High Indoor Humidity Research Articles

Field investigation of lifestyle and indoor environment with COVID-19 in facilities for older adults in cold regions of Japan

The emergence of COVID-19 clusters for older adults has been increasing recently in Japan. Facility staff control cross-ventilation with open windows as the primary measure against COVID-19 in facilities for older adults. In this study, the indoor thermal environment, lifestyle, ventilation method, and other in six facilities for older adults were investigated to understand how facility operation management has changed since the spread of COVID-19. As a result, the indoor air temperature was well-managed in all facilities during both seasons. However, the wet bulb globe temperature was measured above the warning level of 25 °C due to the influence of high indoor humidity in summer. The humidity in the facilities was always controlled under low-humidity conditions during winter. In the lifestyle investigation, many votes suggested that the staff found wearing masks uncomfortable. Most older adults were not wearing masks because it made them feel stuffy. Moreover, the staff opened windows for cross-ventilation without relying on objective judgment. Thus, if effective ventilation is not performed, the ventilation efficiency in the facility deteriorates and raises further infection risks. Therefore, staff in facilities should be maintained appropriate indoor carbon dioxide concentrations by ventilation during the COVID-19 catastrophe.

A novel humidity self-regulating interior wall coating composite based on red mud derived from alumina production

Aimed to resolve the problem of excessively high indoor humidity in subtropical areas and develop a new resource disposal technique for red mud, a novel humidity self-regulating interior wall coating composite based on red mud (HRCRM) was successfully prepared using red mud as a matrix material and vermiculite as a humidity regulator. The effects of component proportion, ambient humidity, exposure time on hygroscopicity of this composite were systematically investigated. This composite exhibited good humidity regulating ability with the largest water absorption rate of 16.38% under experimental conditions. Moreover, various properties were tested including surface drying time, hardness, adhesion, coating appearance, water resistance and reusability, meeting the national standard requirements well. The mechanism was comprehensively analyzed by XRD, TG-DTG, FESEM, and FTIR, indicating that the humidity self-adjusting function of HRCRM was realized by regulating the interlayer water storage of vermiculite. This study can provide theoretical and technical guidance for residential environment improvement in subtropical areas and comprehensive utilization of red mud.

Effects of weather forecasting on indoor comfort and energy savings in office buildings

ObjectiveTo explore whether a climate services approach can enable both energy saving and indoor comfort. MethodsAfter analysis of the local weather forecast, the air conditioning temperature of a government building was set to be adjusted at 7:30, 11:00, and 17:00. The indoor temperature and humidity were measured by using a MAPS6.0 sensor, and thermal comfort was calculated using ISO 7730 standards. Multiple regression analysis was used to examine the correlation between the weather forecast and chiller energy consumption. ResultsAfter a three-stage air conditioning temperature control process was implemented, predicted mean vote values between 0 and 0.5 were achieved for 79.1% of the working hours in the experimental period. Outdoor and air conditioning temperatures were the most critical factors affecting the hourly energy consumption of the air conditioner and water-cooled chiller. With every 1 °C increase in the outdoor temperature, the hourly energy consumption increased by 6.57. Moreover, with every 1 °C increase in the air conditioner temperature, the hourly energy consumption decreased by 8.63. DiscussionA predicted mean vote value of >0.5 was recorded for 15.9% of the working hours; this may be related to high indoor humidity, weather forecast inaccuracies, and the air conditioner being turned on too late in the day. From July to October 2021, 8749 kW h of electricity were saved, and carbon emissions were reduced by 1405 kg. Regulating air conditioning temperatures through weather forecasts can achieve energy savings.

Hygrothermal and Acoustic Performance of Two Innovative Envelope Renovation Solutions Developed in the e-SAFE Project

In order to reach the ambitious decarbonizing goals set by the European Union for 2030, deep renovation of the existing European building stock is a key issue. Within this context, the recently funded H2020 project “e-SAFE” is investigating market-ready wooden envelope renovation solutions for non-historic buildings, which encompass both energy and seismic improvement. The research carried out in the project aims at developing, testing and demonstrating these solutions on a real pilot. More specifically, this paper presents preliminary analyses to verify that the solutions satisfy the requisites set by the national regulations in force in most European countries, in terms of hygrothermal and acoustic performance. The analysis, carried out following relevant technical European Standards and based on calculations, considers different climate conditions and existing wall structures, selected amongst those most commonly adopted in Europe. The results show that the addition of a Cross Laminated Timber (CLT) layer with some wooden-based insulation on the outer side allows reaching very good thermal and acoustic performance. However, interstitial condensation may occur in cold climates under high indoor humidity values. This aspect deserves further investigation accounting for the transient behavior of the walls and all vapor transport mechanisms.

Improvement of the Korean Design Criteria on Wall-To-Wall Junctions to Prevent Condensation in Apartment Houses

Maintaining a proper temperature and humidity in a living space is very important for the health and comfort of apartment residents. Poor residential thermal conditions are recognized as a potential risk to the overall physical health. Thus, building development criteria that maintain an indoor environment separate from the outside environment have been continuously strengthened. However, this has not been the case in Korea, with regards to design criteria for the prevention of indoor condensation. In Korea, condensation occurs indoors frequently, during the winter season. When the outside temperature is low during the winter, a high indoor temperature and humidity would affect the indoor building materials and cause condensation. This study investigated and analyzed the indoor temperature and humidity during winter—when there is a significant difference in the outdoor and indoor temperatures—and conducted a survey on the residents’ lifestyles. Construction design criteria were found to be different from those of the past, and possible causes of changes in temperature and humidity were examined. We intended to establish enhanced design criteria that would prevent indoor condensation, by comparing our results to that of a study conducted in 2003.

Thermal Assessment of Traditional, Partially Subterranean Dwellings in Coastal and Mountainous Regions in the Mediterranean Climate. The Case of Cyprus

Fully, or partially, subterranean dwellings have developed as a distinctive building type from the prehistoric to pre-industrial era in the Mediterranean region, often serving specific purposes. The energy benefits of such spaces are well documented mainly through the investigation of numerous examples found in vernacular architecture. Despite their environmental potentials, subterranean structures remain limited in contemporary design practices. The present paper reports on the findings of a systematic research that examines partially subterranean traditional dwellings in the coastal and mountainous regions of Cyprus, an island in the Eastern Mediterranean. The study focuses on the environmental assessment of these spaces, through the monitoring of air temperature and relative humidity, and on a brief demonstration of various passive strategies for indoor microclimate improvements. Although these structures are not very common in the vernacular architecture of the island, their scientific examination produces useful knowledge in terms of energy savings. This can inform contemporary design applications and form a basis for the drafting of environmental refurbishment guidelines, applicable for this particular building typology. The research indicates favourable temperatures and significant cooling effects in partially subterranean spaces during the hot summer period, especially in mountainous regions. Temperatures in such spaces during the cold winter period are found to exhibit higher values compared to the temperatures of above-ground spaces, although they remain below comfort limits. High indoor humidity is found to be a major problem, in both the summer and winter period, in the coastal regions of the island. It is highlighted that, although partially subterranean spaces have many environmental benefits, as earth offers thermal insulation and heat storage, generalizations should be avoided since a number of varying parameters, such as the local climate, geology, natural ventilation conditions and building materials used, influence considerably their environmental performance.DOI: http://dx.doi.org/10.5755/j01.sace.16.3.16155

An analytical study on perceived experiences of homemakers associated to the causes of indoor pollution

Right to live in a healthy environment is a fundamental human right. It is the basic requirement of all the living beings; including humans, livestock, plant, micro-organisms and the wildlife. In the society man constantly interacts with his environment which affects him both physiologically and psychologically. Study was conducted on the perceived experiences of rural and urban homemakers associated to the different causes of indoor pollution. Most frequently encountered experiences revealed by the respondents were: garbage burning, smoking, paddy burning in fields, high indoor humidity, abundance of dust etc. under the environmental causes. Similarly most frequently perceived experiences of indoor pollution due to chemical causes were: leaking of cooking gas, perfumes, mosquito, insects repellent with mean score = 2.53, room deodorizers, cosmetics, hair spray and insecticides/pesticides. Most frequently experiences under the category of constructional faults and household articles causing indoor pollution were: dust beneath carpet, uncovered dustbins, clogged drain pipes, dusting of rugs/carpet/bedding/sofa, damp and soiled bedding, cooking fumes, wall dampness, damp carpets, roof leakage, leaking pipes and worn off mattress. Maximum mean score was for dust beneath the carpet with mean score 2.50 and the least mean score was for worn of mattresses with mean score 1.77. Perceived experienced due to miscellaneous causes leading to indoor pollution as reported by respondents were: pet waste, cockroaches, lizards, insects, animal dander, stagnated water, fungus, black moulds and spider’s webs.

Studies of thermal comfort and space use in an urban park square in cool and cold seasons in Shanghai

Outdoor open space is important to cities and can provide benefits for healthy urban living. Among the many factors that affect space quality and space use, thermal comfort has drawn increasing attention from both climatologists and planners. Previous studies mostly focus on hot seasons when the primary concern is to avoid solar exposure and mitigate heat stress. In Shanghai, because of the high indoor humidity, people prefer to go outdoors and enjoy more sunshine in autumn and winter. This paper presents a thermal comfort survey in one urban park in Shanghai from November to January to investigate the role thermal comfort plays in affecting people's evaluation of the outdoor space and activity. Meteorological measurements, questionnaire surveys and unobtrusive observations were carried out. Computer simulations were conducted to evaluate the micro-meteorological conditions. The physiological equivalent temperature (PET) was used to evaluate people's objective thermal comfort level based on micro-meteorological conditions. It is found that visitors' overall comfort was largely affected by their subjective thermal sensation vote (TSV). In winter TSV showed the strongest positive relationship with air temperature and solar radiation, which are also the two most important factors that affect visitors' space use. The study reveals that the neutral PET in Shanghai in winter is around 15–29 °C. It was also found that duration of stay and length of residence in Shanghai affected visitors' thermal adaptation. This study can provide understandings of people's outdoor thermal comfort in autumn and winter in Shanghai and help promote outdoor space use.

Energy use and indoor climate of conservation heating, dehumidification and adaptive ventilation for the climate control of a mediaeval church in a cold climate

Mediaeval churches hold substantial historical and cultural values, organs, altars, paintings that need to be preserved. Many of these churches have no climate control systems installed. Thus the indoor climate is mainly determined by the outdoor climate. Focus in this study is on the possibilities to improve indoor climate in originally unheated churches to prevent and protect churches from mould growth and disintegration of wooden parts. A case study in the Church of the Holy Cross in Harju Risti, Estonia, was conducted to test two different indoor climate control systems: dehumidification and an air-to-air heat pump. The systems were controlled with relative humidity to prevent the indoor humidity from dropping low enough to start wood cracking and salt drying in the walls. Based on field measurements, simulation models were calibrated and used to test different climate control systems and their impact on churches’ indoor climate and energy consumption. Our study showed that the adaptive ventilation performs well in high indoor humidity conditions, annual energy consumption of conservation heating with a heat pump is the lowest, and dehumidification is most effective during the cold period.

Using physical–chemical properties of reactants to estimate the performance of photocatalytic oxidation air cleaners

Various ultraviolet photocatalytic oxidation (UV–PCO) technologies are being used to eliminate or minimize different types of indoor air pollution, namely volatile organic compounds (VOCs). However, the removal efficiency of such air cleaning systems for different kind of VOCs could be challenging or completely unpredictable at different indoor environment conditions. This study presents a new systematic experimental method for measuring the performance of UV–PCO systems for different operational test conditions. The experiments were carried out using a continuous single pass system setup with three different types of TiO2 catalysts at high airflow rate and ambient indoor air temperature and humidity levels. The adsorption isotherm for each catalyst was determined individually to find a correlation for each test compounds. The relationship between the PCO rate constant and ionization potential (IP), as a physical and chemical property of selected alcohols compounds was investigated at the steady-state condition. The developed reaction rate correlations can be used as a design parameter to quantify the removal efficiency of other VOCs with the tested experimental system setup.

Assessing the moisture buffering performance of hygroscopic material by using experimental method

It is widely known that the problem of low or high indoor humidity environment has various adverse effects on occupant’s health, durability of the building envelope and energy consumption. In order to create comfortable and healthy indoor environment, it is necessary to maintain the indoor humidity steady in a correct level. Hygroscopic interior material can adsorb and desorb moisture from surrounding air, adopting this material is an energy-efficient way to moderate indoor humidity variations and thus it has been applied as finishing materials in some buildings. However, there is no criterion to evaluate the moisture buffering effect of applying hygroscopic material. In this research investigation, a series of experiments with different applying parameters were designed and carried out in a climate-controlled test chamber. The purpose of this study is to quantitatively evaluate the moisture buffering effect by applying hygroscopic material, as well as to understand the humidity distribution of a hygroscopic material furnished room. Experimental results showed that the effects of moisture adsorption/desorption decreased exponentially when the ambient air change rate per unit area of hygroscopic material increased.

Sources of Propylene Glycol and Glycol Ethers in Air at Home

Propylene glycol and glycol ether (PGE) in indoor air have recently been associated with asthma and allergies as well as sensitization in children. In this follow-up report, sources of the PGEs in indoor air were investigated in 390 homes of pre-school age children in Sweden. Professional building inspectors examined each home for water damages, mold odour, building’s structural characteristics, indoor temperature, absolute humidity and air exchange rate. They also collected air and dust samples. The samples were analyzed for four groups of volatile organic compounds (VOCs) and semi-VOCs (SVOCs), including summed concentrations of 16 PGEs, 8 terpene hydrocarbons, 2 Texanols, and the phthalates n-butyl benzyl phthalate (BBzP), and di(2-ethylhexyl)phthalate (DEHP). Home cleaning with water and mop ≥ once/month, repainting ≥ one room prior to or following the child’s birth, and “newest” surface material in the child’s bedroom explained largest portion of total variability in PGE concentrations. High excess indoor humidity (g/m3) additionally contributed to a sustained PGE levels in indoor air far beyond several months following the paint application. No behavioral or building structural factors, except for water-based cleaning, predicted an elevated terpene level in air. No significant predictor of Texanols emerged from our analysis. Overall disparate sources and low correlations among the PGEs, terpenes, Texanols, and the phthalates further confirm the lack of confounding in the analysis reporting the associations of the PGE and the diagnoses of asthma, rhinitis, and eczema, respectively.

Increasing the indoor humidity levels in buildings with ventilation systems: Simulation aided design in case of passive houses

In modern societies, people spend about 90 percent of their time inside buildings. The challenge of building physics is to ensure that buildings are planned, constructed and built to provide a comfortable and healthy working and living environment. As construction style has changed during recent years, the planning phase has to be much more precise and the need of simulation programs that respond to every little change arises. An increasing problem in Austria is the indoor humidity. In the field of renovated buildings with airtight new building envelopes, mould growth due to high indoor relative humidity (RH) is a persistent problem. On the other hand, in recently realized Austrian passive houses with an air treatment system, the low humidity level of the indoor air is a problem with which scientists have been struggling for some time. It has been observed in numerous measurements and it is also easily computationally detectable that in winter period the indoor relative humidity level often drops below 30% RH. Low and high relative humidity levels have negative effects on the comfort feeling and health of the occupants of the dwelling and should therefore be avoided. However, it is expensive to increase or decrease the humidity in houses mechanically. Therefore, the existing room moisture should be used sensibly in buildings with a ventilation system. In buildings with a high indoor humidity it is necessary to adjust the ventilation depended on moisture production. This paper focuses on low indoor humidity and presents some different methods by which the indoor relative humidity can be regulated. The effects of adapting parameters such as ventilation rate and buffering material in the dwelling were clearly reflected in the measured temperature and relative humidity. “BuildOpt_VIE” software developed at the Vienna University of Technology was used for the dynamic building simulation in this study.

A comparative study of different control strategies for indoor air humidity

There has been a rising concern in controlling the high indoor humidity of hot and humid countries. When an air-conditioned space experiences only part of its design heat load, its humidity tends to rise as a result of the air-conditioning system trying to control the indoor temperature by reducing its cooling capacity. In this study, the part-load dehumidification performances of three temperature control strategies are compared, namely, chilled water flow control, bypass air control and the variable air volume control. Coil simulations are employed to study the part-load performance of these control strategies. The coil model has been validated with experimental data to within ±6.5%. The relative humidity of a space depends of factors such as design sensible heat factor of the space, temperature control strategy employed and load condition experienced by the space. Simulation results have indicated that chilled water control strategy results in the highest indoor humidity throughout the range of conditions studied while variable air volume system provides highly effective dehumidification performance of the cooling coil. Bypass air control appears to be a good option for adoption as it is able to provide an acceptable humidity over a wide range of load conditions without having to affect the air movement within the space.

Beyond the Bench: Mapping the Air in Public Schools

In the home, parents are the primary guardians of a child’s environmental health. However, once the child’s environment moves out of the home, identifying sources of protection can become difficult. The Community Outreach and Education Program (COEP) of Duke University’s NIEHS Environmental Health Sciences Research Center in Durham, North Carolina, has pledged to give children’s environmental health the attention it deserves and is proactively implementing projects to create preventive environmental interventions that protect children before they become sick. One of the main questions the Duke COEP seeks to answer in its outreach activities is whether children are being exposed to environmental factors in school that contribute to asthma incidence. The Duke COEP staff have used geographic information system (GIS) technology in a number of applications to address this question, including a May 2004 assessment of the indoor air environment at nearby New Hope Elementary School. For years, students and staff in the Orange County school system (of which New Hope Elementary is a part) had complained of respiratory problems as well as general discomfort with fluctuating indoor temperatures and a sense that the air in the school buildings was unhealthy. COEP staff were asked to evaluate one sample school in the system and offer recommendations. They selected New Hope Elementary for study, then went into the school and conducted an evaluation of every classroom. The problems they observed included a high relative indoor humidity of around 75–78% (the ideal humidity is 35–40% when the outdoor temperature is 20°F or higher) and imbalances in the heating and cooling system (they observed temperature differences of as much as 5–10°F in separate classrooms in some instances). They also noticed problems exacerbated by failing insulation, such as mold spore development and air flow variations—some rooms would have a distinct breeze, while others had still, damp air. Once they had gathered their data, the COEP staff created a GIS compilation to display the data and analyze the results. The advantage of using GIS technology to interpret information is that it visually integrates previously unlinked sets of information, facilitating the detection of relationships among them. In the case of New Hope Elementary, the GIS map let concerned parents, teachers, school administrators, and education policy makers see a visual representation of the spatial distribution of airflow irregularities and mold spores throughout the school. Based on information gathered from the GIS map, the school administrators replaced carpeting throughout the school with tile floors and thoroughly cleaned the entire duct system, which significantly improved ventilation in the classrooms. “What’s exciting is that we were able to provide information, education, and outreach directly to the faculty and school governance council,” says Marie Lynn Miranda, director of the Duke COEP. Another benefit of the study is the unique learning opportunity it will afford the New Hope Elementary students. All the data from the project will be turned over to the school’s fifth-grade science teachers for development into classroom lesson projects. COEP workers also plan to use the New Hope Elementary study as a model for future initiatives in childhood asthma prevention.

Moisture Generation through Chinese Household Activities

High indoor humidity not only causes degradation of building materials but also thermal discomfort, increased energy use for air-conditioning and it promotes mould growth. Mitigation of indoor moisture problems requires the ability to predict the humidity levels that may prevail in indoor spaces, which in turn requires knowledge about the moisture generation rates of indoor sources. There was, however, a lack of such data for various moisture generating activities in Chinese households. This paper presents the results of surveys and experiments conducted recently to obtain data on the intensities of moisture generation for various household activities, including cooking, bathing, washing clothes and drying, dishwashing and drying, floor mopping and indoor planting. On the basis of the survey and measurement results, moisture generation profiles for typical kitchens, bathrooms, living and dining rooms, and bedrooms have been established for use in inter-zone moisture movement and indoor humidity level predictions for typical residential units in Hong Kong. The models derived for predicting moisture release rates from drying clothes and bathroom air moisture content during shower baths are presented.

Occupational asthma in greenhouse workers.

A prevalence of asthma over 5% has been reported in flower farmers,and work inside greenhouses has emerged as an additional risk factor. Workplace determinants behind this high prevalence has been examined, and a prevalence of sensitization to workplace allergens over 30% has been reported being pollens, moulds, and Tetranychus urticae allergens the main sensitizers. Bronchial challenge tests in the workplace have demonstrated occupational asthma in more than 20% of the sensitized greenhouse growers. Air contamination inside greenhouses is mainly related to moulds, and is facilitated by the high indoor temperature and humidity. Cladosporium, Penicillium, Aspergillus, and Alternaria and a wide range of flower pollens are able to sensitize the greenhouse worker and cause occupational asthma. Tetranychus urticae have allergens shared with other mites, but the low prevalence of cross-sensitization between them confirm that Tetranychus urticae contains species-specific allergens that may cause respiratory symptoms. Additionally, working inside greenhouses has been related to an increase in the prevalence of chronic bronchitis in nonsmokers. The cultivation of greenhouse crops may cause occupational asthma through sensitization to workplace pollens, moulds, and Tetranychus urticae allergens. In greenhouse flower growers, skin testing identifies sensitization to these allergens in one third of the growers, and more than one fifth of the sensitized workers will develop occupational asthma. Greenhouse work has also been related to chronic bronchitis in nonsmokers, suggesting a causal effect of greenhouse air contaminants on this disease as well.

The lessons of noninterventional and interventional prospective studies on the development of atopic disease during childhood.

The lessons of noninterventional and interventional prospective studies on the development of atopic disease during childhood.

Window pane condensation and high indoor vapour contribution - markers of an unhealthy indoor climate?

The aim of this study was to investigate whether window pane condensation and indoor vapour contribution >/= 3 g/m3 could be used as indicators of defective air change rate, high indoor humidity and high mite allergen concentration in mattress dust. Actual ventilation rate, indoor temperature, air humidity (AIH/RH) and concentrations of mite allergen were measured in 59 houses and compared with received outdoor temperatures and air humidity. Indoor vapour contribution defined as the difference between the indoor and the outdoor vapour concentration was calculated. Sensitivity, specificity, predictive values and accuracy were calculated for window pane condensation and high vapour contribution (>/= 3 g/m3), as indicators of defective ventilation (< 0.5 ACH), high indoor humidity (>/= 7 g/kg and >/= 45% RH) and high mite allergen concentration in mattress dust (>/= 2 microg/g). All houses with high humidity and high mite allergen concentrations were positive for the two indicators (high sensitivity), but with a specificity of only 50% so that half of the houses with reported condensation and high vapour contribution turned out to be low pollution houses with adequate high ventilation levels. Both indicators had high negative predictive values and absence of the two indicators almost certainly (97-100%) excluded high indoor pollution with high humidity and high mite concentrations. Overall more than 70% of the dwellings were correctly classified by the two indicators. Absence of window pane condensation on double-glazed windows and low indoor vapour contribution (< 3 g/m3) during the winter are true markers of a dwelling without high indoor air humidity and without high mite allergen concentrations in mattress dust in houses in a cold temperate climate with subzero outdoor temperatures. The presence of the two indicators is associated with a 18-45% risk of high humidity and mite allergen concentrations so in this latter group further measurements are needed for correct classification.

Indoor airborne fungal spores, house dampness and associations with environmental factors and respiratory health in children.

Children living in a damp house are more likely to suffer from respiratory symptoms and it has been suggested that exposure to fungi is an important contributing factor. However, more knowledge about underlying mechanisms for the association are needed. To identify associations between measures of house dampness, levels of airborne fungal spores, housing factors and health outcomes in children. Eighty households with 148 children between 7 and 14 years of age were recruited in the Latrobe Valley, Victoria, Australia. Some 36% of participating children were asthmatic. Six sampling visits were made to each house between March 1994 and February 1995 on a 2-monthly cycle. Samples for airborne total and viable fungal spores were collected from bedrooms, living rooms, kitchens and outdoors. A detailed dwelling characterization, using a questionnaire and inspection surveys, was carried out. Skin-prick tests were performed with extracts of common aeroallergens and a respiratory questionnaire was completed for each child. Large airborne fungal spore concentrations were recorded in association with: musty odour, water intrusion, high indoor humidity, limited ventilation through open windows, few extractor fans and failure to remove indoor mould growth. Visible mould growth or condensation evidence was associated with large concentrations of Cladosporium spores, but not with large total spore concentrations. Penicillium exposure was a risk factor for asthma, while Aspergillus exposure was a risk factor for atopy. Fungal allergies were more common among children exposed to Cladosporium or Penicillium in winter or to musty odour. Respiratory symptoms were marginally more common with exposure to Cladosporium or total spores in winter. Indoor exposure to certain fungal genera in winter was a risk factor for asthma, atopy and respiratory symptoms in children. On the other hand, no significant associations were seen between average viable or total spore concentrations and child health. Actual measurements of fungal spores predict health outcomes better than reported dampness.