Damp Buildings Research Articles

Numerical assessment of dissipation energy capacity in perforated plate steel dampers

The use of perforated metallic shear dampers in buildings has been an adequate strategy for reducing the magnitude of damages caused by earthquakes on primary elements. Furthermore, the amount of energy dissipated by the shear dampers is in turn affected by the geometrical shape of said perforations. Such process is carried out without knowing the most adequate shape or distribution of perforations in relation to an established amount of material.In this research, 5 different steel sheer damper setups will be compared in order to determine how this affects performance and to understand how damper perforation shape affects energy dissipation capacity. The latter is achieved through a performance analysis of dampers under a cyclic load using the finite element analysis software Abaqus. Likewise, the decrease in response to a seismic event of a plane frame will be measured using three different seismic motions for all the different setups used for the researched shear plates

Does evidence support measuring spore counts to identify dampness or mold in buildings? A literature review.

To identify dampness or mold (D/M) in buildings, investigators generally inspect for observable D/M indicators, the presence of which justifies remediation. Investigators may also use microbiological measurement and interpretation strategies with uncertain scientific support. We assessed available evidence supporting uses of spore counts, the microbiological measurement most commonly used to assess D/M. We reviewed published studies assessing relationships between spore counts and observable D/M, across buildings with different observable D/M levels. Penicillium/Aspergillus counts were consistently elevated in damp vs. reference (dry or outdoor) locations. Total spore counts provided a weaker, less consistent signal. The most detailed published analysis could distinguish groups of damp homes but not individual damp homes. Evidence did not validate current interpretations of spore count data for identifying single damp homes. Thus, such interpretations rest primarily on professional judgment. An additional series of informative but ineligible articles demonstrated an unconventional, more powerful "statistically based" comparison of multiple indoor vs. outdoor spore counts for identifying elevated indoor spores (and assumed D/M). Findings suggest that validation of enhanced spore trap approaches, including more samples indoors and outdoors plus statistically based comparisons of specific fungal groups, may allow evidence-based microbial identification of probable dampness in individual buildings.

Coexposure to indoor pollutants in French schools and associations with building characteristics

A nationwide indoor air quality survey was performed between 2013 and 2017 in 602 classrooms from 308 randomly-selected French schools. The concentrations of the following pollutants were measured in indoor air and/or settled dust: aldehydes, volatile and semivolatile organic compounds, fine particles (PM2.5), nitrogen dioxide and metals. Moreover, indoor fungal contamination was assessed. Clustering methods were applied to identify the different profiles of indoor pollution. Five clusters were identified. One cluster (17% of the classrooms) represents classrooms with higher phthalate concentrations but lower concentrations otherwise in both air and dust. Two clusters show higher concentrations either in air (19%) or in dust (24%). The fourth cluster corresponds to classrooms with higher concentrations of pollutants in both air and dust (21%). The last cluster includes classrooms with lower concentrations in both air and dust (19%). The different clusters were characterized according to building characteristics and the outdoor environment with a multivariate analysis. The highly-polluted classroom clusters appear to be old schools, with a lower occurrence of mechanical ventilation, higher outdoor concentrations and more signs of building dampness compared to the other clusters. The classroom cluster with high phthalate concentrations exhibits a higher proportion of synthetic plastic flooring.

An Innovative System for the Treatment of Rising Dampness in Buildings Located in Cold Climates

Signs of wetness in housing are a significant obstacle to the renovation and energy rehabilitation of old and energy-intensive heritage buildings, especially in cold climates. Thus, in order to avoid the numerous possibilities of degradation caused by the moisture transfer phenomena in the building envelope, the a disruptive aeraulic process, which focuses on the ventilation of an air gap between the thermal insulation and the wet wall, has been designed and its assessed. This system avoids the presence of liquid water at the wall surface by maintaining the hygrothermal balance within the wet wall. This enables the mechanical durability of the supporting structure, the absence of biological activity and/or frost and, hence, the durability of the thermal insulation. These issues are investigated through a case study based on a real site. Over a year of measurements, the wet wall was constantly maintained in hygroscopic balance, around 90% RH, guaranteeing the preservation of its mechanical performance, while the insulation layer was kept moisture free. In addition, the proposed model for predicting the appearance and development of biological activity demonstrated its validity, confirming experimental results.These initial results will now lead to the optimization of the aeraulic device, as well as possible use in a summer cooling context to achieve hygrothermal comfort for housing occupants.

Prevalence of Childhood Asthma and Allergies and Their Associations with Perinatal Exposure to Home Environmental Factors: A Cross-Sectional Study in Tianjin, China.

Asthma, rhinitis, and eczema are becoming increasingly prevalent among children in China. Studies have shown that the perinatal period is critical and impacts children’s health. However, research on the associations between perinatal factors and childhood allergic diseases in China are few. We investigated 7366 children of ages 0–8 years old. The childhood asthma and allergies were surveyed by distributing questionnaires, modelled after Dampness in Buildings and Health (DBH) study in Sweden and had been validated. To determine the prevalence of the allergic conditions, explore for potential confounders, and analyze the associations between the allergies and the home environmental factors, chi-square test and binary logistic regression models (enter method) were employed. The prevalence of children’s doctor-diagnosed asthma, rhinitis, and eczema were 4.4%, 9.5%, and 39.1%, respectively. After adjusting for sociodemographic factors, the negative effect of dampness/humidity on children’s health became more obvious, with odd ratios (aORs) of up to 1.70 (95% confidence interval (CI): 1.12–2.57) for doctor-diagnosed asthma (DDA), 2.12 (95% CI: 1.38–3.25) for doctor-diagnosed rhinitis (DDR) and 1.79 (95% CI: 1.46–2.21) for doctor-diagnosed eczema (DDE). With parental smoking, aORs of up to 4.66 (95% CI: 1.99–10.92) for DDA and 1.74 (95%: 1.00–3.02) for DDE. Renovation exhibited aORs of up to 1.67 (95% CI: 1.13–2.47) for DDR. Although they showed no significant associations with some of the health outcomes, contact with animals, in general, were risk factors for the allergic conditions. Generally, the indoor environmental factors around the perinatal period were significant risk factors for the doctor-diagnosed allergic conditions discussed in this study.

Dampness and student-reported social climate: two multilevel mediation models

BackgroundLittle previous research has analysed the relationship between schools’ indoor air problems and schools’ social climate. In this study, we analysed a) whether observed mould and dampness in a school building relates to students’ perceptions of school climate (i.e. teacher-student relationships and class spirit) and b) whether reported subjective indoor air quality (IAQ) at the school level mediates this relationship.MethodsThe data analysed was created by merging two nationwide data sets: survey data from students, including information on subjective IAQ (N = 25,101 students), and data from schools, including information on mould and dampness in school buildings (N = 222). The data was analysed using multilevel mediational models.ResultsAfter the background variables were adjusted, schools’ observed mould and dampness was not significantly related to neither student-perceived teacher-student relationships nor class spirit. However, our mediational models showed that there were significant indirect effects from schools’ observed mould and dampness to outcome variables via school-level subjective IAQ: a) in schools with mould and dampness, students reported significantly poorer subjective IAQ (standardised β = 0.34, p < 0.001) than in schools without; b) the worse the subjective IAQ at school level, the worse the student-reported teacher-student relationships (β = 0.31, p = 0.001) and class spirit (β = 0.25, p = 0.006).ConclusionsProblems in a school’s indoor environment may impair the school’s social climate to the degree that such problems decrease the school’s perceived IAQ.

Construction type influences features of rising damp of blue-brick masonry walls

The occurrence of rising damp in historical buildings results in material deterioration, energy waste, water-related damage, uncomfortable indoor air, and mould growth. The rising process in a real wall is influenced by the construction types, masonry details, environmental conditions, physical properties of brick and mortar. To clarify the features of rising damp influenced by the construction types in blue-brick masonry walls, a solid wall and a cavity wall made of clay blue bricks and lime mortar with a size of 3 m (high) × 1.2 m (wide) × 0.24 m (thick) were constructed to perform a water rising experiment for 600 days in a closed laboratory. The results demonstrated that the construction types directly affected the rising speed and the height of sharp fronts, which were 192 cm in the cavity wall and 168 cm in the solid wall after 600 days. The calculation model of the moisture rising in the solid wall and cavity wall obeyed the sharp front model of a homogeneous wall; however, the environmental conditions affect the rise of sharp front and moisture distribution. The research expands the understanding of the rising damp in real masonry and provides data supporting the moisture simulation, energy consumption, and heritage conservation of brick masonry.

The home environment in a nationwide sample of multi-family buildings in Sweden: associations with ocular, nasal, throat and dermal symptoms, headache, and fatigue among adults.

Risk factors at home for ocular, nasal, throat and dermal symptoms, headache, and fatigue were studied in a nationwide questionnaire survey in Sweden, the BETSI study in 2006. Totally, 5775 adults from a stratified random sample of multi-family buildings participated. Associations between home environment factors and weekly symptoms were analyzed by multi-level logistic regression. In total, 8.3% had ocular symptoms; 11.9% nasal symptoms; 7.1% throat symptoms; 11.9% dermal symptoms; 8.5% headache and 23.1% fatigue. Subjects in colder climate zones had more mucosal and throat symptoms but less fatigue and ocular symptoms. Rented apartments had poorer indoor environment than self-owned apartments. Those living in buildings constructed from 1961 to 1985 had most symptoms. Building dampness, mold and mold odor were risk factors, especially headache and ocular symptoms. Lack of mechanical ventilation system was another risk factor, especially for headache. Environmental tobacco smoke (ETS), electric radiators, and crowdedness were other risk factors. Oiled wooden floors, recent indoor painting, and new floor materials were negatively associated with symptoms. In conclusion, building dampness, mold, poor ventilation conditions, crowdedness, ETS, and emissions from electric radiators in apartments in Sweden can increase the risk of ocular, nasal, throat and dermal symptoms, headache, and fatigue.

Applicability of random decrement technique in extracting aerodynamic damping of crosswind-excited tall buildings

At the vicinity of vortex lock-in wind speed, the nonlinear aerodynamic damping effect is significant. It can greatly promote the surge of crosswind response, even threaten structural safety and serviceability of tall buildings. Techniques dependent on experimental measurement to identify aerodynamic damping have been developed for estimating crosswind response from wind loading spectrum. Random decrement technique (RDT) as one frequently mentioned technique of system identification has been used in literature to extract aerodynamic damping from stochastic crosswind response, although it was originally suitable for linear single degree of freedom system with a constant damping ratio. This study investigates the applicability of RDT in extracting aerodynamic damping of tall buildings. The models of linear and nonlinear aerodynamic damping are applied to simulate crosswind response of a square section tall building. Accordingly, the wind loading spectra based on high-frequency-force-balance (HFFB) testing and the model recommended by AIJ are utilized respectively to consider the effect of random wind load on the characteristics of crosswind response. To examine the accuracy and efficiency of RDT, aerodynamic damping is extracted through two approaches and compared with target value. Moreover, the influence of varying wind loading spectra on amplitude-dependent aerodynamic damping is demonstrated.

A Pilot Study on Baseline Fungi and Moisture Indicator Fungi in Danish Homes.

In many complaint cases regarding bad indoor environments, there is no evidence of visible fungal growth. To determine if the problems are fungi-related, dust sampling is the method of choice among building surveyors. However, there is a need to differentiate between species belonging to a normal, dry indoor environment and species belonging to a damp building envelope. The purposes of this pilot study were to examine which fungal species are present in problem-free Danish homes and to evaluate different detection and identification methods. Analyses showed that the fungal diversity outside was different from the diversity inside and that the composition of fungal species growing indoors was different compared to those found as spores, both indoors and outdoors. Common for most homes were Pseudopithomyces chartarum, Cladosporium allicinum and Alternaria sect. Infectoriae together with Botrytis spp., Penicillium digitatum and Pen. glabrum. The results show that ITS sequencing of dust samples is adequate if supported by thorough building inspections and that food products play as large a role in the composition of the baseline spora as the outdoor air and surrounding vegetation. This pilot study provides a list of baseline fungal species found in Danish homes with a good indoor environment.

Assessment of Rising Damp and Indoor Environmental Quality in Buildings after Torrential Rains in Mallorca, Spain

AbstractAs a result of climate change, water-related disasters have increased in the last decade. In the month of October 2018, in the town of Sant Llorenç (Mallorca, Illes Balears, Spain), torrential rains occurred that caused the overflow of the stream that passes through the municipality, causing personal and material damages (including death). In this research, it is intended to develop a characterization of the damage produced in the middle term (seven months after the natural hazard), through the analysis of hygrothermal conditions, humidity in walls, and indoor air quality in seven houses and in one corner shop. The most used or habitable rooms are selected, analyzing a total of twenty-one rooms. The UNE 171330-2-2014 standard is considered for the determination of environmental risks for the occupants’ health. The results obtained show that the users are aware of the need of ventilating the spaces, but, although hygrothermal comfort conditions and indoor air quality are within acceptable ranges, the rising damp highest level is high, since it even exceeds 2 m high in three of the twenty-one rooms assessed. The importance of diagnosing the effects of damage and the vulnerability of buildings in the event of a natural disaster is shown.

Performance of Adaptive TMD for Tall Building Damping

Performance of Adaptive TMD for Tall Building Damping

Evaluating the effect of building construction periods on household dampness/mold and childhood diseases corresponding to different energy efficiency design requirements.

Despite concerns about building dampness and children' health, few studies have examined the effects of building energy efficiency standards. This study explored the connections between self-reported household dampness and children' adverse health outcomes across buildings corresponding to construction periods (pre-2001, 2001-2010, post-2010). Significant differences of dampness-related indicators were found between buildings; the prevalence was remarkable in pre-2001 buildings. The prevalence of lifetime-ever doctor-diagnosed diseases for children was significantly associated with building dampness (adjust odd ratios>1), but was not affected by construction periods. The hygrothermal performance for a typical residence was simulated, varying in U-values of envelopes and air change rates. The simulated performance improvement increased indoor temperatures in 2001-2010 and post-2010 buildings. The frequency with higher indoor relative humidity was higher in pre-2001 buildings, leading to the highest values for maximum mold index (Mmax ) on wall surface, especially in winter. Compared to buildings in 2001-2010, increased insulation and lower air change rate led to a relatively higher relative humidity in post-2010 buildings, adversely increasing the Mmax values. The findings addressed the positive and negative role of building standard development, which help suggesting appropriate environmental and design solutions to trade-off energy savings and dampness/mold risk in residences.

Performance of TMDI for Tall Building Damping

This study investigates the vibration reduction of tall wind-excited buildings using a tuned mass damper (TMD) with an inerter (TMDI). The performance of the TMDI is computed as a function of the floor to which the inerter is grounded as this parameter strongly influences the vibration reduction of the building and for the case when the inerter is grounded to the earth whereby the absolute acceleration of the corresponding inerter terminal is zero. Simulations are made for broadband and harmonic excitations of the first three bending modes, and the conventional TMD is used as a benchmark. It is found that the inerter performs best when grounded to the earth because, then, the inerter force is in proportion to the absolute acceleration of only the pendulum mass, but not to the relative acceleration of the two inerter terminals, which is demonstrated by the mass matrix. However, if the inerter is grounded to a floor below the pendulum mass, the TMDI only outperforms the TMD if the inerter is grounded to a floor within approximately the first third of the building’s height. For the most realistic case, where the inerter is grounded to a floor in the vicinity of the pendulum mass, the TMDI performs far worse than the classical TMD.

Practitioner-driven research for improving the outcomes of mold inspection and remediation

This commentary is intended to provide a research roadmap for utilizing recent chemical and molecular-biological technological advances for addressing dampness and mold in buildings. The perspective is unique in that both the mold industry practitioners and academic researchers drive the questions. Research needs were derived from a 2018 international workshop attended by practitioners, researchers and governmental representatives, where challenges and opportunities in the mold remediation and restoration field were discussed focusing on the need to develop new tools that improve building diagnosis and clearance certification for mold inspectors and remediators. Suggestions are made on how new technologies surrounding DNA-based sequence analysis for fungal and bacterial identification and real-time chemical sensor technology can be leveraged by practitioners to improve inspection and remediation. The workshop put into effect a logical progression to distill and extract practice-based implications and encourage the process of transfer of the science to practice. Goals for the workshop, and this subsequent paper, are also centered on encouraging US government-funding agencies to better position and define research on the built environment geared for end-user scientists and practitioners to better explore practical solutions to dampness and mold in indoor environments. By facilitating the workshop forum and targeting industry, field practitioners, and government agencies, a sharing of needed commonalities may be infused into future research agendas and outreach efforts.

DNA Sequence-Based Approach for Classifying the Mold Status of Buildings.

Dampness or water damage in buildings and human exposure to the resultant mold growth is an ever-present public health concern. This study provides quantitative evidence that the airborne fungal ecology of homes with known mold growth ("moldy") differs from the normal airborne fungal ecology of homes with no history of dampness, water damage, or visible mold ("no mold"). Settled dust from indoor air and outdoor air and direct samples from building materials with mold growth were examined in homes from 11 cities across dry, temperate, and continental climate regions within the United States. Community analysis based on the sequence of the internal transcribed spacer region of fungal ribosomal RNA encoding genes demonstrated consistent and quantifiable differences between the fungal ecology of settled dust in homes with inspector-verified water damage and visible mold versus the settled dust of homes with no history of dampness, water damage, or visible mold. These differences include lower community richness (padj = 0.01) in the settled dust of moldy homes versus no mold homes, as well as distinct community taxonomic structures between moldy and no mold homes (ANOSIM, R = 0.15, p = 0.001). We identified 11 Ascomycota taxa that were more highly enriched in moldy homes and 14 taxa from Ascomycota, Basidiomycota, and Zygomycota that were more highly enriched in no mold homes. The indoor air differences between moldy versus no mold homes were significant for all three climate regions considered. These distinct but complex differences between settled dust samples from moldy and no homes were used to train a machine learning-based model to classify the mold status of a home. The model was able to accurately classify 100% of moldy homes and 90% of no mold homes. The integration of DNA-based fungal ecology with advanced computational approaches can be used to accurately classify the presence of mold growth in homes, assist with inspection and remediation decisions, and potentially lead to reduced exposure to hazardous microbes indoors.

Critical Response of Multi-Story Damped Bilinear Hysteretic Shear Building Under Multi Impulse as Representative of Long-Period, Long-Duration Earthquake Ground Motions

The critical response is investigated for a multi-story damped bilinear hysteretic shear building model under a multi impulse as a representative of long-period long-duration earthquake ground motions. The critical response for an elastic-plastic single-degree-of-freedom (SDOF) model under a multi impulse was derived in the previous papers. However, it is difficult to derive the critical response for a multi-degree-of-freedom (MDOF) model under a multi impulse because the phase lag among masses induces a complicated situation. In place of deriving an explicit critical response, a criterion on the criticality of the multi impulse for the elastic-plastic MDOF model is derived and the properties of the critical responses are clarified. In the analysis, a new concept of ‘Multi Impulse Pushover (MIP)’ is introduced and the progressive performance evaluation for the increasing input level is conducted. The analysis of energy response (input energy, dissipated energy, etc.) and the comparison with the response to the corresponding sinusoidal wave are made to enhance the reliability and practicality of the proposed method using the multi impulse as a substitute of sinusoidal waves which are representatives of long-period long-duration earthquake ground motions.

Influence of soil-structure interaction (SSI) on optimal design of passive damping devices

Recently, the interest in research for optimization of viscous dampers in design of buildings has been increasing. In this study, the effect of soil-structure interaction has been taken into account for the purpose of optimal design of viscous dampers. A damper optimization method based on a target damping ratio and interstorey drift ratio found in literature has been adapted for a building structure model considering different types of sandy soils. While passive constraints have been taken as upper and lower limits of each damper, active constraints have been considered as a target damping ratio in terms of damping coefficients. The proposed algorithm includes time history analyses that test the designer’s optimal design. Interstorey drift ratios under design earthquakes have been checked at each design step. The first and second mode responses have been considered separately. According to the results obtained from this study, the negative impact of sandy soils on the dynamic behavior of superstructures can be overcome by optimal placement of dampers in buildings. The results of the analyses have shown that soil effects should be taken into account in solving damper optimization problems.

Students' school-level symptoms mediate the relationship between a school's observed moisture problems and students' subjective perceptions of indoor air quality.

Moisture damage can influence the subjective assessment of indoor air quality (subjective IAQ) in various ways. We studied whether the frequency of symptoms reported across students at school level mediates the relationship between observed mold and dampness in a school building and students' subjective IAQ. To answer this research question, we tested a multilevel path model. The analyzed data were created by merging two nationwide data sets: (a) survey data from students, including information on subjective IAQ (N=24,786 students); (b) data from schools, including information on mold and dampness in a school building (N=222). After the background variables were adjusted, schools' observed mold and dampness were directly and significantly related to poor subjective IAQ (standardized beta (β)= 0.22, P=.002). In addition, in schools with mold and dampness, students reported significantly more symptoms (β=0.22, P=.023) than in schools without; the higher the prevalence of symptoms at school level, the worse the students' subjective IAQ (β=0.60, P<.001). This indirect path was significant (P=.023). In total, schools' observed mold and dampness and student-reported symptoms explained 52% of the between-school variance in subjective IAQ.

Fungal Signature of Moisture Damage in Buildings: Identification by Targeted and Untargeted Approaches with Mycobiome Data.

Identifying microbial indicators of damp and moldy buildings remains a challenge at the intersection of microbiology, building science, and public health. Sixty homes in New York City were assessed for moisture-related damage, and three types of dust samples were collected for microbiological analysis. We applied four approaches for detecting fungal signatures of moisture damage in these buildings. Two novel targeted approaches selected specific taxa, identified by a priori hypotheses, from the broad mycobiome as detected with amplicon sequencing. We investigated whether (i) hydrophilic fungi (i.e., requiring high moisture) or (ii) fungi previously reported as indicating damp homes would be more abundant in water-damaged rooms/homes than in nondamaged rooms/homes. Two untargeted approaches compared water-damaged to non-water-damaged homes for (i) differences between indoor and outdoor fungal populations or (ii) differences in the presence or relative abundance of particular fungal taxa. Strong relationships with damage indicators were found for some targeted fungal groups in some sampling types, although not always in the hypothesized direction. For example, for vacuum samples, hydrophilic fungi had significantly higher relative abundance in water-damaged homes, but mesophilic fungi, unexpectedly, had significantly lower relative abundance in homes with visible mold. Untargeted approaches identified no microbial community metrics correlated with water damage variables but did identify specific taxa with at least weak positive links to water-damaged homes. These results, although showing a complex relationship between moisture damage and microbial communities, suggest that targeting particular fungi offers a potential route toward identifying a fungal signature of moisture damage in buildings.IMPORTANCE Living or working in damp or moldy buildings increases the risk of many adverse health effects, including asthma and other respiratory diseases. To date, however, the particular environmental exposure(s) from water-damaged buildings that causes the health effects have not been identified. Likewise, a consistent quantitative measurement that would indicate whether a building is water damaged or poses a health risk to occupants has not been found. In this work, we tried to develop analytical tools that would find a microbial signal of moisture damage amid the noisy background of microorganisms in buildings. The most successful approach taken here focused on particular groups of fungi-those considered likely to grow in damp indoor environments-and their associations with observed moisture damage. With further replication and refinement, this hypothesis-based strategy may be effective in finding still-elusive relationships between building damage and microbiomes.