Analysis of indoor humidity environment in Chinese residential buildings

A high or low humidity environment is related closely to not only many health problems, but also has great influence on the construction durability and energy consumption. It is very important to control humidity level, in order to achieve a healthy and comfortable indoor environment. However, various problems of the air humidity in inhabited dwellings are not yet taken serious consideration in China. Moreover, there is hardly any information available regarding the actual humidity environment in Chinese residential houses. For this reason, it is difficult to select appropriate moderate moisture strategies to maintain a harmonious indoor humidity level.     

Effects of outdoor air conditions on hybrid air conditioning based on task/ambient strategy with natural and mechanical ventilation in office buildings

This research aims to clarify the effects and indoor environmental characteristics of natural and mechanical hybrid air-conditioning systems in office buildings during intermediate seasons and to obtain design data. Natural and mechanical hybrid air conditioning is an air-conditioning system that utilizes natural ventilation and mechanical air-conditioning systems to improve the quality of the indoor thermal and air environment, and to reduce energy consumption. This report first categorizes the available natural ventilation conditions and estimates the amount of natural ventilation available in a model building. Furthermore, based on the concept of task-ambient air conditioning, after controlling the average temperature in the task zone to a target air conditioning temperature (26°C), changes in the outdoor temperature/humidity and the inflow rate, and the indoor environment and amount of cool heat input were studied with changes in the size of the natural vent using three-dimensional Computational Fluid Dynamics (CFD) analysis. The results of these studies indicated that natural ventilation at temperatures lower than the indoor temperature effectively covered the lower indoor task zone through negative buoyancy, which enabled energy-saving air conditioning in the task zone.     

Model-based commissioning for filters in room air-conditioners

This paper proposes a model that can estimate filter resistance using estimated air-conditioner indoor unit air flow rate, which is tightly related to filter fouling conditions. Two sorts of value are used as inputs to estimate air flow rate. One is the power consumed by the fan in the indoor unit of a room air-conditioner and the other is the thermal performance of a room air-conditioner. For the room air-conditioners that the real-time indoor unit fan power consumption is available, fan power consumptions are used as inputs to estimate filter resistance. For the room air-conditioners that are equipped with refrigerant pressure and temperature sensors, this model estimates filter resistance using refrigerant pressure and temperature, air temperature or enthalpy difference between supply and indoor air. This model was validated using a really running multi-evaporator Gas-engine Heat Pump (GHP) system. The maximum and average difference between estimated and measured filter resistance are 12.72% and 5.89% when using the fan power consumption as inputs. When using the air-conditioner thermal performance data, the maximum and average estimation errors are 13.12% and 5.96%. The validation results show that this model is accurate enough for estimating filter resistance. Based on this model, the method for commissioning filters in air-conditioner is discussed. This method is useful for automatically estimating filter resistance and reminding users timely to clean or replace a filter to prevent wasting energy and to maintain desirable indoor environment.     

Ventilation rates and health: multidisciplinary review of the scientific literature

The scientific literature through 2005 on the effects of ventilation rates on health in indoor environments has been reviewed by a multidisciplinary group. The group judged 27 papers published in peer-reviewed scientific journals as providing sufficient information on both ventilation rates and health effects to inform the relationship. Consistency was found across multiple investigations and different epidemiologic designs for different populations. Multiple health endpoints show similar relationships with ventilation rate. There is biological plausibility for an association of health outcomes with ventilation rates, although the literature does not provide clear evidence on particular agent(s) for the effects. Higher ventilation rates in offices, up to about 25 l/s per person, are associated with reduced prevalence of sick building syndrome (SBS) symptoms. The limited available data suggest that inflammation, respiratory infections, asthma symptoms and short-term sick leave increase with lower ventilation rates. Home ventilation rates above 0.5 air changes per hour (h(-1)) have been associated with a reduced risk of allergic manifestations among children in a Nordic climate. The need remains for more studies of the relationship between ventilation rates and health, especially in diverse climates, in locations with polluted outdoor air and in buildings other than offices. PRACTICAL IMPLICATIONS: Ventilation with outdoor air plays an important role influencing human exposures to indoor pollutants. This review and assessment indicates that increasing ventilation rates above currently adopted standards and guidelines should result in reduced prevalence of negative health outcomes. Building operators and designers should avoid low ventilation rates unless alternative effective measures, such as source control or air cleaning, are employed to limit indoor pollutant levels.     

Managing Exposure to Indoor Air Pollutants in Residential and Office Environments

Abstract Sources of indoor air pollutants in residential and office environments can be managed to reduce occupant exposures. Techniques for managing indoor air pollution sources include: source elimination, substitution, modification, pretreatment, and altering the amount, location, or time of use. Intelligent source management requires knowledge of the source's emission characteristics, including chemical composition, emission rates, and decay rates. In addition, knowledge of mechanical and natural outdoor air exchange rates, heating/air-conditioning duct flow rates, and local exhaust fan (e.g., kitchen, bathroom) flow rates is needed to determine pollutant concentrations. Finally, indoor air quality (IAQ) models use this information and occupant activity patterns to determine instantaneous and/or cumulative individual exposure. This paper describes a number of residential and office scenarios for various indoor air pollution sources, several ventilation conditions, and typical occupant activity patterns. IAQ model predictions of occupant exposures for these scenarios are given for selected source management options. A one-month period was used to compare exposures; thus, long-term exposure information is not presented in this paper.     

The impact of information on perceived air quality--'organic' vs. 'synthetic' building materials

As indoor air quality complaints cannot be explained satisfactorily and building materials can be a major source of indoor air pollution, we hypothesized that emissions from building materials perceived as unfamiliar or annoying odors may contribute to such complaints. To test this hypothesis, emissions from indoor building materials containing linseed oil (organic) and comparable synthetic (synthetic) materials were evaluated by a na?ve sensory panel for evaluation of odor intensity (OI) and odor acceptability (OA). The building materials were concealed in ventilated climate chambers of the CLIMPAQ type. When information was provided about the identity and type of building material during the evaluation, i.e. by labeling the materials in test chambers either as 'organic' or 'synthetic', the OI was significantly lower for all the 'organic' materials compared with evaluations without information. Similarly, OA was increased significantly for most 'organic' samples, but not the 'synthetic' ones. The major effect is probably that OA is increased when the panel is given information about the odor source. PRACTICAL IMPLICATIONS: As providing information about the source of odors can increase their acceptability, complaints about indoor air quality may be decreased if occupants of buildings are well informed about odorous emissions from the new building materials or new activities in their indoor environment.     

Characterization and pro-inflammatory potential of indoor mold particles

A number of epidemiological studies find an association between indoor air dampness and respiratory health effects. This is often suggested to be linked to enhanced mold growth. However, the role of mold is obviously difficult to disentangle from other dampness-related exposure including microbes as well as non-biological particles and chemical pollutants. The association may partly be due to visible mycelial growth and a characteristic musty smell of mold. Thus, the potential role of mold exposure should be further explored by evaluating information from experimental studies elucidating possible mechanistic links. Such studies show that exposure to spores and hyphal fragments may act as allergens and pro-inflammatory mediators and that they may damage airways by the production of toxins, enzymes, and volatile organic compounds. In the present review, we hypothesize that continuous exposure to mold particles may result in chronic low-grade pro-inflammatory responses contributing to respiratory diseases. We summarize some of the main methods for detection and characterization of fungal aerosols and highlight in vitro research elucidating how molds may induce toxicity and pro-inflammatory reactions in human cell models relevant for airway exposure. Data suggest that the fraction of fungal hyphal fragments in indoor air is much higher than that of airborne spores, and the hyphal fragments often have a higher pro-inflammatory potential. Thus, hyphal fragments of prevalent mold species with strong pro-inflammatory potential may be particularly relevant candidates for respiratory diseases associated with damp/mold-contaminated indoor air. Future studies linking of indoor air dampness with health effects should assess the toxicity and pro-inflammatory potential of indoor air particulate matter and combined this information with a better characterization of biological components including hyphal fragments from both pathogenic and non-pathogenic mold species. Such studies may increase our understanding of the potential role of mold exposure.     

Physico-chemical characterization of indoor/outdoor particulate matter in two residential houses in Oslo, Norway: measurements overview and physical properties--URBAN-AEROSOL Project

Indoor/outdoor measurements have been performed in the Oslo metropolitan area during summer and winter periods (2002-2003) at two different residential houses. The objective of the measurement study was to characterize, physically and chemically, the particulate matter (PM) and gaseous pollutants associated with actual human exposure in the selected places, and their indoor/outdoor relationship. In this paper, we focus on the PM measurements and examine the relationship between the indoor and outdoor PM concentrations taking into account the ventilation rate, indoor sources and meteorological conditions. The indoor/outdoor measurements indicate the important contribution of the outdoor air to the indoor air quality and the influence of specific indoor sources such as smoking and cooking to the concentration of PM inside houses. However, no specific correlation was found between the indoor/outdoor concentration ratio and the meteorological parameters. This study provides information on the physical characteristics and the relationship of indoor to outdoor concentration of particulate matter in residential houses. Moreover, the parameters that influence this relationship are discussed. The results presented here are specific to the sampled houses and conditions used and provide data on the actual human exposure characteristics which occur in the spatial and temporal scales of the present study.     

家用空调器新风引入前后室内气流组织的对比

现代人们对室内环境的要求不仅仅局限于热湿环境,室内空气品质也越来越受到人们的关注.家用空调器新风引入成为空调器发展的必然趋势,本文针对家用分体空调器的房间顶部新风独立引入方式以及无新风独立空调器的室内温度场和速度场进行了数值模拟,模拟结果表明新风引入前后室内人员周围的热环境变化很小.     

室内空气品质预测新方法

分析了常用的室内空气品质预测方法中存在的问题,根据室内空气品质不满意率和化学污染物对数评价指标间的线性关系,在室内污染物浓度场预测的基础上提出了一种预测室内空气品质的新方法。该方法简单可行,且能综合体现主、客观评价结果。     

厦门某海滨住宅夏季自然通风与室内热环境实测与分析

本文采用自动记录仪,对厦门某海滨住宅夏季自然通风与室内热环境进行实测。根据测得的自然通风时段,分析了自然通风对房间风速及室内热环境的影响。主要结论有:(1)在自然通风条件下,房间白天室内风速均值及波动值较夜间大。(2)房间在自然通风时段,室内气温均值略低于室外,室内气温波动明显低于室外且各房间气温波动差别不大;房间在非自然通风时段,室内气温均值与室外气温相当,室温变化相当平缓。(3)无论是自然通风还是非自然通风,房间的黑球温度与室内空气温度差别很小。(4)当房间处于非自然通风状态时,室内热环境总是处于"不可接受"水平,当房间处于自然通风状态时,其室内热环境几乎全时段达到"可接受"水平,且有的房间在某些时段可达到"热舒适"水平。     

Personal exposures to volatile organic compounds among outdoor and indoor workers in two Mexican cities

There are limited data on exposures to ambient air toxics experienced by inhabitants of urban areas in developing countries that have high levels of outdoor air pollution. In particular, little is known about exposures experienced by individuals working outdoors - typically as part of the informal sector of the economy - as compared to workers in office-type environments that approach the indoor air quality conditions of the more developed countries. The objective of this study is to explore these differences in personal exposures using a convenience sample of 68 outdoor and indoor workers living in Mexico City (higher outdoor air pollution) and Puebla (lower outdoor air pollution), Mexico. Occupational and non-occupational exposures to airborne volatile organic compounds (VOCs) were monitored during a 2 day period, monitoring 2 consecutives occupational and non-occupational periods, using organic vapor monitors (OVMs). Socio-demographic and personal time-location-activity information were collected by means of questionnaires and activity logs. Outdoor workers experienced significantly higher exposures to most VOCs compared to indoor workers in each of these cities. The outdoor workers in Mexico City had the highest exposures both during- and off-work, with maximum occupational exposures for toluene, MTBE, n-pentane, and d-limonene exceeding 1 mg/m(3). The inter-city pattern of exposures between the outdoor workers is consistent with the higher outdoor air pollution levels in Mexico City, and is above exposures reported for urban areas of the more developed countries. Results from this study suggest that elevated outdoor air pollution concentrations have a larger impact on outdoor workers' personal exposures compared to the contribution from indoor pollution sources. This contrasts with the more dominant role of indoor air VOC contributions to personal exposures typically reported for urban populations of the more developed countries.     

Indoor air problems and experiences of injustice in the workplace: A quantitative and a qualitative study

This study explores subjective injustice experiences of individuals suffering from suspected or observed indoor air problems in their workplaces in two studies. We focus on injustice experiences because they influence how individuals cope with and recover from health problems. The first study reports associations between the perceived harmfulness of the indoor environment (ie, mold/inadequate ventilation) and subjective injustice experiences in workplaces in a representative sample of Finnish working‐aged people (N = 4633). Altogether, 37% of the respondents perceived their workplaces’ indoor environments to be harmful. Multivariate logistic regression analyses revealed that the risks of reporting subjective injustice experiences (eg, information, attitudes, and remuneration) were significantly higher for those reporting harmful indoor environments compared to those who reported no such problems (OR 1.28‐1.95 for different situations). The second study explored injustice experiences more closely by qualitatively analyzing the content of 23 essays. These essays were written by people who suffered from suspected or observed indoor air problems in their workplaces. The respondents reported multidimensional experiences of injustice, which related to conflicts, and moral exclusions. Awareness of these psychosocial effects is important for the prevention of unnecessary escalation of psychosocial problems in workplaces with observed and suspected indoor air problems.     

Correlating indoor and outdoor temperature and humidity in a sample of buildings in tropical climates

The incidence of several respiratory viral infections has been shown to be related to climate. Because humans spend most of their time indoors, measures of indoor climate, rather than outdoor climate, may be better predictors of disease incidence and transmission. Therefore, understanding the relationship between indoor and outdoor climate will help illuminate their influence on the seasonality of diseases caused by respiratory viruses. Indoor-outdoor relationships between temperature and humidity have been documented in temperate regions, but little information is available for tropical regions, where seasonal patterns of respiratory viral diseases differ. We have examined indoor-outdoor correlations of temperature, relative humidity (RH), and absolute humidity (AH) over a 1-year period in each of seven tropical cities. Across all cities, the average monthly indoor temperature was 25 ± 3°C (mean ± standard deviation) with a range of 20–30°C. The average monthly indoor RH was 66 ± 9% with a range of 50–78%, and the average monthly indoor AH was 15 ± 3 g/m³ with a range of 10–23 g/m³. Indoor AH and RH were linearly correlated with outdoor AH when the air conditioning (AC) was off, suggesting that outdoor AH may be a good proxy of indoor humidity in the absence of AC. All indoor measurements were more strongly correlated with outdoor measurements as distance from the equator increased. Such correlations were weaker during the wet season, especially when AC was in operation. These correlations will provide insight for assessing the seasonality of respiratory viral infections using outdoor climate data, which is more widely available than indoor data, even though transmission of these diseases mainly occurs indoors.     

Indoor thermal environment and air quality in Chinese-style residential kitchens

This paper reviews the published literature on indoor thermal environment and air quality in Chinese-style residential kitchens (CRKs). The paper first discusses typical characteristics of CRKs, including kitchen layout, cooking methods, and ventilation systems used. Next, the paper describes the current state of the indoor thermal environment and air quality in CRKs. Finally, this paper summarizes measures to control and improve the environment inside CRKs. The results indicate that the indoor environment of CRKs is too hot in summer and exhibits a large vertical temperature difference. No appropriate model was available for accurately evaluating the thermal environment in CRKs. At the same time, CRKs are highly polluted by COx, NOx, TVOC, and particulate matter (PM). Although existing exhaust hoods could improve the indoor environment to some extent, the use of a combined exhaust, make-up air, and air-conditioning system should be considered to provide a comfortable and healthy environment in CRKs.     

办公楼的室内空气品质与新风

根据对上海市区7幢甲级办公楼的室内空气品质和新风量的现场测试结果，试图分析办公楼的室内空气品质和新风量的关系，以及室外空气品质对室内空气品质的影响。     

广州市老年人使用空气调节设备状况及对健康影响调查

老人的健康与建筑室内环境存在重要联系，为了给适老建筑的暖通系统优化设计提供理论依据，有必要探究室内空气调节设备与老人健康的关系。对广州市104位本地老年人进行了问卷调查，收集了老年人的基本健康信息和家庭使用空气调节设备的情况，包括制冷、除湿、采暖和空气净化4种设备及其使用时长，使用习惯。收集到的信息用SPSS20.0进行了统计分析。结果包括广州市老年人家中四种设备拥有率、设备平均使用龄、设备使用时间以及常见日均使用时长；所调查的老年人健康比例达到55.8%。患病老人中心血管疾病的比例最高，其余为风湿性疾病和关节炎等疾病。相关性分析表明，广州地区夏天家庭采取制冷措施的老人患病可能性更小；制冷设备常见日均使用时长与身处空调区域时长的比值越大，老人患病的可能性越小。     

空调新风随机控制系统的实验研究

在非工业场所，CO2浓度不仅代表了CO2本身作为污染物对室内空气的污染程度，而且还能反映室内人员的状况．体现室内人员对新风的需求。利用CO2浓度可以方便地实现新风量的需求控制。参考欧美等国家和地区的标准，室内CO2浓度的允许值取为1000ppm。在控制系统中，传感器不断地将室内CO2浓度信号转换为电信号，通过A／D转换器转换为数字信号送入计算机与给定值比较，由此获得的偏差值经D／A转换器转换为电信号送入控制器，控制器根据此偏差信号，按照设定的控制规律输出电信号并驱动可逆电机转动，调节风门的开度，从而实现新风量的随机控制。新风阀与回风阀是联动的，以此保证空调系统的总送风量仍为设计值。采用传递函数法进行了理论分析，并在实验小室中，进行了控制系统的参数整定。本控制系统能根据室内情况，在保证室内空气品质的前提下，最大程度地减少空调系统的新风量，降低能耗，达到了节能的目的。     

The 3-year follow-up study in a block of flats - experiences in the use of the Finnish indoor climate classification

Indoor climate of two new blocks of flats was investigated. The case building was built for people with respiratory diseases by following the instructions of the Finnish Classification of Indoor Climate, Construction and Finishing Materials, while the control building was built using conventional building technology. The main indoor air parameters (temperature, relative humidity and levels of CO, CO2, ammonia, total volatile organic compounds, total suspended particles, fungal spores, bacteria and cat, dog and house dust mite allergens) were measured in six apartments of both the buildings on five occasions during the 3-year occupancy. In addition, a questionnaire to evaluate symptoms of the occupants and their satisfaction with their home environment was conducted in connection with indoor air quality (IAQ) measurements. The levels of indoor air pollutants in the case building were, in general, lower than those in the control building. In addition, the asthmatic occupants informed that their symptoms had decreased during the occupancy in the case building. This case study showed that high IAQ is possible to reach by careful design, proper materials and equipment and on high-quality construction with reasonable additional costs. In addition, the study indicated that good IAQ can also be maintained during the occupancy, if sufficient information on factors affecting IAQ and guidance on proper use and care of equipment are available for occupants.