44 research outputs found
High-Resolution Indoor Environmental Dataset from a Living Lab with Personalized Environmental Control Systems (PECS)
No full textThe building sector faces growing challenges in balancing energy efficiency with occupant comfort, especially amid climate change, air pollution, and post-pandemic demands on HVAC systems. Personalized Environmental Control Systems (PECS) offer a promising solution by allowing individuals to control their immediate environment (e.g., temperature, air quality), thereby enabling energy savings without sacrificing comfort. Despite their proven benefits, PECS have seen limited market adoption due to the lack of standardized performance evaluation methods and benchmark data.
Computational Fluid Dynamics (CFD) is commonly used to study PECS, but creating accurate CFD models is resource-intensive and requires detailed experimental validation—something many researchers struggle to provide due to limited infrastructure. Currently, only one known benchmark dataset exists, which is not representative of real-world settings.
To address this gap, the current work presents a high-resolution dataset of indoor environmental measurements (air velocity, temperature, and CO₂) from a living lab designed to simulate an open-plan office. The dataset, detailed in an accompanying Excel file, supports the creation and validation of CFD models for spaces equipped with various ventilation setups, including standalone systems and PECS configurations
Modeling of indoor particulate matter deposition to occupant typical wrinkled shirt surface
No full textsponsorship: The authors would like to acknowledge the American University of Beirut (AUB) and the Lebanese National Council for Scientific Research (CNRS-L), Lebanon, for granting a doctoral fellowship to Ms. Douaa Al Assaad. (American University of Beirut (AUB), Lebanese National Council for Scientific Research (CNRS-L), Lebanon)status: Publishe
Evaluation of different personalized ventilation air terminal devices: Inhalation vs. clothing-mediated exposures
No full textsponsorship: The authors would like to acknowledge the American University of Beirut (AUB) and the National Council for Scientific Research of Lebanon (CNRS-L) for granting a doctoral fellowship to Ms. Douaa Al Assaad. In addition, this collaborative research was made possible by the award (QUEX-CENG-ASPIRE-11/12-7) from ASPIRE Zone Foundation, Doha, Qatar. (American University of Beirut (AUB), National Council for Scientific Research of Lebanon (CNRS-L), ASPIRE Zone Foundation, Doha, Qatar|QUEX-CENG-ASPIRE-11/12-7)status: Publishe
Effect of individually controlled personalized ventilation on cross-contamination due to respiratory activities
No full textsponsorship: The authors would like to acknowledge the financial support of the Munib and Angela Masri Institute of Energy and Natural Resources at the American University of Beirut grant award 103973. In addition, the American University of Beirut PhD scholarship to Ms. Katramiz is highly acknowledged. The authors would like to also acknowledge the American University of Beirut (AUB) and the National Council for Scientific Research of Lebanon (CNRS-L) for granting a doctoral fellowship to Ms. Douaa Al Assaad. In addition, this collaborative research was made possible by the award [QUEX-CENG-ASPIRE-11/12-7] from ASPIRE Zone Foundation, Doha, Qatar. (Munib and Angela Masri Institute of Energy and Natural Resources at the American University of Beirut|103973, American University of Beirut PhD scholarship, American University of Beirut (AUB), National Council for Scientific Research of Lebanon (CNRS-L), ASPIRE Zone Foundation, Doha, Qatar|QUEX-CENG-ASPIRE-11/12-7)status: Publishe
Use of steady and intermittent personalized ventilation in indoor environments: Thermal comfort and Indoor air quality
No full textKamel Ghali; Nesreene Ghaddar; Fadl Moukalled; Fouad Azizi; Walid Chakroun; Arsen MelikovThe wellbeing and productivity of occupants in indoor spaces are correlated to their satisfaction with their thermal environment and their breathable air quality. This is highly dependent on the installation of carefully designed and energy-efficient air distribution systems such as personalized ventilation. These systems are individual devices consisting of a ducting network, which outlet delivers conditioned clean fresh air towards the occupant. As the issuing jet is adjustable in flow rate, direction and temperature, personalized ventilators respond to each occupant’s thermal preferences while improving the inhaled air quality compared to standalone total volume ventilation. Research on personalized ventilation has investigated its performance under steady state conditions. In other words, its adjustable operating conditions were constant over prolonged periods of time.
The first part of this work integrates for the first time, the concept of personalized ventilation with dynamic cooling, known to enhance comfort in warm indoor conditions. This is done by supplying the personalized flow rate in a time-dependent sinusoidal profile that fluctuates between a minimum and a maximum at frequencies of 0.3-1 Hz. The occupant is hence given additional freedom to adjust the jet frequency to their liking or revert to steady supply. This device is denoted as intermittent personalized ventilation. This work studies through experimentally validated CFD models, the performance of intermittent personalized ventilation in a space equipped with typical mixing ventilation and another equipped with a chilled ceiling, in enhancing occupants’ thermal comfort. Breathable air quality will also be assessed, and possible energy savings evaluated in comparison with a steady system. It was found that intermittent personalized ventilators enhanced thermal comfort especially in warm indoor conditions (26 C) with increasing frequency. It did not perform well in neutral conditions (24 C). Moreover, due to increased jet turbulence, it provided lower, but nonetheless satisfactory breathable air quality compared to steady personalized ventilation. Energy savings of 16% and 8% were achieved in the case of mixing ventilation and chilled ceiling.
Personalized ventilation has always been viewed as a means to improve indoor quality for the person using it by reducing exposure to gaseous or particulate matter pollutants. However, in the presence of particle emissions, personalized ventilation can contribute to particle deposition on occupants’ clothing, which can act as subsequent sources if triggered by occupants’ physical activities. Hence, personalized ventilation can contribute to second-hand clothing-mediated exposures. This work also investigates through experimentally validated CFD models the effect of different air terminal devices in reducing inhalation exposure while contributing to second-hand clothing exposure. Results showed that a computer mounted panel showed the best performance as it simultaneously decreased all types of exposure. Vertical desk grills decreased inhalation exposure while having negligible effect on second-hand exposure. Round movable panels decreased inhalation exposure but significantly increased clothing mediated exposures
Resilient passive cooling strategies during heat waves:A quantitative assessment in different climates
No full textThe frequency and severity of extreme weather events like heat waves are rising, posing significant challenges for buildings and their cooling systems. To safeguard occupants from potentially hazardous indoor temperatures, buildings and their cooling systems must be designed and managed to withstand these conditions and thus be resilient. This study assessed via building simulations the resilience performance of selected individual passive cooling strategies for five different climates (ASHRAE climate zones 2A, 3A, 3B, 4A, and 6A) and three heatwave periods (historical, future mid-term and future long-term). Resilience performance was assessed with three criteria: heatwave impact (°C·h above a reference standard effective temperature), absorptivity rate (°C/h), and recovery rate (°C/h). Strategies such as solar shading, cool envelope materials, advanced glazing, and ventilative cooling could each reduce the heat wave impact and the absorptivity rates in all studied climates at different levels of efficiency. As the heat waves became more extreme, the performance declined at different rates depending on the climate. Some strategies were more suited to specific climates such as cool envelope materials in climate 2A. Most strategies could not speed up the recovery rates from the heat waves except for ventilative cooling in climate 3B. With careful design to maximize the benefits of favorable wind conditions, every climate could benefit from ventilative cooling strategies to speed up recovery from heat waves
Introducing the concept of Acoustic Personalised Environmental Control systems (Acoustic PECS) within the framework of IEA EBC Annex 87
No full textThe availability of systems that can locally adjust environmental parameters holds the potential to enhance building occupant satisfaction by considering individual sensitivities, expectations, and needs. To this aim, Personalised Environmental Control Systems (PECS) are being studied as solutions that can provide individually controlled environments in the immediate surroundings of an occupant, without affecting directly the entire space and other occupants' environment. The
concept has been primarily developed to address individual control of the thermal environment and perceived air quality, as in chairs with heating/cooling functions and desks equipped with personalized ventilation systems. By extending the concept of PECS to the acoustic domain, a framework on Acoustic PECS is here introduced and exemplified. The study builds on ongoing research within the IEA EBC - Annex 87, dedicated to investigating the Energy and Indoor Environmental Quality Performance of Personalised Environmental Control Systems
Particle release and transport from human skin and clothing: A CFD modeling methodology
No full textParticle release from human skin and clothing has been identified as an important contributor to particulate matter burden indoors. However, knowledge about modeling the coarse particle release from skin and clothing is limited. This study developed a new empirically validated CFD modeling methodology for particle release and transport from seated occupants in an office setting. We tested three modeling approaches for particle emissions: Uniform; Uniform + Localized; and Uniform + Localized with Body Motion; applied to four office scenarios involving a single occupant and two occupants facing each other at 1- and 2-m distances. Uniform particle emissions from skin and clothing underpredicted personal inhalation exposure by as much as 55%-80%. Combining uniform with localized emissions from the armpits drastically reduced the error margin to <10%. However, this modeling approach heavily underestimated particle mass exchange (cross-contamination) between the occupants. Accounting for the occupant's body motion-by applying the momentum theory method-yielded the most accurate personal exposure and cross-contamination results, with errors below 12%. The study suggests that for accurate modeling of particle release and transport from seated occupants indoors, localized body emissions in combination with simplified bodily movements need to be taken into account.status: Publishe
Particle release and transport from human skin and clothing: A CFD modeling methodology
No full textParticle release from human skin and clothing has been identified as an important contributor to particulate matter burden indoors. However, knowledge about modeling the coarse particle release from skin and clothing is limited. This study developed a new empirically validated CFD modeling methodology for particle release and transport from seated occupants in an office setting. We tested three modeling approaches for particle emissions: Uniform; Uniform + Localized; and Uniform + Localized with Body Motion; applied to four office scenarios involving a single occupant and two occupants facing each other at 1- and 2-m distances. Uniform particle emissions from skin and clothing underpredicted personal inhalation exposure by as much as 55%-80%. Combining uniform with localized emissions from the armpits drastically reduced the error margin to <10%. However, this modeling approach heavily underestimated particle mass exchange (cross-contamination) between the occupants. Accounting for the occupant's body motion-by applying the momentum theory method-yielded the most accurate personal exposure and cross-contamination results, with errors below 12%. The study suggests that for accurate modeling of particle release and transport from seated occupants indoors, localized body emissions in combination with simplified bodily movements need to be taken into account.HOBE
Performance of Mixing Ventilation System Coupled With Dynamic Personalized Ventilator for Thermal Comfort
No full textThis study optimizes the performance of a mixing ventilation system coupled with a personalized ventilator that emits a cool sinusoidal horizontal airflow jet towards the occupant upper body in order to achieve good overall thermal comfort and good air quality in the occupant breathing zone. A transient 3-D computational fluid dynamics (CFD) model coupled with a transient bio-heat model was deployed to predict airflow and temperature fields in the space and around the occupant as well as segmental skin temperature profiles for local and overall thermal sensation and comfort analysis.
Simulations were performed using the CFD model to determine the airflow optimal supply frequency, mean flow rate and amplitude at room temperature of 25 °C and PV jet temperature of 22 °C. The system also showed, that when increasing frequency at fixed mean flow rate, thermal comfort increased from by 15.2 %. However when increasing mean flow rate at a fixed frequency, thermal comfort dropped at the low frequency of 0.3 Hz but remained acceptable at the higher frequency of 0.5 Hz.</jats:p
