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

2021 ◽  
Author(s):  
Douaa Al Assad ◽  
Kamel Ghali ◽  
Nesreen Ghaddar ◽  
Elvire Katramiz
Keyword(s):  
Thermal Comfort ◽  
Energy Savings ◽  
Ventilation System ◽  
Displacement Ventilation

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.

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.

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.

Energy Use Comparison of Air Distribution Systems Serving a Section of a School Building

2012 ◽  
Author(s):  
Stillman Jordan ◽  
Randall D. Manteufel
Keyword(s):  
Total Energy ◽  
Distribution System ◽  
Energy Recovery ◽  
Distribution Systems ◽  
Energy Savings ◽  
Ventilation System ◽  
Space Distribution ◽  
Air Distribution ◽  
Displacement Ventilation ◽  
Humid Climate

An optimal air distribution design accomplishes both comfort and ventilation requirements while consuming as little energy as possible. This paper analyzes four different air distribution systems and technologies including single duct variable air volume air handlers, chilled beam cooling systems, total energy recovery wheels, displacement ventilation, and dedicated outside air systems; in an effort to determine the best air distribution system for a representative section of a school in hot and humid climate. The effectiveness of the air distribution systems is evaluated by analyzing how the different technologies take advantage of the natural convective properties of air to create a comfortable environment for the occupied region of the space. Distribution effectiveness and energy consumption must be weighed against considerations such as system complexity and ease of operation. This paper compares several alternative air distribution systems to a baseline single inlet VAV system that is commonly used in new schools designed today. Calculations show that the total energy recovery wheels result in a 16% energy savings over the baseline air distribution system because of the large amount of outside air required in school buildings. Chilled beams are not well suited for schools because of the large amount of outside air required by the space and the sophisticated design and operation needed to prevent condensation from occurring at the chilled beam. The results show that the air distribution system that consumes the least amount of energy is a displacement ventilation system. The system also inherently promotes better indoor air quality as it allows air to naturally rise out and return out of the space with minimal mixing of contaminates that may be recirculated within the room for others to breath. The displacement ventilation system’s overall energy savings of 20% over the baseline is mainly attributed to its total energy recovery wheel and the system’s ability to drastically reduce the cooling load seen by the air cooled chiller by effectively ventilating spaces using less outside air.

scholarly journals The Significance of the Adaptive Thermal Comfort Practice over the Structure Retrofits to Sustain Indoor Thermal Comfort

Energies ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2946
Author(s):  
Aiman Albatayneh ◽  
Mustafa Jaradat ◽  
Mhd Bashar AlKhatib ◽  
Ramez Abdallah ◽  
Adel Juaidi ◽  
...  
Keyword(s):  
Energy Consumption ◽  
Thermal Comfort ◽  
Energy Savings ◽  
Ventilation System ◽  
Minimum Energy ◽  
Computer Software ◽  
Energy Performance ◽  
Building Envelope ◽  
Indoor Thermal Comfort ◽  
Adaptive Thermal Comfort

Any building’s design should sustain thermal comfort for occupants and promote less energy usage during its lifetime using accurate building retrofits to convert existing buildings into low-energy buildings so that the heating and cooling loads can be minimized. Regarding the methodology adopted in this research, an energy model of an educational building located at the German Jordanian University in Jordan was constructed utilizing DesignBuilder computer software. In addition, it was calibrated utilizing real energy consumption data for a 12-month simulation of energy performance. Subsequently, a computerized evaluation of the roles of building envelope retrofits or the adaptive thermal comfort limits in the reduction of the overall building energy consumption was analyzed. The results of the study show that the current building’s external wall insulation, roof insulation, glazing, windows, and external shading devices are relatively energy-efficient but with high cost, resulting in significant financial losses, even though they achieved noticeable energy savings. For instance, equipping the building’s ventilation system with an economizer culminated in the highest financial profit, contributing to an annual energy savings of 155 MWh. On the other hand, in an occupant-centered approach, applying the adaptive thermal comfort model in wider ranges by adding 1 °C, 2 °C, and 3 °C to the existing operating temperatures would save a significant amount of energy with the least cost (while maintaining indoor thermal comfort), taking over any retrofit option. Using different adaptive thermal comfort scenarios (1 °C, 2 °C, and 3 °C) led to significant savings of around 5%, 12%, and 21%, respectively. However, using different retrofits techniques proved to be costly, with minimum energy savings compared to the adaptive approach.

scholarly journals FIELD STUDY ON THE THERMAL COMFORT AND VENTILATION EFFECTIVENESS IN A CONCERT HALL WITH DISPLACEMENT VENTILATION SYSTEM

2002 ◽  
Vol 67 (559) ◽  
pp. 37-44
Author(s):  
Sueng-jae LEE ◽  
Shin-ichi TANABE ◽  
Ken-ichi KIMURA ◽  
Kazuhiro OTAKA ◽  
Makoto KOYAMA ◽  
...  
Keyword(s):  
Thermal Comfort ◽  
Field Study ◽  
Ventilation System ◽  
Displacement Ventilation ◽  
Concert Hall ◽  
Ventilation Effectiveness

scholarly journals Incorporating cooling and ventilation effects into a single IEQ indicator

2019 ◽  
Vol 111 ◽  
pp. 02011
Author(s):  
Matjaž Prek ◽  
Gorazd Krese ◽  
Žiga Lampret
Keyword(s):  
Thermal Comfort ◽  
Indoor Environment ◽  
Cooling System ◽  
Ventilation System ◽  
Whole Body ◽  
Indoor Environmental Quality ◽  
Displacement Ventilation ◽  
Wall Displacement ◽  
Flat Wall ◽  
Ventilation Effectiveness

The influence of dissimilar cooling and ventilation system combinations on indoor environmental quality (IEQ) has been studied. A comparison of chilled ceiling cooling in combination with displacement ventilation, cooling with fan coil unit, and cooling with flat wall displacement inlets was performed. All observed variations were evaluated based on whole-body and local thermal comfort criteria as well as with regard to ventilation effectiveness. The analysis was made based on results of numerical simulations carried out in two steps. First, DesignBuilder was applied to model the buildings’ thermal performance and to evaluate its interaction with the environment. The latter included the calculation of heat gains as well as the heat loss on the boundary surfaces of the observed air-conditioned room. In the second step, ANSYS Fluent was used to simulate the response of indoor environment by utilizing the simulation results obtained in the first step, in order to evaluate the interaction between building and human. Afterwards, the observed thermal comfort and ventilation criteria were merged into a novel indoor environment indicator, which enables to describe the indoor environment quality with a single value. Among the analysed systems, the ceiling cooling system in combination with displacement ventilation was found to be the most suitable as it offers a high level of thermal comfort with adequate ventilation efficiency. Fan coil cooling was the least favourable option in terms of thermal comfort, while flat wall displacement inlets exhibited the lowest ventilation effectiveness. The performed investigation demonstrated the necessity to assess indoor environment with regard to IEQ in addition to energy consumption.

The Indoor Air Quality and Thermal Comfort Experimental Research on the Combined Cooling Ceiling and Displacement Ventilation System

2012 ◽  
Vol 193-194 ◽  
pp. 1048-1051
Author(s):  
Jiu Chen Ma ◽  
Zhi Gang Zhang
Keyword(s):  
Air Quality ◽  
Thermal Comfort ◽  
Indoor Air Quality ◽  
Indoor Air ◽  
Ventilation System ◽  
Displacement Ventilation ◽  
Air Velocity ◽  
Air Conditioning System ◽  
Combined Cooling ◽  
General Guidance

In this energy saving and environment protection society, as a new kind of air conditioning system, the combined cooling ceiling (CC) and displacement ventilation (DV) system has been attracting more and more attention both at home and abroad. This paper has done experiments with different supply air temperature, various supply air velocity and changeable temperature of supply water by simulating to cool a small office in summer. Based on similarity theories, some suggestions are given for the numerical area of cooling parameters under some laboratory conditions. According to PMV, it is also presented in general guidance for indoor air quality and thermal comfort with CC/DV system.

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