the Algerian regulatory technical document. After validation of the Fortran program with literature, it was used to studying the influence of different boundary conditions (bottom and top sides), on the thermal insulation in the building, for many configurations of external walls, usually used in building construction at Batna city (Algeria). Results showed that for the configurations that give bad thermal insulation, the conditions imposed on the top and bottom of the wall have practically no influence on the internal temperature of the multilayers wall, however, the opposite is observed for the configurations ...