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1.
Hodgson AT  Rudd AF  Beal D  Chandra S 《Indoor air》2000,10(3):178-192
Concentrations of 54 volatile organic compounds (VOCs) and ventilation rates were measured in four new manufactured houses over 2-9.5 months following installation and in seven new site-built houses 1-2 months after completion. The houses were in four projects located in hot-humid and mixed-humid climates. They were finished and operational, but unoccupied. Ventilation rates ranged from 0.14-0.78 h-1. Several of the site-built houses had ventilation rates below the ASHRAE recommended value. In both manufactured and site-built houses, the predominant airborne compounds were alpha-pinene, formaldehyde, hexanal, and acetic acid. Formaldehyde concentrations were below or near 50 ppb with a geometric mean value for all houses of 40 ppb. Similarities in the types of VOCs and in VOC concentrations indicated that indoor air quality in the houses was impacted by the same or similar sources. Major identified sources included plywood flooring, latex paint and sheet vinyl flooring. One site-built house was operated at ventilation rates of 0.14 and 0.32 h-1. VOC emission rates calculated at the two conditions agreed within +/- 10% for the most volatile compounds. Generally, the ratios of emission rates at the low and high ventilation rates decreased with decreasing compound volatility. Changes in VOC emission rates in the manufactured houses over 2-9.5 months after installation varied by compound. Only several compounds showed a consistent decrease in emission rate over this period.  相似文献   

2.
S. K. Brown 《Indoor air》1999,9(3):209-215
Abstract Volatile organic emissions from particleboard, medium density fibreboard (MDF) and office furniture have been measured in dynamic environmental chambers, both small and room-sized. Characterisation of product emission properties in small chambers was possible when inter- and intra-sheet variations were considered. Formaldehyde emission factors for all products were approximately double European low-emission specifications and did not decay to the latter for several months. Long-term emission behaviour could not be predicted from short-term measurements. Volatile organic compounds (VOC) emissions were low for the MDF product, higher for particleboard, and highest for laminated office furniture. The compounds emitted differed from those reported in other countries. VOC emissions from the sheet products decreased more quickly than formaldehyde, reaching low levels within two weeks, except for MDF which was found to become a low-level source of hexanal after several months.  相似文献   

3.
This field study measured ventilation rates and indoor air quality in 21 visits to retail stores in California. Three types of stores, such as grocery, furniture/hardware stores, and apparel, were sampled. Ventilation rates measured using a tracer gas decay method exceeded the minimum requirement of California's Title 24 Standard in all but one store. Concentrations of volatile organic compounds (VOCs), ozone, and carbon dioxide measured indoors and outdoors were analyzed. Even though there was adequate ventilation according to standard, concentrations of formaldehyde and acetaldehyde exceeded the most stringent chronic health guidelines in many of the sampled stores. The whole‐building emission rates of VOCs were estimated from the measured ventilation rates and the concentrations measured indoor and outdoor. Estimated formaldehyde emission rates suggest that retail stores would need to ventilate at levels far exceeding the current Title 24 requirement to lower indoor concentrations below California's stringent formaldehyde reference level. Given the high costs of providing ventilation, effective source control is an attractive alternative.  相似文献   

4.
Treatment of fresh air in ventilation systems for air-conditioning consumes a considerable amount of energy and affects the indoor air quality (IAQ). In this study, energy impact on ventilation systems was examined against certain IAQ objectives for indoor formaldehyde exposure risk in air-conditioned offices of Hong Kong. Thermal energy consumptions for ventilation systems and indoor formaldehyde exposure concentrations based on some regional surveys of typical offices in Hong Kong were reviewed. The thermal energy consumptions of ventilation systems operating for CO2 exposure concentrations between 800 ppmv and 1200 ppmv for typical office buildings and the corresponding formaldehyde exposure risks were evaluated. The results showed that, for a reference indoor environment at a CO2 exposure concentration of 1000 ppmv, the average thermal energy saving of ventilation system for a unit increment of the acceptable formaldehyde exposure limit of 1 h (loss of life expectancy of 0.0417 day) was 280 MJ m−2 yr−1; and for a unit decrement of the exposure limit of 1 h, an additional average thermal energy consumption of 480 MJ m−2 yr−1 was expected. This study would be a useful source of reference in evaluation of the energy performance of ventilation strategies in air-conditioned offices at a quantified exposure risk of formaldehyde.  相似文献   

5.
6.
Niu J  Tung TC 《Indoor air》2008,18(1):12-26
Abstract Abstract In the worldwide spread of Severe Acute Respiratory Syndrome (SARS) in 2003, cluster of cases occurred in a number of large high‐rise residential building blocks, especially in Hong Kong. In this study, we examined one of the most likely virus‐spread mechanisms, which is related to the inter‐flat or inter‐zonal airflow through open‐windows caused by buoyancy effects. Dual tracer gases of CO2 and SF6 are employed simultaneously to quantify the amount of the exhaust air coming out of the upper part of the window of a floor that re‐enters the lower part of the open‐window at the immediate upper floor. It was found that the room air could contain up to 7% of the exhaust air from the lower floor, and this occurs at low wind conditions with a combination of indoor–outdoor temperature difference. The results can well explain the earlier governmental finding that DNA strings of SARS Corono‐Virus were detected within the sampled deposits on the window sills of the upper floors of the two index patients’ flats. The preliminary and yet alarming conclusion may be that, in high‐rise buildings, windows flush with a flat façade can be a major route for the vertical spread of pathogen‐containing aerosols.  相似文献   

7.
Treatment of fresh air in ventilation systems for air-conditioned offices consumes a significant amount of energy and affects the indoor air quality (IAQ). In this study, energy impact on the ventilation systems was examined against certain IAQ objectives for indoor airborne bacteria exposure risk in air-conditioned offices of Hong Kong. The relationship between thermal energy consumptions and indoor airborne bacteria exposure levels based on regional surveys was investigated. The thermal energy consumptions of ventilation systems operating for carbon dioxide (CO2) exposure concentrations between 800 and 1200 ppmv for typical office buildings and the corresponding failure probability against some target bacteria exposure levels were evaluated. The results showed that, for a reference indoor environment at a CO2 exposure concentration of 1000 ppmv, the predicted average thermal energy saving of ventilation system for a unit increment of the expected risk of unsatisfactory IAQ of 1% was 55 MJ m−2 yr−1 and for a unit decrement of 1%, the predicted additional thermal energy consumption was 58 MJ m−2 yr−1 respectively. This study would be a useful source of reference in evaluation of the energy performance of ventilation strategies in air-conditioned offices at a quantified exposure risk of airborne bacteria.  相似文献   

8.
This research assesses benefits of adding to California Title‐24 ventilation rate (VR) standards a performance‐based option, similar to the American Society of Heating, Refrigerating, and Air Conditioning Engineers ‘Indoor Air Quality Procedure’ (IAQP) for retail spaces. Ventilation rates and concentrations of contaminants of concern (CoC) were measured in 13 stores. Mass balance models were used to estimate ‘IAQP‐based’ VRs that would maintain concentrations of all CoCs below health‐ or odor‐based reference concentration limits. An intervention study in a ‘big box’ store assessed how the current VR, the Title 24‐prescribed VR, and the IAQP‐based VR (0.24, 0.69, and 1.51 air changes per hour) influenced measured IAQ and perceived of IAQ. Neither current VRs nor Title 24‐prescribed VRs would maintain all CoCs below reference limits in 12 of 13 stores. In the big box store, the IAQP‐based VR kept all CoCs below limits. More than 80% of subjects reported acceptable air quality at all three VRs. In 11 of 13 buildings, saving energy through lower VRs while maintaining acceptable IAQ would require source reduction or gas‐phase air cleaning for CoCs. In only one of the 13 retail stores surveyed, application of the IAQP would have allowed reduced VRs without additional contaminant‐reduction strategies.  相似文献   

9.
A retrofit study was conducted in an unoccupied manufactured house to investigate the impacts of airtightening on ventilation rates and energy consumption. This paper describes the retrofits and the results of the pre- and post-retrofit assessment of building airtightness, ventilation, and energy use. Building envelope and air distribution systems airtightness were measured using fan pressurization. Air change rates were measured continuously using the tracer gas decay technique. Energy consumption associated with heating and cooling was monitored through measurement of gas consumption by the forced-air furnace for heating and electricity use by the air-conditioning system for cooling. The results of the study show that the retrofits reduced building envelope leakage by about 18% and duct leakage by about 80%. The reduction in the house infiltration rates depended on weather conditions and the manner in which the heating and cooling system was controlled, but in general these rates were reduced by about one third. The energy consumption of the house for heating and cooling was reduced by only about 10%, which is relatively small but not totally unexpected given that infiltration only accounts for a portion of the heating and cooling load.  相似文献   

10.
An earlier, simple, parametric study of ventilation is extended to cover more realistic buildings. The mathematical model which forms the basis of the study is briefly described and non-dimensional graphs are derived to present the results of the model in a very compact and comprehensive form.The importance of ceiling leakage when predicting ventilation is demonstrated and the significance of this to validation of models is discussed.It is shown that by making acceptable approximations, a wide range of buildings can be covered by a small number of graphs. This leads to the possibility of a very simple graphical procedure for estimating ventilation with relatively high accuracy. A correspondingly simple means of estimating ventilation associated with turbulent pressure fluctuations is proposed.  相似文献   

11.
This paper discusses the effect of ventilation duct as a particle filter by modeling particle deposition in ventilation ducts, which is the reason that ventilation ducts could “filter” particles. An Eulerian model is employed to predict the particle deposition velocity onto the wall and floor from fully developed turbulent flow in ventilation ducts [Zhao B, Wu J. Modeling particle deposition from fully developed turbulent flow in ventilation duct. Atmospheric Environment 2006;40:457–66], while an empirical equation is proposed to predict the particle deposition velocity onto the ceiling combined with experimental data and, another empirical equation by McFarland et al. [Aerosol deposition in bends with turbulent flow. Environmental Science and Technology 1997;31:3371–7] is used for predicting the particle penetration through the bends, which are hard to analyze by theoretical method.  相似文献   

12.
The interaction between different ventilation strategies, and the adsorption and desorption of volatile organic compounds on material surfaces in small test chambers, is investigated. In test chamber experiments, nylon carpet was exposed to a mixture of toluene and α-pinene at two different dosing rates. The ventilation strategies were chosen to mimic the conditions in real buildings, i.e. with an air exchange rate of 2 h−1 during the working day (8–17) and a rate of 0.67 h−1 during the remainder of the 24 h. The results show that the sorption behavior has to be included when estimating the concentration variations in a room based on source characteristics and ventilation rates. The software application “EnviSim” was used to model the concentrations in a model room based on the experimental conditions. As the ventilation strategy influences the resulting concentrations, it is recommended that the ventilation system be “turned on” a couple of hours before the start of the working day and “turned down” again soon after the occupants have left the building.  相似文献   

13.
The impacts of various ventilation strategies and facade designs on indoor thermal environment for naturally ventilated residential buildings in Singapore are investigated in this study based on thermal comfort index. Four ventilation strategies, nighttime-only ventilation, daytime-only ventilation, full-day ventilation and no ventilation were evaluated for hot-humid climate according to the number of thermal discomfort hours in the whole typical year on the basis of a series of TAS simulations. Parametric studies of facade designs on orientations, window to wall ratios and shading devices were performed for two typical weeks by coupled simulations between building simulation ESP-r and CFD (FLUENT). The results indicate that full-day ventilation for indoor thermal comfort is better than the other three ventilation strategies. With various facade design studies, it was found that north- and south-facing facades can provide much comfortable indoor environment than east- and west-facing facades in Singapore. It is recommended that optimum window to wall ratio 0.24 can improve indoor thermal comfort for full-day ventilation and 600 mm horizontal shading devices are needed for each orientation in order to improve thermal comfort in further.  相似文献   

14.
Mendell MJ 《Indoor air》2007,17(4):259-277
Most research into effects of residential exposures on respiratory health has focused on allergens, moisture/mold, endotoxin, or combustion products. A growing body of research from outside the US; however, has associated chemical emissions from common indoor materials with risk of asthma, allergies, and pulmonary infections. This review summarizes 21 studies in the epidemiologic literature on associations between indoor residential chemical emissions, or emission-related materials or activities, and respiratory health or allergy in infants or children. Associations, some strong, were reported between many risk factors and respiratory or allergic effects. Risk factors identified most frequently included formaldehyde or particleboard, phthalates or plastic materials, and recent painting. Findings for other risk factors, such as aromatic and aliphatic chemical compounds, were limited but suggestive. Elevated risks were also reported for renovation and cleaning activities, new furniture, and carpets or textile wallpaper. Reviewed studies were entirely observational, limited in size, and variable in quality, and specific risk factors identified may only be indicators for correlated, truly causal exposures. Nevertheless, overall evidence suggests a new class of residential risk factors for adverse respiratory effects, ubiquitous in modern residences, and distinct from those currently recognized. It is important to confirm and quantify any risks, to motivate and guide necessary preventive actions. PRACTICAL IMPLICATIONS: Composite wood materials that emit formaldehyde, flexible plastics that emit plasticizers, and new paint have all been associated with increased risks of respiratory and allergic health effects in children. Although causal links have not been documented, and other correlated indoor-related exposures may ultimately be implicated, these findings nevertheless point to a new class of little recognized indoor risk factors for allergic and respiratory disease, distinct from the current set of indoor risk factors. The available evidence thus raises initial questions about many common residential practices: for instance, using pressed wood furnishings in children's bedrooms, repainting infant nurseries, and encasing mattresses and pillows with vinyl for asthmatic children. The findings summarized here suggest a need for substantially increased research to replicate these findings, identify causal factors, and validate preventive strategies.  相似文献   

15.
本文基于福建近年新建住宅的调查调查结果,提取了1梯2户住宅的模式;根据这种模式和现有节能标准,构建了2单元6层住宅,并用软件模拟分析了其在福建典型气候区适时通风与非适时通风的能耗状况。模拟分析表明:(1)无论气候区如何,通风是否适时,住宅南北向布置时能耗最小,而东西向布置时能耗最大;(2)适时通风的节能效果与地区气候有...  相似文献   

16.
Park JH  Byeon JH  Yoon KY  Hwang J 《Indoor air》2008,18(1):44-50
A ventilation system including a dielectric barrier discharger (DBD) and UV-photocatalyst (UVP) filters was designed and tested for simultaneous removal of gaseous and particulate contaminants in a test chamber. The DBD was used in the first stage of electrostatic precipitator (ESP) for particle charging and gas decomposition. An applied DC electric field was used in the second stage of ESP to collect the charged particles. UVP filters were then used to decompose gaseous species, such as formaldehyde (HCHO) and benzene, toluene, and xylene (BTX) including O3, which was inherently produced by the DBD. %Reductions in mass concentration of PM2.5 and number concentration of submicron particles were approximately 79.5% and 76.3%, respectively, after the ventilation with air cleaning system was operated for 5 h. Both HCHO and BTX were completely removed when the initial concentration of each gas was 1 ppm. PRACTICAL IMPLICATIONS: Indoor air quality (IAQ) problems, such as sick building syndrome (SBS), are caused by limited ventilation in high-rise buildings. To overcome these problems, DBD and UVP filters were applied into a lab-scale ventilation system for simultaneous removal of pollutant particles and gases. The data supplied in this study will be useful for designing any actual ventilation system after further research, including scale-up experiments.  相似文献   

17.
This paper analyses the ventilation airflow pattern in a two-bedded hospital room. The whole space of the room is divided in modules by means of curtains and internal partition walls. This configuration has many advantages from the point of view of comfort and medical assistance, but it implies an important restriction as far as ventilation is concerned. The ventilation system consists of an induction unit placed inside the hall ceiling blowing into the room and an exhaust fan in the bathroom. Numerical model solves mass, momentum and mean age of air equations assuming isothermal and stationary flow. Ventilation is evaluated analysing the age of air and the velocity fields inside the room. The results with the initial architectural design of the room show a very deficient ventilation at the patients site. Alternative configurations have been studied, allowing for correct ventilation without renouncing to the assistance advantages. Finally, the optimum configuration of the room is provided, regarding both the comfort of the patients and the cost of execution.  相似文献   

18.
Scientific literature on the effects of ventilation on health, comfort, and productivity in non-industrial indoor environments (offices, schools, homes, etc.) has been reviewed by a multidisciplinary group of European scientists, called EUROVEN, with expertise in medicine, epidemiology, toxicology, and engineering. The group reviewed 105 papers published in peer-reviewed scientific journals and judged 30 as conclusive, providing sufficient information on ventilation, health effects, data processing, and reporting, 14 as providing relevant background information on the issue, 43 as relevant but non-informative or inconclusive, and 18 as irrelevant for the issue discussed. Based on the data in papers judged conclusive, the group agreed that ventilation is strongly associated with comfort (perceived air quality) and health [Sick Building Syndrome (SBS) symptoms, inflammation, infections, asthma, allergy, short-term sick leave], and that an association between ventilation and productivity (performance of office work) is indicated. The group also concluded that increasing outdoor air supply rates in non-industrial environments improves perceived air quality; that outdoor air supply rates below 25 l/s per person increase the risk of SBS symptoms, increase short-term sick leave, and decrease productivity among occupants of office buildings; and that ventilation rates above 0.5 air changes per hour (h-1) in homes reduce infestation of house dust mites in Nordic countries. The group concluded additionally that the literature indicates that in buildings with air-conditioning systems there may be an increased risk of SBS symptoms compared with naturally or mechanically ventilated buildings, and that improper maintenance, design, and functioning of air-conditioning systems contributes to increased prevalence of SBS symptoms.  相似文献   

19.
This paper investigates the airflow and pollutant distribution patterns in a “negative pressure” isolation room by means of objective measurement and computational fluid dynamics (CFD) modeling based on three ventilation strategies. An effective ventilation system is crucial to protect doctors, nurses and other health-care workers from patients with infectious disease. In the preliminary study with Strategy 1, the isolation room has two air supply diffusers and two extract grilles mounted on the ceiling. Strategy 2 retains the air supply diffusers in Strategy 1 but relocates the two extract grilles to the wall behind the bed at 0.3 m above the floor level. Strategy 3 has the same layout as Strategy 2 except the ceiling diffusers are replaced by supply grilles and relocated closer to the wall behind the bed.  相似文献   

20.
Ventilation in the building is to assure a microclimate suitable for humans and animals as well as the durability of structures. Based on the data from literature theoretical heat and moisture balancing ventilation rate calculations for uninsulated cowshed are presented. At an indoor temperature of −6.7 °C and indoor–outdoor temperature difference of 1 °C, the theoretical ventilation rate of 2300 m3/h per cow is necessary to remove the water vapour produced by the cows from the building. At a difference of 2 °C the ventilation rate of 1200 m3/h per cow and at 5 °C 530 m3/h per cow is needed. But these calculated ventilation rates are probably unrealistic. Traditional methods are unreliable for uninsulated cowsheds and instead of that an alternative method for evaluating the ventilation rate is needed.  相似文献   

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