The energy retrofit of existing buildings is a key strategy to reduce the energy costs of the building sector. Amongst the retrofit solutions, the adoption of mechanical ventilation systems ...represents a necessary approach for buildings with high crowding index, such as schools.
The air quality in schools is a main issue since children spend a significant fraction of the year in such microenvironments. To date, the scientific literature has carried out several studies concerning the air quality in naturally ventilated schools worldwide, nonetheless most of the studies performed a general evaluation of the air quality just using the CO2 as a comprehensive indicator. This is an oversimplified approach since the indoor air quality is affected by several pollutants, including airborne particles, whose behavior cannot be predicted by the CO2 one.
The aim of the research is the evaluation of the effect of the ventilation retrofit in a classroom on different indoor air quality parameters and energy consumption. To this end a mechanical ventilation system with a heat recovery unit was installed in a test-classroom and tests with CO2-based demand controlled ventilation were performed. CO2 levels and indoor-to-outdoor particle concentrations were measured and compared to the pre-retrofit ventilation conditions (i.e. manual airing procedures).
Results showed that mechanical ventilation systems have simultaneous positive effects on the different pollutants investigated as well as on ventilation heat losses: indeed, lower indoor-to-outdoor concentration ratios, with respect to the airing approach, were detected simultaneously for CO2, sub-micron particles and PM10.
•Indoor air quality and energy need in a classroom pre-/post-ventilation retrofit.•Indoor and outdoor measurements of CO2, particle number and PM10 concentrations.•Application of a mechanical ventilation system with energy recovery unit.•Improvement of indoor air quality and energy need with the post-retrofit solution.•Energy saving of 32% of the post-retrofit solution with respect the manual airing.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Converging evidence reports that the probability of vertical transmission patterns via shared drainage systems, may be responsible for the huge contactless community outbreak in high-rise buildings. ...Publications indicate that a faulty bathroom exhaust fan system is ineffective in removing lifted hazardous virus-laden aerosols from the toilet bowl space. Common strategies (boosting ventilation capability and applying disinfection tablets) seem unsustainable and remain to date untested. Using combined simulation and experimental approaches, we compared three ventilation schemes in a family bathroom including the traditional ceiling fan, floor fan, and side-wall fan. We found that the traditional ceiling fan was barely functional whereby aerosol particles were not being adequately removed. Conversely, a side-wall fan could function efficiently and an enhanced ventilation capability can have increased performance whereby nearly 80.9% of the lifted aerosol particles were removed. There exists a common, and easily-overlooked mistake in the layout of the bathroom, exposing occupants to a contactless vertical pathogen aerosol transmission route. Corrections and dissemination are thus imperative for the reconstruction of these types of family bathrooms. Our findings provide evidence for the bathroom and smart ventilation system upgrade, promoting indoor public health and human hygiene.
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•Traditional ceiling fan fails to remove hazardous plume in bathrooms.•Ventilation deficiency should be responsible for the vertical COVID transmission.•A side-wall fan has the most efficient aerosol removal capability.•In-site experimental conclusions were coherent with the simulation ones.•Bathroom ventilation reconstructions are encouraged to be performed accordingly.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Background and Objective: Air pollution in industrial work environments has adverse effects on worker health. Among these effects, one can refer to chronic obstructive pulmonary disease and asthma, ...which impose direct and indirect costs on society. Local exhaust ventilation is considered an appropriate approach to remove pollutants released in indoor work environments. This study aimed to develop a smart application for designing and selecting local exhaust ventilation systems. Materials and Methods: This study was designed and performed at two stages. At the first stage, a smart application that could select and design the best local exhaust ventilation system was developed using Visual Basic 6.0. Subsequently, for the validation of this application, the results obtained by the application were compared with the benchmarks. Statistical analysis was performed in SPSS software (version 22), and the Bland-Altman plot was utilized to examine the consistency among the results. Results: Among the parameters, the maximum difference was related to the static pressure drop of the channel with a 5% difference, and the lowest difference was related to the size of the calculated diameters, in which no difference was observed. Bland-Altman plot showed that the standard deviation of the results of the designed software in the calculations of 28 branches of the ventilation systems designed for static pressure, velocity pressure, and total pressure was in the range of ±2SD. Conclusion: Since the software presented in this study has an error of less than 5%, it can be used as a suitable and reliable tool for designing local suction ventilation systems.
Infectious disease outbreaks and epidemics such as those due to SARS, influenza, measles, tuberculosis, and Middle East respiratory syndrome coronavirus have raised concern about the airborne ...transmission of pathogens in indoor environments. Significant gaps in knowledge still exist regarding the role of mechanical ventilation in airborne pathogen transmission. This review, prepared by a multidisciplinary group of researchers, focuses on summarizing the strengths and limitations of epidemiologic studies that specifically addressed the association of at least one heating, ventilating and/or air‐conditioning (HVAC) system‐related parameter with airborne disease transmission in buildings. The purpose of this literature review was to assess the quality and quantity of available data and to identify research needs. This review suggests that there is a need for well‐designed observational and intervention studies in buildings with better HVAC system characterization and measurements of both airborne exposures and disease outcomes. Studies should also be designed so that they may be used in future quantitative meta‐analyses.
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DOBA, FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, UILJ, UKNU, UL, UM, UPUK
Introduction: Air pollution in industrial work environments has adverse effects on worker health, for example, chronic obstructive pulmonary disease and asthma. These diseases impose direct and ...indirect costs on society. In hierarchy controls, local exhaust ventilation is considered an "engineering control" to remove or control contaminants released in indoor work environments. It is one of the preferred ways to control employee exposure to air contaminants. The purpose of this research is to development a smart application for designing, selecting local exhaust ventilation systems. Methods: At the first stage of this action research, was a developed visual Basic 6.0 based smart application for the design and selection of local exhaust ventilation systems. Then, for validation this application results obtained by the application were compared with the benchmarks. SPSS 22 software was used for statistical analysis and Bland–Altman plot was used to examine the agreement between the results Results: Among the parameters, the maximum difference between similar results of the application and benchmark data was related to static pressure, which was 5% different in one series branch, which was balanced with another series branch. And the minimum difference was related to the calculated diameters with zero percent difference. . Bland – Altman plot showed that the standard deviation of the results of the four static pressure, velocity pressure and total pressure is in the range of (± 2 SD). Conclusion: The application developed in this research has acceptable accuracy and its error is less than 5%
The particle motion in a room is affected by the thermal environment and the air supply conditions caused by seasonal changes. In the study, a Lagrangian discrete trajectory model combined with the ...Eulerian fluid method was adopted to simulate the characteristics of indoor airflow and the diffusion of two typical indoor particles with considering different air supply conditions in different seasons. Specifically, the thermal comfort perception, draught rating (DR) of the indoor personnel, and the contaminant removal effectiveness (CRE, ε) of indoor particles under the influences of displacement ventilation (DV) and underfloor air distribution (UFAD) systems were investigated. The results revealed that when considering the indoor thermal comfort under summer and winter air supply conditions, UFAD was found be more effective than the DV system in protecting the temperature difference of indoor personnel. Additionally, the removal effect of PM1 in the breathing area was superior compared to that of the DV system. Regarding the removal effectiveness of PM2.5, the removal performance of both ventilation systems decreased, but the removal effect of the DV system on PM2.5 in the breathing area (with the largest εl of 1.55) was significantly better than that of the UFAD system under winter operating conditions. It is essential for the selection of the ventilation system to consider the thermal comfort of indoor occupants, as different ventilation systems have varying capabilities to remove particles of different sizes. Therefore, choosing an appropriate ventilation system is crucial for enhancing indoor air quality, and the findings of this study provide a basis for improving indoor air quality.
•Indoor airflow and pollutant dispersion was investigated in different seasons.•The motion of particles was influenced by the thermal environment.•Thermal comfort of the indoor personnel varied under different ventilation systems.•Underfloor air distribution can create more comfortable temperature differences.•Particle removal effectiveness of displacement ventilation was better in winter.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ
Changes in the upwelling and degassing of carbon from the Southem Ocean form one of the leading hypotheses for the cause of glacial-interglacial changes in atmospheric carbon dioxide. We present a ...25,000-year-long Southem Ocean radiocarbon record reconstructed from deep-sea corals, which shows radiocarbon-depleted waters during the glacial period and through the early déglaciation. This depletion and associated deep stratification disappeared by -14.6 ka (thousand years ago), consistent with the transfer of carbon from the deep ocean to the surface ocean and atmosphere via a Southem Ocean ventilation event Given this evidence for carbon exchange in the Southem Ocean, we show that existing deep-ocean radiocarbon records from the glacial period are sufficiently depleted to explain the -190 per mil drop in atmospheric radiocarbon between -17 and 14.5 ka.
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BFBNIB, NMLJ, NUK, PNG, SAZU, UL, UM, UPUK
With the improvement of the airtightness of modern buildings, installing ventilation systems indoors is becoming increasingly important, which works for a long time continuously and needs to be ...monitored in real‐time. However, the complex wiring of monitoring sensors makes assembly and maintenance more difficult. This work reports a hybridized triboelectric‐electromagnetic nanogenerator (HNG) as a power supply of a self‐powered wireless monitoring system for ventilation systems. The HNG integrates an air inlet cover, a stator with coils and interdigitated copper electrodes, a rotor with magnets, fluorinated ethylene propylene films, and optimized built‐in wind blades. The HNG scavenges wind energy from a ventilation system and serves as a power supply for electric applications. Under the wind speed of 6.5 m s−1 in the ventilation system, the maximum stabilized voltage and maximum instantaneous current of the HNG are 177.5 V and 0.049 A, which can charge smartphones and light up a bulb. Furthermore, the HNG realizes the self‐powered wireless transmission of temperature and humidity sensing nodes. This work demonstrates an effective wind energy harvester, providing an innovative strategy for monitoring the condition of the ventilation system and broadening the thoughts of prospective energy harvesting.
A power supply of monitoring sensors for the ventilation system is presented, which is based on the hybridized triboelectric‐electromagnetic nanogenerator driven by wind energy. The device can scavenge wind energy and realize the self‐powered wireless transmission of temperature and humidity sensing nodes. This work confirms an innovative strategy for monitoring the condition of the ventilation system.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
This article presents a min-consensus-based distributed control method for multizone ventilation systems. The proposed method consists of two stages: In stage 1, the ratio of the supplied airflow to ...the desired value for each zone achieves the agreement by regulating zone damper angles according to a newly designed min-consensus protocol. The convergence of this protocol is guaranteed by rigorous theoretical analysis. In stage 2, the fan voltage is regulated to bring supplied airflow of each zone to its respective desired value. The proposed method can achieve fast and accurate tracking of desired airflow for each zone while satisfying the ASHRAE standard that at least one zone damper should be nearly fully open. Compared with existing airflow control methods, the proposed method has following advantages: First, it does not require the explicit duct model and complicated data collection procedures.Second, with the proposed method, the airflow supplied to each zone can be adjusted to the desired value in a shorter time (less than 4 min). Third, the proposed method is a distributed control method and thus has the benefit of good scalability and reconfigurability. The effectiveness of the proposed method is validated on an experimental testbed of a real ventilation system.
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