Ambiguities, Changes, and Contradictions in Building Wall Literature

2008 ◽  
pp. 10-10-7
Author(s):  
RJ Kudder ◽  
KM Lies ◽  
BA Faith
Keyword(s):  
Building Wall

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 Experimental testing of exterior wall mounted mechanical ventilation exhaust air outlet devices

2021 ◽  
Vol 246 ◽  
pp. 02001
Author(s):  
Ülar Palmiste ◽  
Tauno Meier ◽  
Jarek Kurnitski ◽  
Hendrik Voll
Keyword(s):  
Mechanical Ventilation ◽  
Experimental Testing ◽  
Airflow Rate ◽  
Tracer Gas ◽  
Qualitative Comparison ◽  
Smoke Visualization ◽  
Air Jets ◽  
Air Jet ◽  
Building Wall ◽  
Face Velocity

The purpose of the study was to experimentally test the performance of four types of wall-mounted mechanical ventilation exhaust air outlet devices. A full-scale mock-up of a segment of an external wall with an exhaust air outlet was constructed. The tested exhaust air devices include a gravity louver, fixed-blade louver, louver plate, and exhaust nozzle. The performance assessment included two types of experiments over the exhaust airflow rate range of 25–94 l/s at isothermal conditions with no influencing wind: (i) the particle tracer method with smoke to visualize the exhaust air jets from the outlets, and (ii) the tracer gas method to measure the dilution of CO2 concentration in the exhaust air jet. Furthermore, the aerodynamic performance was comparatively evaluated in terms of pressure drop and exhaust air face velocity at the outlet. The qualitative comparison of airflow patterns by smoke visualization showed notable differences between the tested device types. Concentration decrease evaluation indicated that the exhaust air pollutants are more efficiently transported away from the building wall by exhaust outlets that discharge at 0–45 degrees downwards from the horizontal plane. Discharge angles 60–90 degrees downwards produced a wall-attached jet and the pollutant tracer concentration remained relatively high in the vicinity of the wall.

Study of Sawdust and Expanded Polystyrene as Cavity Filler Material on the Effect of Thermal Conductivity in Perforated Clay Brick

2017 ◽  
Vol 890 ◽  
pp. 411-414
Author(s):  
Mun Kou Lai ◽  
Abdullah Salem Basalem Maged
Keyword(s):  
Thermal Conductivity ◽  
Specific Heat ◽  
Temperature Change ◽  
Electricity Consumption ◽  
Expanded Polystyrene ◽  
Filler Material ◽  
Waste Products ◽  
High Specific Heat ◽  
Building Wall ◽  
Good Potential

The main objective of this paper is to reduce the amount of external heat penetrating the building wall, hence reducing the cooling load requirements and eventually the electricity consumption. Expanded polystyrene and wood sawdust were chosen as filler material to reduce the thermal conductivity in perforated bricks because both are commonly found waste products with good potential due to their lightweight, low thermal conductivity and high specific heat. It was found that bricks with polystyrene recorded the lowest temperature change. Although sawdust has a much higher thermal conductivity, the temperature change is almost similar to that of polystyrene. This could be attributed by the higher density of wood, which means more mass are occupying the same volume of space. Hence, the paper found that thermal conductivity, specific heat capacity and density of the filler material can influence the effective thermal conductivity of the perforated brick.

Investigation of Physical, Mechanical and Thermal Properties of Building Wall Materials

2017 ◽  
Vol 751 ◽  
pp. 521-526 ◽  
Author(s):  
Jiraphorn Mahawan ◽  
Somchai Maneewan ◽  
Tanapon Patanin ◽  
Atthakorn Thongtha
Keyword(s):  
Compressive Strength ◽  
Thermal Properties ◽  
Water Absorption ◽  
Calcium Silicate Hydrate ◽  
Lightweight Concrete ◽  
Physical And Mechanical Properties ◽  
Mechanical And Thermal Properties ◽  
Thermal Insulating ◽  
Building Wall ◽  
Wall Materials

This research concentrates to the effect of changing sand proportion on the physical, mechanical and thermal properties of building wall materials (Cellular lightweight concrete). The density, water absorption and compressive strength of the 7.0 cm x 7.0 cm x 7.0 cm concrete sample were studied. It was found that there are an increase of density and a reduction of water absorption with an increase of sand content. The higher compressive strength can be confirmed by higher density and lower water absorption. The physical and mechanical properties of lightweight concrete conditions conformed to the Thai Industrial Standard 2601-2013. The phases of CaCO3 and calcium silicate hydrate (C-S-H) in the material indicate an important factor in thermal insulating performance.

Research and simulation analysis of thermal performance and hygrothermal behavior of timber-framed walls with different external thermal insulation layer: Cork board and anticorrosive pine plate

2020 ◽  
pp. 174425912093672
Author(s):  
Haiyan Fu ◽  
Yewei Ding ◽  
Minmin Li ◽  
Yu Cao ◽  
Wenbo Xie ◽  
...  
Keyword(s):  
Thermal Insulation ◽  
Thermal Performance ◽  
Simulation Analysis ◽  
Living Environment ◽  
Wall Structure ◽  
Cold Winter ◽  
Winter Climate ◽  
Hygrothermal Behavior ◽  
Building Wall ◽  
Mold Spore

In order to improve the comfort of the living environment, the thermal performance and temperature–humidity regulation of the exterior walls of two timber-framed structure buildings is theoretically calculated and experimentally studied in this study. Both of the two buildings are located in Nanjing, China, the hot-summer and cold-winter zone. Then WUFI is used to simulate and predict the changes of temperature, relative humidity, and water content of the two timber-framed structure buildings, to strengthen the theoretical analysis of the thermal and humidity coupling of the external walls, and to propose an optimal design scheme for the insulation and temperature and humidity regulation of the external walls. The main results show that the tested thermal conductivity is basically consistent with the predicted value, which prove that WUFI simulation can effectively predict the thermal insulation performance of the external wall. The two timber-framed structure buildings are both suitable for the cold areas, and the reasonable optimization of the design of the structure is the key to the insulation of the building wall. Timber-framed structure is proved to have good temperature–humidity regulation effect. The moisture content of the two timber-framed structure buildings is stable, and the annual temperature and winter humidity are within the appropriate humidity range, which indicates that the wall design is suitable for Nanjing hot-summer and cold-winter climate zone. Four types of wall structure indoor mold spore germinations are less likely, which is not easy to produce the mold. The above research aims to optimize the design of the energy-saving wall of the timber-framed structure and create a comfortable and healthy living environment.

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