Experimental assessment of the impact of natural ventilation on indoor air quality and thermal comfort conditions of educational buildings in the Eastern Mediterranean region during the heating period

The Covid-19 outbreak has resulted in new patterns of home occupancy, the implications of which for indoor air quality (IAQ) and energy use are not well-known. In this context, the present study investigates 8 flats in London to uncover if during a lockdown, (a) IAQ in the monitored flats deteriorated, (b) the patterns of window operation by occupants changed, and (c) more effective ventilation patterns could enhance IAQ without significant increases in heating energy demand. To this end, one-year’s worth of monitored data on indoor and outdoor environment along with occupant use of windows has been used to analyse the impact of lockdown on IAQ and infer probabilistic models of window operation behaviour. Moreover, using on-site CO2 data, monitored occupancy and operation of windows, the team has calibrated a thermal performance model of one of the flats to investigate the implications of alternative ventilation strategies. The results suggest that despite the extended occupancy during lockdown, occupants relied less on natural ventilation, which led to an increase of median CO2 concentration by up to 300 ppm. However, simple natural ventilation patterns or use of mechanical ventilation with heat recovery proves to be very effective to maintain acceptable IAQ. Practical application: This study provides evidence on the deterioration of indoor air quality resulting from homeworking during imposed lockdowns. It also tests and recommends specific ventilation strategies to maintain acceptable indoor air quality at home despite the extended occupancy hours.

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Application of Wind as a Renewable Energy Source for Passive Cooling through Windcatchers Integrated with Wing Walls

Energies ◽

10.3390/en11102536 ◽

2018 ◽

Vol 11 (10) ◽

pp. 2536 ◽

Cited By ~ 13

Author(s):

Payam Nejat ◽

Fatemeh Jomehzadeh ◽

Hasanen Hussen ◽

John Calautit ◽

Muhd Abd Majid

Keyword(s):

Air Quality ◽

Indoor Air Quality ◽

Indoor Air ◽

Natural Ventilation ◽

Passive Cooling ◽

Quality Factors ◽

Ventilation Performance ◽

Wing Walls ◽

The Impact ◽

Ventilation Systems

Generally, two-third of a building’s energy is consumed by heating, ventilation and air-conditioning systems. One green alternative for conventional air conditioner systems is the implementation of passive cooling. Wing walls and windcatchers are two prominent passive cooling techniques which use wind as a renewable resource for cooling. However, in low wind speed regions and climates, the utilization of natural ventilation systems is accompanied by serious uncertainties. The performance of ventilation systems can be potentially enhanced by integrating windcatchers with wing walls. Since previous studies have not considered this integration, in the first part of this research the effect of this integration on the ventilation performance was assessed and the optimum angle was revealed. However, there is still gap of this combination; thus, in the second part, the impact of wing wall length on the indoor air quality factors was evaluated. This research implemented a Computational Fluid Dynamics (CFD) method to address the gap. The CFD simulation was successfully validated with experimental data from wind tunnel tests related to the previous part. Ten different lengths from 10 cm to 100 cm were analyzed and it was found that the increase in wing wall length leads to a gradual reduction in ventilation performance. Hence, the length does not have a considerable influence on the indoor air quality factors. However, the best performance was seen in 10 cm, that could provide 0.8 m/s for supply air velocity, 790 L/s for air flow rate, 39.5 1/h for air change rate, 107 s for mean age of air and 92% for air change effectiveness.

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Natural ventilation and indoor air quality in educational buildings: experimental assessment and improvement strategies

Energy Efficiency ◽

10.1007/s12053-016-9485-0 ◽

2016 ◽

Vol 10 (4) ◽

pp. 839-854 ◽

Cited By ~ 8

Author(s):

Ricardo M. S. F. Almeida ◽

Manuel Pinto ◽

Paulo G. Pinho ◽

Luís T. de Lemos

Keyword(s):

Air Quality ◽

Indoor Air Quality ◽

Indoor Air ◽

Natural Ventilation ◽

Experimental Assessment ◽

Improvement Strategies ◽

Educational Buildings

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Seasonal variations and the influence of ventilation rates on IAQ: A case study of five low-energy London apartments

Indoor and Built Environment ◽

10.1177/1420326x211017175 ◽

2021 ◽

pp. 1420326X2110171

Author(s):

Samuel Stamp ◽

Esfand Burman ◽

Clive Shrubsole ◽

Lia Chatzidiakou ◽

Dejan Mumovic ◽

...

Keyword(s):

Air Quality ◽

Indoor Air Quality ◽

Indoor Air ◽

Seasonal Variations ◽

Natural Ventilation ◽

Low Energy ◽

Ventilation Rates ◽

The Impact ◽

Indoor And Outdoor

The indoor air quality (IAQ) of five low-energy London apartments has been assessed through the measurement of 16 key pollutants, using continuous and diffusive methods across heating and non-heating seasons. This case study approach aimed to assess the presence of pollutants within low-energy apartments and to better understand the role of ventilation and seasonal variations in indoor air quality. The results indicate strong seasonal variations, driven by increased natural ventilation rates over the summer monitoring period. A combined metric for indoor and outdoor pollutants ( Itot) suggests that the IAQ in the winter ( Itot = 17.7) is more than twice as bad as that seen in the summer ( Itot = 8.6). Formaldehyde concentrations were lower in the non-heating season, indicating increased ventilation rates more than offset increased off-gassing, in contrast to findings in other studies. However, increased summertime ventilation rates were observed to increase the proportion of outdoor pollutants entering the internal environment. This resulted in higher indoor concentrations of NO2 in the summer than the winter, despite significant reductions in outdoor concentrations. These results demonstrate the impact of ventilation practices upon IAQ, the influence of occupant actions and the complex relationship ventilation rates play in balancing indoor and outdoor sources of air pollution.

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Numerical analysis of the impact of natural ventilation on the Indoor Air Quality and Thermal Comfort in a classroom

E3S Web of Conferences ◽

10.1051/e3sconf/201911101023 ◽

2019 ◽

Vol 111 ◽

pp. 01023 ◽

Cited By ~ 1

Author(s):

George-Mãdãlin Chitaru ◽

Andrei Istrate ◽

Tiberiu Catalina

Keyword(s):

Numerical Simulation ◽

Air Quality ◽

Thermal Comfort ◽

Indoor Air Quality ◽

Indoor Air ◽

Natural Ventilation ◽

Simulation Software ◽

Educational Institutions ◽

Research School ◽

The Impact

Indoor air quality (IAQ) inside educational institutions is an important topic in the field of building and health research. School absenteeism and educational performance have been linked to poor air quality inside classrooms. A numerical simulation software has been used to test 5 different scenarios of natural ventilation during summer and winter. CO2 levels, air relative humidity, operative temperature and PMV were used as indoor air quality and thermal comfort indicators. Results have shown high CO2 and humidity levels when all windows are closed, and a variable improvement when different natural ventilations strategies are employed. A detailed procedure for the numerical simulation has been presented.

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Natural ventilation may not improve indoor air quality

AccessScience ◽

10.1036/1097-8542.br0309202 ◽

2020 ◽

Keyword(s):

Air Quality ◽

Indoor Air Quality ◽

Indoor Air ◽

Natural Ventilation

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Effects of Climatic Conditions, Season and Environmental Factors on CO2 Concentrations in Naturally Ventilated Primary Schools in Chile

Sustainability ◽

10.3390/su13084139 ◽

2021 ◽

Vol 13 (8) ◽

pp. 4139

Author(s):

Muriel Diaz ◽

Mario Cools ◽

Maureen Trebilcock ◽

Beatriz Piderit-Moreno ◽

Shady Attia

Keyword(s):

Air Quality ◽

Indoor Air Quality ◽

Indoor Air ◽

Primary Schools ◽

Co2 Concentration ◽

Building Design ◽

Climatic Conditions ◽

Indoor Environmental Quality ◽

Co2 Concentrations ◽

The Impact

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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The impact of mechanical ventilation operation strategies on indoor CO2 concentration and air exchange rates in residential buildings

Indoor and Built Environment ◽

10.1177/1420326x20960767 ◽

2020 ◽

pp. 1420326X2096076

Author(s):

Pedro F. Pereira ◽

Nuno M. M. Ramos

Keyword(s):

Mechanical Ventilation ◽

Air Quality ◽

Exchange Rates ◽

Indoor Air Quality ◽

Indoor Air ◽

Residential Buildings ◽

Ventilation Strategy ◽

The Impact ◽

Mechanical Extraction ◽

Air Exchange

In Portugal, residential buildings commonly have their ventilation strategy changed after commissioning. This occurs due to the building managers' willingness to reduce shared costs with the electricity needed for fan operation. However, this option is not technically supported, and the effects of such a strategy on indoor air quality-related to human pollutants are yet to be quantified. CO2 was monitored in 15 bedrooms and air exchange rates were calculated for each room. The air exchange rate values ranged from 0.18 to 0.53 h−1 when mechanical extraction ventilation was off, and from 0.45 to 0.90 h−1 when mechanical extraction ventilation was on, which represents an average increase of 119%. With the current intermittent ventilation strategy, all rooms remain above 1500 ppm for a given percentage of time, and 12 rooms presenting CO2 concentrations above 2000 ppm. Simulations of theoretical CO2 concentrations, for a non-interrupted mechanical ventilation strategy show that no rooms would accumulate CO2 concentrations above 2000 ppm, and only 25% would present CO2 concentrations above 1500 ppm. Pearson correlations between the monitored CO2 and human and spatial factors identified two relevant parameters. Those parameters correspond to ratios between CO2 generation and floor area ([Formula: see text]), and airflow with CO2 generation ([Formula: see text]). The proposed ratios could be used as ways to optimise ventilation costs and indoor air quality.

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Indoor Air Quality (IAQ): Accuracy of Natural Ventilation for Temperature, Air Flow Rate and Relative Humidity (RH) in School Building Classrooms

International Journal of Engineering & Technology ◽

10.14419/ijet.v7i3.9.15271 ◽

2018 ◽

Vol 7 (3.9) ◽

pp. 42

Author(s):

Norsafiah Norazman ◽

Adi Irfan Che Ani ◽

Nor Haslina Ja’afar ◽

Muhamad Azry Khoiry

Keyword(s):

Air Quality ◽

Relative Humidity ◽

Indoor Air Quality ◽

Indoor Air ◽

Natural Ventilation ◽

Air Flow ◽

Weather Conditions ◽

Potential Health ◽

The Hours ◽

Hot Weather

Indoor Air Quality (IAQ) is an essential matter in achieving students’ satisfaction for the learning process. Building’s orientation is a factor that may encourage sufficient natural ventilation for the classroom occupants. Inadequate ventilation is an issue for most existing classrooms. The purpose of this paper is to analyze the accuracy of natural ventilation in classrooms. Therefore, experimental on 20 classrooms has been conducted by using Multipurpose Meter at secondary school buildings in Malaysia. The findings indicated that the accuracy of natural ventilation testing was below the permissible limits throughout the hours monitored, thus this may cause potential health hazards to the students. Temperature and air flow rates were lower than 23 °C and 0.15 m/s respectively, it fulfilled the basic requirements as a standard learning environment. However, measurements taken showed the overall relative humidity (RH) in the classrooms can be categorized as acceptable with 40% to 70% range. On the basis of these findings, it is evident that naturally ventilated classrooms are important especially due to energy efficiency, whereas mechanical ventilation should only be installed as an alternative under extremely hot weather conditions.

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The Potential of Natural Ventilation in Single-Sided Ventilated Apartment to Improve Indoor Thermal Comfort and Air Quality

ASME 2011 5th International Conference on Energy Sustainability, Parts A, B, and C ◽

10.1115/es2011-54129 ◽

2011 ◽

Cited By ~ 1

Author(s):

M. F. Mohamed ◽

M. Behnia ◽

S. King ◽

D. Prasad

Keyword(s):

Air Quality ◽

Thermal Comfort ◽

Indoor Air Quality ◽

Indoor Air ◽

Natural Ventilation ◽

Architectural Element ◽

Flat Design ◽

Effective Ventilation ◽

Computational Fluid Dynamics Cfd ◽

Ventilation Performance

Cross ventilation is a more effective ventilation strategy in comparison to single-sided ventilation. In the NSW Residential Flat Design Code1 (RFDC) the majority of apartments are required to adopt cross ventilation. However, in the case of studio and one-bedroom apartments, it is acknowledged that single-sided ventilation may prevail. Deep plan studio and one-bedroom apartments may achieve lower amenity of summer thermal comfort and indoor air quality where mechanical ventilation is not provided by air conditioning. Since compliance with the code may allow up to 40% of apartments in a development in Sydney to be single sided, it is important to understand the natural ventilation performance of such apartments. The objective of this paper is to investigate the natural ventilation potential in single-sided ventilated apartments to improve indoor air quality and thermal comfort. This investigation includes simulating various facade treatments involving multiple opening and balcony configurations. Balcony configurations are included in this study because, in Sydney, a balcony is a compulsory architectural element in any apartment building. The study uses computational fluid dynamics (CFD) software to simulate and predict the ventilation performance of each apartment configuration. This study suggests that properly configured balconies and openings can significantly improve indoor ventilation performance for enhanced indoor air quality and thermal comfort, by optimizing the available prevailing wind. However, it is important to note that inappropriately designed fac¸ade treatments also could diminish natural ventilation performance.

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