Product Description
This digital document is a journal article from Building and Environment, published by Elsevier in . The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.

Description:
Monitoring of aerosols is typically performed over 3h to diurnal time scales for outdoor concentration levels and 15min to 8h scales indoors. At these scales, concentration is assumed to be well mixed with little spatio-temporal variability around the sampler. Less attention has been given to the potential for acute exposure to contaminants during the initial minutes after a point-source release, where point-wise concentrations may greatly exceed the well-mixed conditions. Here, we seek to demonstrate that the commonly used well-mixed assumption is flawed in the first minutes after a contaminant is released because point-wise concentration levels are initially highly non-uniform and are influenced by turbulent structures caused by the presence of obstacles in the room. This assumption was examined by releasing 3@mm aerosols in a test room with HEPA filter ventilation and by varying controlled conditions of room furnishings (furnished vs. unfurnished) and contaminant release locations (at the inlet vent or under a desk). For each experiment, aerosol concentrations were measured simultaneously at seven locations by nephelometry. Complementary computational fluid dynamics simulations were performed to lend confidence to the experiments and to provide detailed pictures of the velocity and particle concentration profiles. The experimental and numerical results corroborated the hypothesis. For both release locations in the furnished room, a completely well-mixed condition did not occur 600s after the release, and aerosol dispersion was dictated by the turbulent airflow pattern. For the empty room, there was significantly less spatial variability in the point-wise measured concentrations after 300s than for the furnished room. This information may aid in evaluating the potential for occupant exposure to aerosolized hazardous substances and in supporting optimization of detector placement. ... Read more

Product Description
This digital document is a journal article from Building and Environment, published by Elsevier in 2004. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.

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Building-related health complaints and symptoms represent a significant occupational health problem. Elevated concentrations of various types of indoor pollutants, frequently associated with inadequate ventilation, have been implicated as a potential cause. The objective of this research is to model and evaluate the performance of several ventilation methods in pollutant removal from indoor environments. Pollutant sources are assumed to be at the floor level, one with a constant emission rate and the other a fast decaying source (volatile organic compound emissions from a wood stain). Three ventilation methods, namely displacement ventilation and two mixing systems using a side grille and ceiling square diffuser respectively are studied. A computer model has been applied to simulate the distributions and the time history of the pollutant concentrations in a mockup office. Experimental data of velocity, temperature, and tracer gas concentration distributions in the chamber with the displacement diffuser are obtained to validate the airflow model. Simulation results show that different ventilation methods affect the pollutant distributions within the room. When the pollutant sources are distributed on the floor and not associated with a heat source or initial momentum, displacement ventilation behaves no worse than perfect mixing ventilation at the breathing zone. Conventional ''mixing'' diffusers, on the other hand, could perform better or worse than a perfect mixing system. The computer model could be used for selecting appropriate ventilation systems to maximize indoor air quality for occupants. ... Read more

Product Description
This digital document is an article from Journal of the Air & Waste Management Association, published by Air and Waste Management Association on February 1, 2002. The length of the article is 4342 words. The page length shown above is based on a typical 300-word page. The article is delivered in HTML format and is available in your Amazon.com Digital Locker immediately after purchase. You can view it with any web browser.

Citation Details
Title: Air intake contamination by building exhausts: Tracer gas investigation of atmospheric dispersion models in the urban environment. (Technical Paper).(Statistical Data Included)
Author: Louis Lazure
Publication: Journal of the Air & Waste Management Association (Refereed)
Date: February 1, 2002
Publisher: Air and Waste Management Association
Page: 160(7)

Article Type: Statistical Data Included

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Product Description
This digital document is a journal article from Atmospheric Environment, published by Elsevier in 2004. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.

Description:
Ambient fine particle (PM"2"."5) concentrations are associated with premature mortality and other health effects. Urban populations spend a majority of their time in indoor environments, and thus exposures are modified by building envelopes. Ambient particles have been found to penetrate indoors very efficiently (penetration efficiency P~1.0), where they are slowly removed by deposition, adsorption, and other mechanisms. Other particles are generated indoors, even in buildings with no obvious sources like combustion devices, cooking, use of aerosol products, etc.. The health effects of indoor generated particles are currently not well understood, and require information on concentrations and exposure levels. The current work apportions residential PM"2"."5 concentrations measured in the EXPOLIS study to ambient and non-ambient fractions. The results show that the mean infiltration efficiency of PM"2"."5 particles is similar in all four cities included in the analysis, ranging from 0.59 in Helsinki to 0.70 in Athens, with Basle and Prague in between. Mean residential indoor concentrations of ambient particles range from 7 (Helsinki) to 21@mgm^-^3 (Athens). Based on PM"2"."5 decay rates estimated in the US, estimates of air exchange rates and indoor source strengths were calculated. The mean air exchange rate was highest in Athens and lowest in Prague. Indoor source strengths were similar in Athens, Basle and Prague, but lower in Helsinki. Some suggestions of possible determinants of indoor generated non-ETS PM"2"."5 were acquired using regression analysis. Building materials and other building and family characteristics were associated with the indoor generated particle levels. A significant fraction of the indoor concentrations remained unexplained. ... Read more

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This digital document is a journal article from Atmospheric Environment, published by Elsevier in 2006. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.

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This study investigated the formation of secondary pollutants resulting from household product use in the presence of ozone. Experiments were conducted in a 50-m^3 chamber simulating a residential room. The chamber was operated at conditions relevant to US residences in polluted areas during warm-weather seasons: an air exchange rate of 1.0h^-^1 and an inlet ozone concentration of approximately 120ppb, when included. Three products were used in separate experiments. An orange oil-based degreaser and a pine oil-based general-purpose cleaner were used for surface cleaning applications. A plug-in scented-oil air freshener (AFR) was operated for several days. Cleaning products were applied realistically with quantities scaled to simulate residential use rates. Concentrations of organic gases and secondary organic aerosol from the terpene-containing consumer products were measured with and without ozone introduction. In the absence of reactive chemicals, the chamber ozone level was approximately 60ppb. Ozone was substantially consumed following cleaning product use, mainly by homogeneous reaction. For the AFR, ozone consumption was weaker and heterogeneous reaction with sorbed AFR-constituent VOCs was of similar magnitude to homogeneous reaction with continuously emitted constituents. Formaldehyde generation resulted from product use with ozone present, increasing indoor levels by the order of 10ppb. Cleaning product use in the presence of ozone generated substantial fine particle concentrations (more than 100@mgm^-^3) in some experiments. Ozone consumption and elevated hydroxyl radical concentrations persisted for 10-12h following brief cleaning events, indicating that secondary pollutant production can persist for extended periods. ... Read more

Product Description
This digital document is an article from ASHRAE Transactions, published by American Society of Heating, Refrigerating, and Air-Conditioning Engineers, Inc. on July 1, 2009. The length of the article is 3982 words. The page length shown above is based on a typical 300-word page. The article is delivered in HTML format and is available immediately after purchase. You can view it with any web browser.

From the author: With computer servers' exponential growth in power for a 7' rack density from sub-10kW (34,121Btu/hr) of yester-years, to 30kW (102,363Btu/hr) in the last half decade, current product launches of over 60kW (204,726Btu/hr), there is significant desire and product research by datacenter cooling equipment vendors, as well as computer server equipment vendors, to introduce liquid-cooling solutions in various forms, such as direct equipment level or providing air-to-liquid heat-exchanging at the rack. In this paper, we would like differentiate the equipment for Telecom Central Office (CO) environment to the more industry dominant Datacenter (DC) environment. A holistic examination, from network equipment design to the Telecom CO requirements, is followed in explaining the different hurdles along the way in implementing liquid cooling in the Telecom environment.

Citation Details
Title: Hurdles in deploying liquid cooling in NEBS environment.(network equipment-building system)(Report)
Author: Herman Chu
Publication: ASHRAE Transactions (Magazine/Journal)
Date: July 1, 2009
Publisher: American Society of Heating, Refrigerating, and Air-Conditioning Engineers, Inc.
Volume: 115Issue: 2Page: 211(10)

Article Type: Report

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Product Description
This digital document is an article from ASHRAE Transactions, published by American Society of Heating, Refrigerating, and Air-Conditioning Engineers, Inc. on January 1, 2010. The length of the article is 5743 words. The page length shown above is based on a typical 300-word page. The article is delivered in HTML format and is available immediately after purchase. You can view it with any web browser.

From the author: Field investigations of two different factories were carried out in Zhenjiang and Shanghai during the cool season to analyze the relation among indoor environment, humans, and productivity. In particular, this study examined the effect of the working environment and other factors on thermal comfort and productivity in factories. In this study, the mean thermal neutral temperature was 19.0 [degrees]C (or 66.2 [degrees]F) in the factory during the cool season. The results show that productivity (103.2% in Zhenjiang and 100.6% in Shanghai) does not reach its maximum when the occupants' thermal sensation votes (TSV) are neutral or comfort. The highest productivity (105.1% in Zhenjiang and 104.7% in Shanghai) occurs when the TSV of the subjects is slightly cool. The productivity in a slightly warm state is 104.5% in Zhenjiang (103.4% in Shanghai), which is also higher than that in a neutral state. A slightly cooler or warmer environment might enhance productivity more than in a neutral, comfortable environment. People in an environment with good air quality supply could easily obtain high productivity if the thermal environment is acceptable. Compared with other factors, maintaining good indoor air quality might be the best way to maintain higher productivity for the factories in this survey.

Citation Details
Title: Thermal environment and productivity in the factory.(Report)
Author: Xiaojiang Ye
Publication: ASHRAE Transactions (Magazine/Journal)
Date: January 1, 2010
Publisher: American Society of Heating, Refrigerating, and Air-Conditioning Engineers, Inc.
Volume: 116Issue: 1Page: 590(10)

Article Type: Report

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Product Description
This digital document is a journal article from Atmospheric Environment, published by Elsevier in . The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.

Description:
Deposition to indoor surfaces influences human exposures and material damage from airborne particulate matter. Experiments were conducted to study the deposition of monodisperse particles in the diameter range 0.9-9@mm from turbulent flow onto smooth and rough vertical chamber surfaces. Fluorescent particles were injected continuously into a stirred 1.8-m^3 aluminum chamber for a period of several hours. Deposition was measured on smooth glass plates and sandpaper with four different roughness scales that had been mounted on two opposing vertical sidewalls. Deposition velocities were determined as the ratio of deposited particle flux density to airborne particle concentrations. Contrary to expectations, particle deposition onto smooth and rough vertical surfaces was observed to increase with diameter for most conditions, especially for the larger particle sizes. Deposition velocity increased only moderately with increasing surface roughness. ... Read more

Product Description
This digital document is a journal article from Building and Environment, published by Elsevier in 2004. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.

Description:
Combining demand-controlled ventilation (DCV) and economizer control can achieve adequate and even better indoor air quality with minimum cooling/heating energy consumption in buildings. The control instability during the transition processes between different control modes is among the major difficulties faced when combining DCV control with economizer control in applications. The practical energy benefit is another concern when using free cooling in the subtropical climate like Hong Kong. A robust control strategy, using ''freezing'', gain scheduling, I-term reset and feedback transition control for different transition processes, is developed addressing the instability problems. The energy benefit of using economizer control is evaluated by over one year's comparison tests on two air-handling units in a building. ... Read more

Product Description
This digital document is a journal article from Building and Environment, published by Elsevier in 2007. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.

Description:
Researchers or engineers are paying more and more attention to personalized ventilation due to its unique features of providing satisfying thermal comfort and high indoor air quality. How the contaminants, especially the particles disperse in a personalized ventilation room is, therefore, deserved to be studied carefully, as contaminants' distribution determines indoor air quality (IAQ). In this paper, dispersion of particles with aerodynamic diameter of 0.5-10@mm in a room ventilated by a personalized ventilation system is investigated by computational fluid dynamics (CFD). A three-dimensional model is employed to model particle dispersion around a human body, as well as the airflow and temperature distribution is simulated after experimental validation. The cases of personalized ventilation, and mixing ventilation under different air supply volumes are simulated. The results show that the personalized ventilation is not always the best resolution for particle removal, as different sizes of particles could have different dispersion characteristics even under the same air supply volume by different ventilation modes. ... Read more

Product Description
This digital document is a journal article from Atmospheric Environment, published by Elsevier in 2005. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.

Description:
A model for the prediction of emission of volatile organic compounds (VOCs) from dry building material was developed based on mass transfer theory. The model considers both diffusion and convective mass transfer. In addition, it does not neglect the fact that, in most cases, the initial distribution of VOCs within the material is non-uniform. Under the condition that the initial amount of VOCs contained in the building material is the same, six different types of initial VOC distributions were studied in order to show their effects on the characteristics of emission. The results show that, for short-term predictions, the effects are significant and thus cannot be neglected. Based on the fact that the initial distribution of VOCs is very difficult to directly determine, a conjugate gradient method with an adjoint problem for estimating functions was developed, which can be used to inversely estimate the initial distribution of VOCs within the material without a priori information on the functional form of the unknown function. Simulated measurements with and without measurement errors were used to validate the algorithm. This powerful method successfully recovered all of the aforementioned six different types of initial VOC distributions. A deviation between the exact and predicted initial condition near the bottom of the material was noticed, and a twin chamber method is proposed to obtain more accurate results. With accurate knowledge of the initial distribution of VOCs, source models will be able to yield more accurate predictions. ... Read more

Product Description
This digital document is a journal article from Building and Environment, published by Elsevier in 2006. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.

Description:
Paints are widely used in residential and commercial buildings. The surface areas covered by this kind of coatings are usually very large. The volatile organic compounds (VOCs) emissions from such kind of materials will affect indoor air quality decisively. A relatively simple but physically-based model was developed to simulate VOCs emissions from paints. The model parameters have distinct physical meanings and thus the model is easy to scale up. The field and laboratory emission cell (FLEC) was used to investigate the VOCs emissions from commercially available water-based emulsion paint. Totally 23 individual VOCs were detected and quantified, the most abundant VOC was 1-ethyl-3-methylbenzene. Test data were used to obtain model parameters and to validate the proposed model. Good agreements between experimental data and model predictions were evidenced. Paints applied on two different substrates aluminium and particle board were simulated. Results indicated that real substrates like particle board would act like a 'sponge', which lowers the peak concentration but prolongs the presence of VOCs from the applied paint. ... Read more

Product Description
This digital document is a journal article from Atmospheric Environment, published by Elsevier in 2007. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.

Description:
Residential and commercial HVAC filters that have been loaded with particles during operation in the field can remove ozone from intake or recirculated air. However, knowledge of the relative importance of HVAC filters as a removal mechanism for ozone in residential and commercial buildings is incomplete. We measured the ozone removal efficiencies of clean (unused) fiberglass, clean synthetic filters, and field-loaded residential and commercial filters in a controlled laboratory setting. For most filters, the ozone removal efficiency declined rapidly but converged to a non-zero (steady-state) value. This steady-state ozone removal efficiency varied from 0% to 9% for clean filters. The mean steady-state ozone removal efficiencies for loaded residential and commercial filters were 10% and 41%, respectively. Repeated exposure of filters to ozone following a 24-h period of no exposure led to a regeneration of ozone removal efficiency. Based on a theoretical scaling analysis of mechanisms that are involved in the ozone removal process, we speculate that the steady-state ozone removal efficiency is limited by reactant diffusion out of particles, and that regeneration is due to internal diffusion of reactive species to sites available to ozone for reaction. Finally, by applying our results to a screening model for typical residential and commercial buildings, HVAC filters were estimated to contribute 22% and 95%, respectively, of total ozone removal in HVAC systems. ... Read more

Product Description
This digital document is a journal article from Building and Environment, published by Elsevier in 2006. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.

Description:
Demand Control System (DCV) is designed to optimise the energy consumption with respect to the demand of outdoor air quantity based on the number of people indoors. However, if significant indoor pollutant sources exist, which is not a function of the number of people, the DCV may cause the indoor air quality to be unacceptable. This paper discusses a procedure of calibrating the building in respect of managing the indoor air quality. The objective is to set the minimum fresh air quantity which is a function of the indoor pollutant concentrations rather than metabolic carbon dioxide. Radon is used as an example because it is a common pollutant embedded in the building materials of high-rise buildings in Hong Kong. This paper also presents a year-round record of the indoor air quality in a typical high-rise building which is very useful for building indoor air quality (IAQ) design. ... Read more

Product Description
This digital document is a journal article from Atmospheric Environment, published by Elsevier in 2006. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.

Description:
We apply a simulation model to explore the effect of a house's multicompartment character on a nonsmoker's inhalation exposure to secondhand tobacco smoke (SHS). The model tracks the minute-by-minute movement of people and pollutants among multiple zones of a residence and generates SHS pollutant profiles for each room in response to room-specific smoking patterns. In applying the model, we consider SHS emissions of airborne particles, nicotine, and carbon monoxide in two hypothetical houses, one with a typical four-room layout and one dominated by a single large space. We use scripted patterns of room-to-room occupant movement and a cohort of 5000 activity patterns sampled from a US nationwide survey. The results for scripted and cohort simulation trials indicate that the multicompartment nature of homes, manifested as inter-room differences in pollutant levels and the movement of people among zones, can cause substantial variation in nonsmoker SHS exposure. ... Read more

Product Description
This digital document is a journal article from Atmospheric Environment, published by Elsevier in 2005. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.

Description:
As part of a large study investigating indoor air in residential houses in Brisbane, Australia, the purpose of this work was to quantify the particle deposition rate of size classified particles in the size range from 0.015 to 6@mm. Particle size distribution resulting from cooking, repeated under two different ventilation conditions in 14 houses, as well as changes to particle size distribution and PM"2"."5 concentration as a function of time, were measured using a scanning mobility particle sizer (SMPS), an aerodynamic particle sizer (APS), and a DustTrak. Deposition rates were determined by regression fitting of the measured size-resolved particle number and PM"2"."5 concentration decay curves, and accounting for air exchange rate. The measured deposition rates were shown to be particle size dependent and they varied from house to house. The lowest deposition rates were found for particles in the size range from 0.2 to 0.3@mm for both minimum (air exchange rate: 0.61+/-0.45h^-^1) and normal (air exchange rate: 3.00+/-1.23h^-^1) ventilation conditions. The results of statistical analysis indicated that ventilation condition (measured in terms of air exchange rate) was an important factor affecting deposition rates for particles in the size range from 0.08 to 1.0@mm, but not for particles smaller than 0.08@mm or larger than 1.0@mm. Particle coagulation was assessed to be negligible compared to the two other processes of removal: ventilation and deposition. This study of particle deposition rates, the largest conducted so far in terms of the number of residential houses investigated, demonstrated trends in deposition rates comparable with studies previously reported, usually for significantly smaller samples of houses (often only one). However, the results compare better with studies which, similarly to this study, investigated cooking as a source of particles (particle sources investigated in other studies included general activity, cleaning, artificial particles, etc). ... Read more

Product Description
This digital document is a journal article from Building and Environment, published by Elsevier in 2004. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.

Description:
Environmental tobacco smoke and particles emitted during cooking are among two very common activates which cause serious indoor air quality problem for residential environments. To better understand the potential effectiveness of engineering control strategies, a series of simulations were conducted in a single-floor seven-zone apartment. Control strategies investigated including dilution, source segregation and indoor air filtration unit. Air infiltration rate, inter-zonal air flows and concentration level between zones were evaluated by CONTAMW for various cooking and smoking activities. Steady-state and transient simulations incorporated with activity schedule were performed and exposure exercise was conducted. Results indicate that the effectiveness of the control schemes vary considerably. In some scenarios, operating the indoor air filtration unit does not reduce the concentration. ... Read more

Product Description
This digital document is a journal article from Atmospheric Environment, published by Elsevier in 2004. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.

Description:
Measurements of mass concentrations of 35 trace elements (TEs) and of total fine particulate matter (PM"2"."5) were conducted at 20 residences and six high school rooms in Mira Loma, California, from September 2001 to January 2002. Sulfur (S) and silicon (Si) were the most abundant TEs measured (excluding a residence with heavy smokers). On average, total TE concentrations were lower indoors relative to outdoors; the proportion of TEs in total PM"2"."5 was also lower indoors relative to outdoors. Among indoor sites, TE concentrations were found to be lower inside the schoolrooms relative to inside the residences. Environmental tobacco smoke (ETS) was found to contribute significantly to elevated levels of total TE inside residences; however, concentrations of carcinogenic TEs were not significantly different between residences with and without smokers. Potassium (K) and chlorine (Cl) were the most abundant species in a residence with frequent indoor smokers. Combustion-related elements were more enriched inside the residences relative to crustal elements. ... Read more

Product Description
This digital document is a journal article from Building and Environment, published by Elsevier in 2007. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.

Description:
This paper reported the investigation of the performance of floor-supply displacement ventilation with swirl diffusers or perforated panels under a high cooling load (nearly 90W/m^2). The experiment was carried out in a full-scale environmental chamber to obtain reliable data on the floor-supply displacement ventilation for the validation of a computational-fluid-dynamics (CFD) program. Numerical simulations using CFD program were to evaluate the performance of the system for a large workshop. The impacts of several parameters, such as the air change rate, number of diffusers, diffuser location, occupant location, furniture arrangement, partition location, and arrangement of exhausts, on the indoor environment were investigated based on the thermal comfort level and indoor air quality. This study ranked the impacts of these parameters on indoor environment. ... Read more

Product Description
This digital document is a journal article from Building and Environment, published by Elsevier in . The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.

Description:
A study was conducted into the ventilation effectiveness of a ventilation system within a public transport interchange (PTI) in Hong Kong. A computational fluid dynamics (CFD), steady state computational model of the PTI was used to investigate and predict the typical pollutant emission pattern for buses. In Hong Kong, the displacement ventilation (DV) scheme is often employed for the PTI. The numerical simulation investigates the effectiveness of the DV system in removing pollutants from the occupied zone. An alternative model is proposed where the supply is located at the ceiling and the exhausts are located at the lower part of the columns. It was found that both systems could adequately ventilate the PTI; however, the ceiling based air supply system is able to provide improved thermal comfort and indoor air quality (IAQ). ... Read more