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© 2019 Chipozya Tembo Silungwe, Josephine Mutwale Ziko and Edward Jims Sakala. This open access article is distributed
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American Journal of Engineering and Applied Sciences
Original Research Paper
Identification of Retrofits Needed in Old Office Buildings to
Achieve Thermal Comfort
Chipozya Tembo Silungwe, Josephine Mutwale Ziko and Edward Jims Sakala
Department of Construction Economics and Management, Copperbelt University, Kitwe, Zambia
Article history
Received: 23-08-2019
Revised: 24-08-2019
Accepted: 13-09-2019
Corresponding Author:
Chipozya Tembo Silungwe
Department of Construction
Economics and Management,
Copperbelt University, Kitwe,
Zambia
Email: chipozya@yahoo.co.uk
Abstract: Building designs normally are made to offer a given level of
comfort to occupants without any mechanical intervention. However, with
the advent of global warming temperatures globally have been seen to rise
making the occupants of most buildings uncomfortable. The immediate
solution has been to add mechanical ventilation, which comes at an added
cost of installation and running a building. A case study of old office
blocks was used to determine the natural aspects of ventilation that can be
utilized on existing old buildings to improve thermal comfort of the
occupants after establishing the discomfort. The findings indicate that
most office occupants have discomfort due to poor ventilation. This can
be minimized with the use of high solar reflectivity roofing, appropriately
colored walls, skylights, increased number of air vents and wide windows
which are appropriately positioned.
Keywords: Natural Ventilation, Offices, Thermal Comfort, Zambia
Introduction
Climate change mainly in the form of global
warming has resulted in most buildings not being
comfortable thermally when used in their original design
hence the need for adaptation. Adaptation should be
focused on institutional (hostel, health, education,
social/cultural) and commercial (hotel, retail, office,
administration) buildings rather than usually short-lived
industrial types of buildings (Bengtsson et al., 2007). It
is inevitable that structures age and outgrow their
original functions. With changes in technology and
lifestyle, construction and design are constantly updated
to meet modern demands and older structures are left in
the wake of change (Clark, 2008). The planet is
experiencing climate change with an increase in
temperature being experienced in most places making
thermal comfort for the occupants more important than
ever. Retrofitting an existing building can oftentimes be
more effective than building a new facility to attain
thermal comfort for occupants. Since buildings consume
a significant amount of energy (40 percent of the nation's
total U.S. energy consumption), particularly for heating
and cooling (32 percent) and because existing buildings
comprise the largest segment of the built environment, it
is important to initiate energy conservation retrofits to
reduce energy consumption and the cost of heating,
cooling and lighting buildings while promoting thermal
comfort for occupants in the final analysis. This study
focused on how old buildings could be retrofitted using
natural means or by design to promote thermal comfort
for occupants. The study sought:
To identify factors contributing to thermal
discomfort experienced by occupants
To identify the nature and impact of the discomfort
experienced by office occupants.
To identify the preference measures to be
implemented to promote natural thermal comfort
The organization of the paper in the next section
outlines briefly the literature relevant to the study, the
methodology that was used is given in the preceding
section, then findings are presented and discussed. Finally
a conclusion and recommendations of the study are given.
Literature Review
Old Buildings
Buildings are thought of as being very permanent
structures. After all, most cities are filled with buildings
that are hundreds of years old and in some cases, much
older and just like everything else they depreciate over
time. They have life cycles and they need to be regularly
maintained and periodically renovated in order for them
to survive. Although there is no standard definition for
“old buildings”, Bengtsson et al. (2007) states that “a
large number of structures constructed around the 1970s
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are in need for maintenance. Old buildings are
characterized by old ventilation systems, cracks, wear
and tear and in need of renovations and maintenance.
While new builds on the other hand tend to be energy
efficient and as a result provide better thermal comfort to
occupants. Many of the old buildings were created at a
time when environmental standards were much lower
and little or no consideration was given to sustainability.
As a result, there are now many opportunities to retrofit
existing buildings with sustainability-enhancing
technology, delivering efficiency benefits for owners and
tenants alike (Lendlease, 2017) and improve the thermal
comfort for the occupants.
According to Bengtsson et al. (2007) the inventory of
non-residential buildings suggest that climate change
adaptation should be focused on institutional (hostel,
health, education, social/cultural) and commercial (hotel,
retail, office, administration) buildings rather than usually
short lived industrial types of buildings. This criterion
undoubtedly suits this case study which falls within the
description of old buildings of commercial nature. When
older buildings are compared to the new buildings, older
buildings seem to hold qualities that have since been lost
in modern designs such as historic qualities and as the
management of older buildings remains one of the major
challenges cities face as they try to make urban
environments more sustainable, investing in an innovative
solution is more important than ever (Lendlease, 2017).
Elefante (2007), emphasized the importance of dealing
with the existing building stock. Quoting then-current
statistics about the proportion of existing versus new, a
point was made that no amount of new green construction
can get us where we need to go if we ignore existing
buildings: ideally “four out of every five existing
buildings will be renovated over the next generation while
two new buildings are added”. This is because it may
sometimes be more economical to renovate than to
demolish and rebuild. Therefore, it is often during
renovations that retrofits are introduced to improve
thermal comfort, modernize and thereby making old
buildings more energy efficient.
Retrofitting and Thermal Comfort
Retrofitting refers to the addition of new technology or
features to older systems, the improving of existing
buildings with energy efficiency equipment. Whilst the
National Refurbishment Centre (2012) defines the term
Retrofitting as “the installation of individual or multiple
energy efficiency measures to an existing building”. An
energy efficiency measure is any technology that improves
the energy performance of the building, such as loft
insulation, advanced heating controls and renewable energy
generation technologies. The later definition of retrofitting
is adopted for this study as the focus is to make existing
buildings more energy efficient with the occupant in mind.
Thermal comfort is the condition of mind which
expresses satisfaction with the thermal environment
(Lim, 2012). From the aforementioned thermal
comfort is difficult to define because a range of
environmental and personal factors need to be taken
into account when deciding on the temperatures and
ventilation rates that make individuals feel
comfortable. The best that can be realistically
achieved in any situation is an environment, which
satisfies the majority of people.
Climate change, which is both an increase in long-term
average temperatures as well as an increase in climate
variability, is due to an increased concentration of
greenhouse gases in the earth’s atmosphere has a lot to do
with thermal comfort. As documented in the fourth
assessment report of the IPCC (2014), the emissions of
greenhouse gases have increased by 78% from 1970 to
2011, due to human activities. The increased greenhouse
gas emissions have led to an increase in the greenhouse
gas concentration in the earth’s atmosphere, which traps
some of the sun’s heat. The well-observed impacts of this
increased greenhouse gas concentration is an increase in
the earth’s global average surface temperature, increase in
sea levels and last but not least the melting of the Northern
Hemisphere’s snow cover (IPCC, 2014).
Warming of the urban environment in summer is a
particular issue of concern for human health, due to
the risk of excess heat stress. Climate change is
projected to increase summer day and night-time
temperatures and will also intensify the urban heat
island effect in cities. Adapting cities to climate
change is therefore a high priority for urban planners
and designers (Cavan and Aylen, 2012).
In October 2016, the Zambia Meteorological
Department (ZMD) (2016) reported the unusual
maximum temperatures of 40 and 41°C in some parts of
Zambia as compared to other times were the highest
recorded temperatures in October has been 37°C, with the
lowest recorded temperatures at 9°C (George, 2017).
These hot-temperature regimes were associated with the
hot-dry and hot-wet seasons Zambia recorded its hottest
temperatures in history, October 13, when the mercury
recorded 42.4°C (108.3°F) in Mfuwe. The previous
record was 42.3°C (108.3 F) set on November 17, 2005.
Throughout the month of October daytime temperatures
will generally reach highs of around 32°C (90°F), at
night the average minimum temperatures drops down to
17°C (63°F) (Ibid).
General comfortable conditions for people working
indoors performing light sedentary work are as follows,
between 20 and 26 degrees Celsius, depending on the time
of year and clothing worn, relative humidity 30-60%,
optimal air movement 0.1-.05 m/s (naturally ventilated) and
0.1-0.2 m/s (air-conditioned) (Bjorn, 2017). When people
are dissatisfied with their thermal environment, not only is it
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a potential health hazard, it also impacts on their ability to
function effectively (CIOB, 2017). Human health is
particularly sensitive to climate and weather patterns
because many diseases in the tropics are associated with
temperature and precipitation changes. One of the ways to
achieve thermal comfort is through natural ventilation.
Natural Ventilation
Ventilation should be controllable by the occupants.
Individual control of ventilation improves the user
satisfaction. This means that individual means of
controlling the thermal comfort should be provided.
Operable windows provide one way to control ventilation
and should be provided, particularly, if climatic conditions
and location of building are favorable for natural
ventilation (CIB, 2004). According to Hazim (2010)
natural ventilation is where the airflow in a building is as
a result of wind and buoyancy through openings or
cracks within the building envelope. Zhai et al. (2015);
Normura and Hiyama (2017) further posit that natural
ventilation should be efficient enough to reduce building
energy need and improve indoor air quality.
Natural ventilation efficiency and building thermal
comfort are affected by both internal and external factors
(Cai Feng and Wai Ling, 2010). Internal factors are
majorly dependent on openings control setup and building
designs and can be varied or engineered for the desired
conditions (Wikipedia, 2017) while external factors
include building orientation, location and prevailing
weather conditions. These are usually natural and
constrained. Some of the mechanisms used to control
thermal comfort include the following listed below.
Opening Controls
Adoption of manual control of windows is to have
the window opening and closure left to the occupants.
Windows in this strategy are opened by the occupants
this usually happens whether or not the outside
temperature is above the inside temperature. Though
considered the lowest cost option, a challenge in this
strategy is that at times occupants neglect or forget to open
and close the windows when the outdoor conditions vary
in an unpredictable manner hence leading to thermal
comfort problems (Window, 2012). Zhai et al. (2015)
notes that for openings to be effective more than one is
required. Further, the openings should be positioned in a
way that minimizes obstructions if much air flow is
needed and vice versa if not much air is needed. The
occupants’ neglect of either failing to close or open
openings could be circumvented with automated opening
systems which should be operated with a temperature
control setting in mind to be effective.
Automated Window Control
In automated window control, an automatic window
control device is installed on the window (s). This device
has a temperature sensor set to a set point temperature
that opens the windows when the inside temperature is
higher than the outside temperature and closes the
window when the inside temperature is lower than the
outside temperature (Carrilho et al., 2003). Here
windows can be opened to a variable width depending
on the change in inside temperature. Of paramount
importance in opening window opening systems are the
desired window to wall ratios that are normally set by
standards that normally required in building regulation.
Window Wall Ratio (WWR)
According to Marino et al. (2017), Window-to-Wall
Ratio (WWR) also known as window area is considered
as a very important parameter affecting the thermal
performance of a building. WWR is usually measured as
the percentage area determined by dividing the building’s
total glazed area by its exterior envelope wall area.
Optimized window design is vital in achieving thermal
comfort with no additional financial investment and a
reduction on dependence on air conditioning coupled with
reduction of discomfort periods are realized (Ibid).
Lighting Control
As a method of reducing internal loads generated from
lights, electric lights can be controlled (Design Builder,
2010). Daylight luminance level in a zone depends on
many factors, including sky conditions, sun position and
location, size and glass transmittance of windows, window
shades and reflectance of interior surfaces (Hazim, 2010).
Lights should be properly positioned and selected to
ensure that they do not interfere with the thermal comfort
of occupants. Apart from the walls, the roofing system
also plays a significant role in promoting thermal comfort.
Roofing Sheet Type
The excessive heat transferred through the roof is one
of the main causes of thermal discomfort in warm
humid/tropic climatic conditions, which prevail in the
tropical zone. Therefore, the selection of the most
appropriate roof orientation and materials will be
important for desirable thermal performances of passive
buildings (Jayasinghe et al., 2003).
Thermal Insulation
There are many different types of thermal insulation
materials, e.g., loose fills, rock wool and boards. The
materials acts as a barrier, which slows heat flow in the
summer and heat loss in other seasons, but it is only
effective where there is a temperature difference between
the inside and outside of the building or between two areas
inside a building (Todd and Cue, 2013). If a significant
proportion of people are experiencing discomfort in a
work area for a long period of time the causes of the
discomfort should be investigated (Nigel et al., 2009) as
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thermal discomfort often times contributes to poor
productivity. It is evident that the coating of external
surfaces with cooling painting will contribute to the
reduction of cooling demand. However, in locations with
high solar radiation, the application of reflective coatings
may counteract the performance of the building envelope
during the cold season period, as the building may not
take advantage of the excess insulation (Ibid).
Wind
Lechner (2015); Olgyay (1963) asserts that desirable
air movements should be utilized for cooling in hot
periods and as a relief from vapor pressure during times
of high absolute humidity. Conversely, air movements
should be blocked and avoided during the cold season as
air movement affects body cooling (Ibid). Air movement,
does not decrease temperature but causes a cooling
sensation due to heat loss by convection and due to
increased evaporation from the body. As velocity of air
movement increases, the upper comfort limit is raised.
However, this rise slows down as higher temperatures
are reached. Wind therefore plays a significant role in
promoting thermal comfort.
Thermal Adaptive Categories
There are basically three categories of thermal
adaptation; these are physiological adaptation,
psychological adaptation and behavioral adaptation
(Susana, 2011). Others considerations that shape a persons
for adaptation include culture, gender and thermal
expectations. Therefore, thermal comfort is a controversial
issue that becomes even more controversial when
investigating thermal satisfaction in a group of people
working in a common space, such as the occupants of an
office building (Fanger 2001).
According to De dear and Brager (2001) the
adaptation is based on the idea that outdoor climate
influences indoor comfort because humans can adapt to
different temperatures during different times of the year.
The adaptive hypothesis predicts that contextual factors,
such as having access to environmental controls and past
thermal history can influence building occupant’s
thermal expectations and preferences.
Numerous researchers have conducted field studies
worldwide in which the survey building occupants about
their thermal comfort while taking simultaneous
environmental measurements. Analyzing a database of
results from 160 buildings revealed that occupants of
naturally ventilated buildings accept and even prefer a
wider range of temperatures than their counterparts in
sealed, air-conditioned buildings because their preferred
temperatures depends on outdoor conditions
(ANSI/ANSHRAE 2013). These results were incorporated
in the ASHRAE 55-2004 Standards as the adaptive comfort
model (ANSI/ANSHRAE 2013).
Methodology
A case study approach is more appropriate when the
researcher wants to understand an organization’s
phenomena within their real-life contexts (Stake, 2000;
Yin, 2003). The case study for this research focused on
the Copperbelt University specifically the School of the
Built Environment and School of Business office blocks.
The Copperbelt University is a public higher learning
institution located in Kitwe (Copperbelt province),
Zambia. It was established by the act of parliament in
1987 (Southern African Regional Universities Association,
2014). The University is ranked second in Zambia after the
University of Zambia. The two schools under the university
(case studies) have different office partitions and sizes. The
reason for selecting the old (School of Built Environment
SBE) and new building (School of Business SOB) is the
nature of the study since its focus is on the retrofitting of old
structures for thermal comfort adaptability, which has a
parametric basis. The School of the built environment has
19 office spaces with a majority of naturally ventilated
offices, while the school of business studies has 16 office
spaces to be considered, which brings our total population
to 35 offices. Judgmental sampling was used in sampling
considering mainly orientation of offices.
Guidelines outlined in the ASHRAE 55 were used as
guides in determining margins of human thermal comfort.
ASHRAE states that thermal comfort inside buildings is
achieved when indoor environmental conditions satisfy
80% of office occupants, owing to the fact that it is
practically impossible to please all the occupants even some
of the time. Literature has defined the meaning of common
terms in thermal comfort. These have been broadly debated
and defined in ASHRAE-55 2010 (ASHRAE, 2004) and
ISO-7730 1995 (EN ISO, 1995), such as:
1. Thermal comfort: Condition of mind, which
expresses satisfaction under certain thermal
environments
2. Acceptable thermal environment: When at least 80%
of the occupants would agree that the thermal
environment is acceptable
3. Thermal sensation: A conscious feeling graded into
seven categories: cold, cool, slightly cool, neutral,
slightly warm, warm and hot
The main primary data collection tools were a two part
survey questionnaire, an observation checklist and
photographs. A total of 19 questionnaires for school of
built environment and a total of 16 questionnaires for
school of business were administered to the office
occupants, bringing the total of questionnaires to 35, with
a success rate 95% returned, hence making the sample
representative and the inference can be made from it valid
for analysis and generalization to similar cases. Data were
analyzed, mainly using frequencies and content analysis.
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Fig. 1: Case a school of built environment
Fig. 2: Case b school of business
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Characteristics of the Case Study
The Copperbelt University offices were used as cases
to determine the nature of the discomfort and the
necessary solutions needed to promote thermal comfort.
The offices comprised of two separate cases built at
different times one in 1979 Case A (SBE) (Fig. 1) and
the other in 2008 Case B (SOB) (Fig. 2). The School of
the built environment, which has 19 office spaces with a
majority of naturally ventilated offices, while the school
of business studies has 16 office spaces to be considered
on the ground floor, which brings our total population to
35 offices. Offices for SBE are single storey with
asbestos roof with a pitch of no more than 22 degrees.
The ceiling is particle board painted white with PVA
paint. The walls are 200mm concrete block-work
covered in cement mortar plaster (roughcast external
walls) and the windows are single glazed with 4 mm
clear glass except for toilets. The school has two
buildings the first building is tiled with ceramic tiles and
building two has PVC tiles. The interior of both
buildings is painted with white with PVA paint the
exterior is finished in ruff cast for School of Built
Environment (SBE) and School of Business (SOB). For
the school of business, the office blocks are also single
stored though some offices are located at the bottom of
double storey buildings. The walls are 200 mm block
wall and floor is terrazzo. The roofing is IT4 painted
green with a particle board ceiling painted white.
Results and Discussion
Response Rate
A structured questionnaire was used to obtain data
and the response rate for SBE was 17/19 0ffice
representing 90% of the occupants while for the SOB all
16 office occupants responded representing 100%
response rate. Therefore, the validity of the office
occupants thermal discomfort could be considered valid
as the response rate was high as shown in Table 1.
Temperature Changes for the Case Study
The data from the Copperbelt university
meteorological station, for the year 2016 and 2017,
months of October showing the minimum and maximum
temperatures fluctuations is illustrated below in Fig. 3 and
4 and analyzed.
To understand and assess the impact of climate change
on the universities office occupants fully, it’s important to
first know the thermal comfort trends and the comfort zone
temperatures for Kitwe or the Copperbelt University, using
Humphrey’s comfort equation. The relationship between
the indoor thermal comfort and outdoor mean temperature
presented by Humphrey’s equations are used to define the
ranges of the indoor thermal comfort for Kitwe for the
Naturally Ventilated Buildings (NVB). For naturally
ventilated buildings: Tc = 11.9+0.534 Tm, Where Tc is the
comfort temperature and Tm is the mean outdoor
temperature. A comfort zone within which temperatures
are generally acceptable can be taken to extend some 2-3°C
either side of this optimum temperature.
Comfort Temperature Equation:
11.9 0.534Tc Tm
where, Tc is comfort temperature, Tm is the monthly
mean temperature which in this case is for October 2016
and October 2017.
Therefore:
11.9 0.534 16.12
21
Tc
Tc C
This is the comfort zone, temperature for the
Copperbelt University 2016.
So once we add the 2-3 on either sides this comes to
24°C and 18°C as the Comfort temperatures for 2018:
11.9 0.534 18.03Tc
Tc = 22°C (Comfort Temperature, October, 2017)
19°C and 25°C, after removing -3 and adding +3.
It can be seen that even after adding and subtracting
the allowance the comfort temperatures are partially
within the recommended range.
This is the comfort zone, temperatures for the
Copperbelt University 2017. Findings indicate an increase
of 1°C in climate change between the year 2016 and 2017
and this is projected to increase the hot-season day and
night-time temperatures even more as shown by literature,
this will cause the urban heat effects to intensify with higher
temperatures, henceforth adapting the two case studies to
climate change is a high priority for the Copperbelt
university, if such devastating effects of climate change on
thermal comfort are to be eliminated.
As established from the equations, 21°C and 22°C is
the preferred comfortable temperature for the Copperbelt
University (Kitwe) for the years 2016 and 2017
respectively. Further analysis shows that from the year
2016 to 2017 there has been an increase in the comfort
temperatures of 1°C degree Celsius, this might not be a
significant number but it’s a very huge increase in terms
of temperature increase and this clearly shows that the
comfort levels for people are clearly decreasing with
increase in comfort temperature levels. Further analysis
shows that temperatures have been high on average as far
as 41°C Celsius which is far more beyond the comfort
temperatures of 21°C and 22°C degree Celsius. Should the
temperatures increase beyond the comfort temperatures,
this will result in thermal discomfort.
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Fig. 3: Minimum and maximum temperature changes for October 2016
Fig. 4: Minimum and maximum temperature changes for October 2017
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Table 1: Response rate
No. of questionnaires No. of questionnaires
Respondents Sample size Distributed received Response rate
School of Built Environment (SBE) 19 19 17 90%
School of Business (SB) 16 16 16 100%
Total 35 35 33 94%
Air velocity, on the other hand, did not appear to
significantly predict thermal comfort scores, as it was
within the recommended range of 0.1 and 1.5 m/s.
Previous thermal comfort research has shown that
psychological variables can be even more important than
environmental variables in predicting thermal comfort
(De Dear and Brager, 2001). Given that air velocity is just
one of the four physical environmental variables that
could affect thermal comfort (Fanger, 2001) and that
there might be other psychological factors that were
influencing thermal comfort during the time of the
survey, it is likely that the effects of air velocity might
have been masked by these other variables.
According to Yeang (2006) air movement of 1 m/s
will reduce an air temperature of 30.25C to an effective
temperature of 27.25C. Ceiling fans, which uses a sixth
of the amount of energy as air conditioning, would be a
good strategy to supplement natural ventilation if the
required rate of natural ventilation is too low (Yeang,
2006; 215; Heiselberg et al., 2002).
Dissatisfaction of Occupants
Slightly more than half (56.92%) of the office
occupants were clearly dissatisfied with the temperatures
in their workspace. The high temperatures are as a result
of increase of 1°C in temperatures between the year 2016
and 2017. This is further projected to increase during the
hot-season day and night-time. This has caused the urban
heat effects to intensify with higher temperatures leading
to high discomfort levels. From the findings of this
research the following impacts were identified from the
increase in temperature:
Increased occurrences of overheating in offices, due
to the rapid increase in temperatures
As outside temperatures become higher, the
potential to provide cooling with comfort ventilation
falls off, resulting in higher discomfort levels
Higher levels of unproductivity, since the environment
has become unconducive due to the thermal discomfort
Higher demands for cooling (space) design
mechanisms leading to high maintenance costs as
more energy is being used for cooling
Majority of the office occupants 78.79% (SBE
57.58% and SOB 21.21%) surveyed agreed that thermal
discomfort disrupts their productivity whilst 15.15% did
not agree that thermal discomfort disrupts their
productivity. Notably the majority of the respondents
that disagreed (9.09%) and strongly disagreed (6.06%)
are those that occupy the Air-conditioned offices as they
stressed the point that, they are able to adjust the air-
conditioner to suit their needs at a particular moment or
rather throughout the year.
The major consequences as articulated by the office
occupants was fatigue, dizziness, sweating, drowsy,
headache, fan blowing hot air for those that use the fan
for ventilation, gasping for air and sweating in the early
hours of the day especially in the school of built
environment. In the Air-conditioned Offices, the main
cause of thermal discomfort was lighting as most
demanded the increase of the window size (height and
widening the windows). Other effects of thermal
discomfort mentioned included Sickness and reduction
in Self-esteem due to Body odor this was articulated by
some office occupants.
The findings have further showed that 76.47% (13
out of 17) respondents from the School of Built
environment identified too little air movements in the
offices resulting from poor cross ventilation and this is
supported by the by the fact 41.18% of the windows in
the school of built environment are dysfunctional and on
occasion there is no cross ventilation due to the design
and surrounding buildings. On the contrary, the school of
business has 100% functional windows and as a result
less than half of the occupants 43.75% (7 out of 16
respondents) stated the presence of too little air
movements and this explains the higher comfort levels
by SOB office occupants. With these findings, this
research has concluded that adapting old buildings at the
institution will contribute to the thermal comfort of
office occupants moreover Jomehzadeh et al. (2017)
point out that global warming currently threatens
mankind hence an emphasis on natural cooling which
could also reduce energy consumption of buildings.
Factors Contributing to Thermal Discomfort
Thermal sensation levels are shown in Fig. 5 for both
cases. Discomfort levels from the School of Built
Environment can be attributed to many factors namely:
Poor ventilation, due to blocked air-vents and lack
of air-vents for some offices
58.82% dysfunctional windows while the school of
business has 100% functional windows
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Poor lighting in more than half of the offices (56%)
where lighting systems are dangling and so close to
the office work station
Poor window shading mechanism systems from
offices in the school of built environment;
Lack of sustainable design features of the
building envelope e.g., trees and other buildings
blocking ventilation
Discomfort levels in the school of business are
attributed to increase in temperature and poor cross
ventilation in a few cases and blocked air vents. Clearly
both designs seem to need some improvements for
enhancing thermal comfort as it has been argued that
design plays a primary role in promoting performance
compared to other features such as floor area (Normura
and Hiyama (2017).
Preferences for Promoting Thermal Comfort
School of Business Needs and Preferences
School of Built Environment office occupants (Fig.
6) needs and preferences are blinds as indicated by 10 out
of 17 respondents (58.82%), 8 out of 17 want their
windows widened for a thermally comfortable working
environment. There was an equal preference for air vents
and window awnings of 41.18% 7 out of 17 respondents
(41.18%) and in like manner the need for skylights and
aluminium doors was 29.41% (5 out of 17
respondents) and on the contrary, double glazed
windows was the least preffered and needed
mechanism with a score of 5.88% (1 out of 17
respondents), to mention but a few. Air-conditioning
score of 88.24% was recorded, however it should be
noted this research is centred on natural ventilation
and air-conditioning was incorporated only to show
comparisons and substantiate the results between the
two case studies.
Similarly, as can be seen from the Fig. 7, the School
of Business office occupants voted 62.5% (10 out of 16
respondents) in need of air-conditioning and followed by
blinds which scored 56.25% (9 out of 16 respondents).
This difference could be attributed to the fact that most
people in the school of business have more supportive
thermal comfort mechanisms such as blinds, proper
curtains, operable windows and clear air vents, this can
also be seen from Fig. 1.
A comparative analysis between the two schools
clearly shows that the demands from the school of
business are lower as opposed to the school of built
environment. The school of built environment has few
windows that open and close and most of them are in
a very poor state and need immediate attention.
Fig. 5: Thermal sensation
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DOI: 10.3844/ajeassp.2019.420.431
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Fig. 6: SBE preferences
Fig. 7: Preferences for thermal comfort for SOB office occupants
Chipozya Tembo Silungwe et al. / American Journal of Engineering and Applied Sciences 2019, 12 (3): 420.431
DOI: 10.3844/ajeassp.2019.420.431
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Table 2: Proposed improvements
Feature Proposed improvement
Wall (block work) Increase number of Air vents, paint external walls
white for a solar reflectivity of 50%-90%
Windows (pressed steel with single clear glazing) Blinds, Widen windows, roller shades and curtains,
Window awnings, functional windows
Doors (Flush for interior) Aluminum glass doors and windows
Roof (asbestos (SBE) and IT4 (SOB) Install cooling tiles with high solar reflectivity index and
emittance, install high solar reflectivity roofing as opposed
to asbestos, Skylights such as or corrugated roof type
Such windows showed the presence of rust and are
sticky and can hardly open. In light of all this,it is
clearly noticeable that the school of built environment
exhibit more needs and such magnitude of needs
symbolises lack of such thermal comfort enhancers and
mechanisms which further entails that the office
occupants are not thermally satisfied.
Recommendations for Promoting Thermal Comfort
Table 2 summarizes the interventions that can be
implemented to promote thermal comfort from the two
cases studies as suggested by occupants.
Conclusion
At a global level rising temperatures have impacted the
human habitant negatively due to climate change. The
study has revealed that the occupants are experiencing
thermal discomfort attributed mainly to poor ventilation
resulting in poor productivity and increased cooling costs
through the use of fans and other mechanical means. In
view of this use of high solar reflectivity roofing,
appropriately colored walls, skylights, increased number
of air vents and wide windows that are appropriately
positioned has been recommended. However, as this was a
case study these recommendations can only be applied to
buildings with similar design and climate conditions.
Further research can be done on the cost implications of
the proposed recommendations.
Acknowledgement
All the respondents for research from school of Built
Environment and School of Business.
Author’s Contributions
The following were the contributions made by the
authors.
Chipozya Tembo Silungwe: Contributed to
conceptualization, supervision and manuscript preparation.
Josephine Mutwale Ziko: Helped in the development
of the literature.
Edward Jims Sakala: Responsible for conducting
research and analysis.
Ethics
Authors should address any ethical issues that may
arise after the publication of this manuscript.
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