scholarly journals Heat and moisture transfer in wall-to-floor thermal bridges and its influences on the insulation performance

2021 ◽  
Vol 2069 (1) ◽  
pp. 012216
Author(s):  
Yucong Xue ◽  
Jian Ge ◽  
Yifan Fan
Keyword(s):  
Water Vapour ◽  
Moisture Transfer ◽  
Structural Safety ◽  
Building Envelopes ◽  
Thermal Bridge ◽  
Thermal Bridges ◽  
Heat Transfers ◽  
Heat And Moisture ◽  
Insulation Performance ◽  
Transient Numerical Simulation

Abstract The moisture modifies the characteristics of heat transfer in building envelopes. Multiple factors, including the distinct hygric properties of various material, gravity, etc., affect the moisture content, resulting in a non-uniform distribution of water vapour in different parts of the envelope (e.g. column, beam, the main part of exterior walls). Usually, the more water vapour in a material, the higher the thermal conductivity, resulting in more heat transfers here. Moreover, condensation easily occurs where there is wet, marking such parts have risks both on structural safety and mould growth. The wall-to-floor thermal bridge (WFTB) occupies the largest area among all kinds of thermal bridges that formed by frame structures. In this study, we aimed to quantify the influence on heat loss through WFTB when the moisture transfer in envelopes is considered. The average apparent thermal resistance of WFTB (R TB, ave) was defined to access the insulation performance of WFTB in practical application. The results of transient numerical simulation indicated that when the moisture transfer is considered, the insulation performance of building envelopes decreases significantly, while the adverse effect of WFTB on heat insulation becomes less pronounced. The results indicated that the measures of insulation for WFTB should be reconsidered when the moisture transfer is considered.

Fiber Hygroscopicity Affects Thermo-Moisture Comfort of Elastic Knitted Fabric

2011 ◽  
Vol 332-334 ◽  
pp. 731-734
Author(s):  
Li Ya Zhou ◽  
Pei Hua Zhang ◽  
Wei Shen ◽  
Mei Di Xie
Keyword(s):  
Water Vapour ◽  
Liquid Water ◽  
Moisture Transfer ◽  
Subjective Evaluation ◽  
Water Transfer ◽  
Knitted Fabric ◽  
Heat And Moisture Transfer ◽  
Water Vapour Absorption ◽  
Heat And Moisture ◽  
Transfer Properties

In the present paper, the influences of fiber hygroscopicity on elastic knitted cotton and cotton blended Modal (50/50) fabric in heat and moisture transfer properties and comfort were studied. The rate of moisture regain, moisture transportation and liquid wicking performance were tested. Besides, wear trials were carried to collect subjective evaluation of thermo-moisture comfort sensation of the wearer. It is found that elastic knitted fabric of cotton-Modal/Spandex has better water vapour absorption and permeability as well as better liquid water transfer and spreading capacity. During wear trial, cotton-Modal/spandex fabric B caused significantly lower wet and sticking perception than cotton/spandex fabric A.

Hygrothermal Behavior of Thermal Insulating Material Based on Technical Hemp and its Application in Construction

2013 ◽  
Vol 860-863 ◽  
pp. 1223-1226
Author(s):  
Jiri Zach ◽  
Jitka Peterková ◽  
Martin Sedlmajer
Keyword(s):  
Building Materials ◽  
Moisture Absorption ◽  
Moisture Transfer ◽  
Natural Fibers ◽  
High Moisture ◽  
Building Envelopes ◽  
Thermal Insulating ◽  
Energy Demands ◽  
Hygrothermal Behavior ◽  
Heat And Moisture

Natural insulation materials have great potential of development given the contemporary requirements of the society in terms of reducing the energy demands of the production of building materials and the reduction of CO2emissions. Natural fibers are characteristic by their high moisture absorption and combustibility. The paper describes the results of research in the field of heat and moisture transfer within the structure of insulating materials based on natural fibers (hemp). The results of the experiments provided input data for computational simulations of hygrothermal behavior of hemp based fiber insulation applied in building envelopes.

scholarly journals Simulation Research on the Effect of Coupled Heat and Moisture Transfer on the Energy Consumption and Indoor Environment of Public Buildings

Energies ◽  
2019 ◽  
Vol 12 (1) ◽  
pp. 141 ◽  
Author(s):  
Shui Yu ◽  
Yumeng Cui ◽  
Yifei Shao ◽  
Fuhong Han
Keyword(s):  
Energy Consumption ◽  
Indoor Environment ◽  
Moisture Transfer ◽  
Building Envelope ◽  
Thermal Calculation ◽  
Heat And Moisture Transfer ◽  
Building Envelopes ◽  
Coupled Heat And Moisture ◽  
Heat And Moisture ◽  
Humidity Environment

A building envelope is a multi-layer porous structure. It transfers heat and moisture to balance the indoor and outdoor temperature difference and water vapor partial pressure difference. This is a typical coupled heat and moisture migration process. When the space is filled with moist air, water or ice, it will directly affect the thermal properties of the material. With respect to moisture coming through the wall into the indoor building, it will also affect the indoor environment and the energy consumption due to the formation of latent heat. However, the moisture transfer process in the building envelopes is not taken into account in the current conventional thermal calculation and energy consumption analysis. This paper analyzes the indoor thermal and humidity environment and building energy consumption of typical cities in Harbin, Shenyang, Beijing, Shanghai, and Guangzhou. The results show that it is obvious that the coupled heat and moisture transfer in the building envelopes has an impact on the annual cooling and heating energy consumption, the total energy consumption, and the indoor thermal and humidity environment. The geographical location of buildings ranging from north to south influences the effect of coupled heat and moisture transfer on the annual energy consumption of the building, moving from positive to negative. It is suggested that the additional coefficient of the coupled thermal and moisture method can effectively correct the existing energy consumption calculation results, which do not take the consumption from the coupled heat and moisture in the building envelopes into account.

Comparison of Thermal Bridges Calculate Method through Window Jamb

2013 ◽  
Vol 855 ◽  
pp. 130-133
Author(s):  
Rastislav Ingeli
Keyword(s):  
Heat Conduction ◽  
Thermal Conductance ◽  
Theoretical Background ◽  
Building Envelope ◽  
Building Construction ◽  
Building Envelopes ◽  
Thermal Bridge ◽  
Detailed Specification ◽  
Flow Through ◽  
Thermal Bridges

This paper is focused on comparison of thermal bridges calculate method through window jamb in building envelopes. The present approach is based on an integrated 2D dynamic simulation. The theoretical background of the adopted approach is presented. The reliability of this approach in evaluating thermal bridges as well as its applicability to different geometric shapes is proved. Detailed specification and calculation of each thermal bridge in these buildings should be taken into account. the heat flow through a building construction is considered to be of the onedimensional (1D) type. This is because the thermal conductance and temperature differential in this direction are much greater than that in the lateral directions. The thermal bridge is the part of the building envelope through which heat conduction is multi-dimensional. Therefore, in recent studies, the problem of heat conduction in the building construction has been treated as a multi-dimensional.

Thermal Bridges Minimizing through Window Jamb in Low Energy Buildings

2014 ◽  
Vol 899 ◽  
pp. 66-69 ◽  
Author(s):  
Rastislav Ingeli ◽  
Boris Vavrovič ◽  
Miroslav Čekon ◽  
Lucia Paulovičová
Keyword(s):  
Thermal Protection ◽  
Low Energy ◽  
Building Envelopes ◽  
Thermal Bridge ◽  
Window Systems ◽  
Significant Difference ◽  
Low Energy Buildings ◽  
Window Position ◽  
High Thermal Resistance ◽  
Thermal Bridges

Building envelopes with high thermal resistance are typical for low-energy buildings. Detailed specification and calculation of each thermal bridge in these buildings should be taken into account. This paper is focused on thermal bridges minimizing through typical window systems in building envelopes. The aim of this article is to analyze the window position influence, as regards on thermal performance and to point out the installation modality in accordance with the characterization of the windows performance. This can be done by quantifying the percentage increment of the window jamb thermal transmittance. The calculated results also demonstrate that there is significant difference between results obtained by various available calculation approaches. This can be significant especially in buildings with high thermal protection.

scholarly journals Automatic Detection of Linear Thermal Bridges from Infrared Thermal Images Using Neural Network

2021 ◽  
Vol 11 (3) ◽  
pp. 931
Author(s):  
Changmin Kim ◽  
Jae-Sol Choi ◽  
Hyangin Jang ◽  
Eui-Jong Kim
Keyword(s):  
Neural Network ◽  
Detection Method ◽  
Early Stage ◽  
Thermal Anomaly ◽  
Building Envelopes ◽  
Subjective Judgment ◽  
Thermal Images ◽  
Thermal Bridge ◽  
Thermal Bridges ◽  
Infrared Thermal Images

Detecting thermal bridges in building envelopes should be a priority to improve the thermal performance of buildings. Recently, thermographic surveys are being used to detect thermal bridges. However, conventional methods of detecting thermal bridges from thermal images rely on the subjective judgment of audits. Research has been conducted to automatically detect thermal bridges from thermal images to improve problems caused by such subjective judgment, but most of these studies are still in the early stage. Therefore, this study proposes a linear thermal bridge detection method based on image processing and machine learning. The proposed method includes thermal anomaly area clustering, feature extraction, and an artificial-neural-network-based thermal bridge detection. The proposed method was validated by detecting the thermal bridges in actual buildings. As a result, the average precision, recall, and F-score were 89.29%, 87.29, and 87.63%, respectively.

Heat and moisture transfer properties of a firefighter clothing with a new fire-resistant underwear

2021 ◽  
pp. 152808372199377
Author(s):  
SH Eryuruk ◽  
H Gidik ◽  
V Koncar ◽  
F Kalaoglu ◽  
X Tao ◽  
...  
Keyword(s):  
Thermal Comfort ◽  
Water Vapour ◽  
Moisture Transfer ◽  
Transmission Rate ◽  
Heat And Moisture Transfer ◽  
Vapour Permeability ◽  
Moisture Management ◽  
Dynamic Wear ◽  
Heat And Moisture ◽  
Transfer Properties

Under dynamic wear conditions, moisture management and heat transfer behaviour of clothing between the human body and its environment are very important attributes for comfort and performance. Especially considering heavy works like firefighting, it is important to analyse liquid moisture management and thermal comfort properties of fabrics that influence moisture sensation and personnel comfort feeling significantly. This study mainly investigates thermal comfort and moisture management properties of a firefighter clothing with a new fire resistant underwear. Analysing single layer fabric (underwear, outer shell, moisture barrier and thermal barrier) performance properties, together with their three-layered and four-layered combinations gives a better understanding of comfort and protective performance. For characterizing the fabric structures, weight, thickness, FTIR analysis and SEM-EDX tests were conducted. Heat and moisture transfer properties were measured with limited flame spread, thermal resistance (skin model), water vapour transmission rate (dish method), thermal conductivity, air permeability, thermal diffusion, water vapour resistance, moisture management transfer (MMT) and water vapour permeability tests.

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