Thermal Comfort and Energy Savings in a Simulated Office Conditioned by a Transient Personalized Ventilator and a Displacement Ventilation System

2020 ◽  
Author(s):  
Douaa Al Assad ◽  
Kamel Ghali ◽  
Nesreen Ghaddar ◽  
Elvire Katramiz
Keyword(s):  
Thermal Comfort ◽  
Energy Savings ◽  
Ventilation System ◽  
Rate Of Change ◽  
Comfort Level ◽  
Thermal Manikin ◽  
Cfd Model ◽  
Displacement Ventilation ◽  
Additional Energy ◽  
Personalized Ventilation

Abstract The aim of this work is to evaluate the performance of an intermittent personalized ventilation (IPV) system assisting a displacement ventilation (DV) system to improve thermal comfort and save energy. This will be conducted by developing a transient 3D computational fluid dynamics (CFD) model of an occupied office space equipped with systems. The occupant is modeled by a heated thermal manikin replicating the human body. The CFD model is coupled with a transient bio-heat model to compute segmental skin temperatures and their rate of change. The latter are taken as input into Zhang’s comfort model to predict and overall thermal comfort. The model was used to conduct a case study, where the overall thermal comfort and energy savings will be assessed for the IPV + DV These results will be compared with those of steady personalized ventilation (PV) + DV and standalone DV systems. By varying the IPV frequency in the typical indoor range of [0.3 Hz – 1 Hz], it was found that the IPV + DV system was able to enhance comfort compared to steady PV + DV and a standalone DV. In addition, an energy analysis was conducted and it was shown that the IPV was able to achieve considerable energy savings compared to a steady PV + DV at the same thermal comfort level. Moreover, relaxing the DV supply temperature to higher occupied zone temperatures, can provide additional energy savings while still maintaining comfort levels in the space.

Development and application of an integrated virtual thermal-acoustic manikin design used inside an office space

2021 ◽  
Vol 263 (2) ◽  
pp. 4226-4237
Author(s):  
Eusebio Conceição ◽  
Mª Ines Conceição ◽  
Mª Manuela Lúcio ◽  
João Gomes
Keyword(s):  
Air Quality ◽  
Thermal Comfort ◽  
Sound Propagation ◽  
Ventilation System ◽  
Comfort Level ◽  
Quality Level ◽  
Thermal Manikin ◽  
Reverberation Time ◽  
Surrounding Space ◽  
Personalized Ventilation

In this study an integrated virtual thermal-acoustic manikin design used inside ventilated and occupied office spaces is developed and applicated. The component of the virtual thermal manikin evaluates the internal airflow and occupants' thermal, thermo-physiology and clothing systems and calculates the thermal comfort and the indoor air quality levels. The component of the virtual binaural manikin evaluates the direct and indirect sound and calculates the reverberation time. The space geometry with complex topology is developed using a Computer Aid Design (CAD), while the occupants' geometry is made using geometric equations. The grid generation, in the surrounding space surfaces and around the external occupants' surfaces geometry, is used to calculate the radiative heat exchanges and the sound propagation. In this study, performed in an office room occupied by eight persons and equipped with personalized ventilation system, the thermal comfort level, the air quality level and the space reverberation time is evaluated and discussed. In accordance with the obtained results the values are, in general, in accordance the actual standards.

Effective Mixed-Mode Ventilation System With Intermittent Personalized Ventilation for Improving Thermal Comfort in an Office Space

2020 ◽  
Author(s):  
Elvire Katramiz ◽  
Nesreen Ghaddar ◽  
Kamel Ghali
Keyword(s):  
Thermal Comfort ◽  
Control Strategy ◽  
Mixed Mode ◽  
Natural Ventilation ◽  
Energy Savings ◽  
Ventilation System ◽  
Energy Performance ◽  
Building Performance Simulation ◽  
Office Space ◽  
Personalized Ventilation

Abstract The mixed-mode ventilation (MMV) system is an energy-friendly ventilation technique that combines natural ventilation (NV) with mechanical air conditioning (AC). It draws in fresh air when the outdoor conditions are favorable or activates otherwise the AC system during occupancy hours. To improve performance of the MMV system, it is proposed to integrate it with an intermittent personalized ventilation (IPV) system. IPV delivers cool clean air intermittently to the occupant and enhances occupant thermal comfort. With the proper ventilation control strategy, IPV can aid MMV by increasing NV mode operational hours, and improve the energy performance of the AC system by relaxing the required macroclimate set point temperature. The aim of this work is to study the IPV+MMV system performance for an office space application in terms of thermal comfort and energy savings through the implementation of an appropriate control strategy. A validated computational fluid dynamics (CFD) model of an office space equipped with IPV is used to assess the thermal fields in the vicinity of an occupant. It is then coupled with a transient bio-heat and comfort models to find the overall thermal comfort levels. Subsequently, a building-performance simulation study is performed using Integrated Environmental Solutions-Virtual Environment (IES-VE) for an office in Beirut, Lebanon for the typical summer month of July. An energy analysis is conducted to predict the savings of the suggested design in comparison to the conventional AC system. Results showed that the use of IPV units and MMV significantly reduced the number of AC operation hours while providing thermal comfort.

Reducing Energy Demand in Commercial Buildings: Balancing Convection and Radiant Cooling

2010 ◽  
Author(s):  
Lee Chusak ◽  
Andrew Harris ◽  
Ramesh Agarwal
Keyword(s):  
Thermal Comfort ◽  
Energy Demand ◽  
Energy Savings ◽  
Ventilation System ◽  
Computational Domain ◽  
Exterior Wall ◽  
Displacement Ventilation ◽  
Comfort Levels ◽  
Isothermal Wall ◽  
Chilled Ceiling

Using Computational Fluid Dynamics (CFD) software, three different cooling systems used in contemporary office environments are modeled to compare energy consumption and thermal comfort levels. Incorporating convection and radiation technologies, full-scale models of an office room compare arrangements for (a) an all-air overhead system (mixing ventilation), (b) an all-air raised floor system (displacement ventilation), and (c) a combined air and hydronic radiant system (displacement ventilation with a chilled ceiling). The computational domain for each model consists of one isothermal wall (simulating an exterior wall of the room) and adiabatic conditions for the remaining walls, floor, and ceiling (simulating interior walls of the room). Two sets of computations were conducted. The first set of computations utilized a constant temperature isothermal exterior wall, while the second set utilized an isothermal wall that changed temperatures as a function of time simulating the temperature changes on the exterior wall of a building throughout a 24 hour period. Results show superior thermal comfort levels as well as substantial energy savings can be accrued using the displacement ventilation, especially the displacement ventilation with a chilled ceiling over the conventional mixing ventilation system.

scholarly journals Determination of Optimum Envelope of Religious Buildings in Terms of Thermal Comfort and Energy Consumption: Mosque Cases

Energies ◽  
2021 ◽  
Vol 14 (20) ◽  
pp. 6597
Author(s):  
Ahmet Bircan Atmaca ◽  
Gülay Zorer Gedik ◽  
Andreas Wagner
Keyword(s):  
Thermal Properties ◽  
Energy Consumption ◽  
Thermal Comfort ◽  
Thermal Insulation ◽  
Energy Savings ◽  
Gain Factor ◽  
Building Envelope ◽  
Comfort Level ◽  
Humid Climate ◽  
Savings Rate

Mosques are quite different from other building types in terms of occupant type and usage schedule. For this reason, they should be evaluated differently from other building types in terms of thermal comfort and energy consumption. It is difficult and probably not even necessary to create homogeneous thermal comfort in mosques’ entire usage area, which has large volumes and various areas for different activities. Nevertheless, energy consumption should be at a minimum level. In order to ensure that mosques are minimally affected by outdoor climatic changes, the improvement of the properties of the building envelope should have the highest priority. These optimal properties of the building envelope have to be in line with thermal comfort in mosques. The proposed method will be a guide for designers and occupants in the design process of new mosques or the use of existing mosques. The effect of the thermal properties of the building envelope on energy consumption was investigated to ensure optimum energy consumption together with an acceptable thermal comfort level. For this purpose, a parametric simulation study of the mosques was conducted by varying optical and thermal properties of the building envelope for a temperature humid climate zone. The simulation results were analyzed and evaluated according to current standards, and an appropriate envelope was determined. The results show that thermal insulation improvements in the roof dome of buildings with a large volume contributed more to energy savings than in walls and foundations. The use of double or triple glazing in transparent areas is an issue that should be considered together with the solar energy gain factor. Additionally, an increasing thickness of thermal insulation in the building envelope contributed positively to energy savings. However, the energy savings rate decreased after a certain thickness. The proposed building envelope achieved a 33% energy savings compared to the base scenario.

scholarly journals Operation Testing of an Advanced Personalized Ventilation System

Energies ◽  
2019 ◽  
Vol 12 (9) ◽  
pp. 1596 ◽  
Author(s):  
Csáky ◽  
Kalmár ◽  
Kalmár
Keyword(s):  
Air Quality ◽  
Thermal Comfort ◽  
Indoor Air Quality ◽  
Indoor Air ◽  
Distribution System ◽  
Noise Level ◽  
Background Noise ◽  
Ventilation System ◽  
Air Distribution ◽  
Personalized Ventilation

Using personalized ventilation systems in office buildings, important energy saving might be obtained, which may improve the indoor air quality and thermal comfort sensation of occupants at the same time. In this paper, the operation testing results of an advanced personalized ventilation system are presented. Eleven different air terminal devices were analyzed. Based on the obtained air velocities and turbulence intensities, one was chosen to perform thermal comfort experiments with subjects. It was shown that, in the case of elevated indoor temperatures, the thermal comfort sensation can be improved considerably. A series of measurements were carried out in order to determine the background noise level and the noise generated by the personalized ventilation system. It was shown that further developments of the air distribution system are needed.

Numerical analysis of local thermal comfort in a plan office under natural ventilation

2019 ◽  
Vol 29 (7) ◽  
pp. 972-986 ◽  
Author(s):  
Xiang Deng ◽  
Zijing Tan
Keyword(s):  
Thermal Comfort ◽  
Natural Ventilation ◽  
Meteorological Data ◽  
Ventilation System ◽  
Comfort Level ◽  
Open Plan ◽  
Computational Fluid Dynamics Cfd ◽  
Internal Volume ◽  
Local Thermal Comfort ◽  
Primary Focus

The utilisation of automatic controlled natural wind in office buildings to maintain indoor thermal comfort has gained wide attention in recent years. Generally, it is not necessary to ensure that the whole internal volume of a building with large open spaces meets thermal comfort requirements. Primary focus should be on occupied areas. Accordingly, the local thermal comfort in an open-plan office with automatic controlled natural ventilation system was investigated numerically and experimentally. A computational fluid dynamics (CFD)-based method was presented for indoor environment and thermal comfort prediction. Long-term in situ measurement was conducted during summer and transition seasons. The meteorological data were collected by a mini weather station located on the roof of the target building. Meanwhile, indoor air velocity, temperature, turbulence intensity and wall temperatures were recorded locally. Three thermal comfort indices, i.e. thermal stratification represented by percentage dissatisfied (PD), the extended predicted mean vote (PMVe) and draught rate were employed to evaluate the thermal comfort level of the interested areas during natural ventilation period. The numerical results revealed a risk of local thermal dissatisfaction under low outdoor temperature and strong windy conditions.

Sign in / Sign up

Export Citation Format

Share Document