scholarly journals Energy Performance of Earthen Walls In A Hot Climate of Morocco

2019 ◽  
Vol 8 (12) ◽  
pp. 2395-2404 ◽  
Keyword(s):  
Thermophysical Properties ◽  
Time Lag ◽  
Radiation Heat Transfer ◽  
Thermal Characteristics ◽  
Transient Heat Conduction ◽  
Energy Performance ◽  
Second Step ◽  
Clay Bricks ◽  
Hot Climate ◽  
Apparent Thermal Conductivity

The building sector consumes more than 25% of energy consumption in Morocco. So, the reducing of the energy cost of building has become a necessity. In this context, the objectives of this work are to investigate the thermophysical properties and the energy performance of earthen walls made from three types of unfired clay bricks. This work is broken into two steps. In the first step the apparent thermal conductivity was obtained experimentally using the hot plate method. In the second step, the thermophysical properties obtained were used to calculate the decrement factor and the time lag of complete walls mad from these materials by solving the transient heat conduction equation with periodic loadings using the eigenfunction expansion and the integrating factor methods. The effect of the outer and inner combined convection and radiation heat transfer coefficient on these dynamic thermal characteristics was studied. The optimum thickness of the walls was also calculated. Finally, the effect of thermal insulation on energy performance of the walls was studied

scholarly journals Thermal characterization of a new effective building material based on clay and olive waste

2018 ◽  
Vol 149 ◽  
pp. 02053 ◽  
Author(s):  
Lamrani Mohamed ◽  
Khalfaoui Mohamed ◽  
Laaroussi Najma ◽  
Khabbazi Abdelhamid
Keyword(s):  
Thermal Properties ◽  
Thermophysical Properties ◽  
Building Material ◽  
Volume Fraction ◽  
Raw Materials ◽  
Thermal Characteristics ◽  
Thermal Characterization ◽  
Energy Performance ◽  
Clay Bricks ◽  
Mass Fractions

The influence of thermophysical properties of wall materials on energy performance and comfort in traditional building was investigated. The clay is the most commonly used sustainable building material. The study looked at the effects of the addition of pomace olive on the thermophysical properties of clay bricks to improve the energy efficiency of this ecological material. An experimental measurement of thermal properties of clay mixed with pomace olive was carried out by using the transient and steady state hot-plate and flash methods. The experimental methods are applied to measure the thermal properties of the composite material. The estimation of these thermal characteristics is based on a one dimensional model and the experimental errors are found less than 3%. The composite samples were prepared with different granular classes and mass fractions of the pomace olive in the mixture. The results show that the density of the new material was not substantially influenced by the size of the pomace olive. However, the thermal conductivity and diffusivity decrease from 0.65 W.m-1.K-1 and 4.21×10-7 m2.s-1 to 0.29 W.m-1.K-1 and 2.47×10-7m2.s-1, respectively, according to the variation of the volume fraction of pomace olive from 0 (pure clay) to 71% showing that the olive pomace can be used as effective secondary raw materials in the making of clay bricks.

scholarly journals Experimental Study on the Thermal Behavior of Exterior Coating Textures of Building in Hot and Arid Climates

2021 ◽  
Vol 13 (8) ◽  
pp. 4175
Author(s):  
Islam Boukhelkhal ◽  
Fatiha Bourbia
Keyword(s):  
Energy Consumption ◽  
Surface Temperature ◽  
External Surface ◽  
Thermal Characteristics ◽  
Energy Performance ◽  
Building Envelope ◽  
Interior Space ◽  
Design Elements ◽  
Aesthetic Appearance ◽  
Reduction Of Energy Consumption

The building envelope is the barrier between the interior and exterior environments. It has many important functions, including protecting the interior space from the climatic variations through its envelope materials and design elements, as well as reduction of energy consumption and improving indoor thermal comfort. Furthermore, exterior building sidings, in addition to their aesthetic appearance, can have useful textures for reducing solar gains and providing good thermal insulation performance. This research examined and evaluated the effect of external siding texture and geometry on energy performance. For this objective, a field in situ testing and investigation of surface temperature was carried out on four samples (test boxes) with different exterior textures and different orientations, under the climate zone of Constantine–Algeria during the summer period. The results indicated significant dependability between the exterior texture geometry, the percentage of shadow projected, and external surface temperature. The second part of the research involved a similar approach, exploring the effect of three types of particles with the same appearance but with different thermal characteristics. It was concluded that the natural plant aggregates “palm particles” had the best performance, which contributed to a significant reduction of external surface temperature reaching 4.3 °C, which meant decreasing the energy consumption.

scholarly journals The Impact of Variable Thermal Conductivity of Insulation Materials on the Building Energy Performance in Hot Climate

2019 ◽  
Vol 103 ◽  
pp. 02001 ◽  
Author(s):  
Maatouk Khoukhi ◽  
Ahmed Hassan ◽  
Shaimaa Abdelbaqi
Keyword(s):  
Thermal Conductivity ◽  
Energy Performance ◽  
Variable Thermal Conductivity ◽  
Transfer Model ◽  
Ambient Conditions ◽  
K Value ◽  
Hot Climate ◽  
Building Wall ◽  
Wall Assembly ◽  
The Impact

This paper illustrates the impact of embedding an insulation layer of variable thermal conductivity in a typical building wall on the cooling effect and energy performance. The evaluation was performed by applying a conjugate heat transfer model, which was tested in extremely hot conditions of Al Ain (UAE). The thermal performance of a building incorporating insulation layers of variable thermal conductivity (k-value) was compared to a non-variable thermal conductivity system by quantifying the additional heat transferred due to the k-relationship with time. The results show that, when the k-value is a function of operating temperature, its effects on the temperature profile through the wall assembly during daytime is significant compared with that obtained when a constant k-value for the polystyrene (EPS) insulation is adopted. A similar trend in the evolution of temperatures during the day and across the wall section was observed when EPS material with different moisture content was evaluated. For the polyurethane insulation, the inner surface temperature reached 44 °C when constant k-value was adopted, increasing to 48.5 °C when the k-value was allowed to vary under the same ambient conditions.

scholarly journals BIM and BEM Methodologies Integration in Energy-Efficient Buildings Using Experimental Design

Buildings ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 491
Author(s):  
Jorge González ◽  
Carlos Alberto Pereira Soares ◽  
Mohammad Najjar ◽  
Assed N. Haddad
Keyword(s):  
Experimental Design ◽  
Energy Efficient ◽  
Thermal Characteristics ◽  
Energy Performance ◽  
Building Envelope ◽  
Climatic Zones ◽  
Energy Efficient Buildings ◽  
Energy Modelling ◽  
Building Information ◽  
Energetic Performance

Linking Building Information Modelling and Building Energy Modelling methodologies appear as a tool for the energy performance analysis of a dwelling, being able to build the physical model via Autodesk Revit and simulating the energy modeling with its complement Autodesk Insight. A residential two-story house was evaluated in five different locations within distinct climatic zones to reduce its electricity demand. Experimental Design is used as a methodological tool to define the possible arrangement of results emitted via Autodesk Insight that exhibits the minor electric demand, considering three variables: Lighting efficiency, Plug-Load Efficiency, and HVAC systems. The analysis concluded that while the higher the efficiency of lighting and applications, the lower the electric demand. In addition, the type of climate and thermal characteristics of the materials that conform to the building envelope have significant effects on the energetic performance. The adjustment of different energetic measures and its comparison with other climatic zones enable decision-makers to choose the best combination of variables for developing strategies to lower the electric demand towards energy-efficient buildings.

Transient Heat Conduction in a Rod of Finite Length With Variable Thermal Properties

1960 ◽  
Vol 27 (4) ◽  
pp. 617-622 ◽  
Author(s):  
W. H. Chu ◽  
H. N. Abramson
Keyword(s):  
Thermal Properties ◽  
Heat Conduction ◽  
Finite Length ◽  
Thermophysical Properties ◽  
Numerical Procedure ◽  
Transient Heat Conduction ◽  
Theoretical Solution ◽  
Rod Of Finite Length

This paper presents a theoretical solution for transient heat conduction in a rod of finite length with variable thermal properties. A numerical procedure is developed and the results of one example are presented and compared with the corresponding solution for the case of constant properties. Application to the problem of determination of thermophysical properties is discussed briefly.

scholarly journals Impact of Insulation Type and Thickness on the Dynamic Thermal Characteristics of an External Wall Structure

2018 ◽  
Vol 10 (8) ◽  
pp. 2835 ◽  
Author(s):  
Jihui Yuan
Keyword(s):  
Time Lag ◽  
Thermal Characteristics ◽  
Thermal Capacity ◽  
Wall Structure ◽  
External Wall ◽  
Thermal Transmittance ◽  
Wall Structures ◽  
The Impact ◽  
Time Lead ◽  
Surface Factor

The dynamic thermal characteristics of external wall structures are directly related to indoor thermal comfort and energy savings in buildings; they are also complicated and worth investigating. Thermal insulation in external wall structures has become a popular topic of investigation in the domain of building energy efficiency. This study aims to find the impact of insulation type and thickness on the dynamic thermal characteristics of external wall structures using a homogeneous multi-layer building external wall structure and three types of insulation materials that are widely used in Japan. The impact of insulation type and thickness on seven thermal characteristics of external walls, including thermal transmittance, decrement factor or amplitude attenuation, time lag, thermal admittance, time lead for thermal admittance, surface factor, and thermal capacity, was evaluated by numerical methods in this study. It was shown that insulation type and thickness would have a significant effect on thermal transmittance, decrement factor and time lag, but yield no significant change in thermal admittance, time lead for thermal admittance, surface factor, and the thermal capacity of external wall structures.

scholarly journals Optimal Thermal Characteristics of the Courtyard in the Hot and Arid Climate of Isfahan

Buildings ◽  
2018 ◽  
Vol 8 (12) ◽  
pp. 166 ◽  
Author(s):  
Roya Hasehzadeh Haseh ◽  
Mehdi Khakzand ◽  
Morteza Ojaghlou
Keyword(s):  
Thermal Comfort ◽  
Middle Eastern ◽  
Thermal Characteristics ◽  
Arid Climate ◽  
Second Step ◽  
Traditional Architecture ◽  
Optimal Form ◽  
The Third ◽  
Simulation Process

The courtyard is a common and traditional architectural concept in Middle Eastern countries, especially Iran. This study presents practical solutions to arrive at the optimal form and features of a courtyard based on this traditional architecture to cope with the hot and arid climate of Isfahan, Iran. A model using the ENVI-met 3.1 software was used to simulate the courtyard orientation, the height of the wall enclosure, the albedo of the materials and the vegetation level in Isfahan. As the first step of the simulation, different orientations were simulated. Based on the results, the northern courtyard is recommended as the optimum orientation for the remainder of the simulation process. A high wall enclosure is recommended in the second step of simulation to ensure cool temperatures at noon and warmth at night. In the third step, it is advised to use low-albedo material in the courtyards to avoid the extra reflected radiation of used materials on the inhabitants. The final step suggests that more than 50% of the courtyard plan should be covered by greenery to ensure thermal comfort in the courtyards. Based on these suggestions, designers can create more sustainable courtyards that are better suited to the hot and arid climate of Isfahan.

Effects of wall masonry layer’s thermophysical properties and insulation position on time lag and decrement factor

2014 ◽  
Vol 25 (2) ◽  
pp. 371-377 ◽  
Author(s):  
Lianying Zhang ◽  
Jiyuan Zhang ◽  
Fenghao Wang ◽  
Yuan Wang
Keyword(s):  
Thermophysical Properties ◽  
Time Lag

Pore Structure and Thermal Characteristics of Clay Bricks

2014 ◽  
Vol 982 ◽  
pp. 104-107 ◽  
Author(s):  
Monika Čáchová ◽  
Dana Koňáková ◽  
Eva Vejmelková ◽  
Martin Keppert ◽  
Kirill Polozhiy ◽  
...  
Keyword(s):  
Thermal Properties ◽  
Structural Material ◽  
Physical Properties ◽  
Thermal Characteristics ◽  
Clay Brick ◽  
Pore System ◽  
Clay Bricks ◽  
Vacuum Saturation ◽  
The Difference ◽  
System Characteristics

Clay brick was perhaps to be the first artificial structural material. First bricks were dried by sun; later people had started to burn bricks by fire and in that time further enhancements appeared. This article deals with two kinds of fired clay bricks; basic physical properties, pore system characteristics and thermal properties are studied. The values of basic physical properties by water vacuum saturation vary slightly; bulk density shows values around 1880 kg/m3 and in the case of open porosity it is around 27%. Regarding thermal properties the difference is higher, obtained results of thermal conductivities in dried state vary by about 33%.

A Micro-Insulation Concept for MEMS Applications

2009 ◽  
Vol 131 (5) ◽  
Author(s):  
Rui Yao ◽  
James Blanchard
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Radiation Heat Transfer ◽  
Thermal Conversion ◽  
Power Source ◽  
Radioactive Isotopes ◽  
Small Scale ◽  
Power Sources ◽  
Planar Surfaces ◽  
Apparent Thermal Conductivity

Small scale, thermally driven power sources will require appropriate insulation to achieve sufficiently high thermal conversion efficiencies. This paper presents a micro-insulation design, which was developed for a thermionic microbattery, which converts the decay heat from radioactive isotopes directly to electricity using a vacuum thermionic diode. The insulation concept, which is suitable for any small scale application, separates two planar surfaces with thin, semicircular posts, thus reducing conduction heat transfer and increasing the relative radiation heat transfer. In this case, the surfaces are silicon wafers and the columns are SU-8, a photoresist material. The experimental results indicate that this design is adequate for a practical power source concept, and they are supported by a numerical model for the effective thermal conductivity of the structure. The results show that a typical design of 20 columns/cm2 with a 200 μm diameter and a 10 μm wall thickness has an apparent thermal conductivity on the order of 10−4 W/m K at a pressure of 1 Pa. System models of a thermionic power source indicate that this is sufficiently low to provide practical efficiency.

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