Abstract:
In recent times, the multi-story school building has emerged as a new trend in
Nigeria due to land cost in the urban area and population increase due to urban
migration resulting from insecurity in rural areas. Among other factors, the
floor level and space orientation are believed to affect its natural ventilation.
Electricity per capita consumption in Nigeria is very low, suggesting passive
ventilation in the building. The ventilation in the classroom is usually through
wind-driven systems (windows). The study sought to establish the variation of
natural ventilation among classrooms on different floor levels and orientations.
In the ex-post facto design, instruments were employed to observe wind speeds
and directions in and around selected classrooms in a school building block
with two wings on three-floor levels, a perimeter fence, and a built-up
residential area. The classrooms on the ground floor were half-opened
casement windows, while those on the upper floors had sliding windows. Data
generated were subjected to descriptive statistical analysis. In the longer wing
classrooms, the mean wind speed and standard deviation obtained were
0.17m/s and 0.123 on the ground floor; 0.15m/s and 0.104 on the first floor;
and 0.18m/s 0.126 on the second floor. Corresponding results in the shorter
wing classrooms were 0.12m/s and 0,077 on the ground floor; 0.11m/s and
0.095 on the first floor; and 0.17m/s and 0.126 on the second floor. Ventilation
coefficients were 0.13, 0.11, and 0.13 respectively on the ground, first, and
second floors in the longer wing classrooms, while those in the shorter wing
classrooms were 0.13, 0.12, and 0.19 respectively. The findings revealed some
direct variation in natural ventilation with the floor level in the studied classrooms, which was more manifested as the floor level increased upwards.
In conclusion, the floor level and orientation affect wind-driven ventilation.
There is also a need for further field studies on more suitable cases (higher
floor levels) to ascertain the level of significance of this variation and the
optimisation window area based on floor levels for orientation for wind-driven
natural ventilation.
