Damp Buildings Research Articles

Implementation of electrical impedance tomography for analysis of building moisture conditions

PurposeThe paper aims to present an innovative solution for evaluation study of the dampness level of walls and historical buildings.Design/methodology/approachElectrical tomography enables one to obtain a distribution pattern of wall dampness. The application of modern tomographic techniques in conjunction with topological algorithms will allow one to perform very accurate spatial assessment of the dampness levels of buildings. The proposed application uses the total variation, Gauss–Newton and level set method to solve the inverse problem in electrical tomography.FindingsResearch shows that electrical tomography can provide effective results in damp buildings. This method can provide 2D/3D moisture distribution pattern.Research limitations/implicationsThe impact of this technique will be limited to inspection of the facility after floods or assessment of historical buildings.Practical implicationsThe presented method could eventually lead to a much more effective evaluation of moisture in the walls.Social implicationsThe solution has commercial potential and could result in more cost-effective monitoring of historical buildings, which have an economic impact on society.Originality/valueThe authors propose a system for imaging spatial moistness of walls and historic buildings based on electrical tomography and consisting of a measuring device, sensors and image reconstruction algorithms.

Actions, attitudes and beliefs of occupants in managing dampness in buildings

PurposeDampness in buildings affects the health of occupants, structural stability and energy efficiency of buildings. Solutions to managing dampness focus on promoting the use of damp-proof construction materials, enhancing methods to avoid the introduction of moisture during construction and creating the awareness on the health effect of dampness. These solutions are incomplete without the identification of behaviours that occupants require to manage dampness. Given that dampness is characterised by the availability of a source, a route for the moisture to travel and driving force for moisture movement, the occupants can be said to play a significant role in contributing to dampness. The paper aims to discuss these issues.Design/methodology/approachAs a result, this study seeks to examine the behaviours of occupants manifested to manage dampness in residential buildings. To achieve the aim, a qualitative research method was employed, under which interviews were carried out. Occupants in households in the northern and southern parts of England were interviewed to identify the actions, attitudes and beliefs in managing dampness.FindingsThe findings revealed actions such as aeration and the use of anti-damp sprays. From the findings, dampness instilled attitudes such as anger, moodiness and unhappiness. In addition, dampness instilled cleaning habits in occupants due to the lack of comfort moulds create and the awareness of its health impact.Research limitations/implicationsThis research also contributes to existing debates on dampness reduction specifically in residential buildings.Originality/valueThe identification of these behaviours creates the awareness for occupants on their roles in managing dampness and how dampness affects their behaviours in addition to the health impact.

How much temperature will increase the efficiency of electro-osmosis?

Electro-osmosis is popularly used as a pump to dry soils or to reduce rising damp in buildings, but the literature results are contradictory. The basic formula of electro-osmosis has been analysed to point out its dependence on temperature, which is masked behind two coefficients, i.e. the dielectric ‘constant’ of water (that is not constant), and the coefficient of dynamic viscosity. These two physical quantities have been calculated with the accurate formulae by Malmberg and Maryott (the dielectric constant) and Voegel (the dynamic viscosity). The electro-osmosis formula includes the ratio between these two coefficients. Although the two formulae that represent them are formulated with equations having a formally different mathematical apparatus, their ratio strictly follows a straight line with values increasing with temperature. Dividing this equation by its initial value (i.e. considered at 0.1 °C) one obtains the Temperature Magnification Factor (TMF) that indicates how much the effectiveness of the system may vary with temperature. TMF is linearly increasing and has been calculated for the whole range of liquid water, i.e. from 0.1 to 99.9 °C. In the interval of the most common wall temperatures, from 0 to 50 °C, TMF increases from 1 to 2.5, showing that in summer, or in warm climate, the efficiency of this method is much higher (e.g. 2.5 times) than in winter or in cold regions. A comparison of the effectiveness of electro-osmotic interventions against rising damp can only be made for buildings under the same climate conditions. This explains the contradictory results found in the literature when case studies from different geographic areas, and different climates, are compared.

Sterigmatocystin in foodstuffs and feed: aspects to consider

ABSTRACT Sterigmatocystin (STC) is a possible human carcinogen (2B) according to International Agency for Research on Cancer classification and has been associated with immunotoxic and immunomodulatory activity, together with mutagenic effects. It might be found in numerous substrates, from foods and feeds to chronically damp building materials and indoor dust. Although European Food Safety Authority concluded that the exposure to STC to be of low concern for public health, reinforces the need of data concerning exposure of European citizens. Climate change can represent an increased risk of exposure to STC since it is a crucial factor for agro-ecosystem powering fungal colonisation and mycotoxin production This aspect can represent an increased risk for European countries with temperate climates and it was already reported by the scientific community.

Effectiveness of methods against rising damp in buildings: Results from the EMERISDA project

Rising damp is a recurrent hazard to ancient buildings in Europe and its relevance is expected to increase in the future, due to climate changes. The presence of rising damp in walls does not only create an unpleasant climate in buildings, but it also enhances damage processes such as frost action, salt crystallization and biological growth, with possible consequences on the health of the inhabitants. The relevance of this problem is reflected by the large variety of products on the market. The wide and differentiated offer and the scarce scientific information on the effectiveness of the methods make it difficult, (even) for professionals working in the field, to choose a suitable intervention on a sound basis. The JPICH-financed project EMERISDA (2014–2017) [1] aimed at evaluating the effectiveness of different intervention methods against rising damp. The project involved universities, research institutes, heritage agencies and companies (producers and contractors) in Belgium (BBRI, co-ordinator), Italy (CNR-ISAC, Universita’ Ca’ Foscari Venezia, Restauri Speciali s.r.l., Diasen s.r.l.) and The Netherlands (Delft University of Technology and the Cultural Heritage Agency of the Netherlands). The research methodology included the use of an on-line questionnaire and experimental research in laboratory, on scale models and on-site. Both traditional methods, such as chemical injection, and more recent techniques, such as the so-called “electro-physical” methods have been investigated. [2] The following results of the EMERISDA project are presented in this paper: - Results from on-line questionnaire.- Definition of an experimental procedure for the assessment of the presence of rising damp and of the effectiveness of the intervention.- Prototype of decision support tool, which provides insight into the feasibility and risks of existing methods against rising damp and supports actors involved in conservation in the choice and application of the methods against rising damp.

“Dampness” and “Dryness”: What is important for children's allergies? A cross-sectional study of 7366 children in northeast Chinese homes

This study investigates associations of building dampness indicators, and perceptions of moldy odor, humidity and dryness (Dampness and Dryness, D&D) with children's asthma and allergies. Data were obtained from a cross-sectional study in Tianjin and Cangzhou, China from 2013 to 2014. Completed surveys were returned by 7366 families with children 0–8 years old. We studied D&D factors both in the current residence and the residence where the children lived immediately after birth. A total of 4.4% of the children had doctor-diagnosed asthma; 9.5% had doctor-diagnosed rhinitis; and 39.1% had doctor-diagnosed eczema. Most of the dampness indicators, perceptions of odors, and perceived dryness, were significantly associated with children's asthma and allergies. A reporting bias in parents (or guardians) who themselves had allergies was not found to be the reason for the associations between D&D and health effects. Compared with either previous or current exposure to D&D, continuous exposure to D&D was a greater risk for children's asthma and allergies. Perceived dryness was the most important studied risk factor for children's allergies in either current or previous homes.

New technique for treating rising damp in historical buildings: Wall base ventilation

Abstract Intervene in historic constructions increasingly requires extensive and objective knowledge of what one will be working with. The multifaceted aspect of the works needed on this kind of constructions tends to encompass a growing number of different tasks, with the imperative need to know the causes of many of the problems that affect these buildings and the possible treatments that can solve them. Moisture transfer in walls of old buildings, which are in direct contact with the ground, leads to a migration of soluble salts responsible for many building pathologies. We know that many of the techniques currently used to reduce rising damp are not much effective, when dealing with walls of considerable thickness and heterogeneous materials, as is the normal case of historic constructions. Bearing this in mind, a new technique to treat rising damp in historic constructions has been developed and patented in Portugal. The technique consists of ventilating the base of walls through a natural ventilation process or by installing a hygroregulated mechanical ventilation device. The process of development and validation of this new technique will be presented as well as the most recent studies to improve it. A detailed presentation of the diagnosis, design and works made on a historic building in the north of Portugal, will be done. Some system limitations and some corrections that needed to be performed will also be presented.

Gene expression of indoor fungal communities under damp building conditions: Implications for human health.

Dampness and visible mold growth in homes are associated with negative human health outcomes, but causal relationships between fungal exposure and health are not well established. The purpose of this study was to determine whether dampness in buildings impacts fungal community gene expression and how, in turn, gene expression may modulate human health impacts. A metatranscriptomic study was performed on house dust fungal communities to investigate the expression of genes and metabolic processes in chamber experiments at water activity levels of 0.5, 0.85, and 1.0. Fungi at water activities as low as 0.5 were metabolically active, focusing their transcriptional resources on primary processes essential for cell maintenance. Metabolic complexity increased with water activity where communities at 1.0 displayed more diverse secondary metabolic processes. Greater gene expression at increasing water activity has important implications for human health: Fungal communities at 1.0 aw upregulated a greater number of allergen-, mycotoxin-, and pathogenicity-encoding genes versus communities at 0.85 and 0.5 aw . In damp buildings, fungi may display increases in secondary metabolic processes with the potential for greater per-cell production of allergens, toxins, and pathogenicity. Assessments in wet versus dry buildings that do not account for this elevated health impact may not accurately reflect exposure.

Efficiency evaluation of treatments against rising damp by scale models and test in situ

Abstract The presence of water in masonries is one of the most relevant cause of decay in historic buildings. If water is present, particularly rising damp, degradation processes such as biological growth, powdering due to salt crystallization cycles may arise and be intensified. Treatment against rising damp is therefore generally advised for the protection and preventive conservation of historic buildings. Within this framework, the JPICH Project “Effectiveness of methods against rising damp in buildings: European practice and perspective – EMERISDA” (2014–2017) aimed at a scientifically based evaluation of the effectiveness of different methods against rising damp and at decision support tool definition for a conscious choice use of these methods in the practice of conservation. During the present paper the methodology adopted on site for the evaluation of the efficiency of methods aiming at stopping/limiting rising damp on masonries is described. Specifically, results concerning the treatments on masonries with chemical injections (solvent and water based) and with plasters application on scale models and the case study of Agora in Ferrara (Italy) are presented.

Climate Change and the Impact on Respiratory and Allergic Disease: 2018.

The purpose of this paper is to review allergic respiratory disease related to indoor and outdoor exposures and to examine the impact of known and projected changes in climate. The global burden of disease directly attributed to climate change is very difficult to measure and becomes more challenging when the capacity of humans to adapt to these changes is taken into consideration. Allergic respiratory disease, such as asthma, is quite heterogenous, though closely associated with environmental and consequently immunologic interaction. Where is the tipping point? Our climate has been measurably changing for the past 100years. It may indeed be the most significant health threat of the twenty-first century, and consequently tackling climate change may be the greatest health opportunity. The impacts of climate change on human health are varied and coming more into focus. Direct effects, such as heatwaves, severe weather, drought, and flooding, are apparent and frequently in the news. Indirect or secondary effects, such as changes in ecosystems and the impact on health, are less obvious. It is these changes in ecosystems that may have the greatest impact on allergic and respiratory diseases. This review will explore some ways that climate change, current and predicted, influences respiratory disease. Discussion will focus on changing pollen patterns, damp buildings with increased mold exposure, air pollution, and heat stress.

Dampness problems in Tianjin dwellings: A cross-sectional study of associations with building characteristics and lifestyles

This study investigated the association of building characteristics and occupant behaviours with building dampness indicators. Data were from a cross-sectional study in urban Tianjin and rural Cangzhou, China, from 2013 to 2014. We studied two fundamental types of Chinese dwellings: bungalows typical of rural locales and apartments in low- and high-rise buildings typical of urban settings. Occupants of bungalows reported more dampness indicators than apartment dwellers. Risk factors for one or more dampness indicators included natural ventilation without fans, older dwellings and coal stove or Kang heating system (a brick bed installed in the bedroom for heating and sleeping). All these factors were typical of bungalows, which generally used older building technologies including non-insulated external walls, wooden frame windows, electric fans for cooling and no exhaust fan ventilation. Occupant behaviours that decreased the risk for dampness indicators included frequent window opening and daily cleaning, regardless of the type of dwelling. Indoor dampness was highly correlated with mouldy and humid odour, and paradoxically (although not a new finding) with the perception of air dryness.

Rising damp in historical buildings: A Venetian perspective

Considering several real case studies, moisture distribution due to rising damp in Venetian brick masonries is discussed and empirical models are developed. Moisture content and soluble salt data of 25 historical buildings in Venice are analysed. Data are scrutinized using statistical methods, obtaining contour plots and estimating the validity of linear and non-linear models. The models confirm that masonries are usually soaked with water till 120–150 cm over sea level, while the evaporation zone ranges in height from 200 cm to 350 cm. In the perpendicular section, moisture distribution depends on several contingent factors such as, among them, the proximity and the exposition of the external façades to the water action.

Construction Practices Contributing to Rising Damp in Kumasi Metropolitan and Ejisu Municipal Assemblies in Ghana

Buildings represent significant investment of developers and, as such, it is important to ensure value for the capital injected into the construction of buildings. Unfortunately, due to neglect of proper construction practices, buildings are facing defects, and one of such defects is rising damp. This study sought to identify some of the construction practices contributing to rising damp in buildings and their effects and suggest some remedial measures for controlling and treatment of rising damps. Snowball sampling and purposive sampling techniques were used to gather data from a cross section of 78 building environment professionals in Kumasi and Ejisu who have experienced the effects of moisture rise. Relative Importance Index was used to rank the significance of the causes. The study revealed that failure to use damp-proof membrane or course, presence of groundwater, porosity of masonry, and concrete element sand flooding were the main causes of rising damp. Undersetting and saw slotting, making good plumbing leakages, using approved waterproof chemical injection, and application of admixtures were the main measures recommended to avert rising damp.

Inflammation-associated gene expression in RAW 264.7 macrophages induced by toxins from fungi common on damp building materials

Most fungi that grow on damp building materials produce low molecular weight compounds, some of which are known to be toxic. In this study, we tested the hypothesis that exposure to some metabolites of fungi common on damp building materials would result in time-, dose-, and compound-specific responses in the production of various chemokines by RAW 264.7 cells. Cell cultures were exposed to a 10−7M or 10−8M metabolite dose for 2, 4, 8 or 24h. Metabolite concentrations used were based on those that might be expected in alveolar macrophages due to inhalation exposure from living or working in a damp building. Compared to controls, exposure provoked significant time-, dose- and compound-specific responses manifest as differentially elevated secretion of three of nine cytokines tested in culture supernatant of treated cells. The greatest number of cytokines produced in response to the metabolites tested were in andrastin A-treated cells (GM-CSF, TGFβ1, Tnf-α) followed by koninginin A (TGFβ1 and Tnf-α) and phomenone (GM-CSF, TGFβ1). Chaetoglobosin A, chaetomugilin D and walleminone exposures each resulted in significant time-specific production of Tnf-α only. This investigation adds to a body of evidence supporting the role of low molecular weight compounds from damp building materials as pathogen associated molecular patterns (PAMPs). Along with fungal glucan and chitin, these compounds contribute to the non-allergy based respiratory outcomes for people living and working in damp buildings.

Metabolites of Trichoderma species isolated from damp building materials.

Buildings that have been flooded often have high concentrations of Trichoderma spores in the air while drying. Inhaled spores and spore and mycelial fragments contain large amounts of fungal glucan and natural products that contribute to the symptoms associated with indoor mould exposures. In this study, we considered both small molecules and peptaibol profiles of T. atroviride, T. koningiopsis, T. citrinoviride, and T. harzianum strains obtained from damp buildings in eastern Canada. Twenty-residue peptaibols and sorbicillin-derived metabolites (1-6) including a new structure, (R)-vertinolide (1), were characterized from T. citrinoviride. Trichoderma koningiopsis produced several koninginins (7-10), trikoningin KA V, and the 11-residue lipopeptaibols trikoningin KB I and trikoningin KB II. Trichoderma atroviride biosynthesized a mixture of 19-residue trichorzianine-like peptaibols, whereas T. harzianum produced 18-residue trichokindin-like peptaibols and the 11-residue harzianin HB I that was subsequently identified from the studied T. citrinoviride strain. Two α-pyrones, 6-pentyl-pyran-2-one (11) and an oxidized analog (12), were produced by both T. atroviride and T. harzianum. Aside from exposure to low molecular weight natural products, inhalation of Trichoderma spores and mycelial fragments may result in exposure to membrane-disrupting peptaibols. This investigation contributes to a more comprehensive understanding of the biologically active natural products produced by fungi commonly found in damp buildings.

Optimal Distribution of Damping Coefficients for Viscous Dampers in Buildings

Design guidelines for implementing viscous dampers to buildings have been broadly included in seismic design codes worldwide. Although the relationship between the damping coefficient of viscous dampers and the added damping ratio to the structure has been theoretically studied, the process of distributing the damping coefficient onto each story of a building has not been regulated by the codes. For practical applications, some distribution methods have been previously proposed. However, no comparison has been made between these proposed methods considering the controllability and design economy. In this paper, two search methods based on the genetic algorithms (GAs) are adopted to examine the optimal distribution of damping coefficients. The results are then compared with a variety of existing distribution methods. A comparison is made for the distribution methods assuming the same added damping ratio for the structure. Three two-dimensional frames are adopted in the comparison: a regular moment frame, a moment frame with a soft-story, and a setback building. The results indicated that similar seismic response reduction can be achieved by using different distribution methods if the supplemental damping ratio is the same, while the optimal story damping coefficient can be obtained by using the proposed optimization method. Moreover, the “story shear strain energy to efficient stories” (SSSEES) method, among others, offers advantages in terms of seismic reduction efficiency, economical design, and practical application simplicity.

Building dampness and mold in European homes in relation to climate, building characteristics and socio-economic status: The European Community Respiratory Health Survey ECRHS II.

We studied dampness and mold in homes in relation to climate, building characteristics and socio-economic status (SES) across Europe, for 7127 homes in 22 centers. A subsample of 3118 homes was inspected. Multilevel analysis was applied, including age, gender, center, SES, climate, and building factors. Self-reported water damage (10%), damp spots (21%), and mold (16%) in past year were similar as observed data (19% dampness and 14% mold). Ambient temperature was associated with self-reported water damage (OR=1.63 per 10°C; 95% CI 1.02-2.63), damp spots (OR=2.95; 95% CI 1.98-4.39), and mold (OR=2.28; 95% CI 1.04-4.67). Precipitation was associated with water damage (OR=1.12 per 100mm; 95% CI 1.02-1.23) and damp spots (OR=1.11; 95% CI 1.02-1.20). Ambient relative air humidity was not associated with indoor dampness and mold. Older buildings had more dampness and mold (P<.001). Manual workers reported less water damage (OR=0.69; 95% CI 0.53-0.89) but more mold (OR=1.27; 95% CI 1.03-1.55) as compared to managerial/professional workers. There were correlations between reported and observed data at center level (Spearman rho 0.61 for dampness and 0.73 for mold). In conclusion, high ambient temperature and precipitation and high building age can be risk factors for dampness and mold in homes in Europe.

Influence of SSI on Period and Damping of Buildings Supported by Shallow Foundations on Cohesionless Soil

This study investigates the influence of soil–structure interaction (SSI) on period and damping of steel moment-resisting frame buildings supported by shallow footings on dry sand deposits. A series of impact hammer tests were conducted on a 3-story and a 6-story model steel frame for this purpose. Different base conditions (e.g., loose and dense sand beds, surface and embedded footings, heavily loaded and lightly loaded footings) were considered to gain a complete understanding of inertial SSI effects. Experimental results were compared with FEMA provisions as well as with analytical results obtained from a finite-element model. The period and damping amplifications are more prominent in the case of the 3-story building than in that of the 6-story building, indicating more sensitivity of short and stiff buildings to SSI over the taller ones. For a heavily loaded 3-story building on loose sand, the period and damping amplifications are 21 and 330%, respectively. Although the analytical results match well with those of the experiment, FEMA provisions tend to overestimate the responses, especially for the 6-story building.

Air Channel Function For Solving Moisture Problems In Buildings

The purpose of the research is to find adequate solution against rising damp in historical buildings. The improvement in this case is the use of ventilated air channels. A special group of historical buildings are churches because they do not use routines as for example museums, galleries.We designed 4 differently constructed ventilated air channels. These are: open or closed, with overpressure and underpressure. As a verification we use a relevance to these constructions which we simulated in software Ansys CFX the air flow of channels. We modelled the equal segments of the channels.The best solution of these constructions are the ventilated air channels with underpressure system. In this solution we measured the highest values of air velocity. Nevertheless this solution is not an aesthetic form of construction, because the pipes are set on the facade. But these pipe are put inside the drainage pipe.This research should offer the solution for architects against problems of rising damp in historical buildings. To find the right solution is necessary to research every case. The aim of the research is to prepare the design process of the ventilated air channels for the architects without the simulation of every building, cross section or geometry of the construction.

Use of EMW radiation in the building industry at defects in buildings

This paper discusses theory and application of microwave radiation and experimental optimization of microwave radiation to eliminate moisture content in wood elements. It will be appreciated that the rising moisture leaking into the structure, resulting in defects and structures of the buildings themselves. Owing to its properties, microwave radiation has been used in the construction industry in modern times, in particular to dry wet masonry of buildings. Effects of electromagnetic radiation on building structures lead to relatively sharp decreases in moisture content from damp building structures or elements. The influence of electromagnetic radiation on building structures lead to oscillation of water molecules contained in the material, which cause a phase transformation of water into vapour. Consequently, the vapour evaporates from the moist material, thereby drying the element exposed to radiation. The article describes experiments carried out at the Faculty of Civil Engineering of the Faculty of Technology in Brno that demonstrate successful decrease of water content in building materials using microwave radiation. First, the understanding of microwave radiation will be discussed. Following an analysis of research results an optimum intensity of microwave radiation sources as well as the necessary length of the irradiation of microwave radiation have been determined with respect to the particular type of building material and the success rate of elimination of moisture.