Nonlinear robust control of air handling units to improve the indoor air quality & CO2 concentration: A comparison between H∞ & decoupled sliding mode controls

Between the ages of 6 and 18, children spend between 30 and 42 h a week at school, mostly indoors, where indoor environmental quality is usually deficient and does not favor learning. The difficulty of delivering indoor air quality (IAQ) in learning facilities is related to high occupancy rates and low interaction levels with windows. In non-industrialized countries, as in the cases presented, most classrooms have no mechanical ventilation, due to energy poverty and lack of normative requirements. This fact heavily impacts the indoor air quality and students’ learning outcomes. The aim of the paper is to identify the factors that determine acceptable CO2 concentrations. Therefore, it studies air quality in free-running and naturally ventilated primary schools in Chile, aiming to identify the impact of contextual, occupant, and building design factors, using CO2 concentration as a proxy for IAQ. The monitoring of CO2, temperature, and humidity revealed that indoor air CO2 concentration is above 1400 ppm most of the time, with peaks of 5000 ppm during the day, especially in winter. The statistical analysis indicates that CO2 is dependent on climate, seasonality, and indoor temperature, while it is independent of outside temperature in heated classrooms. The odds of having acceptable concentrations of CO2 are bigger when indoor temperatures are high, and there is a need to ventilate for cooling.

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Mitigation Strategies for Overheating and High Carbon Dioxide Concentration within Institutional Buildings: A Case Study in Toronto, Canada

Buildings ◽

10.3390/buildings10070124 ◽

2020 ◽

Vol 10 (7) ◽

pp. 124 ◽

Cited By ~ 1

Author(s):

Claire Tam ◽

Yuqing Zhao ◽

Zaiyi Liao ◽

Lian Zhao

Keyword(s):

Carbon Dioxide ◽

Air Quality ◽

Indoor Air Quality ◽

Air Temperature ◽

Indoor Air ◽

Indoor Environment ◽

Thermal Conditions ◽

Co2 Concentration ◽

Hvac System

Indoor air quality and thermal conditions are important considerations when designing indoor spaces to ensure occupant health, satisfaction, and productivity. Carbon dioxide (CO2) concentration and indoor air temperature are two measurable parameters to assess air quality and thermal conditions within a space. Occupants are progressively affected by the indoor environment as the time spent indoors prolongs. Specifically, there is an interest in carrying out investigations on the indoor environment through surveying existing Heating, Ventilation, Air Conditioning (HVAC) system operations in classrooms. Indoor air temperature and CO2 concentration in multiple lecture halls in Toronto, Canada were monitored; observations consistently show high indoor air temperature (overheating) and high CO2 concentration. One classroom is chosen as a representative case study for this paper. The results verify a strong correlation between the number of occupants and the increase in air temperature and CO2 concentration. Building Energy Simulation (BES) is used to investigate the causes of discomfort in the classroom, and to identify methods for regulating the temperature and CO2 concentration. This paper proposes retro-commissioning strategies that could be implemented in institutional buildings; specifically, the increase of outdoor airflow rate and the addition of occupancy-based pre-active HVAC system control. The proposed retrofit cases reduce the measured overheating in the classrooms by 2-3 °C (indoor temperature should be below 23 °C) and maintain CO2 concentration under 900 ppm (the CO2 threshold is 1000 ppm), showing promising improvements to a classroom’s thermal condition and indoor air quality.

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Indoor air quality and health in schools

Jornal Brasileiro de Pneumologia ◽

10.1590/s1806-37132014000300009 ◽

2014 ◽

Vol 40 (3) ◽

pp. 259-268 ◽

Cited By ~ 16

Author(s):

Ana Maria da Conceição Ferreira ◽

Massano Cardoso

Keyword(s):

Air Quality ◽

Indoor Air Quality ◽

Indoor Air ◽

Respiratory Diseases ◽

Reference Value ◽

Signs And Symptoms ◽

Co2 Concentration ◽

Air Pollutant ◽

Carbon Dioxide Co2 ◽

The City

Objective: To determine whether indoor air quality in schools is associated with the prevalence of allergic and respiratory diseases in children. Methods: We evaluated 1,019 students at 51 elementary schools in the city of Coimbra, Portugal. We applied a questionnaire that included questions regarding the demographic, social, and behavioral characteristics of students, as well as the presence of smoking in the family. We also evaluated the indoor air quality in the schools. Results: In the indoor air of the schools evaluated, we identified mean concentrations of carbon dioxide (CO2) above the maximum reference value, especially during the fall and winter. The CO2 concentration was sometimes as high as 1,942 ppm, implying a considerable health risk for the children. The most prevalent symptoms and respiratory diseases identified in the children were sneezing, rales, wheezing, rhinitis, and asthma. Other signs and symptoms, such as poor concentration, cough, headache, and irritation of mucous membranes, were identified. Lack of concentration was associated with CO2 concentrations above the maximum recommended level in indoor air (p = 0.002). There were no other significant associations. Conclusions: Most of the schools evaluated presented with reasonable air quality and thermal comfort. However, the concentrations of various pollutants, especially CO2, suggest the need for corrective interventions, such as reducing air pollutant sources and improving ventilation. There was a statistically significant association between lack of concentration in the children and exposure to high levels of CO2. The overall low level of pollution in the city of Coimbra might explain the lack of other significant associations.

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Method for Estimation of CO2 Gains from Persons in Builidings

Proceedings ◽

10.3390/proceedings2201309 ◽

2018 ◽

Vol 2 (20) ◽

pp. 1309 ◽

Cited By ~ 2

Author(s):

Antonio Rodero ◽

Dorota Anna Krawczyk

Keyword(s):

Carbon Dioxide ◽

Air Quality ◽

Indoor Air Quality ◽

Indoor Air ◽

Carbon Dioxide Concentration ◽

Co2 Concentration ◽

Males And Females ◽

Sources Of Co2

Carbon dioxide concentration is an important parameter to know Indoor Air Quality of a building. One of the most important sources of CO2 in poor ventilated building is human activity. This work presents a method for experimental determination of human CO2 generation rate based on measuring of time evolution of indoor CO2 concentration. The method is applied to 5 rooms of an educational building from Bialystok (Poland). Similar carbon dioxide gains were obtained in all rooms, around 0.0046 L/s, which correspond to theoretical CO2 generation rates of a sedentary activity for persons, males and females, between 21–30 years old, characteristics of occupants of analyzed rooms.

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The Influence of Surgical Staff Behavior on Air Quality in a Conventionally Ventilated Operating Theatre during a Simulated Arthroplasty: A Case Study at the University Hospital of Parma

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph17020452 ◽

2020 ◽

Vol 17 (2) ◽

pp. 452

Author(s):

Cesira Pasquarella ◽

Carla Balocco ◽

Maria Eugenia Colucci ◽

Elisa Saccani ◽

Samuel Paroni ◽

...

Keyword(s):

Air Quality ◽

Indoor Air Quality ◽

Indoor Air ◽

Co2 Concentration ◽

University Hospital ◽

Surgical Team ◽

Operating Theatres ◽

Turbulent Air Flow ◽

Air Conditioning Systems ◽

Staff Behavior

Surgical staff behavior in operating theatres is one of the factors associated with indoor air quality and surgical site infection risk. The aim of this study was to apply an approach including microbiological, particle, and microclimate parameters during two simulated surgical hip arthroplasties to evaluate the influence of staff behavior on indoor air quality. During the first hip arthroplasty, the surgical team behaved correctly, but in the second operation, behavioral recommendations were not respected. Microbiological contamination was evaluated by active and passive methods. The air velocity, humidity, temperature, and CO2 concentration were also monitored. The highest levels of microbial and particle contamination, as well as the highest variation in the microclimate parameter, were recorded during the surgical operation where the surgical team behaved “incorrectly”. Turbulent air flow ventilation systems appeared more efficient than in the past and very low air microbial contamination was reached when behavior was correct. Therefore, adherence to behavioral recommendations in operating theatres is essential to not undermine the effectiveness of the heating, ventilation, and air conditioning systems and employed resources.

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Indoor Air Quality Improvement by Simple Ventilated Practice and Sansevieria Trifasciata

Atmosphere ◽

10.3390/atmos11030271 ◽

2020 ◽

Vol 11 (3) ◽

pp. 271 ◽

Cited By ~ 2

Author(s):

Kanittha Pamonpol ◽

Thanita Areerob ◽

Kritana Prueksakorn

Keyword(s):

Air Quality ◽

Indoor Air Quality ◽

Indoor Air ◽

Co2 Concentration ◽

Tropical Region ◽

Air Conditioner ◽

Electricity Cost ◽

Consequent Reduction ◽

Feasible Option ◽

Poor Ventilation

Optimum thermal comfort and good indoor air quality (IAQ) is important for occupants. In tropical region offices, an air conditioner is indispensable due to extreme high temperatures. However, the poor ventilation causes health issues. Therefore, the purpose of this study was to propose an improving IAQ method with low energy consumption. Temperature, relative humidity, and CO2 and CO concentration were monitored in a poorly ventilated office for one year to observe seasonal variation. The results showed that the maximum CO2 concentration was above the recommended level for comfort. Simple ventilated practices and placing a number of Sansevieria trifasciata (S. trifasciata) plants were applied to improve the IAQ with the focus on decreasing CO2 concentration as well as achieving energy saving. Reductions of 19.9%, 22.5%, and 58.2% of the CO2 concentration were achieved by ventilation through the door during lunchtime, morning, and full working period, respectively. Placing S. trifasciata in the office could reduce the CO2 concentration by 10.47%–19.29%. A computer simulation was created to observe the efficiency of simple practices to find the optimum conditions. An electricity cost saving of 24.3% was projected for the most feasible option with a consequent reduction in global warming potential, which also resulted in improved IAQ.

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Numerical and Experimental Analysis on Indoor Thermal Environment in Commercial Kitchen

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.518-523.4435 ◽

2012 ◽

Vol 518-523 ◽

pp. 4435-4438

Author(s):

Da Hua Jiang ◽

Zhi Hua Wang ◽

Fa En Shi ◽

Ru Shan Ren

Keyword(s):

Air Quality ◽

Indoor Air Quality ◽

Indoor Air ◽

Thermal Environment ◽

Co2 Concentration ◽

Maximum Value ◽

Work Area ◽

Indoor Contaminants ◽

The Impact

It is of great importance to study the impact of the cooking generated contaminants on the indoor air quality in the kitchen since cooking is regarded as the main source of indoor contaminants. This study aims investigate and analysis the indoor air quality of kitchen with using CFD numerical analysis method via the velocity, temperature, humidity CO2 concentration .It is concluded that The temperature distribution are large difference in the kitchen and the maximum value is up to 324K on the work area which near the cooking ,and the CO2 concentration which is close to the stove is 1420ppm,1370ppm, 1470ppm respectively, and it is more than the acceptance criteria (CO2<1000ppm) 42%,37% and 47% respectively. It is serious impact on the staff's physical health.

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Investigation and Evaluation of Winter Indoor Air Quality of Primary Schools in Severe Cold Weather Areas of China

Energies ◽

10.3390/en12091602 ◽

2019 ◽

Vol 12 (9) ◽

pp. 1602 ◽

Cited By ~ 4

Author(s):

Fusheng Ma ◽

Changhong Zhan ◽

Xiaoyang Xu

Keyword(s):

Air Quality ◽

Indoor Air Quality ◽

Indoor Air ◽

Primary Schools ◽

Co2 Concentration ◽

Ventilation Rate ◽

Cold Weather ◽

Limited Information ◽

Physical Measurements ◽

Window Opening

The indoor air quality (IAQ) in classrooms has attracted more and more attention. Unfortunately, there is limited information relating to IAQ in the primary schools in severe cold weather areas of China. In this study, a field investigation on the IAQ of a primary school of Shenyang in northeast China was carried out by physical measurements and questionnaire surveys. The carbon dioxide (CO2) concentration in selected classrooms was continuously measured for a week, and the corresponding ventilation rate was calculated. Meanwhile, the perceptions of the IAQ, the purpose and the comfort degree of window opening have also been recorded from 106 pupils, aged 9–12. The results indicate the ventilation rate is considerably inadequate in about 99% of the class time due to the low frequency of window opening. The average daily CO2 concentration in these classrooms is 1510–3863 ppm, which is far higher than the recommended value of 1000 ppm. Most pupils understand that the purpose of opening windows in winter is to improve air quality. However, there are big differences between the measurement results and subjective judgments of indoor air quality. Contrary to the high measured CO2 concentration, around 70% pupils consider the air fresh, and only 3.7% pupils are dissatisfied and even very dissatisfied with IAQ in their classroom. It is necessary to change the existing manual window opening mode, because the pupils’ subjective judgment affects the window opening behavior.

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A Field Survey on Indoor Air Pollution in School Classrooms with Different Ventilation Methods

E3S Web of Conferences ◽

10.1051/e3sconf/201911101020 ◽

2019 ◽

Vol 111 ◽

pp. 01020

Author(s):

Ko Murakami ◽

Kenta Sakai ◽

Daisuke Nakamura ◽

Haruno Ishikawa ◽

Sayana Tsushima ◽

...

Keyword(s):

Elementary Schools ◽

Heat Exchange ◽

Air Quality ◽

Indoor Air Quality ◽

Indoor Air ◽

Indoor Air Pollution ◽

Ventilation System ◽

Co2 Concentration ◽

Field Surveys ◽

Air Conditioning Systems

The purpose of this study was to investigate the actual indoor air quality within two elementary schools with different types of ventilation methods, and to obtain data pertaining to the emission of bioeffluents within the schools. Field surveys on indoor air quality were conducted at two public elementary schools in Tokyo, both equipped with air-conditioning systems. School-A was also equipped with a heat-exchange ventilation system, while School-B did not have a ventilation system. Results of the study revealed that the target ventilation volume for the heat-exchange ventilation system in School-A was not achieved, indoor air quality in School-B was better in relatively cool conditions than School-A because of the habit of opening windows attached, there was a positive correlation between nonanal and decanal and CO2 concentration in summer, and the concentration of bioeffluents nonanal and decanal may be higher at high temperatures even under the same level of ventilation.

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Measurement and Simulation of Indoor Air Quality and CO2 Concentration in a Hotel Room

ASME 2010 10th Biennial Conference on Engineering Systems Design and Analysis, Volume 4 ◽

10.1115/esda2010-25143 ◽

2010 ◽

Author(s):

Ehsan Asadi ◽

Manuel Gameiro da Silva ◽

Jose´ J. Costa

Keyword(s):

Air Quality ◽

Simulation Model ◽

Indoor Air Quality ◽

Indoor Air ◽

Co2 Concentration ◽

Simulation Software ◽

Building Simulation ◽

Airflow Rate ◽

Air Exchange Rate ◽

Ventilation Performance

Indoor air quality (IAQ) is nowadays universally recognized as an important issue that affects the comfort and health of people, as well as their productivity. This paper describes the relationship of indoor CO2 concentration to building air quality and ventilation, with a focus on how CO2 can be used to evaluate and predict air quality and ventilation performance, namely the infiltration airflow rate. Besides it shows the ability of ESP-r building simulation software for predicting the CO2 concentration and the air exchange rate in a building. For this purposes a room of a hotel located in the urban area of Coimbra was chosen. The developed simulation model was then validated against empirical results. It was shown that a fair degree of agreement between ESP-r results and the experimental observation exist for the zones. High accuracy of the simulation model showed that building simulation software, namely ESP-r can provide a better understanding of indoor environmental conditions and be a powerful tool in finding the best modification measures for improving the indoor air quality in a building.

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