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NEW FRONTIERS IN PASSIVE VENTILATION OF
STUDENT HOSTELS IN HOT-HUMID TROPICAL
ENVIRONMENTS: A Design Strategy for
Effective Passive Ventilation.
*Uzuegbunam F.O.
Abstract
To conserve fossil-fuel energy and to resources and reduce the incidence of man-made causes of global warming,
calls for application of effective natural ventilation design strategies in the student hostels. The aim is to evaluate
the effectiveness of passive ventilation of student hostels in the hot-humid tropical environment of Eastern
Nigeria. It went further to improve on it as it was found to be ineffective. The objectives were as follows: (i) to
determine the nature of passive ventilation in Student Hostels in the hot-humid tropical environment arising from
different design strategies in the study area, (ii) to determine if there was any significant difference in the
effectiveness of passive ventilation of the building arising from western and southern orientations, (iii) to
determine if there were significant correlations between design strategies and passive ventilation in the Student
Hostels in the study area. This study adopted experimental research, in combination with descriptive survey, and
ex post factor correlated case study research methods. First hypothesis yielded an F-value of 21.639 at less than
0.05 significant levels. It was therefore rejected. Correlation analysis was used to tested the second hypothesis.
Ventilation against the design of Drew and Fry hostel scored 0.27. Ventilation variables against Ekwueme hostel
scored 0.18 and it scored 0.49 against Ogbuefi hostel. The study concluded that there were significant
correlations between design strategies and passive ventilation in the student hostels of the study area.
Key Words:
Environment.
Design Strategy; Effective Passive Ventilation; Student Hostels; Hot-Humid; Tropical
Background to the Study
Concerns over climate change and the reduction of high emissions of green house
gases have become the bases for the exploitation of suitable alternatives to which
Passive Ventilation is one of the strategies for indoor thermal comfort and Cooling of
student hostels in the tropics (Rajapaksha 2004). Ventilation is defined as the supply
of outside air to indoor and the replacement of vitiated air. Ventilation is required
among other needs, to supply sufficient oxygen for respiration and maintenance of
safe carbon dioxide concentration within acceptable limits. It is also required to
control odors and to maintain conducive thermal environment indoor (Chand 1976).
Provision of ventilation for physiological comfort is required in hot humid climates,
and either thermal mass or evaporative cooling for body cooling with night
ventilation for structural cooling is required, also in hot humid climate (Arens and
Watanabe, 1986; Lechner, 1991).
*Department of Architecture, University of Nigeria, Enugu Campus.
[email protected] +2348037093582
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The Tropical Environment
STATEMENT OF THE PROBLEM.
The obviously harsh climatic and high thermal conditions of the student hostels in
Nigeria have raised doubts and fear as to the possibility of adequately providing a
design strategy for effective passive ventilation that will cater for such needs in hot
humid tropical environment without resorting to active ventilation and cooling
systems such as the use of mechanical appliances (Uzuegbunam, 2011). Based on
literature reviewed and the field investigations, it was inferred that there was poor
application of design strategies for effective Passive Ventilation of buildings in hot
humid tropics. This resulted in overheating the in-doors of buildings like student
hostels in the hot humid tropical environment(Uzuegbunam, 2011). Indrika
Rajapaksha (2004) stated that in thermal point of view, design strategies in
modifying the indoor overheating is of greater significance in promoting passive
cooling in the tropical environment, and recommended natural ventilation as an
appropriate Passive system.
AIMS OF THE STUDY
The aim of this study is to evaluate the effectiveness of post occupancy passive
ventilation of student hostels in the hot-humid tropical environment of Enugu
campus of the University of Nigeria. It went further and investigated the design
strategies popular in this climatic region, with two major prevailing wind
conditions, controlling the hot-humid and the dry cold weather conditions, and
their effectiveness in passive ventilation of student hostels of the study area.
OBJECTIVES OF THE STUDY
?
To determine the nature of passive ventilation in student hostels in the hothumid tropical environment in the study area.
?
To determine if there is any significant difference in the effectiveness of
passive ventilation of the hostel buildings arising from the western and
southern orientations.
?
To determine if there are significant correlations between design strategies
and passive ventilation in the hot-humid tropical environment in the study
area.
?
To collect empirical micro climatic data for this zone and to determine the
appropriate ventilation design strategies and criteria, for their physical
application in the study area.
RESEARCH HYPOTHESES
The following hypotheses were formulated for this study:
Ho1:
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There is no significant difference in the ventilation in Student Hostels on a
New Frontiers In Passive Ventilation of Student Hostels in Hot-humid Tropical Environments: A Design
Strategy for Effective Passive Ventilation.
typical tropical still day in Nigeria, from the acceptable global standard.
Ho2:
There is no significant relationship between design strategy and effective
passive ventilation in Student Hostels in hot humid tropical environment of Nigeria.
SIGNIFICANCE OF THE STUDY
The significance of the research is as follows:
?
The empirical evidence on causal relationships between passive ventilation
systems and the application of the design strategies in the study area was
established.
?
The study also highlighted an effective Passive ventilation system by
effective application of appropriate mitigation strategy for passive
ventilation of student hostel in the tropical environment.
?
This study, therefore, became significant as it filled this essential void in
literature. The result of the study will also help architects and designers to
become better able to identify and use the effective ventilation systems to
improve ventilation and thermal comfort in student hostel designs.
SCOPE OF THE STUDY
This study was spread around two major categories.
?
The first category covers the review of the trend and tact of modern
ventilation design strategy and climatic activity with regards to the building
envelope.
?
The second area covered research on climatic zone of the hot humid tropical
environment of Enugu, Enugu State of Eastern Nigeria.
LIMITATIONS OF THE STUDY
?
This research was mostly geared towards architectural solution; the
parameters for experimental tests were limited to the fundamentals.
?
The experimental equipments available for the tests only produced results
for indoor air temperature, indoor air velocity, indoor relative humidity,
outdoor air temperature, outdoor air velocity and outdoor relative humidity
values.
?
The experiments were limited to the fundamentals, so the research did not
include study on materials assessments, but utilized available data for
simulation and tests.
AREA OF THE STUDY
This research was specifically concerned with Effective Passive Ventilation of
student hostels in the hot humid tropical environment of Nigeria. The student hostels
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The Tropical Environment
owned privately and publicly in the University of Nigeria, Enugu campus, Enugu
State of Nigeria was used for the case study specifically. Nigeria derived its name
from the Niger River, which is one of the most prominent physical features on the
map of the country. Nigeria is the most populous country in Africa, with a population
figure of over 150 million inhabitants. The land mass of Nigeria lies in Latitudes
N9.0328° north of the Equator and Latitude E7.2920° east of the Greenwich
Meridian. Nigeria shares boundary on the west with the Republic of Benin and on the
east with the United Republic of Cameroon. At the north-eastern tip, Nigeria shares
water board with the Republic of Chad on the lake. The northern boundary is shared
with the Republic of Niger. The southern coast lines are on the Gulf of Guinea of the
Atlantic Ocean. See fig. 1.2
UNIVERSITY OF NIGERIA
University of Nigeria was established to have in place a functional, globally
competitive and research focused University, which is not just an ivory tower, but
responsive to the needs of society while delivering world class education and
knowledge. It was expected to be in the forefront of research and development,
innovation, knowledge transfer and human resource development in the global
academic terrain, while promoting the core values which will ensure the restoration
of the dignity of man. It has two campuses, the main campus at Nsukka and the
Enugu campus where the study hostels are located. The Enugu campus of the
University lies at latitudes N6.2528° north of the Equator and latitude E7.3022° east
of the Greenwich Meridian. It has nine hostels of three typologies which were
presented in this ventilation study. The student population in Enugu campus is about
five thousand seven hundred and seventy out of which only three thousand six
hundred and sixty seven are house on campus in the nine hostels of the three
typologies. See fig. 1.3 & 1.4.
THEORETICAL FRAMEWORK
?
Climate is the regular pattern of weather conditions of a particular place or an
area with particular weather conditions.
?
It is the interaction between the Sun, land, and water throughout the year that
results in what is called weather. These interactions produce daily, as well as
seasonal temperature, humidity, and wind patterns that vary substantially
between locations even in close geometric proximity.
?
Climate as an inevitable member of nature has effects that are sometimes
unpredictable. The climate of an enclosed space is determined in thermal
comfort parameters as the logical factor of the enclosure itself. It is made up
of the indoor air temperature, indoor air velocity and indoor air relative
humidity (Uzuegbunam, 2011).
54
New Frontiers In Passive Ventilation of Student Hostels in Hot-humid Tropical Environments: A Design
Strategy for Effective Passive Ventilation.
Definition of Ventilation
Ventilation is usually defined as the supply of outside air to the interior, for air motion
and the replacement of vitiated air. It is needed (i) to maintain carbon-dioxide
concentration of air within safe limits and to provide sufficient oxygen content in air
for respiration, (ii) to control odor, (iii) and to maintain satisfactory thermal
environment indoors (Chand, 1976). Burberry (1979) stated that ventilation is the
change or movement of air within buildings. Sue Roaf et al (2004) defined
ventilation as the movement of air within a building and between the building and the
outdoors.
Different Types of Ventilation
Ventilation can be achieved through natural (PASSIVE) or mechanical means
(ACTIVE). This research limited itself to natural ventilation systems only.
Natural ventilation is controlled by two factors: pressure variation due to wind and
stack effect due to temperature difference between air inside and air outside a
building.
SUMMARY OF LITERATURE REVIEW.
A literature search was conducted on a design strategy for effective Passive
ventilation of Student Hostels in the hot humid tropical environment, in order to
provide a sound base for investigation of innovative and dedicated efforts of the
current state of the art, and to identifying potential case study buildings. The review
also presented results of the climate characteristics and building conditions of the
region, to identify any potential barrier issues that might limit the application of
natural ventilation systems and passive cooling, such as building code requirements.
Natural ventilation systems have been studied and increasingly applied in Europe
Watson(1982), (RIBA 1965), in Iran Santamouris (1998), in Malaysia by Rahman
(1999), Rajapaksha (2004, 2003, 2002), Kwok (1998) in Hawaii Cheung (1999) in
Hong Kong, in India by Kukreja (1970), in Nigeria, Godwin (1988), Izomoh (1988),
Komolafe (1996, 1988), Uji (2002) just to mention but a few. This study undertook
significantly, ventilation systems adapted in the design of student hostel buildings for
passive ventilation in the hot humid tropical environments.
DESIGNING WITH THE CLIMATE
? The climate change in terms of global warming has some inevitable effect on
human comfort as we have longer dry seasons and warmer weather now,
which are very unpredictable.
?
The climate integrated design is a strategy that seeks to take advantage of the
climatic issues like temperature, humidity, rain fall and wind patterns to
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The Tropical Environment
New Frontiers In Passive Ventilation of Student Hostels in Hot-humid Tropical Environments: A Design
Strategy for Effective Passive Ventilation.
produces a positive effect and reflection on an architectural design of a
building (Uzuegbunam, 2011).
is structuring of the investigation, for the purpose of identifying variables and their
relationship to one another.
CONCEPTUAL FRAMEWORK
The Concept of this work was organized to satisfy the desired goal of determining the
effectiveness of the design strategies for passive ventilation of student hostels in the
hot-humid tropical climate. It created an efficient and cost effective comfortable way
to effectively and passively ventilate the student hostels in this study area. This was
based on consideration of alternate organizational concepts. It included all the
factors which may influence the study, such as the natural, social, cultural, visual,
and functional requirements. Observing what people did and the way they did it
determined the bases for this organizational concept. Activities that required
considerable interaction and repeated communications were programmed in a
compact and centralized space on single but communicable levels. Centralized
locations were appropriated for activity spaces or activities that are most often used
by the majority (Uzuegbunam, 2011). Ventilation and Exhaust system, which is also
BernoulliVenturi effect, was the base design strategy applied for the indoor
ventilation. The cooling and preservation of the air quality was also by induced
stack-effect within the building. The apertures were compartmentalized in modules
and the operation very flexible. This made it possible to control or closed them on a
very cold day where heating is required. This was very desirable because of the hot
temperatures and high humidity of the hot humid tropical zone, experienced most of
the year.
POPULATION OF STUDENTS AND HOSTELS IN THE STUDY
The population of this study comprised of all the boarding students in the hostels of
University of Nigeria, Enugu Campus above, in the hostels owned by the Institution
or privately owned, numbering about three thousand, six hundred and sixty seven
(667) students in (9) hostels.
RESEARCH METHODOLOGY
This discussed the research method used in the study, experimental procedure and
methods employed in analyzing the data. Specifically, the procedure took into
consideration the following:?
Research Design
?
Student Population in the Hostels of Study
?
Sample and Sampling Technique
?
Data Collection Method
?
Methods of Data Analysis
?
Evaluations of Strategies for Solution
RESEARCH DESIGN
Research design is a kind of road map that guides the researcher in the investigation,
and formats which the researcher employs in order to systematically apply the
scientific method, in the investigation of the research problem. Also, research design
56
SAMPLE AND SAMPLING TECHNIQUE
The samples consisted of 10% of total number, of each prototype of the student
hostels, made up of Males, Females and Under Graduate and Post Graduate students.
In all, one from the five hostels, of Drew & Fry, one from the three hostels of
Ekwueme & Associates, and the only privately owned hostel designed by Ogbuefi &
partners, each representing the different groups and typologies. The stratified
random sampling technique was used to obtain the samples for this study. This means
that the hostels were randomly selected in the appropriate sample types.
DATA COLLECTION
The data collection methodology for the research experiments for this work was
categorized sequentially into three steps stated as follows; Building typology
information as one of the base cases for the research was collected from literature and
experimental models. Building fenestrations and apertures information as one of the
base cases for the research was collected from the thermal/ventilation adaptive
experimental models. Building orientation data was collected as one of the base
cases which the experimental models will directly address and was utilized in the
comparative analysis together with the other base cases. Micro-climatic data and
related information on Passive ventilation systems as it affects student hostels in the
Tropics, with emphases on Enugu, and the University of Nigeria, Enugu Campus
Hostels was collected by the researcher at the field, using the equipments. Mesoclimatic data as it relates to the zone for a period not less than ten years, for
concurrency and comparative studies. This information was obtained from the
Nigerian Meteorological Agency (NIMET), Abuja.
METHODS OF DATA ANALYSIS.
?
For the development of an absolute measurement to architectural design
strategy, definite answers to the following questions are useful. Firstly, how
can design strategy be meaningfully and precisely measured? Secondly, what
variables are appropriate for the measurement of these effects?
(Uzuegbunam, 2011)
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New Frontiers In Passive Ventilation of Student Hostels in Hot-humid Tropical Environments: A Design
Strategy for Effective Passive Ventilation.
The Tropical Environment
?
The answers to the above questions provided the basic framework for the
statistical analyses of this research. The methodology for precise
measurement of the effectiveness of the design strategy involved
development of a measuring index or scale for quantification of architectural
design strategy in absolute terms (Uzuegbunam, 2011).
?
The climate of an enclosed space has been defined as the logical factor of the
enclosure itself, which is made up of the indoor air temperature, indoor air
velocity and indoor air relative humidity (Uzuegbunam, 2011).
?
For the purpose of this exercise, it was hypothesized that design strategy can
be more meaningfully and precisely measured using a composite index of
known indoor climatic factors, created by the design strategy
(Uzuegbunam, 2011).
Based on this assumption, the climatic factors of indoor air movement or velocity,
indoor temperature and indoor relative humidity factors were reduced statistically
using Principal Component Analysis (PCA), into one factor that could be called
Room Climate. Any change in the value of any of the factors or the principal
components that produced that climate will result in a different PCA factor. Changes
in any of these variables, wind velocity, temperature and humidity will automatically
create a different room climate (Uzuegbunam, 2011).
INPUT SYSTEM
The input consists of two categories of data, climatic data and the related information
that was gathered in the stages of this work, through existing data banks (secondary
data) already available on passive cooling and natural ventilation systems in the hot
and humid tropical environments of Enugu in the Eastern Nigeria. Another set of data
was gathered by using building physics measuring equipments (Digital
thermometer, Thermo-anemometer and Infrared thermal sensor) to measure air
temperature, relative humidity and air velocity (primary data). Field investigations
were conducted and simulations performed in PHOENICS-VR simulation program.
OUTPUT SYSTEM
?
The base cases in the experimental models were simulated for the two
seasons of the year, namely, rainy and dry seasons.
?
The results from the simulations and field investigations with the subsequent
climatic data were collected.
?
They were analyzed using graphical analysis, statistical mode and charts, for
the detailed report on Passive ventilation in hot humid Tropics.
PROBLEM IDENTIFICATION
The information that came out of the output system was used to identify the major
58
problem sources for Passive Ventilation of student hostels in hot-humid tropics,
alongside the seasonal wind directions. Both Base Cases and Simulations were used
to show the significance, through evaluation of the possible application of design
strategies, if improved Ventilation could be possible under some conditions, made
possible by building orientation, building morphology, openings into the building,
maximal external wall exposure, wind speed in combination with stack effect for
thermal comfort by passive cooling in hot humid tropical environment.
EVALUATION OF STRATEGIES FOR SOLUTION
Based on the output that came out of the base case results and simulations, the
objective for passive Ventilation of student hostels, and to enhance passive cooling of
Student hostel by the physical building Designs were identified.
Also on these results obtained, design guidelines in terms of Design typology was
produced under different combinations as against the different climatic conditions.
See Table 1
Typology selection criteria:
The selection criteria utilized for identifying the study samples was generated
through a typology study of the hostel buildings in the campus. These criteria
characterized the buildings types as models each of which assumes similar
characteristics with others in the same category. A general survey of the hostel
districts presented a mostly gentle topography for the entire built environment. This
suggests that airflow conditions which impacted on the buildings will present similar
receptive effects within the same archetype. The typical properties considered for the
archetypes included. See fig 1.5
1.
2.
3.
4.
Layout similarity (building form)
Orientation similarity
Volume
Architectural characters (building façade characters)
Experimentation and Evaluation of the Two Seasonal Wind Directions (Rainy
and Dry)
Field survey was conducted on the three main hostel typologies selected for this
study. The aim of this survey was to collect experimental data for the relevant climate
studies and analysis of these hostels. The analysis determined the performances of
these buildings on the following parameters; Air temperature, Humidity and Air flow
(air velocity)
Each of the hostel types were evaluated on this parameters and measurements were
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The Tropical Environment
New Frontiers In Passive Ventilation of Student Hostels in Hot-humid Tropical Environments: A Design
Strategy for Effective Passive Ventilation.
taken with specific measuring points observed for each case. The measuring points
were as follows:
Room air temperature measured at 1.2 meters above the ground at the center of each
of the rooms selected for the survey. The 2nd floor and the most middle positioned
rooms were used for the survey in order to get the most efficient location for clear
exposure to that particular outdoor climate conditions.
Room Humidity measured at 1.2 meters above the ground at the center of each of the
rooms selected for the survey.
Room air velocity - measured at 1.2 meters above the ground at the center of each of
the rooms selected for the survey.
season, while the dry season wind was normal. This pattern which probably occurred
due to deflection of wind direction by terrain, vegetation, building cluster, climate
change and other environmental factors contribute greatly to the problem of effective
harvesting of the natural airflow during the rainy season. Further research is required
to further investigate the influence of climate change and other factors on the wind
patterns in our environments. This will assist in providing adequate and accurate
information for the building professionals. The CFD simulation performed using the
wind path information in Tables 2 and 3 produced the actual behavior of the air
movement around the hostel buildings in University of Nigeria, Enugu Campus as
shown in the figures 1.10 and 1.11.
Problem Identification
Evolution of solution
RAINY SEASON EXPERIMENTS
Outdoor climate measurements measured at the roof level (i.e. at about 12.6m above
ground).
Fig 1.12 shows roof plan and roof vent design using Bernoulli' Principles to aid stack
effect.
These floor plans show a design of a building with similar treatment on every side
and equal ventilation potentials in the design considerations for harvesting the wind,
no matter the directions, the paths may be, with also possibility for stack induced
Bernoulli's effect in the core with recommended minimum number of floors and
height for effective performance. Fig 1.13 shows Architectural representations of
Bernoulli's principles induced stack in the atrium with the warm vitiated from the
high level air inlet vents of the rooms, rise to the roof and out through the roof vents
and out of the building, generating current by temperature gradient. Table 4 & 5
show the Factors, used in Principal Compound Analysis (PCA) that was applied to
the climatic factors of the south wing of the Post Graduate Hostel Rooms
(Temperature, Wind velocity and Relative Humidity) for a common factor. The
Factor analysis was used to bring all the factors to one common factor. This common
factor was to represent the climatic effect of that part of the building which is the
result of the design strategy applied for that aspect of the building. Table 6 shows the
result of Factor analysis, using Principal Compound Analysis (PCA) as was applied
to the climatic factors of the west wing of the Post Graduate Hostel Rooms
(Temperature, Wind velocity and Relative Humidity) for a common factor that was
here called PG-West Climate. The Factor analysis was used to bring all the factors to
one common factor. This common factor was to represent the climatic effect of that
part of the building which is the result of the design strategy applied for that aspect of
the building.
From the Data presented, Previous literature on the climatic classifications of Nigeria
classify the Nigeria wind pattern into the northwards (SW) moist air between April- October
and the southward (NE) dry air between November-March coming from the north. The wind
part was found not to be universal, consistent or in consonance with the given period for
rainy season. That made orientation, a major factor in wind driven passive ventilation system
inconsequential and irrelevant as the wind could not be properly harvested. See Table 2 and
Fig 1.10.
From this investigation, a number of conclusions relating to the appropriateness of
hostel orientation in this region can be drawn. It was therefore evident that the
building orientation may be the major factor that was restraining passive ventilation
from the outdoor flow. Within this context, only the east facing wing of the PG hostel
and those not shielded from the pressure of the wind can effectively apply passive
ventilation controls for indoor comfort during this season as the pressure of the wind
is shield from other structures by structures before them as shown in wind parts
above and the wind pressure diagram below.
Therefore for the majority of these hostels, ventilation was significantly restricted
below acceptable standard by the design strategy with little or nothing on still days as
the wind pressure was significantly reduced. For Ho1 the answer is in the affirmative,
yes there is a significant difference between them
DRY SEASON EXPERIMENTS
This information on Table 2 and 3 has been the background for all passive design
solutions and building orientation for Nigerian professionals. Measuring at the
height of 12.6m, the wind paths recorded presented a different pattern for the rainy
60
RESEARCH HYPOTHESIS 1
Ho1: There was no significant climatic difference in passive ventilation of the student
hostels arising from western and southern orientations.
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Test of Hypothesis No. 1
The principal component analysis was also used to obtain the climatic factors of PGWest and PG-South. These climatic factors were compared using analysis of
variance technique (ANOVA). One way ANOVA was utilized to test the hypothesis
above with the aid of SPSS. The result of F value in the ANOVA conducted for PG
hostel (Drew&Fry) was 21.639, with 0.00 level of significance The result of ANOVA
was very high and the percentage level of significance was above 95%. This
therefore rejected the Null hypothesis (Ho1) which stated that (there was no
significant climatic difference arising from west and south building orientations
differences. Thus accepting the alternative hypothesis stating that, there was
significant climatic difference arising from west and south building orientations
differences. The implication was that building orientation in conjunction with
microclimate had a serious impact in climatic differences. Sustainable architecture
should be design to adapt to variation in climatic differences that may arise at
different seasons of the year. See Table 7
RESEARCH HYPOTHESIS No. 2
Ho2: There were no significant correlations between design strategies as determine
by climatic effects and passive ventilation in the students hostel in hot humid tropical
environment of the study area.
Test of Hypothesis 2
The study applied correlation analysis with the aid of SPSS to empirically determine
the levels of correlation. The result of the correlation analyses were presented and
analyzed in the table below. Based on the correlation result, the Null hypothesis
which stated that there were no significant correlations between design strategies as
determined by climatic effects and passive ventilation in the students hostel in hot
humid tropical environment of the study area was rejected. Thus, the study firmly
concluded that there were significant correlations between design strategies as
determined by climatic effects and passive ventilation in the students hostel in hot
humid tropical environment of the study area. The levels of the correlations are
presented and discussed in Table 8.
SUMMARY OF THE FINDINGS
The orientation of buildings along particular axis is no longer tenable because of the
unpredictable nature of the wind path. The critical unpredictable properties of the
wind paths in the micro climates of the tropical environments makes it imperative for
a rethink of the predetermined standards for buildings in this region.
The work of Cheung (1999) also revealed the influence of surrounding buildings. He
reported that despite the abundant free wind for natural ventilation in Beijing, the
12m x 12m demonstration Building, located between two other higher buildings, in
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New Frontiers In Passive Ventilation of Student Hostels in Hot-humid Tropical Environments: A Design
Strategy for Effective Passive Ventilation.
Vanke City Garden, could not enjoy natural ventilation also.
This was in agreement with this finding and reinforces the need for re-engineering
and re-tooling towards an appropriate design strategy for effective passive
ventilation in the student hostels in hot humid tropical environment.
The concept of wind driven ventilation system, particularly cross ventilation, seem
to be novel, but the principles around the concept are no longer tenable with the
unpredictable nature of the wind paths and still days which have significant negative
effect on wind driven passive ventilation system in buildings in hot humid tropics.
Contribution to Knowledge
This study was able to objectively and scientifically contribute to knowledge, by
determining for the first time, the effectiveness of the different design strategies and
typologies in passive ventilation of student hostels in the hot-humid tropical
environment of the study area.
Also the study provided empirical data which was originally unavailable on this
micro climatic zone.
The effectiveness of the different application of ventilation design strategies and the
unpredictable wind paths of the study area were established for comparison and use
by other researchers and designers.
It was also disclosed that orientation, which was the most significant factor of wind
driven ventilation system was no more plausible as the wind paths were
unpredictable, unreliable and not universal.
Finally, the study provided the answers to the design strategy that could militate
against every of the possible scenario in hot-humid tropical environment and also
determined their effectiveness in the study area.
CONCLUSSION
In conclusion, there exists a growing concern about energy use in Nigeria and the
world over.
Nigeria, with its rapid growth of student population and hostel developments, the
rising energy cost, coupled with the emission of fossil fuel, the building sector is and
will continue to be a major energy end user.
Since the critical unpredictable elements of the hot-humid microclimatic zone of the
study area, contradicted efforts in producing or utilizing the set of predetermined
standards for the buildings in this region, innovative façade designs which are geared
towards climate active principles should be encouraged.
The concept of cross ventilation system may be novel, but the principles around the
concepts seem significantly impracticable for such environments as the UNEC
hostel region.
The statistical data confirmed the effectiveness of the different design strategies for
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The Tropical Environment
passive ventilation in student hostels and the appropriate design strategy for
mitigation. This if correctly applied with the other determinants like apertures, could
mitigate the effect.
It was established that there was significant relationship between applications of
design strategy and effective passive ventilation in Student Hostels in hot humid
tropical environment of the study area.
Thus, there was need for re-engineering and re-tooling towards a design strategy for
effective passive ventilation in student hostels in hot humid tropical environment of
the study area.
RECOMMENDATIONS
Further research is required to investigate the influence of climate change and other
factors on the wind patterns in our environment. This will assist in providing
adequate and accurate information for the building professionals in passive
ventilation of buildings. The microclimate of a building site can make or mar a
climate responsive design strategy. The proper study of wind path can effectively
provide options for an effective design strategy and technique for an adequate
passive ventilation of buildings in hot humid tropical environment, like the study
area.
High-level windows for the leeward, inside of the building should be provided for
both wind and stack effect as the design situation might warrant.
Roof vents and other ventilation inducing techniques should be incorporated as a
design strategy for wind driven in combination with stack ventilation systems.
Multi-storied buildings are recommended for maximal wind harvest and improved
stack.
Maximized wind harvest inlets should be provided on every external wall for
variable wind direction.
SUGGESTIONS FOR FURTHER STUDIES
i. The effect of global warming and climate change on the wind paths on the hot
humid tropical environments.
ii. The effect of sitting new hostel buildings within the existing sites without regards
to the wind paths and its effect on the ventilation of the old and new buildings.
iii. The cause of the change in wind paths of this micro climate.
New Frontiers In Passive Ventilation of Student Hostels in Hot-humid Tropical Environments: A Design
Strategy for Effective Passive Ventilation.
REFERENCES
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APPENDICES
List of Table captions
Table 1. Hostel typology grouping
TYPE [A]
Drew & Fry Hostels
TYPE [B]
Ekwueme Hostels
Roaf S., Fuentes M. and Thomas S. (2004) ECOHOUSE 2: Architectural Press,
Linacre House, Jordan Hill, Oxford OX2 8Dp, 200 Wheeler Road,
Burlington, MA 01803.
Adelabu hall
Kenneth Dike hall
Santamouris M. (1998) Natural Ventilation in Buildings. A Design Guide. London:
James & James (Science Publishers) Ltd.
Manuwa hall
Mbonu Ojike hall
TYPE [C]
Ogbuefi Hostel
(New Female
Hostel)
Schulze F. (1989) Mies Van der Rohe: a critical biography. 1989.
Tablada A, De la Pena A.M, and DeTroyer F. Thermal Mass of Natural Ventilatied
Buildings in Warm Humid Climates; Field Survey. PLEA 2005. Beirut.
Source: Author's Field Survey
Table 2
Tablada A, Barcelo C, and DeTroyer F. Micro-climatic Measurements in the Belen
Area of Old Havana and the three Courtyard Buildings: Comparison with
the Meteorological Station Data. PLEA 2004. Eindhoven, 1131-1136.
Tantasavasdi C., J. Srebric, Q, Chen (2001) Natural Ventilation Design for Houses in
Thailand. Thailand: Energy and Buildings. 33,8,815-824..
Uji Z. (2002) Evolution of Design Thought. Yola: Paraclete Publishers.
Uzuegbunam F. O. (2011) Towards a Design Strategy for Passive Ventilation of
Student Hostels in Hot-Humid Tropical Environment of Enugu Campus,
University of Nigeria. Unpublished Ph.D. Thesis 20011.
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Von Meiss P. (1991) Elements of Architecture, from Form to Space. Lausanne,
Switzerland: Chapman and Hall. I-10
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New Frontiers In Passive Ventilation of Student Hostels in Hot-humid Tropical Environments: A Design
Strategy for Effective Passive Ventilation.
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Sources:
Source:
Sources:
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New Frontiers In Passive Ventilation of Student Hostels in Hot-humid Tropical Environments: A Design
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Table 7
Sum of
Squares
Between
Groups
List of Figure captions
ANOVA of Drew & Fry Hostel
(Combined)
Linear Term
Unweighted
Mean Square
F
Sig.
8.761
8.761
21.639
.000
8.761
8.761
21.639
.000
8.761
8.761
21.639
.000
5.263
.405
Weighted
Within Groups
Total
14.024
Source: Author's Field Work (SPSS Correlation Analysis Result 2010)
Table 8. Correlation Variables Results of Ventilation and different design
Strategies
S/N
Correlation Variables
1
Ventilation against Drew & Fry
2
Ventilation against Ekwueme
3
Ventilation against Ogbuefi
4
Drew & fry against Ekwueme
5
Drew & fry against Ogbuefi
6
Ekwueme against Ogbuefi
Very High
Score
High
Score
Moderate
Score
.
Low
Score
0.271
0.176
Fig 1.2 Map of Enugu within the
context of Nigeria and Africa
0.494
0.905*
0.611*
-0.406
Source: Author's Field Work (SPSS Correlation Analysis Result 2010)
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New Frontiers In Passive Ventilation of Student Hostels in Hot-humid Tropical Environments: A Design
Strategy for Effective Passive Ventilation.
Fig 1.3 Map of University of Nigeria, Enugu Campus
(Source; Department of Geoinfomatics and Surveying, UNEC)
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The Tropical Environment
The following principles were considered for the typology grouping.
New Frontiers In Passive Ventilation of Student Hostels in Hot-humid Tropical Environments: A Design
Strategy for Effective Passive Ventilation.
Typology [A] Nkuruma Hall (PG Hostel) Designed by Drew & Fry.
A. Layout system or building form
Ground floor plan
Typical floor plan (1st and 2nd floors)
B. Building orientation principles
C. Volumetric principles
D. Architectural character
Fig 1.5.
Considering these principles, the hostel building types were categorized into the
following typologies:
76
Fig 1.6: Nkuruma Hall . Source: Author's Field Survey
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New Frontiers In Passive Ventilation of Student Hostels in Hot-humid Tropical Environments: A Design
Strategy for Effective Passive Ventilation.
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Typology [B] Lady Ibiam Hostel (UG Hostel) Designed by Ekwueme &
Associates.
st
Ground floor plan
Typical floor plan (1st, 2nd and 3rd floors)
nd
rd
Fig. 1.9 Typical floor plan (1 , 2 and 3 floors)
Presidential hostel details (New Female Hostel)
Source: Author's Field Survey
Fig. 1.8. Lady Ibiam Hall details. Source: Author's Field Survey
Typology [C] Presidential hostel (New Female Hostel) Designed by Ogbuefi
& Partners
Fig. 1.10
78
Fig. 1.11
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New Frontiers In Passive Ventilation of Student Hostels in Hot-humid Tropical Environments: A Design
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