Control Indoor Air Research Articles

Assessing indoor air temperature settings in residential buildings during the COVID-19 era

While comfort models provide reliable evidence for designing building thermal environments, they may not be adequate for assessing building energy consumption due to factors beyond comfort. These factors influence occupants' actual control of their thermal environment. This study assessed how residential building occupants control indoor air temperature to maintain their comfort during the COVID-19 era. A dataset established from the ‘Donate Your Data’ program administered by Ecobee Inc. was utilised. The dataset was collected from 86,658 thermostats belonging to 65,535 users in the United States over multiple years, along with metadata that includes characteristics of the users and their homes. Statistical analysis was performed to suggest an indoor temperature range at which 90 % of collected data falls when the prevailing mean outdoor air temperature is between −10 °C and 37 °C, which effectively covers a wide variety of climate conditions. The estimated range of indoor air temperatures was 6.3 K before the pandemic, but it decreased by 1 K–5.3 K during the pandemic, implying that occupants used more energy to maintain a comfortable indoor air temperature during the pandemic. Our model can be useful in designing indoor temperature settings in residential buildings based on outdoor temperature.

Effectiveness of the Fuzzy Logic Control to Manage the Microclimate Inside a Smart Insulated Greenhouse

Agricultural greenhouses incorporate intricate systems to regulate the internal climate. Among the crucial climatic variables, indoor temperature and humidity take precedence in establishing an optimal environment for plant production and growth. The present research emphasizes the efficacy of employing intelligent control systems in the automation of the indoor climate for smart insulated greenhouses (SIGs), utilizing a fuzzy logic controller (FLC). This paper proposes the use of an FLC to reduce the energy consumption of a greenhouse. In the first step, a thermodynamic model is presented and experimentally validated based on thermal heat exchanges between the indoor and outdoor climatic variables. The outcomes show the effectiveness of the proposed model in controlling indoor air temperature and relative humidity with a low error percentage. Secondly, several fuzzy logic control models have been developed to regulate the indoor temperature and humidity for cold and hot periods. The results show the good performance of the proposed FLC model as highlighted by the statistical analysis. In fact, the root mean squared error (RMSE) is very small and equal to 0.69% for temperature and 0.23% for humidity, whereas the efficiency factor (EF) of the fuzzy logic control is equal to 99.35% for temperature control and 99.86% for humidity control.

Heat and mass transfer analysis of desiccant-coated heat exchanger with desiccants and metal-organic framework for bus air conditioning applications

Desiccant-coated heat exchangers (DCHEs) in air conditioning offer advantages like independent temperature and humidity control, reduced energy consumption, and high performance. However, the availability of desiccants with high water adsorption and low thermal energy requirements is limited. The present study proposes that aluminum fumarate (Al-Fum) MOF-coated heat exchangers will outperform conventional desiccants, especially at low regeneration temperatures (around 50°C). In order to evaluate this hypothesis, the performance of DCHEs was evaluated with a validated analytical model for different solid desiccant coatings: silica gel, zeolite, and Al-Fum MOF. Water vapor sorption characteristics, heat and mass transfer, and adsorption and desorption capacities were determined. The results showed that the Al-Fum MOF-coated heat exchanger outperformed silica gel and zeolite at low regeneration temperatures under adiabatic conditions. The MOF exhibited superior water uptake capacity (0.39 g/g) between 20% and 80% RH compared to the other studied conventional desiccants. Moreover, the MOF achieved the lowest outlet air temperature. At 19.5 g/kgda, the MOF demonstrated higher adsorption rates (4 % and 0.3 %) than zeolite and silica gel. These findings highlight the potential of Al-Fum MOFs as energy-efficient solutions for controlling indoor air humidity, particularly for latent-sensible heat separation systems with conventional vapor compression bus air-conditioning systems.

Simultaneous thermal zoning and demand control ventilation

Heating, Ventilation, and Air Conditioning systems play a crucial role in controlling indoor air conditions, including temperature, humidity, and CO₂ concentration, to ensure human comfort and safety. Thermal zoning and demand-controlled ventilation have demonstrated enhancements in comfort and energy efficiency. This study aims to develop a mathematical model for a Heating, Ventilation, and Air Conditioning system employing an estimated state-feedback control algorithm to optimize indoor comfort and energy savings while minimizing sensor requirements. The model encompasses dynamic equations governing CO₂ concentration and temperature in a five-room building. Temperature regulation is achieved by adjusting the airflow from a cooling unit with dampers, while CO₂ levels are managed by controlling the proportion of fresh air intake. To showcase the advantages of the proposed control approach, comparisons were made with alternative methods based on response performance, energy consumption, and sensor requirements. The estimated state-feedback control outperformed other approaches, requiring only one temperature and one CO₂ sensor at the mixed return. Additional occupancy sensors in each room are not necessary if an Extended Kalman filter is utilized. This technique exhibits scalability, adaptable to varying output variables and room configurations, and holds promise for broader implementation in the HVAC industry. By optimizing energy consumption and maintaining indoor air quality, this approach aligns with established sustainability metrics, promoting environmental responsibility. Compliance with health and safety audit standards ensures the fulfillment of social targets, while adherence to regulations and laws ensures governance targets are met.

How to measure and control indoor air quality based on intelligent digital twin platforms: A case study in China

In order to address the current disparity between indoor air quality assessment, prediction, and control, this study proposes an intelligent management approach for indoor air quality based on digital twin platforms. By collecting and fusing multi-level, and multi-dimensional data at the physical level, a comprehensive data integration and analysis platform is established in the digital realm, encompassing the ‘Sense-Integrate-Retrieve-Analyze-Feedback’ framework. Various digital technologies, such as the Internet of Things (IoT), Building Information Modeling (BIM), and machine learning, are utilized to integrate and visualize multi-source heterogeneous data through a lightweight web-based interface so that data retrieval, rapid prediction, and intelligent control are feasible based on various backend algorithm models. Compared to traditional measurement methods, this system offers broader spatiotemporal coverage, increased mobility, and less disruption to physical infrastructure, which underscores the sophistication of monitoring technology, data integration, and environmental management. The proposed intelligent platform has been validated in a traditional Chinese dwelling, and practical results demonstrate that most air quality problems occur in the early morning of winter while this system can swiftly predict and issue control signals for adjustments in occupied spaces exceeding predefined healthy thresholds. Field measurements confirmed that most air quality problems can be solved within 30 min after their appearance. By eliminating data silos through real-time synchronization and remote intelligent control via the digital platform, it bridges the gap between problem identification by managers and problem resolution by end-users, ensuring timely responses to indoor air quality concerns.

Comparison of Real‐Time PM2.5 Between Rural and Urban Homes in Southwest China Based on Field Measurement: Insight Into the Cooking Activity Contribution

People generally spend most of their time indoors; thus, household air pollution (HAP), especially indoor air pollution, is of paramount importance. In this study, real‐time particulate matter (PM2.5) monitors were used to collect high temporal resolution concentrations of fine PM2.5 in different microenvironments from 104 urban and rural households in Guizhou Province to investigate the urban–rural difference in HAP and the contribution of cooking activity to HAP. Results showed that PM2.5 concentrations among different rural microenvironments varied largely, ranging from 26.10 ± 33.27 (mean ± standard deviation) in the bedroom to 69.20 ± 72.50 μg/m3 in the kitchen while varying slightly across various urban microenvironments, ranging from 32.30 ± 17.5 in the living room to 34.65 ± 16.37 μg/m3 in the kitchen. Cooking activity can rapidly increase PM2.5 concentrations in the kitchen, whose peaks were at least five times higher than baseline levels. The contribution of cooking to the kitchen PM2.5 was 18.43 ± 12.17% and 5.39 ± 4.15% in rural and urban homes, respectively. Biomass burning affected indoor PM2.5 concentrations significantly, where rural households using biomass had the highest PM2.5 levels than households burning other fuels. This study identified the urban–rural disparities in household PM2.5 pollution and the contributions of cooking activities to HAP, illustrating the importance of cooking activities to indoor air pollution, which can assist in controlling indoor air pollution.

Bacteriological Assessment of Indoor Air Quality in Keystone (Male) Hostel, University of Benin, Benin City

This study examined and identified the level of bacteria present in the hostel to evaluate the potential health hazards for the residents and establish guidelines for controlling indoor air quality. Six (6) rooms were sampled out of 25 rooms at the keystone hostel, each with a height of 10 feet, and an average dimension of 9 feet by 10 feet. The study was done in July and November, 2023. Passive air sampling of settle plate method was employed. The isolates were identified using standard cultural and biochemical identification method. The outcome revealed that the concentration of bacteria isolates rose as media exposure time increased. In July, the maximum bacteria concentration was observed in room 37 at 20min (21.5 x 102CFU/m3) and the minimum in room 49 at 20 min (0.02 x 102 CFU/m3. The concentration of bacteria in room 48 at 20 min was (0.1 x 102 CFU/m3), room 47 at 20 min (11.0 x 102 CFU/m3), room 38 at 20 min (16.5 x 102 CFU/m3), room 39 at 20 min (10.5 x 102 CFU/m3), While for the month of November, the highest bacteria concentration was seen in room 37 at 20min (26.5 x 102 CFU/m3) and the least at room 49 at 20 min (0.09 x 102 CFU/m3). The concentration of bacteria at other room 48 at 20 min (0.3 x 102 CFU/m3), room 47 at 20 min (13.5 x 102 CFU/m3), room 38 at 20 min (19.2 x 102 CFU/m3), room 39 at 20 min (15.1 x 102 CFU/m3). A total of seven (7) distinct bacteria species: Escherichia coli (60%), Staphylococcus aureus (100%), Streptococcus pyogenes (50%), Bacillus cerus (30%), Seratia marcescens (30%), Klebsiella spp (50%) and Proteus spp (50%) were isolated and identified in four rooms ( 37, 38, 39, and 47), with six occupants each, while room 48 and 49 had two occupants respectively; hence bacterial load were relatively non-significant. However, Staphylococcus aureus, Streptococcus pyogenes and Bacillus cerus were identified as the most pathogenic isolates seen in the rooms under study. The study highlights the potential impact of occupancy levels on microbial presence within indoor spaces. The results shows that students in rooms 37, 38, 39 and 47 have a high risk of health and disease implications due to poor ventilation and overcrowding, unlike the students in rooms 48 and 49 with low risk of infectious diseases. Therefore, the study recommends a periodic indoor air quality assessment in the students’ hostel, implementation of good health hygiene practices, maintaining environmental sanitation and managing the environmental factors that supports the multiplication of the bacteria especially in the dry season are crucial to preventing the spread of diseases in the hostel.

Development of an Optimal Control Method for the Concentration of Degradable Substances

Indoor environments affect occupant hygiene, comfort, and productivity. Special treatments, such as spraying essential oils, disinfectant gases, and water vapor or droplets, have been proposed to improve indoor comfort in recent years. Therefore, a method to control the concentrations of these beneficial substances is required. To control the indoor concentration distribution of various degradable substances emitted indoors, this article proposes a novel method that uses the linear relationship between the source and concentration distributions. The method was evaluated through numerical experiments using CFD. Furthermore, the effects of the deposition (Dep) and decomposition (Dec) of the substances on the performance were assessed. The method successfully determined the optimal emission intensities for each emission source to make the concentration field close to the objective—the uniform distribution—in the experiment. When substances decomposed in the air or were deposited on the walls, the performance of the optimal control decreased compared to the case without Dec or Dep. This indicated that the occurrence of Dec or Dep lowered the optimization performance by enhancing the unevenness of the concentration field in the area near the emission source and far from the source. The Dep case showed relatively lower performance than the Dec case because the Dep occurred more spatially unevenly than the Dec. In addition, the more emission sources employed, the smaller the gap between the objective and the optimized concentration field. This method will help control indoor air quality more efficiently.

Indoor Air Pollution: A Review on the Challenges in Third World Countries

Background: The challenges of third-world countries toward curbing indoor air pollution seem insurmountable as its solution is closely linked to their economic incapacities, lifestyle, and existing outdoor air quality. The economic incapacities include types of the cookstove, fuel sources, types of insecticides and pesticides, building patterns, indoor fermentation activities (such as leaving dirty plates and biological waste in the house for a long time), and regulation on the use of deodorants. Aside from the common pollutants from these sources, the reactive chemistry of pollutants leads to other kinds of pollutants which have been reported to be short-lived but dangerous. Objectives: The objectives of the study are to: profile emerging indoor pollutants; examine the pollutant dynamics and their impact on unplanned regions of developing countries; offer solutions to curb indoor pollution in the identified region; elaborate on the cost analysis of existing solutions and how irrelevant they may be due to the rising poverty index; and project how government policies could help in reducing indoor pollution. Design: This paper is a review that wholistically examined indoor pollution. A total of fifty-six articles was reviewed in addition to the data obtained from MERRA-2. Results: The study observed that indoor air pollution dynamics are more complex—compared to outdoor air pollution. It was observed that the possibility to control indoor air pollution is based on the type of pollutants, the reactive chemistry of the pollutants, and ventilation in the building. This review shows that poverty is one of the many reasons why indoor air pollution would be a source of menace for a long time in third-world countries. Several solutions to curbing indoor air pollution were considered with a principal focus on cost and availability. Limitations: Most experimental results that were used to corroborate postulates were obtained from the literature. The accuracy of those experiments and the sensitivity of the equipment used cannot be verified. Conclusion: The plant-based technique was identified as a perfect solution to indoor air pollution control in third-world countries but the local architecture and lifestyle of most third-world countries constitute a threat to its adoption. It was observed that less than 8% of third-world countries have specific Air Quality Acts which have not been amended for decades. Most third-world countries have a general Environmental Act with air quality as a sub-section in the Act with very low fines for violators. The inclusion of indoor air quality as a vital public health issue in third-world countries is necessary for the preservation of lives and posterity.

Design and Characterization of an Upscaled Dielectric Barrier Discharge-Based Ten-Layer Plasma Source for High-Flow-Rate Gas Treatment

Dielectric barrier discharge (DBD)-based technology is considered a promising alternative for controlling indoor air pollutants. However, its limited processing capacity and lack of design techniques have restricted its use in practical applications. This paper introduces a methodology for designing upscaled DBD reactors with a processing capacity of up to 1000 L/min for treating high-flow-rate gases to mitigate indoor air pollution. A ten-layer high-flow-rate DBD reactor was constructed, with fundamental characterizations, including electrical and spectroscopic measurements, conducted to verify the feasibility of the proposed methodology. In particular, the flow paths of the ten-layer DBD reactor were optimized by incorporating an air diffuser and perforated metal plates, all without significant modifications. Computational fluid dynamics simulations showed a remarkably improved velocity uniformity (0.35 m/s to 0.04 m/s, as evidenced by the velocity standard deviation) in the 10 flow channels. These simulation results were consistent with the experimental results, wherein the velocity standard deviation reduced from 1.38 m/s to 0.13 m/s. Moreover, multi-gas plasma ignition for up to six gas species and high-flow-rate plasma generation of up to 1000 L/min were achieved. These results provide the foundation for developing DBD technologies for practical applications in high-flow-rate gas treatment, particularly for controlling indoor air pollution.

Development and Validation of a Methodology to Measure Exhaled Carbon Dioxide (CO2) and Control Indoor Air Renewal

The measurement of carbon dioxide (CO2) has emerged as a cost-effective and straightforward technique for indirectly managing indoor air quality, aiding in the reduction of the potentially pathogen-laden aerosol concentrations to which we are exposed. Unfortunately, inadequate practices often limit the interpretation of CO2 levels and neglect methodologies that ensure proper air renewal. This study presents a novel methodology for measuring and controlling indoor CO2 levels in shared spaces, comprising four stages: analysis, diagnosis, correction protocols, and monitoring/control/surveillance (MCS). This methodology underwent validation in practical settings, including a cultural center (representing spaces with uniform activities) and 40 commercial spaces (with diverse activities) in Zaragoza, Spain. The results indicate the feasibility of swiftly implementing measures to enhance shared air renewal, with the immediate opening of doors and windows being the most direct solution. The proposed methodology is practical and has the potential to mitigate the risk of the aerosol transmission of respiratory diseases. Consequently, we anticipate that this work will contribute to establishing methodological foundations for CO2 measurement as a valuable, standardized, and reliable tool.

Electrospun‐SiO2‐Nanofiber‐Reinforced Cellulose Aerogel Loaded with ZIF‐67 for Air Filtration and Formaldehyde Adsorption

AbstractIndoor air pollution, which is detrimental to the human respiratory, nervous, and cardiovascular systems, is of increasing concern because considerable time is spent indoors. Thus, there is an urgent need to develop improved methods for controlling indoor air pollution. In this study, electrospinning and freeze‐drying methods are used to prepare a cellulose–silica nanofiber (C‐SNF) aerogel loaded with zeolitic imidazolate framework‐67 (ZIF‐67) for use in indoor air purification systems. The C‐SNF aerogel doped with 0.75 wt.% SiO2 nanofiber (SNF) exhibits a maximum compressive stress of 8.7 MPa, which is higher than that (6.4 MPa) of a pure cellulose aerogel. The compressive modulus of the aerogel exceeds 85% of its original value after 100 compression cycles. The C‐SNF aerogel exhibits a filtration efficiency of 99.91% against 0.3 µm salt particles at 32 L min−1, which is higher than that of the pure cellulose aerogel (51.25%). Moreover, a stable removal efficiency of 99.92% toward 2.5 µm particulate matter (PM2.5) is observed after ten cycles. Notably, the addition of ZIF‐67 to C‐SNF (ZIF‐67@C‐SNF) aerogel by in situ growth method resulted in a porosity of 92.3% and formaldehyde removal of 93.75%. The ZIF‐67@C‐SNF aerogel can be used in various applications including indoor‐air and adsorptive‐filtration masks.

Predicting the energy consumption of a VRF heat pump using manufacturer performance data and limited experimentation for dynamic data collection

The variable refrigerant flow (VRF) air conditioner is widely used because it can control indoor air conditioning units individually, allowing for efficient energy use. However, accurately modeling a VRF system is challenging because of its complex operating mechanism. Despite this challenge, manufacturers often only provide basic system information that adheres to regulatory standards, and they do not typically disclose detailed product specifications. In this study, for describing actual VRF system operation and estimating system performance reasonably, calibrated catalog-based performance estimation model is proposed using a small amount of experimental data. The proposed model uses a machine learning method to predict the power input of a VRF via the XGBoost algorithm. The results show that the prediction performance of the proposed model has an R2 higher than 0.9 and root mean squared error (RMSE) less than 0.2, whereas the typical catalog-based model has an R2 of 0.07 and RMSE of 0.54. The proposed model using only 20 % or more experimental data collected during the 12 h period outperforms the existing catalog-based model significantly.

Non-uniform state-based Markov chain model to improve the accuracy of transient contaminant transport prediction

Rapid prediction of indoor airborne contaminant distribution is crucial for controlling indoor air quality. Markov chain technology, which uses matrix multiplication, is computationally efficient in this field. The combination of computational fluid dynamics (CFD) with Markov chain technology has gained significant attention among researchers. The partitioning of the indoor zone directly affects the size and values of the transition matrix, which is the core of the Markov chain and impacts both the cost and accuracy of calculations. Although coarse matrix Markov chain models incur relatively lower computational costs, effective methods for state partitioning are lacking. This study proposes an improved method for non-uniform state partitioning based on velocity to enhance the computational accuracy of Markov chain models with coarse matrices. First, we used the airflow velocity field obtained by CFD simulation to divide the states and obtain non-uniform states. Subsequently, we obtained the transition matrix corresponding to non-uniform states and applied it to the Markov chain model for predictive calculation. We compared the predictive results of the non-uniform state-based Markov chain model with experimental and CFD simulation data, which showed that the model had a good predictive performance for transient contaminant transport and that the non-uniform state partitioning method improved predictive accuracy. Additionally, we discussed the effects of different numbers of states and time steps on computational accuracy.

Investigation on Energy Use in Passive Design House at High Altitude Climate in Malang City, Indonesia

Indonesia is a tropical climate, hence building controlling air ventilation and humid condition have been a challenge to meet residents’ convenience. It is often energy usage that is majorly used to control indoor air climate circulation. The passive design has recently received increasing attention as an option to reduce energy consumption and abate carbon footprint by taking advantage of local climatic conditions of building features. This pilot study seeks to identify the relationships between real energy consumption data and building design data. A dwelling house located in Malang, Indonesia was selected as a sample building for the study which introduces a method to use real energy consumption data to calculate the extra energy use related to tropical indoor thermal conditions. The 24 h observation result was validated through interviews with residents, before analyzing with criteria of ideal climate conditions from the literature study. This study also presents relationships between the increase in mean daily energy consumption data and trends of humidity building design data. In conclusion, this present study establishes the starting point for exploring all features affecting the tropical climate benefits of passive design for building energy efficiency.

Sick building syndrome in air-conditioned museum

ABSTRACT Exposure to indoor contaminants in air-conditioned buildings can cause serious health effects to their occupants. The failure to control indoor air contaminants is one of the factors that contribute to poor indoor air quality (IAQ) and is a major contributor to sick building syndrome (SBS) symptoms. This study aims to investigate the relationship between the maintenance of mechanical ventilation and air conditioning (MVAC) that is installed in museums towards IAQ and SBS. Data were collected through site visits and observations with a combination of field measurements and a questionnaire survey. The field measurements results show that several locations in the museums were in a state of heat discomfort. The recorded measurement of air velocity was very low and the average level of HCHO concentrations are above the permissible level. The correlation test between the satisfaction level of MVAC maintenance on IAQ and SBS also shows significant relationships, indicating that MVAC maintenance in the museum affects the comfort and health of the occupants.

A Review of Portable Air Cleaner Devices: Purification Processes, Performance Standards, and Effectiveness in Controlling Indoor Air Pollutants

Background and Objective: Indoor air pollutants are among the five most important environmental health risks. In recent years, concerns regarding indoor air quality in buildings have increased. This review has investigated studies conducted on portable air cleaners. Materials and Methods: After determining the keywords, conducting comprehensive searches in the internet databases, and taking into account the inclusion and exclusion criteria, a complete review was conducted to obtain the latest findings and the general trend of the studies. Results: Portable air cleaner devices are very diverse and are divided based on the type of technology used. Many standards have been developed to evaluate the performance of these devices in different countries, but none of them cover all aspects of performance. The effectiveness of these devices in removing VOCs is between 20% and 80%, depending on the type of technology and other influencing factors, and their effectiveness in removing suspended particles is between 70% and 95% on average. Furthermore, their efficiency in controlling COVID-19 is reported to be above 80% in cases where HEPA filters with grades 13 and above are used. Conclusion: Devices equipped with the HEPA filtration process have been found to be very effective in controlling indoor suspended particles. The use of devices equipped with UVGI, plasma, and ozone technologies should be accompanied by caution due to dangerous by-products.

Indoor Air Pollution Monitoring System

This work presents an investigation of indoor air pollution using a combination of biomedical engineering (BME) sensors and indoor air sensors. Indoor air quality is a significant factor affecting human health, and monitoring and controlling indoor air pollution have become essential for indoor environ- mental quality management. In this study, BME techniques are employed to analyze indoor air pollutants, and an indoor air sensor is used to measure and monitor the indoor air quality in real-time. The study involves the deployment of a network of sensors in an indoor environment, data collection, and analysis using machine learning algorithms. The results show that the combination of BME and indoor air sensors is an effective approach for detecting and mitigating indoor air pollution, and provides valuable insights for the development of indoor air quality management systems. This study contributes to the growing body of research on indoor air quality and provides new strategies for improving indoor air quality and safeguarding human health.

Development of Smart Air Purifier for Reducing Indoor Particulate Matter

Indoor air quality is crucial to observe because most people spend 90% of their time in the room. Indoor air quality is influenced by various parameters, especially PM 2,5, from a mixture of air outside and inside the room itself. If the occupants are exposed to this parameter continuously, it will affect the occupant’s health significantly. Hence, it is necessary to control indoor air quality if this parameter exceeds the specified quality standards. One technology to reduce PM 2,5 is an air purifier. Air purifiers are generally composed of an exhaust fan, HEPA filter, and pre-filter. One of the air purifiers’ evolution is the smart-air-purifier. Smart-air-purifier can automatically adjust the speeds of the fan so as can minimizes electricity costs. The designed smart system can classify PM 2,5 concentration based on fuzzy logic to flow rate settings using pulse width modulation (PWM). In addition, to analyze the performance of the smart air purifier, we test it in a chamber. The test results show the performance of the smart air purifier in reducing PM 2,5, the clean air delivery rate measurement of the smart air purifier, and its power consumption which can minimize 67.42% of electricity use than commercial air purifiers.

Evaluating the Feasibility of Hybrid Ventilation in Educational Spaces: A Simulation Study in the Basque Country Climate

Abstract This paper delves into the examination of indoor comfort in classroom environments and its interplay with ventilation on human wellbeing in scenarios of varying indoor carbon dioxide concentrations. The assessment of these parameters was done according to the provisions outlined in the Spanish national Regulation of Thermal Installations in Buildings (RITE). This study also compares various ventilation strategies, namely natural, mechanical and hybrid ventilation, commenting the pros and cons of each method in the climate of the Basque Country, Spain. To do so, a classroom in the School of Architecture in the Basque Country was modelled in thermal simulation software. Simulations were carried out for full days in 10-minute intervals using Design Builder and considered three different exterior scenarios (a cold day, temperate day, and a warm one) and three different ventilation systems (natural, mechanical with simple flux, and hybrid). Two additional scenarios where added for control, one with no ventilation at all and another with a partial, constant, natural ventilation, like was done during the COVID-19 pandemic. Thus, the natural ventilation option was evaluated under four conditions (windows always closed, windows constantly open 15 %, COVID-19 mode, and windows operated by thermal sensation of the user). The mechanical system evaluated consisted of a constant flux ventilation for IDA 2 IAQ with an air flux of 12.5 L/s per person. The modelled hybrid system consisted in a combination of simple flux mechanical ventilation and open windows and doors under some particular conditions. An occupancy rate of 50 % of the theoretical maximum occupancy of the classroom and a scheduled heating operation were considered. This article presents the CO2 concentration, energetic balance and thermal comfort results obtained in the simulation and compares between the different scenarios. The results showed that the hybrid ventilation system was able to effectively control indoor air quality, providing a healthy and comfortable environment for occupants. The hybrid system demonstrated improved energy efficiency compared to the natural ventilation system, while maintaining an acceptable indoor air quality. Overall, the results of this study highlight the importance of considering hybrid ventilation in educational spaces in the northern Basque Country climate. The study provides valuable insights for building design and operation, especially for renovation of existing schools and educational facilities that lack any means of mechanical ventilation, showing some of the potential for hybrid ventilation to improve indoor air quality and energy efficiency.