Energy saving and indoor thermal comfort evaluation using a novel local exhaust ventilation system for office rooms

Ahmed, Ahmed Qasim; Gao, Shian; Kareem, Ali Khaleel

doi:10.1016/j.applthermaleng.2016.08.217

Cited by 49 publications

(14 citation statements)

References 41 publications

(10 reference statements)

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“…This process led to a reduction in the Energies 2020, 13, 1070 9 of 17 air temperature at the head zone, which subsequently reduced the temperature difference between the head and ankle levels and improved the local thermal comfort. It was similar to the findings that were revealed by Ahmed et al [8]. The values of DR for seven settings were generally less than 10% and in an acceptable range, which could be ascribed to the low air velocity (less than 0.1 m/s) of the occupied zone according to Figure 9, as mentioned above.…”

Section: Thermal Comfort Evaluationsupporting

confidence: 90%

“…= concentration of contaminant in exhaust. [8,40] ; normalized concentration C n = C p C e C p = concentration of contaminant in breathing zone; C e = concentration of contaminant in exhaust [8,40].…”

Section: Overall Performance Assessmentmentioning

confidence: 99%

“…ASHRAE [7] also concluded that the UFAD system might provide significant heating saving relative to overhead system. One interesting finding in these two studies [6,7] was that UFAD produced less thermal stratification than MV in heating mode, which was the opposite in cooling mode [8][9][10].…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Numerical Study on Effects of Air Return Height on Performance of an Underfloor Air Distribution System for Heating and Cooling

Fan

Zheng

et al. 2020

Energies

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The exhaust/return-split configuration is regarded as an important upgrade of traditional under-floor-air-distribution (UFAD) systems due to its higher energy efficiency. Moreover, existing studies are mostly focused on the effect of the return vent height on the performance of an UFAD system under cooling conditions. Knowledge of the performance under heating conditions is sorely lacking. This paper presents a numerical evaluation of the performance characteristics of an UFAD system with six different heights of the return vents in heating operation by comprehensively considering thermal comfort, air quality, and energy consumption. The results show that, in the heating mode, the general thermal comfort (predicted mean vote-predicted percentage dissatisfied (PMV-PPD) values) and indoor air quality indices (mean age of air and volatile organic compounds (VOCs) concentration) were greatly improved and energy consumption was slightly reduced with a lower return vent height. Although these were opposite to the findings of our previous study regarding the performance in cooling mode, an optimal return vent height in terms of the comprehensive all-year performance can be recommended. This method provides insight into the design and optimization of the return vent height of UFAD for space heating and cooling.

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Section: Thermal Comfort Evaluationsupporting

confidence: 90%

Section: Overall Performance Assessmentmentioning

confidence: 99%

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Numerical Study on Effects of Air Return Height on Performance of an Underfloor Air Distribution System for Heating and Cooling

Fan

Zheng

et al. 2020

Energies

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“…Note that several PV types included in relatively few articles are not presented in this figure and can be found in the references. These less popular PV types include ductless personalized ventilation (DPV) [118], local exhaust ventilation for offices (LEVO) [111,112], movable slot diffuser plate (MSDP) [82], natural personalized ventilation (NPV) [83], robotic personal air conditioning (RPAC) [107], targeted personalized ventilation (TPV) [122], and wide-cover personalized ventilation (WCPV) [101]. [29,37], (c) CMPV [88,89] and DMPV [120], (d) DF and CF [103,104].…”

Section: Pv Types With Background Hvac Systemsmentioning

confidence: 99%

A Review of CFD Analysis Methods for Personalized Ventilation (PV) in Indoor Built Environments

et al. 2019

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Computational fluid dynamics (CFD) is an effective analysis method of personalized ventilation (PV) in indoor built environments. As an increasingly important supplement to experimental and theoretical methods, the quality of CFD simulations must be maintained through an adequately controlled numerical modeling process. CFD numerical data can explain PV performance in terms of inhaled air quality, occupants’ thermal comfort, and building energy savings. Therefore, this paper presents state-of-the-art CFD analyses of PV systems in indoor built environments. The results emphasize the importance of accurate thermal boundary conditions for computational thermal manikins (CTMs) to properly analyze the heat exchange between human body and the microenvironment, including both convective and radiative heat exchange. CFD modeling performance is examined in terms of effectiveness of computational grids, convergence criteria, and validation methods. Additionally, indices of PV performance are suggested as system-performance evaluation criteria. A specific utilization of realistic PV air supply diffuser configurations remains a challenging task for further study. Overall, the adaptable airflow characteristics of a PV air supply provide an opportunity to achieve better thermal comfort with lower energy use based on CFD numerical analyses.

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“…Many previous studies have presented that the learning/work performance and occupant health conditions in educational institutions are closely related to the indoor environmental parameters, which include thermal comfort [2][3]. Efforts have since been sought to improve thermal comfort by incorporating new air conditioning and mechanical ventilation (ACMV) systems, improving ventilation strategy, controlling occupancy level and others [4][5]. In the hot-humid regions, more cooling and ventilation systems are used in modern buildings to improve and sustain thermal comfort, but at the cost of increasing energy use.…”

Section: Introductionmentioning

confidence: 99%

Thermal Environment Analysis of a Scientific Laboratory using Computational Fluid Dynamics

et al. 2019

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University staff and students typically spend most of their time indoors. This paper evaluates the thermal environment of an air-conditioned scientific laboratory in a tertiary educational institution in Malaysia using Computational Fluid Dynamics (CFD). This computational technique has been used in analysing the indoor environments and has been found to be useful in aiding facilities management. A pilot survey was conducted to collect the required information such as indoor parameters and boundary conditions for the setting up of a CFD model of the laboratory. The model was then simulated based on the data obtained from field observations. Results indicate that the laboratory users sitting at different rows and work desks would experience different thermal sensations. The mean air temperature was below the recommended comfort zone specified in the local energy standard, but the air velocities were generally within the acceptable range. Based on the calculated predicted mean vote (PMV) and predicted percentage dissatisfied (PPD) indices, most of the users would be thermally uncomfortable, and a warmer environment was preferred. Recommendations were made to regulate the inlet air temperature of the laboratory to improve thermal comfort of laboratory users and for energy saving purposes.

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Energy saving and indoor thermal comfort evaluation using a novel local exhaust ventilation system for office rooms

Cited by 49 publications

References 41 publications

Numerical Study on Effects of Air Return Height on Performance of an Underfloor Air Distribution System for Heating and Cooling

Numerical Study on Effects of Air Return Height on Performance of an Underfloor Air Distribution System for Heating and Cooling

A Review of CFD Analysis Methods for Personalized Ventilation (PV) in Indoor Built Environments

Thermal Environment Analysis of a Scientific Laboratory using Computational Fluid Dynamics

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