scholarly journals Energy in buildings: A review of models on hygrothermal transfer through the porous materials for building envelop

2021 ◽  
Author(s):  
Macmanus Chinenye Ndukwu ◽  
Merlin Simo-Tagne ◽  
Ifiok Edem Ekop ◽  
Mathew I. Ibeh ◽  
Maureen A. Allen ◽  
...  
Keyword(s):  
Boundary Conditions ◽  
Building Materials ◽  
Mass Conservation ◽  
Building Envelope ◽  
Different Boundary Conditions ◽  
Building Envelop ◽  
Hygroscopic Nature ◽  
Model Equations ◽  
Building Walls ◽  
Heat And Moisture

The hygrothermal transfer is very important for the design of a building envelope for thermal comfort and economic and energy analysis of the building envelope. The applications of various materials in building envelope have been studied extensively. The study presents several models for the hygrothermal transfer for various building walls. Several energy and mass conservation equations with different boundary conditions and input considerations were presented in this paper for concrete, bricks and wooden walls. The effect of hysteresis was ignored in developing most model equations, while few considered flow pattern of fluid through the wall surfaces. Due to the flexibility of Luikov models, it formed the basis for modelling the coupled heat and mass transfer for porous material independent of hygroscopic nature with different boundary conditions defined according to the geometry and orientations. The influence of type of wall, orientation, thickness, the density of the material and climatic variations on the temperature and moisture evolutions within the building materials was more pronounced. Literature, presenting imaging models using imagery software like COMSOL multi-physics, CFD etc. were scarce considering that microscopic imagery is now deployed to measure the heat and moisture evolution in materials. Future models should include shrinkage or expansion influence on the fibrous material like wood due to their behaviour under environmental condition.

scholarly journals Modeling of Coupled Heat and Mass Transfers in a Stabilized Earthen Building Envelope with Thatched Fibers

Fibers ◽  
2018 ◽  
Vol 6 (4) ◽  
pp. 75
Author(s):  
Madeleine Nitcheu ◽  
Donatien Njomo ◽  
Pierre Meukam ◽  
Cyrille Fotsing Talla
Keyword(s):  
Moisture Content ◽  
Building Materials ◽  
Numerical Solutions ◽  
Moisture Transfer ◽  
Building Envelope ◽  
One Dimensional ◽  
Composites Materials ◽  
Model Equations ◽  
Mass Transfers ◽  
Heat And Moisture

In order to reduce the heat and mass transfers in buildings, which increase energy bills, the development of composites materials such as earth bricks stabilized with thatch fibers is important for their construction. This paper aims to study a one-dimensional model of heat and moisture transfer through porous building materials. The coupled phenomena of heat and mass transfer are described by the Luikov model. Equations and boundary conditions are discretized using the finite difference method. The results obtained illustrate the temporal evolutions of the temperature and the moisture content, as well as the distributions of the temperature and moisture content inside the wall. The profile of the temperature and water content that are obtained are compared with the other numerical solutions that are available in the literature.

In Situ Measurement of Thermal Resistance of Building Envelope at the Residential Occupancy in Indonesia

2015 ◽  
Vol 771 ◽  
pp. 191-194 ◽  
Author(s):  
Wahyu Sujatmiko ◽  
Hermawan Kresno Dipojono ◽  
F.X. Nugroho Soelami ◽  
Soegijanto
Keyword(s):  
Thermal Resistance ◽  
High Performance ◽  
Building Materials ◽  
Precast Concrete ◽  
Green Building ◽  
Building Envelope ◽  
Building Wall ◽  
Ashrae Standards ◽  
Building Walls

Abstract. This paper presents the measurement results of three building wall materials which are commonly used for residential housings in Indonesia, namely clay brick, batako (concrete brick), and precast concrete. In-situ measurement of the steady state thermal flow (heat flux) at building walls (envelopes) is conducted in order to determine the thermal resistance of building wall according to ASTM C1155. The results show that all three building materials having a thermal resistance values are far below the energy conservation provisions of ASHRAE 90.1 and especially when compared to the provision of high performance green building ASHRAE 189.1 It is found that precast concrete has higher thermal resistance (or has lower thermal conductivity) than that of other two materials, hence a better compliance to the ASHRAE standards.

The Analysis of Coupled Heat and Moisture Transfer in Building Envelop Based on Numerical Simulation

2012 ◽  
Vol 450-451 ◽  
pp. 1471-1476
Author(s):  
Shui Yu ◽  
Xu Zhang
Keyword(s):  
Building Materials ◽  
Moisture Transfer ◽  
Capillary Condensation ◽  
Building Energy ◽  
Environment Impact ◽  
Heat And Moisture Transfer ◽  
Common Structure ◽  
Building Envelop ◽  
Coupled Heat And Moisture ◽  
Heat And Moisture

The research of coupled heat and moisture transfer is a complex process, which is the fundamental of decreasing building energy consumption; improving IAQ and increasing the durability of building envelop. CHAMPS-BES software is an outcome of a joint effort between Building Energy and Environmental Systems Laboratory (BEESL) and Institute for Building Climatology (IBK). This software is used for analysis and prediction of hygrothermal performance of building enclosures; impact of outdoor climate and pollution on indoor environment; impact of VOC emissions from building materials and indoor furnishings on indoor air quality. This paper introduces the basic mathematic and physic model, boundary condition, climate condition etc, and analyzes the coupled heat and moisture transfer through common structure of building envelop in Shanghai. According to simulation results, main materials of the wall in ITIS have to endure larger range of temperature than ETIS that leads to the life of materials shorter. Capillary condensation occurs on inside surface of the wall easily when RH is larger than 70% and the minimum pore size of finish layer is around 5×10-9m avoiding capillary condensation and mold growth

scholarly journals Application Method of a Simplified Heat and Moisture Transfer Model of Building Construction in Residential Buildings

Energies ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4180
Author(s):  
Joowook Kim ◽  
Michael Brandemuehl
Keyword(s):  
Latent Heat ◽  
Moisture Transfer ◽  
Residential Buildings ◽  
Building Energy ◽  
The United States ◽  
Building Envelope ◽  
Outdoor Environment ◽  
Transfer Model ◽  
Heat And Moisture Transfer ◽  
Heat And Moisture

Several building energy simulation programs have been developed to evaluate the indoor conditions and energy performance of buildings. As a fundamental component of heating, ventilating, and air conditioning loads, each building energy modeling tool calculates the heat and moisture exchange among the outdoor environment, building envelope, and indoor environments. This paper presents a simplified heat and moisture transfer model of the building envelope, and case studies for building performance obtained by different heat and moisture transfer models are conducted to investigate the contribution of the proposed steady-state moisture flux (SSMF) method. For the analysis, three representative humid locations in the United States are considered: Miami, Atlanta, and Chicago. The results show that the SSMF model effectively complements the latent heat transfer calculation in conduction transfer function (CTF) and effective moisture penetration depth (EMPD) models during the cooling season. In addition, it is found that the ceiling part of a building largely constitutes the latent heat generated by the SSMF model.

scholarly journals The Effect of the Thermal Mass of the Building Envelope on Summer Overheating of Dwellings in a Temperate Climate

Energies ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4117
Author(s):  
Tadeusz Kuczyński ◽  
Anna Staszczuk ◽  
Piotr Ziembicki ◽  
Anna Paluszak
Keyword(s):  
Building Materials ◽  
Heat Waves ◽  
Residential Buildings ◽  
Building Envelope ◽  
Temperate Climate ◽  
Maximum Temperature ◽  
Thermal Mass ◽  
Occupant Behavior ◽  
Average Maximum ◽  
Night Ventilation

The main objective of this paper is to demonstrate the effectiveness of increasing the thermal capacity of a residential building by using traditional building materials to reduce the risk of its excessive overheating during intense heat waves in a temperate climate. An additional objective is to show that the use of this single passive measure significantly reduces the risk of overheating in daytime rooms, but also, though to a much lesser extent, in bedrooms. Increasing the thermal mass of the room from light to a medium heavy reduced the average maximum daily temperature by 2.2K during the first heat wave and by 2.6K during the other two heat waves. The use of very heavy construction further reduced the average maximum temperature for the heat waves analyzed by 1.4K, 1.2K and 1.7K, respectively, giving a total possible reduction in maximum daily temperatures in the range of 3.6 °C, 3.8 °C and 4.3 °C. A discussion of the influence of occupant behavior on the use of night ventilation and external blinds was carried out, finding a significant effect on the effectiveness of the use of both methods. The results of the study suggest that in temperate European countries, preserving residential construction methods with heavy envelopes and partitions could significantly reduce the risk of overheating in residential buildings over the next few decades, without the need for night ventilation or external blinds, whose effectiveness is highly dependent on individual occupant behavior.

scholarly journals Mechanics of tubular helical assemblies: ensemble response to axial compression and extension

2021 ◽  
Author(s):  
Jacopo Quaglierini ◽  
Alessandro Lucantonio ◽  
Antonio DeSimone
Keyword(s):  
Boundary Conditions ◽  
Elastic Properties ◽  
Central Region ◽  
Mechanical Response ◽  
Different Boundary Conditions ◽  
Kirchhoff Rods ◽  
Model Versus ◽  
The Individual ◽  
Opposite Chirality

Abstract Nature and technology often adopt structures that can be described as tubular helical assemblies. However, the role and mechanisms of these structures remain elusive. In this paper, we study the mechanical response under compression and extension of a tubular assembly composed of 8 helical Kirchhoff rods, arranged in pairs with opposite chirality and connected by pin joints, both analytically and numerically. We first focus on compression and find that, whereas a single helical rod would buckle, the rods of the assembly deform coherently as stable helical shapes wound around a common axis. Moreover, we investigate the response of the assembly under different boundary conditions, highlighting the emergence of a central region where rods remain circular helices. Secondly, we study the effects of different hypotheses on the elastic properties of rods, i.e., stress-free rods when straight versus when circular helices, Kirchhoff’s rod model versus Sadowsky’s ribbon model. Summing up, our findings highlight the key role of mutual interactions in generating a stable ensemble response that preserves the helical shape of the individual rods, as well as some interesting features, and they shed some light on the reasons why helical shapes in tubular assemblies are so common and persistent in nature and technology. Graphic Abstract We study the mechanical response under compression/extension of an assembly composed of 8 helical rods, pin-jointed and arranged in pairs with opposite chirality. In compression we find that, whereas a single rod buckles (a), the rods of the assembly deform as stable helical shapes (b). We investigate the effect of different boundary conditions and elastic properties on the mechanical response, and find that the deformed geometries exhibit a common central region where rods remain circular helices. Our findings highlight the key role of mutual interactions in the ensemble response and shed some light on the reasons why tubular helical assemblies are so common and persistent.

Field temperature and moisture loads from a building envelope as the basis for accelerated aging of barrier membranes

2019 ◽  
Vol 46 (11) ◽  
pp. 969-978 ◽  
Author(s):  
Marzieh Riahinezhad ◽  
Augusta Eve ◽  
Marianne Armstrong ◽  
Peter Collins ◽  
J.-F. Masson
Keyword(s):  
Building Materials ◽  
National Research Council ◽  
Accelerated Aging ◽  
Bimodal Distribution ◽  
Building Envelope ◽  
Rate Of Change ◽  
Single Family ◽  
Field Exposure ◽  
Aging Conditions ◽  
Materials Used

Temperature and relative humidity (RH) data within the building envelope of a single-family home at the National Research Council of Canada’s Canadian Centre for Housing Technology were collected over five years. We report on the distribution, rate of change, and the limits of temperature and moisture variations for south-easting wall and south-facing wall and roof systems to better understand the in-situ environmental conditions to which building materials and components typical of homes in North America may be subjected. Over an average year, wall temperature varied from −25 °C to +45 °C, and temperature followed a bimodal distribution, with maxima at 0 °C to 5 °C and 15 °C to 20 °C. Each maximum represented about 1100 h of field exposure. Roof temperatures, which spanned a temperature range from −35 °C to 75 °C, did not show a Gaussian distribution but were characterized as being multi-modal. From values of temperature and RH, absolute moisture contents within the building envelope were found to range between 1 and 55 g/m3, with the most common values being 6–8 g/m3. The application of this information is discussed and related to the development of realistic accelerated aging conditions to obtain a more accurate durability assessment of building envelope materials used in Canadian dwellings.

scholarly journals A Non-Destructive System Based on Electrical Tomography and Machine Learning to Analyze the Moisture of Buildings

Sensors ◽  
2018 ◽  
Vol 18 (7) ◽  
pp. 2285 ◽  
Author(s):  
Tomasz Rymarczyk ◽  
Grzegorz Kłosowski ◽  
Edward Kozłowski
Keyword(s):  
Machine Learning ◽  
Spatial Analysis ◽  
Building Materials ◽  
Supervised Machine Learning ◽  
Electrical Tomography ◽  
High Processing Speed ◽  
Image Pixels ◽  
Architectural Significance ◽  
Building Walls ◽  
Non Destructive

This article presents the results of research on a new method of spatial analysis of walls and buildings moisture. Due to the fact that destructive methods are not suitable for historical buildings of great architectural significance, a non-destructive method based on electrical tomography has been adopted. A hybrid tomograph with special sensors was developed for the measurements. This device enables the acquisition of data, which are then reconstructed by appropriately developed methods enabling spatial analysis of wet buildings. Special electrodes that ensure good contact with the surface of porous building materials such as bricks and cement were introduced. During the research, a group of algorithms enabling supervised machine learning was analyzed. They have been used in the process of converting input electrical values into conductance depicted by the output image pixels. The conductance values of individual pixels of the output vector made it possible to obtain images of the interior of building walls as both flat intersections (2D) and spatial (3D) images. The presented group of algorithms has a high application value. The main advantages of the new methods are: high accuracy of imaging, low costs, high processing speed, ease of application to walls of various thickness and irregular surface. By comparing the results of tomographic reconstructions, the most efficient algorithms were identified.

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