**2.2 Natural ventilation in educational buildings**

Educational buildings are usually segmented into rooms with a number of people involved in various activities when in use. Thermal comfort in these buildings is important for the convenience of the occupants. Ventilation designs of educational buildings are based on factors such as the projected number of


### **Table 2.**

*Recommended amount of air to provide acceptable indoor air quality.*

#### **Figure 2.**

*Mode of natural ventilation: (a) natural ventilation due to pressure difference. (b) Natural ventilation due to temperature difference [27].*

In a study carried out in Denmark to measure indoor climatic conditions in classrooms [31], a comparison of different ventilation systems was done (**Figure 4**). The results obtained revealed that mechanical ventilation and natural ventilation with added exhaust fan performed better than the other systems. This indicates that the basic passive ventilation using window may not be adequate for educational

*Denmark study classrooms: (a) classroom with automatically operable windows and exhaust fan;*

From other studies it has been observed that 30 students in a classroom would produce about 2.3 and 2.7 kWh of heat per hour and 500 litres of CO2. These are indoor loads that need to be removed to improve the thermal comfort and IAQ of

the classroom. Adequate classroom ventilation will solve these issues [32].

The research was conducted at Olabisi Onabanjo University, College of Engineering and Environmental Studies, Ibogun Campus, Ifo, Ogun State, Nigeria located 240°SW on the Longitude 3.0990 and latitude 6.8080. The location has an annual average temperature of about 28.5°C and wind speed of about 4 m/s. The average relative humidity is about 63%. The study was performed in the selected

buildings and may require the aid of other systems.

*(b) mechanically ventilated classroom [31].*

**3. Methodology**

**3.1 Study area**

**83**

**Figure 4.**

**Figure 3.**

*Selected (overcrowded) lecture hall.*

*Computational Analysis of a Lecture Room Ventilation System*

*DOI: http://dx.doi.org/10.5772/intechopen.92725*

occupants and ambient conditions such as average temperature and relative humidity. In many places like Nigeria, power considerations require that energy consumption in these buildings should also be kept as low as possible. This may require the use of natural or passive ventilation which is strongly dependent on the airflow circulation pattern within room spaces, which can be achieved by temperature differences (buoyancy forces) or pressure differential between two points (**Figure 2**) [27]. Adequate ventilation in educational facilities is of great importance as reviews of previous studies in school environments [28–29] shows that there are inadequacies in the indoor air quality (IAQ) in many classrooms leading to higher risk of health-related issues especially in preschool environments. It was also noted that this problem is predominant in developed countries. However, the same challenges are encountered in developing countries especially during the hot season where classrooms are mostly overcrowded (**Figure 3**). In a study in China to improve the ventilation design of school buildings [30], it was noted that despite the fact that school buildings are actually designed for natural or mechanical ventilation, inadequate ventilation occurs. Furthermore, during hot season and due to crowded classrooms the ventilation system becomes inadequate thus affecting learning. It is therefore inferred that in tropical regions and developing countries where natural ventilation is being used, the number of students in a classroom, the outdoor temperature and the activities in the lecture hall affects the ventilation performance of the lecture hall.

*Computational Analysis of a Lecture Room Ventilation System DOI: http://dx.doi.org/10.5772/intechopen.92725*

**Figure 3.** *Selected (overcrowded) lecture hall.*


#### **Figure 4.**

occupants and ambient conditions such as average temperature and relative humidity. In many places like Nigeria, power considerations require that energy consumption in these buildings should also be kept as low as possible. This may require the use of natural or passive ventilation which is strongly dependent on the airflow circulation pattern within room spaces, which can be achieved by temperature differences (buoyancy forces) or pressure differential between two points (**Figure 2**) [27]. Adequate ventilation in educational facilities is of great importance as reviews of previous studies in school environments [28–29] shows that there are inadequacies in the indoor air quality (IAQ) in many classrooms leading to higher risk of health-related issues especially in preschool environments. It was also noted that this problem is predominant in developed countries. However, the same challenges are encountered in developing countries especially during the hot season where classrooms are mostly overcrowded (**Figure 3**). In a study in China to improve the ventilation design of school buildings [30], it was noted that despite the fact that school buildings are actually designed for natural or mechanical ventilation, inadequate ventilation occurs. Furthermore, during hot season and due to crowded classrooms the ventilation system becomes inadequate thus affecting learning. It is therefore inferred that in tropical regions and developing countries where natural ventilation is being used, the number of students in a classroom, the outdoor temperature and the activities in the lecture hall affects the ventilation

*Mode of natural ventilation: (a) natural ventilation due to pressure difference. (b) Natural ventilation due to*

performance of the lecture hall.

**82**

**Figure 1.**

**Figure 2.**

*temperature difference [27].*

*Ventilation rates for fresh air control [26].*

*Zero-Energy Buildings - New Approaches and Technologies*

*Denmark study classrooms: (a) classroom with automatically operable windows and exhaust fan; (b) mechanically ventilated classroom [31].*

In a study carried out in Denmark to measure indoor climatic conditions in classrooms [31], a comparison of different ventilation systems was done (**Figure 4**). The results obtained revealed that mechanical ventilation and natural ventilation with added exhaust fan performed better than the other systems. This indicates that the basic passive ventilation using window may not be adequate for educational buildings and may require the aid of other systems.

From other studies it has been observed that 30 students in a classroom would produce about 2.3 and 2.7 kWh of heat per hour and 500 litres of CO2. These are indoor loads that need to be removed to improve the thermal comfort and IAQ of the classroom. Adequate classroom ventilation will solve these issues [32].
