scholarly journals Influence of the Airflow in a Solar Passive Building on the Indoor Air Quality and Thermal Comfort Levels

Atmosphere ◽  
2019 ◽  
Vol 10 (12) ◽  
pp. 766 ◽  
Author(s):  
Eusébio Conceição ◽  
João Gomes ◽  
Hazim Awbi
Keyword(s):  
Air Quality ◽  
Thermal Comfort ◽  
Indoor Air Quality ◽  
Indoor Air ◽  
Numerical Study ◽  
Change Rate ◽  
Comfort Levels ◽  
Air Change Rate ◽  
Typical Summer ◽  
Shading Devices

The influence of the airflow in a solar passive building on the indoor air quality and thermal comfort levels was investigated. The numerical study for a university library was conducted using a software that simulates the building thermal behavior with complex topology, in transient conditions, for evaluating the indoor air quality and occupants’ thermal comfort levels for typical summer and winter days. Solar radiation was used as a renewable energy source to increase simultaneously the thermal comfort and air quality levels and reduce building energy consumption. Regarding the solar passive building, consideration was given to all of the building structure envelope, shading devices and interior details, while in the solar active building active ventilation was used. To analyze the airflow that simultaneously provides the best indoor air quality and thermal comfort levels, a new integral methodology based on the minimization of the total number of uncomfortable hours was used. The results show that it was possible to determine an air change rate that ensures a good compromise between thermal comfort and indoor air quality. An optimal air change rate of two and three renewals per hour had been determined, respectively, for winter and summer conditions.

Numerical Study on Indoor Air Quality of Commercial Kitchen in China

2011 ◽  
Vol 374-377 ◽  
pp. 1100-1105 ◽  
Author(s):  
Xiao Tan Hou ◽  
An Gui Li ◽  
Zhi Hua Wang ◽  
Yu Jiao Zhao
Keyword(s):  
Air Quality ◽  
Indoor Air Quality ◽  
Indoor Air ◽  
Numerical Study ◽  
Average Concentration ◽  
Energy Utilization ◽  
Change Rate ◽  
Air Supply ◽  
Air Change Rate

Indoor air quality of commercial kitchen is investigated and analyzed through velocity, temperature, humidity, and CO2 concentration under different air change rate and supply air temperature. the best air change rate is 30 times per hour and air supply temperature is 301.15K for kitchen, the mean value of the minimum velocity and standard deviation is 0.410m/s and 0.129 respectively, the maximum of the average concentration of CO2 is 659.78ppm, which is less than the acceptance criteria (CO2<1000ppm), and the energy utilization coefficient is maximum of 1.352. Research results show that this air supply mode can optimize indoor air quality.

scholarly journals Quality of life control by selected methods of air exchange in a typical apartment building

2021 ◽  
Author(s):  
Iveta Bullová ◽  
Peter Kapalo ◽  
Dušan Katunský
Keyword(s):  
Air Quality ◽  
Indoor Air Quality ◽  
Indoor Air ◽  
Allergic Diseases ◽  
Well Being ◽  
Indoor Climate ◽  
Apartment Building ◽  
Change Rate ◽  
Air Change Rate ◽  
Negative Effect

Air change rate is an important parameter for quantification of ventilation heat losses and also affects the indoor climate of buildings. Indoor air quality is significantly associated with ventilation. If air change isn't sufficient, trapped allergens, pollutants and irritants can degrade the indoor air quality and affect the well-being of a building's occupants. Many studies on ventilation and health have concluded that lower air change rates can have a negative effect on people’s health and low ventilation may result in an increase in allergic diseases. Quantification of air change rate is complicated, since it is affected by a number of parameters, of which the one of the most variable is the air-wind flow. This study aims to determination and comparison of values of the air change rate in two methods - by quantifying of aerodynamic coefficient Cp = Cpe - Cpi – so called aerodynamic quantification of the building and the methodology based on experimental measurements of carbon dioxide in the selected reference room in apartment building.

scholarly journals Energy Production in Solar Collectors in a University Building Used to Improve the Internal Thermal Conditions in Winter Conditions

2021 ◽  
Vol 246 ◽  
pp. 03005
Author(s):  
Eusébio Conceição ◽  
João Gomes ◽  
Mª Manuela Lúcio ◽  
Hazim Awbi
Keyword(s):  
Air Quality ◽  
Thermal Comfort ◽  
Indoor Air Quality ◽  
Indoor Air ◽  
Energy Production ◽  
Numerical Study ◽  
Thermal Conditions ◽  
Solar Collectors ◽  
Transient Conditions ◽  
Winter Conditions

In this numerical study the energy production in solar collectors in a University building used to improve the internal thermal conditions is made. Passive and active solutions, using external solar collector and internal thermo-convectors, are used. The numerical simulation, in transient conditions, is done for a winter typical day with clean sky. This numerical study was carried out using a software that simulates the Building Dynamic Response with complex topology in transient conditions. The software evaluates the human thermal comfort and indoor air quality levels that the occupants are subjected, Heated Ventilation and Air Conditioned energy consumption, indoor thermal variables and other parameters. The university building has 107 compartments and is located in a Mediterranean-type environment. External solar water collectors, placed above the building’s roof, and internal thermo-convectors of water/air type, using mixing ventilation, are used as passive and active strategies, respectively. The thermal comfort level, using the Predicted Mean Vote index, and the indoor air quality, using the carbon dioxide concentration, are evaluated. The results show that in winter conditions the solar collectors improve the thermal comfort conditions of the occupants. The indoor air quality, in all ventilated spaces, is also guaranteed.

Evaluation of comfort levels in office space equipped with HVAC system based in personalized ventilation system using energy produced in DSF systems

2020 ◽  
pp. 65-74
Author(s):  
Eusébio Conceição ◽  
Mª Inês Conceição ◽  
Mª Manuela Lúcio ◽  
João Gomes ◽  
Hazim Awbi
Keyword(s):  
Air Quality ◽  
Numerical Model ◽  
Thermal Comfort ◽  
Indoor Air Quality ◽  
Indoor Air ◽  
Numerical Study ◽  
Ventilation System ◽  
Airflow Rate ◽  
Hvac System ◽  
Personalized Ventilation

In this study the numerical simulation of a Heating, Ventilating and Air Conditioning (HVAC) system, based in a personalized ventilation system, installed in an occupied office desk is made. The energy is produced in a Dual Skin Facades (DSF) system installed in the outdoor environment. The personalized ventilation system, placed above and below the writing area, installed in the desk central area. The office desk is occupied by eight virtual manikins. The numerical simulation is made in a winter typical day. This numerical study considers a coupling of a differential numerical model and an integral numerical model. The differential numerical model simulates the Computational Fluids Dynamics (CFD), evaluates the air velocity, air temperature, turbulence intensity and carbon dioxide concentration and calculates the indoor air quality. The integral numerical model simulates the Multi-Node Human Thermo-physiology Model, evaluates the tissue, blood and clothing temperatures distribution and calculates the thermal comfort level. The HVAC system, based on a DSF system, is built using three DSF unities, is equipped with internal venetian blinds. Each one, installed in a virtual chamber, is turned to south. The personalized ventilation system, made with eight upper and eight lower air terminal devices, is installed in the desk central area. On each table top two upper and two lower air terminal devices are considered in the left and right manikin area, while on each side of the table two upper and two lower air terminal devices are placed between the manikins. The office desk is occupied by eight virtual manikins, one sitting on each table top and three sitting on each side of the meeting table. In this numerical study, carried out in winter conditions, the occupants’ clothing level is 1 clo. In these situations a typical activity level of 1.2 met is considered. The evolution of indoor environmental conditions, in the DSF and in the office room, are calculated during a full winter typical day. The thermal comfort, the indoor air quality, the effectiveness for heat removal, the effectiveness for contaminant removal and the Air Distribution Index (ADI), are evaluated. In accordance with the obtained results the thermal comfort levels increase when the air renovation rate increases and the indoor air quality level increases when the air renovation rate increases. However, the ADI is quite constant when the inlet airflow rate increases, because the thermal comfort number decreases when the inlet airflow rate increases and the air quality number increases when the inlet airflow rate increases.

scholarly journals ANALYSIS OF THE INFLUENCE OF AIR EXCHANGE DISTRIBUTION BETWEEN ROOMS ON THE APARTMENT ENERGY CONSUMPTION

2021 ◽  
pp. 39-50
Author(s):  
V. Deshko ◽  
I. Bilous ◽  
I. Sukhodub ◽  
O. Yatsenko
Keyword(s):  
Energy Consumption ◽  
Air Quality ◽  
Indoor Air Quality ◽  
Indoor Air ◽  
Building Energy ◽  
Optimal Operation ◽  
Change Rate ◽  
Air Change Rate ◽  
Building Engineering ◽  
Air Exchange

Modern results of Ukrainian buildings energy analysis show that 30-50% of the energy for heating goes to heat the supply air, and that is the largest share in the building energy balance. In terms of energy consumption, efficiency of the air exchange mode largely depends on occupancy schedule and air distribution in time and space. The application of air exchange schedule approach makes more sense in case when individual heating control is carried out. Therefore, during occupied hours, the comfortable ventilation level can be ensured, and, during unoccupied hours, it can be reduced to a minimum. According to the results of the study, the use of intermittent air exchange mode in the studied apartment on weekdays, leads to decrease in energy consumption compared to constant air exchange at the level of upper values of the ventilation schedule. In terms of energy efficiency, the use of the constant air change rate from ASHRAE Std 62 is the most efficient approach. In terms of indoor air quality and concentration of CO2 and VOCs, the scheduled air exchange approach with increased air change rates (from EN 16798) during occupied hours is more efficient. Therefore, the use of required and experimental air change rate values to create the hourly schedules allows to define more precisely a building energy consumption and to choose an optimal operation schedule for building engineering systems to provide thermal comfort and indoor air quality during occupied hours.

scholarly journals Improving Indoor Air Quality in Classrooms via Wind-Induced Natural Ventilation

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Mohannad Bayoumi
Keyword(s):  
Air Quality ◽  
Indoor Air Quality ◽  
Indoor Air ◽  
User Satisfaction ◽  
Natural Ventilation ◽  
Special Treatment ◽  
Generic Model ◽  
Change Rate ◽  
Air Change Rate ◽  
Warm Climates

Student performance in classrooms is related to the indoor environmental quality. High air change rates are necessary to secure an acceptable level of indoor air quality and provide fresh air, which require large amounts of energy and technical installations. Mostly, mechanically supplied air is partially mixed with the return air. In warm climates, the capacity for natural ventilation is not fully exploited in modern buildings. During periods of acceptable outdoor temperatures, buildings need to adapt and employ available free renewable resources, such as wind. In this context, the building form, orientation, and envelope openings are crucial to enable an increased air change rate, user satisfaction, and energy savings. Owing to the difficulty of providing cross-ventilation in buildings with double-loaded corridors, single-sided ventilation is the most common approach. This study investigates the methods to improve the wind-driven air exchange of classrooms in warm climates, where naturally ventilated corridors help increase air movement. This study examines the potential of a set of alternatives within the context of a generic model regarding the pressure distribution, thermal sensation, air velocity, and air change rate. The study suggests that no single opening scenario can be applied to all façades at any time. Each façade requires special treatment. Decisions on natural ventilation need to be made during the early design stages for each façade. It was found that with the aid of low-tech modifications, remarkable increases in air change rates, in some cases up to 14.5 times that of the typical single-sided ventilation case, could be achieved.

Numerical simulation of the influence of external urban environmental conditions in the building windows performance

2020 ◽  
pp. 112-123
Author(s):  
Eusébio Conceiçã ◽  
João Gomes ◽  
Maria Manuela Lúcio ◽  
Maria Inês Conceição ◽  
Hazim Awbi
Keyword(s):  
Air Quality ◽  
Thermal Comfort ◽  
Indoor Air Quality ◽  
Indoor Air ◽  
Environmental Conditions ◽  
Numerical Study ◽  
Carbon Dioxide Concentration ◽  
System Control ◽  
Hvac System ◽  
Indoor Thermal Comfort

This paper presents a numerical study of the influence of external urban environmental conditions, namely, the solar radiation, in the building windows performance. A software that simulates the building thermal behaviour with complex topology, in transient conditions, is developed and used in the study of indoor air quality and indoor thermal comfort of the occupants of a building, under typical summer conditions. As management strategy was implemented a control system to the Heating, Ventilation and Air Conditioning (HVAC) using the PMV (Predicted Mean Vote) index as controllable variable. The studied university building is located in a Mediterranean-type climate in the south of Portugal. The indoor thermal comfort, evaluated by the PMV index, and the indoor air quality, evaluated by the carbon dioxide concentration, were obtained for all occupied spaces. In order to evaluate the implemented control strategy a set of results was obtained for the situations with and without HVAC system control. To exemplify the results obtained, two large compartments were chosen, one with windows facing South and the other without windows. As main conclusion, it can be stated that the use of the HVAC system controllable by the PMV index allows acceptable levels of thermal comfort within the category C of the ISO 7730 standard, and acceptable levels of indoor air quality within the limit proposed by the ASHRAE 62.1 standard.

scholarly journals Production of thermal energy in University building greenhouses in cold climate conditions

2021 ◽  
Vol 246 ◽  
pp. 03004
Author(s):  
Eusébio Conceição ◽  
João Gomes ◽  
Maria Manuela Lúcio ◽  
Hazim Awbi
Keyword(s):  
Air Quality ◽  
Thermal Comfort ◽  
Indoor Air Quality ◽  
Thermal Energy ◽  
Indoor Air ◽  
Numerical Study ◽  
Cold Climate ◽  
International Standards ◽  
Climate Conditions ◽  
Heated Air

The present work focuses on the production of thermal energy in University building greenhouses in cold climate conditions. The building model uses a system of energy and mass balance integral equations, which are solved by the Runge–Kutta–Felberg method with error control. This numerical study is about the thermal behaviour of a university building with complex topology, in winter and transient conditions. The thermal comfort of the occupants, using the Predicted Mean Vote index, and the indoor air quality, using the carbon dioxide concentration, are evaluated. This building has 319 compartments distributed by four floors and it is equipped with one internal greenhouse in the third floor. This greenhouse is located on the south facing facade and the heated air in this space will be transported to compartments located on the north facing façade. The spaces subject to the influence of the heated air coming from the greenhouse improve the level of thermal comfort of its occupants. The level of indoor air quality in occupied spaces is acceptable according to international standards.

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