Current Journal of Applied Science and Technology
22(6): 1-19, 2017; Article no.CJAST.33904
Previously known as British Journal of Applied Science & Technology
ISSN: 2231-0843, NLM ID: 101664541
An Integrated Building Performance Index for
Assessing Office Buildings in Nigeria
Olanipekun Emmanuel Abiodun1*, Olugboyega Oluseye1
and Ojelabi Raphael Abiodun2
1
Department of Building, Obafemi Awolowo University, Ile-Ife, Osun State, Nigeria.
2
Department of Building, Covenant University, Ogun State, Nigeria.
Authors’ contributions
This work was carried out in collaboration between all authors. All authors read and approved the
final manuscript.
Article Information
DOI: 10.9734/CJAST/2017/33904
Editor(s):
(1) Sylwia Myszograj, Department of Water Technology, Sewage and Wastes, University of Zielona Gora, Poland.
(2) Verlicchi Paola, Department of Engineering, University of Ferrara, Via Saragat 1, Ferrara, Italy.
Reviewers:
(1) Matthew Kwaw Somiah, Takoradi Technical University, Ghana.
(2) Olatunde Folaranmi Adedayo, Federal University of Technology, Nigeria.
Complete Peer review History: http://www.sciencedomain.org/review-history/20391
rd
Original Research Article
Received 3 May 2017
Accepted 11th July 2017
th
Published 5 August 2017
ABSTRACT
Building performance is a function of a number of variables each of which is important to analyse
concurrently when conducting a POE study. The development of framework for assessing buildings
is significant as it will provide an evaluation tool for ensuring sustainable buildings. This study
developed an index for evaluating the overall performance of office buildings in Nigeria. A Total of
51 professionals in the built environment were surveyed. The data obtained were analysed using
content analysis technique, pair wise comparison (one sample t-test) and regression analysis. The
results showed that; the performance criteria which are pertinent to the performance of office
building in order of their importance were building integrity (54.54), indoor air quality (53.69), safety
and security (64.04), thermal (46.77), spatial (7.27%), visual (44.01), spatial (43.33) and acoustic
performance (43.62); priority placed by individual professional, architects rated safety and security
and building integrity (18) most important and acoustic least (9) important, builders rated IAQ and
visual performance (20) most important and building integrity (8) least important, estate surveyors
ranked safety (21) and building integrity (17) performance most important and acoustic
performance (7) least important, mechanical engineers rated safety (22) and building integrity (0)
_____________________________________________________________________________________________________
*Corresponding author: E-mail: eolanipe@oauife.edu.ng, oolugboyega@yahoo.com;
Olanipekun et al.; CJAST, 22(6): 1-19, 2017; Article no.CJAST.33904
performance most important and acoustic performance (7) least important. A regression model
based on the TBP criteria identified was developed (TBP Index = 13.36ð+12.57ŋ+12.46Ɣ+15.34ω+
12.38ɸ+15.58φ+18.30ψ). It was concluded that safety and security was rated most significant of all
the performance mandates, followed by indoor air quality, building integrity, thermal performance,
spatial performance, visual performance and acoustic performance.
Keywords: Total building performance; office buildings; building performance; building diagnostics;
building performance framework.
To deliver a project that is acceptable in all the
performance areas, conflicts must be resolved
between performance mandates because the
submissions of various studies show that,
performance requirements in each of the
performance categories cannot be understood in
isolation from the other. [4] concluded that
building performance is only achievable through
the holistic integration of all building performance
criteria which results from the interactions
between the identified performance mandates.
He went further to say that the performance
success of any performance mandate is
dependent on the result of effective integration
among individual systems and components
and their interface with the building’s occupancy.
In the opinion of [2], although individual
building system has been designed to meet
the specific performance criteria, evaluation of
office space should go beyond looking at a
single building requirement and that there
exist a need to look at the interrelationship
of
performance
mandates
to
provide
healthy buildings for occupants and most
important to reduce energy consumption
during the construction and operation of
buildings.
1. INTRODUCTION
For many decades, scholars and professionals in
built environment carried out investigations to
understand how buildings performed after they
have
been
constructed
and
occupied.
Specifically to understand how satisfied
occupants were with the workplaces they
occupied [1]. Building performance assessment
was done either in the context of fire safety,
indoor air quality, thermal efficiency and result of
oil crisis in the western world, which has led
to the design of air tight building systems.
The rationale for carrying out this kind of
performance evaluation of buildings was is to
determine the success of physical design
solutions that have been deployed. Evaluation of
this kind is of great importance in assessing a
specific area of performance, of a particular type
of building.
Although each of these micro-level criteria is
important in facilitating understanding on how
well the building is fulfilling the users’ and
functional requirements. It is equally true that
individual building system has been designed to
meet the specific performance criteria but, as it
was demonstrated in 1970’s, often, an emphasis
on a single performance such as energy, without
consideration for the range of performance
areas, most times results in failures in other
performance areas, such as Sick Building
Syndrome (SBS) and loss of productivity due to
lack of adequate indoor environmental quality
as well as degradation failures [2,3]. This is
because current assessment protocols are either
unitary in discipline or are focused only on one
specific aspect of whole host of performance
issues.
The implication of the above statements is
that, an all-inclusive approach is needed to
assess the overall behaviour of the building and,
in the long term. Good building performance
is thus dependent upon the satisfactory
performance of all the mandates as they
share an interrelated relationship. By itself total
building performance evaluations techniques
are desirable to consider these complex
interrelationships in the conception, design,
specification, installation and use of components
and assemblies within buildings [5]. The ability to
define and measure building performance
holistically has potentially important long lasting
benefits related to the evaluation and valuation
of buildings [6]. This is where the concept of total
building performance can play an important role
[7].
Building performance is a function of a number
of variables each of which is important to
analyse concurrently when conducting a POE
study. It is now known that one performance
mandate cannot be dissociated from the other
performance qualities.
2
Olanipekun et al.; CJAST, 22(6): 1-19, 2017; Article no.CJAST.33904
For long term strategic planning and design,
developing a framework based on TBP paradigm
for assessing building performance will provide
information about what kinds of a building will be
needed in the future to accommodate
organization’s expected development. The
development of framework for assessing
buildings is significant as it will provide an
evaluation tool for ensuring sustainable
buildings. Data spawned from the assessment
results can also be fed back into the design,
operate and maintenance process, to improve
the performance of future building stock.
The performance assessment methodology
developed would create a yardstick by which
building performance can be benchmarked.
Hence, this paper aims to develop an index for
assessing overall performance of office buildings
with a view to improving quality of future office
building design in Nigeria by examining
performance criteria which are relevant to the
assessment of office buildings; evaluating the
priority placed on the identified criteria; and
developing a regression model based on the
identified TBP criteria.
Office is a place where people spent a
substantial amount of time, about 90% of their
time [8]. As the industry moves towards service
sector, office has become the predominant work
place and financial centres today. Therefore, its
performance has a significant impact on indoor
environment and indirectly the wellbeing and
productivity of the workers. The health, safety,
wellbeing and comfort of employees in a highperformance office building are of paramount
concern. To achieve these impacts, however, the
office building must form an integrated design
approach that focuses on meeting a list of
objectives: Productivity, improved health, greater
flexibility
and
enhanced
energy
and
environmental performance.
Thus, knowing the indicators for assessing its
performance become imperative [4]. There is
growing interest on the part of clients and
construction professionals in Nigeria to design
and construct office buildings which meet
business and people objectives. Lack of reliable
data and knowledge of the relevant indicators of
building, their ability to make correct decision
may be impaired. In view of this, there is the
need advance a comprehensive performance in
Nigeria. With these various aspects taken into
consideration, the concept of Total Building
Performance (TBP) concept appears to be very
attractive solution in the development of an
assessment framework to ensure good indoor air
quality, thermal comfort conditions, energy
efficiency as well as fostering occupant
wellbeing, health and productive in Nigerian
office buildings.
2. LITERATURE REVIEW
There has been a worldwide movement to
develop systems that can provide all-inclusive
but manageable performance assessment
fragment for buildings the concept of Total
Building Performance (TBP) developed by the [4]
and [5] has been pinpointed as an apt approach
to the development of the assessment
framework as it takes in hand a set of
coordinated strategies aimed at bringing about a
performance and quality driven construction
industry. This concept looks into and develops
processes contributing to the delivering of
integrated and high performance buildings with
respect to needs and resource availability. It is
contended by researchers [6,5];[5] noted that a
minimum of six performance areas are needed
to describe the performance of the built
environment for building occupant effectiveness.
The TBP concept embraces these six
principal performance mandates, namely,
spatial, acoustic, thermal, visual, Indoor Air
Quality (IAQ) and building integrity. The TBP
approach is the most holistic as well as being
performance based. It is a user oriented building
diagnostic and appraisal tool. The performance
mandate connotes a set of user’s preference and
response with respect to the spaces created.
The main drivers are the users perceived needs
within a building.
Modern trends in building performance
evaluation demand a paradigm shift from one
aspect of performance criteria to holistic
approach, which is manageable yet developed
enough to encompass performance dimensions
along a broad range of aspects. Presently, there
are quite a number of building assessment
systems developed internationally to appraise
buildings in different parts of the world. These
systems might not be applicable in the context of
Nigeria due to geographical and cultural
differences. In addition, when there is lack of
reliable data and the knowledge of the relevant
indicators of office building performance, the
designers, built environment professionals and
organization’s ability to make a convincing case
for its recommendation is also significantly
reduced. Through the evaluation of occupied
facilities, there performance can be reviewed to
assure users satisfaction.
3
Olanipekun et al.; CJAST, 22(6): 1-19, 2017; Article no.CJAST.33904
Early studies on building performance evaluation
have focused on measuring and assessing one
aspect of performance criteria as well as
performance of products rather than whole
buildings [4]. Criteria such as durability, water
tightness, air permeability and so on were used
to measure the performance of specific
components at micro-level. Nevertheless, an
emphasis on one performance area often
resulted in the failure of the other performance
areas. Considerable number of clients/occupants
dissatisfaction has also arisen despite this effort.
Thus, building evaluations that continue in
singular areas are going to create more
problems by doing so. Hence, the resulting
maxim can only happen that the evaluating
community must began with a comprehensive
outline of TBP to be achieved, which is finite
enough to be manageable in the field, yet
developed enough to represent that ‘integrated
multi-sensory evaluator’ known as human
being.
issues and processes. However, measurement
of performance alone does not depend on
measurability. It also takes factors that are
significantly relevant and may not yet be
measurable into account. The methodologies
that are adopted in the process of evaluation are
also significant factors. The performance
approach involves two basic stages, namely;
identification and selection of the required
standards are carried out in the first stage which
is the audit stage or the measurement. While the
second stage involves the comparing of the
measured results with the benchmark or the
optimal standards. This is the assessment stage.
The real process and procedures may be
complex. The most important step is to
understand before embarking on a performance
measurement exercise, what performance really
means and the leading indicators which provide
a measure of the defined performance. If you
cannot measure performance, it cannot be
understood nor improved [22,23].
Several studies have been conducted on various
building types and in different parts of the world
using the concept of total building performance.
Researchers like [5,7,8,9,10,4] and [11], had
put in a lot of research effort which had led
to the development of assessment models
or
frameworks
for
evaluating
building
performance.
Criteria such as durability, water-tightness and
air permeability and so on can be used to
measure
the
performance
of
specific
components at the “micro-level”. Albeit it remains
indisputable that, this approach has limitations in
evaluating the total performance of a building
which by implication needs to be carried out at
the “macro-level” (i.e. the building as a whole)
[24,25,9]. Tools which specializes in measuring
specific features and attributes of a building and
environment are available, among which are
Post Occupancy Evaluation [26, 27,28], Concept
of Total Building Performance (TBP) and
Building Diagnostics [29,30], Building Quality
Assessments [31] and ORBIT [32].
Although, interest in building performance
evaluation has significantly increased in recent
years, and development of holistic assessment
framework for building performance evaluation
has presumed a wider interest which is now a
more widely practiced for passing judgment on
the values and shortcomings of completed
buildings. In Nigeria, for instance, performance
evaluation of buildings in use had been carried
out traditionally, with the aim of determining the
success of physical design solutions in terms of
either thermal comfort, adaptive behaviour or
optimization of energy use [12-16]. Despite this,
sufficient anecdotal evidence and studies by [17]
and [18] have shown that office buildings are not
‘bio-climatic’ responsive and indoor comfort is
always a problem, which affect the habitability of
the occupants.
3. RESEARCH METHODOLOGY
In order to identify the relevant performance
indicators, seven performance mandates namely
Thermal Performance, Visual Performance,
Acoustic Performance, Indoor Air Quality,
Spatial Performance, Building Integrity as well as
Safety and Security were highlighted and
explicated under the TBP approach adopted in
this study. Via the review of literature survey,
a
number
of
existing
and
significant
performance indicators that served as means of
evaluating each of the seven mandates were
identified.
Gajendran [19] has shown that the performance
concept is the most systematized approach for
evaluating buildings. Measurability is a key
criterion and crucial element to the whole
performance concept [20,21]. It is pertinent to
the objective understanding of performance
It has been documented that buildings have
certain basic attributes that are essentially the
same for all buildings [24]. In view of this, this
4
Olanipekun et al.; CJAST, 22(6): 1-19, 2017; Article no.CJAST.33904
ultimately, the needs of the user should take
precedence, and that the role of the experts
should construe those needs into building
performance requirements. The study population
includes
professionals
with
significant
experience and knowledge in the field of
office buildings design and construction. Data
was collected through questionnaires with 51
building professionals consisting of architects,
builders, estate surveyors, and mechanical
engineers.
study stratified the performance indicators
identified into two types: Basic Attributes and
Features. Basic attributes are the fundamental
performance indicators against which each
performance mandate is to be gauged. Basic
features, on the other hand, are the additional
indicators that support in enhancing the
performance level, it is possible to assess the
fundamental performance of office buildings on a
common basis, by differentiating between these
two groups of indicators, yet at the same time be
able to reward the high performance buildings
which have specific features to further improve
its overall performance. Questionnaire was used
to elicit information on the identified performance
mandates and their corresponding performance
indicators from selected respondents. Given the
complex nature and structure of modern
buildings and the ranges of variables that are
involved in them, development of a meaningful
performance assessment system must be transdisciplinary, rather than purely a uni-disciplinary
process. This would, thus, require the technicalknow-how of professionals within the building
industry, who have to translate and implement
the requirements of the developers and users.
Although the TBP concept is majorly usersoriented, but, experts-based system would make
a better choice for the purpose of this study as
the expert respondents would have garnered
more feedbacks and experience of what users
require in buildings. Likewise, users are also
have at their disposer, the technical knowledge
of the buildings. Their perspectives can aid in
facilitating a better appraisal in which it considers
a range of key factors which affect the holistic
performance of the building. As most building
problems call for an interdisciplinary approach, it
is pertinent to include experts from various
disciplines. While the views of these individuals
are associated with their unique disciplines, the
expertise in the group is often greater than the
sum of the expertise of its individual members
[6]. So, it would be more useful to garner the
opinions from a multi-disciplinary group of
experts. However, it must be foregrounded that,
The technique used for the sampling is
purposive sampling. The respondents were
made to grade the significance of each mandate
as compared to one another in a supposedly
typical office building on a Visual Analog Scale
(VAS).
The scale consists of a straight horizontal line
that measures 100 mm in length with verbal
descriptors at each end to aid easy
understanding of the mandates that are being
graded. It is pertinent that the use of the VAS is
clearly
explicated
to
each
respondent.
Respondents were instructed to mark the
location on the line that corresponds to the
degree of importance they placed as they
compared each of the mandates to one another.
This gave them the greatest freedom to choose
the extent of significance that they placed on
each mandate relative to other mandates. Figure
1 shows the usage of the VAS in the study. If
one finds that visual performance in an ideal
typical office building is much more important
than thermal performance, one would mark on
the line provided at a location that is nearer to
Visual Performance. The shorter the distance of
the mark from the end of Visual Performance,
the higher the degree of importance placed on
visual performance in relation to thermal
performance. In Fig. 1, greater importance is
stressed on visual performance as compared to
thermal performance as a result of the fact that,
the mark on the line is nearer to the end of
Visual Performance.
Fig. 1. Visual Analog scale used for the study
5
Olanipekun et al.; CJAST, 22(6): 1-19, 2017; Article no.CJAST.33904
The data obtained were analysed using Content
analysis, Paired Comparison Analysis, Kendall
coefficient of agreement, and Tukey Kramer
procedure. One-Sample T-Test was used to
compare each VAS score of every basic attribute
and feature to the neutral point of 50 mm.
relevant performance criteria are identified and,
scoring method is proposed to serve as a
yardstick to evaluate performance of the
attributes and features within each mandate. To
determine the relative importance or desirability
level of the various performance indicators,
weights were also calculated from the survey
results. The proposed TBP assessment
framework is then developed by incorporating all
these components together using regression
analysis. First, the building professionals,
themselves, were interviewed to list the
attributes they considered important in a high
performance building, in an open-ended
interview. This seeks to elicit their independent
views on the criteria of a high performance office
building. Content analysis is employed to
determine the performance aspects deemed
important by the professionals.
4. RESULTS
FINDINGS
In the second section of the survey, the
professionals were asked to grade the relative
importance of each performance mandate to
other mandates with respect to an ideal typical
high performance office building using a pairwise comparison approach. The rationale for
data analysis is, thus, to determine the
degree of consensus among the experts’ ratings
and also the relative significance of each
performance mandate to the others in
assessing the holistic building performance.
Subsequently,
weights
were
developed
for each performance mandate based on the
survey results. This seeks to rationalise
greater
priority
to
be
allocated
to
performance mandates that command a higher
weightage.
Indoor air quality and security were by far the
most frequently mentioned (14.55%) category or
concept relating to respondents’ comments
about important factors that they would look for
in a high performance office building. This
implies priority and often preference for good
indoor air and security performance in a building.
This finding is not surprising especially in a
tropical country like Nigeria where airconditioning has almost become a necessity in
buildings. Included under this heading is green
environment. Included under the Security
Performance category was mention of corridor
safety as shown in Table 1.
AND
DISCUSSION
4.1 Examination of Office
Performance Criteria
OF
Building
Content analysis revealed that most of the
survey data collected via the open-ended
interview fits very aptly or are closely related to
the seven performance mandates adopted in
this study: Thermal Performance, Visual
Performance, Acoustics Performance, Indoor Air
Quality (IAQ) Performance, Spatial Performance,
Building Integrity and Safety & Security. Table 1
shows the ranking of the total building
performance concepts that fit into the seven
categories and related to them based on the
frequency of times mentioned by the experts.
The total number of responses related to each
performance mandate and the relative frequency
based on percentage of times it is mentioned is
shown in Table 1. It also shows a breakdown on
the number of responses related to individual
criterions and the relative frequency in terms of
percentage as well.
Thermal Performance criterion, receiving 8.98%
of the survey sample’s mentions, is the
third most frequent response as seen in Table 1.
It is observed, from the results, that the
percentage of mentions for Spatial Performance
(7.27%), Building integrity (6.36%) and
Visual Performance (4.55%) only differs very
marginally, although, they are graded as the first
and second place respectively. In terms of total
number of responses, there were 8 mentions for
Spatial Performance, 7 mentions for Building
integrity and 5 mentions for Visual Performance
which represents a small difference too. Hence,
these three mandates command a comparable
level of importance to the experts as evident in
the open-ended interview.
The third section of the survey required the
experts to grade the importance of basic
attributes and desirability of features within the
respective performance mandates. Identification
of significant attributes and features which are
relevant to office building performance was
made possible via the analysis of the collated
data. In a likewise manner, weights were also
developed for individual performance attributes
and features based on the survey results.
Similarly, this justifies the greater attention to be
focused on appraisal of attributes and features
which carry a higher weightage.
6
Olanipekun et al.; CJAST, 22(6): 1-19, 2017; Article no.CJAST.33904
Table 1. Ranking of other performance issues based on frequency of times mentioned
Criterion
Indoor air quality
Green environment
Safety and Security
Corridor safety
Thermal performance
Spatial performance
Building integrity
Energy efficient
Adequate water supply
Internet facilities
Computer appliances
Refrigerator, television set
Fittings
Functionality
Visual performance
Acoustic performance
Column Total
F
16
14
9
8
7
5
2
61
Criterion mentioned
Overall mandate level
Individual criterion level 2
%
Rank
F
%
14.55%
1
16
14.55%
7
6.36%
12.73%
2
4
12.73%
8
7.27%
8.18%
3
9
8.18%
7.27%
4
8
7.27%
6.36%
5
7
6.36%
11
10%
4
3.63%
8
7.27%
2
1.82%
1
0.91%
1
0.91%
7
6.36%
4.55%
6
5
4.55%
1.82% 1.82%
7
2
1.82%
56.17%
110
100.0%
Acoustic performance concept was also reflected
in the response as shown in Table 1.
Energy Efficiency 10%) remains the most
frequent issue that the sampled building experts
had expressed their concern for. (Some
respondents indicated in their responses that
energy efficiency is an inevitable factor that
cannot be overlooked as it affects the company’s
bottom line. More than half of the respondents
feel that energy efficiency is a relevant factor if a
high performance building is to be ensured. Also,
reference is made to its relation to thermal and
visual performances in a building.
However, it is of great importance to note that,
the majority of the respondents’ most times,
often, mentioned performance issue is ‘air
quality’. This category ranked first in terms of
frequency of mentions (16.55%). Security comes
next receiving 12.73% of the sample survey’s
mentions and corridor safety is the only
mentioned performance criterion within this
category at a response rate of 7.27%. This
finding is not surprising as the safety and
security of the building has an impact on the
operation efficiency of the building throughout its
whole life cycle. Thermal performance ranked
after Security at 8.89% in terms of percentage of
responses. Acoustics Performance (1.82%) is
ranked the lowest, receiving relatively fewer
mentions as compared to the other 6 categories
mentioned earlier. This might be attributed to the
perception of the professionals: users are
generally more tolerant towards acoustic
discomfort as compared to other factors as long
as the noise level is within the acceptable
range.
4.2 Evaluation of the Priority Placed on
Office Building Criteria
In Section II of the questionnaire, the
respondents were asked to rate the level of
importance among the seven mandates pairwise at a time between all 21 possible pairs by
marking on the VAS. No numerical values
were shown on the scale to allow greater
flexibility in rating the importance level so that
respondents were not “forced” to confine
their ratings to certain range as in the case
of conventional questionnaires using ordinal
scales.
Responses apart from the seven performance
mandates deployed were, also, recorded and
analyzed individually and differently. It postulates
that these additional concepts are closely related
or, may be made up of subgroups of the seven
performance mandates adopted under the TBP
approach.
If
the
respondent
perceives
Thermal
Performance of a high performance building to
be more important than Visual performance, the
respondent would mark a stroke on the scale
nearer to the end of Thermal Performance. The
importance rating of each performance mandate
7
Olanipekun et al.; CJAST, 22(6): 1-19, 2017; Article no.CJAST.33904
The result from the test of significance had
shown that the degree of agreement among the
experts did not occur by chance. Thus, there is
agreement among the experts even while they
have different backgrounds in their ratings of the
importance of the performance mandates in total
building performance. In this regards, it would
then be significant to use the experts’ ratings to
calculate the weights of the performance
mandates consequently.
in comparison to another mandate is measured
from the VAS, this is 100 mm long.
A rating below 50 indicates a lesser importance
of a performance mandate when compared to
other mandates. On the other hand, a rating
above 50 indicates that performance mandate is
higher or more important when compared with
other mandates. If the two mandates in
comparison are equally important, this would
thus be reflected by a rating of 50. The experts’
ratings were first analyzed to determine the
degree of agreement among these experts.
Albeit, it is expected that the experts will
express a wide range of opinions as a result of
their
different
backgrounds.
This
trend
has already been reflected from the content
analysis results obtained from the open-ended
survey, it is however relevant to determine the
degree of agreement among the experts
concerning mandates affecting total building
performance.
In addition to showing that the ratings is not
coincidental but that there is agreement among
the experts in their importance ratings, it is
pertinent and of great interest to examine the
rate of recurrence for individual mandate. This
helps to illustrate the degree of agreement that
the experts have in their importance ratings of
each mandate in comparison to other mandates.
A matrix which tabulates the mean pair-wise
importance ratings of each pair of performance
mandates is shown in Table 3. The overall
importance rating of each performance mandate
is obtained by summing up the individual ratings
of that mandate in comparison to each of the
other six mandates across the rows.
Since the data in this study are paired
comparisons,
the
Kendall coefficient of
agreement used to determine the degree of
agreement among the experts.
Table 2. Preference matrix showing the total frequency of pair-wise comparison ratings of the
50 experts
Mean importance
rating
ð
ŋ
Ɣ
ω
ɸ
φ
ψ
ð
ŋ
Ɣ
ω
ɸ
φ
ψ
1―
46.68
45.74
70.85
41.28
52.34
64.47
46.68
―1
52.98
53.4
43.19
67.23
63.83
45.74
52.98
―1
64.89
54.68
61.06
56.38
70.85
53.4
64.89
―
46.17
51.7
69.15
41.28
43.19
54.68
46.17
―
53.83
71.49
52.34
67.23
61.06
51.7
53.83
―
58.94
64.47
63.83
56.38
69.15
71.49
58.94
―
ð= Thermal Performance, ŋ= Visual Performance, Ɣ= Acoustic Performance, ω= Indoor Air Quality, ɸ= Spatial
Performance, φ= Building Integrity, ψ= Safety and Security
Table 3. General importance rating of each performance mandate in an office building
Mean importance
rating
ð
ŋ
Ɣ
ω
ɸ
φ
ψ
ð
23
23
33
21
27
33
ŋ
Ɣ
ω
ɸ
φ
ψ
28
28
27
15
24
18
30
22
23
27
24
17
20
25
24
18
18
18
16
16
15
24
27
29
34
33
33
28
31
33
8
24
26
35
27
35
36
Raw
score
143
131
126
161
142
160
205
Olanipekun et al.; CJAST, 22(6): 1-19, 2017; Article no.CJAST.33904
studied for ratings that fall outside the 95%
confidence interval.
The matrix provides a good summary of the
relationships
between
the
performance
mandates, reflecting the mean comparative
importance rating of one mandate to the others,
as well as the general importance of each
mandate relative to the others. The entries
nd
th
tabulated in the 2 to 8 column constitute the
mean importance ratings of the 50 experts in the
pair-wise comparison between the mandate in
each row to every other mandate from the 2nd
th
to the 8 column.
Upon further examination, the number of experts
who rated the basic attributes and features as
considerably very different from the others in the
group i.e. their ratings fall outside the 95%
confidence interval, is still considered small,
comprising less than 10% of the sample at the
very most. It is the occurrence of these few
outliers that caused the great diversity in the
standard deviations and since the outliers only
constitutes a very small percentage (less than
10%), the survey results are still considered
reliable. Notably, the dispersion in ratings varies
for different attributes and features which
implied that the experts had differing
opinions on different attributes and features.
The differences are perhaps attributed to
their professions and experiences. However,
observation of the data showed that there is still
good agreement and consistency among the
majority of the experts in their ratings of these
basic attributes and features.
The last column in the matrix shows the general
importance rating of each performance mandate
obtained by aggregating the mean pair-wise
ratings of that mandate across the row. Each row
score in the last column represents the relative
significance of each performance mandate in
total building performance, taking into account its
relationship with the other six mandates. It can
be seen from Table 3 that Safety and Security
got the highest row score (205) while Acoustic
Performance settled for the lowest score in
comparison (126) among all the mandates.
The suggests that, standard deviations,
maximum and minimum VAS scores associated
with each basic attribute and feature of the
seven performance mandates are presented in
Table 4 and Table 5. In this analysis, a VAS
score of 50 is taken to be the cut-off point
beyond which an attribute or feature is
considered to be significant or useful. As shown
in Table 4, it is observed that the mean ratings of
the basic attributes within the seven mandates
are on the whole considered high (with VAS
score exceeding 50) this shows that the experts
perceive these attributes to be relevant
indicators in the appraisal of building
performance. In this regard, it is observed from
Table 5 that the mean VAS score for the features
generally lie above the 50 mark. It can be
inferred that the experts appear to rate most of
the features as useful and important in their
contribution towards the performance of the
respective mandates.
While a VAS score of 50 and above for a basic
attribute or feature may be considered to be
relevant or desirable in its contribution towards
the respective performance mandates, it is
inadequate to conclude that they are indeed
relevant or desirable based on their mean rating
value alone. Before any conclusion can be made
the attributes and features have to be proven
statistically as being relevant or desirable in their
contribution towards total building performance
to vindicate their inclusion in the assessment
framework. The one sample T-test is appropriate
in this case to statistically determine the
attributes and features that are considered
significantly relevant or desirable by the experts.
Those that are not can then be excluded in order
to further streamline the assessment framework.
In using the one sample T-test, it is usually
assumed that the dependent variable is normally
distributed. As such, before conducting the one
sample T-test, the normality in the distributions
of basic attributes and features have to be
checked. The one sample t-test was carried out
for all the basic attributes and features under
their corresponding performance mandates to
compare their VAS scores with the midpoint of
50. This is the cut-off point beyond which any
basic attribute or feature is considered to be
important or desirable respectively by the
experts. The test value used in the one- tailed ttest was 50.
However, it is of great importance to observe
that the standard deviations of the VAS scores
are in generally and relatively high. This for
instance may be explained by the extreme
difference in ratings as reflected by the
maximum and minimum VAS scores. As
expected, it is not possible for the experts to
reach total consensus on the importance and the
desirability of the basic attributes and features
thus, resulting in the great standard deviations.
In view of this, the survey data is carefully
9
Olanipekun et al.; CJAST, 22(6): 1-19, 2017; Article no.CJAST.33904
always been the key indicator of thermal
performance of the indoor environment as it is
the most directly felt element as compared to the
rest of the attributes. Temperature largely
governs a person’s general feeling of hot or cold
and office workers had often reported that
temperature inconsistency tend to be more
abrasive than conditions that are consistently
cold or hot [8]. This aptly suggests that people
are generally more sensitive to changes in air
temperature.
4.2.1 Analysis of top basic attribute and
feature
within
each
performance
mandate
As all the basic attributes within the seven
mandates have been found to be significantly
relevant, they would be included in the
assessment framework as key performance
indicators in the later stage. Based on the list of
existing basic attributes and features, the top
basic attribute and feature within each
performance mandate is identified in accordance
to the highest computed mean rating. The top
basic attributes and features within each
performance mandate are presented in Table 6.
As a result of the different perceptions and views
on the level of thermal comfort, it is no wonder
that VAV is considered as a desirable feature in
the building by the experts. In order to deliver
conditions that are more closely orchestrated to
fit the needs of the individuals, VAV whereby the
supply air temperature is adjusted by sensors
located in the area that the system serves can
help to enhance thermal comfort.
As seen from the Table 6, the air temperature
obtained the highest mean importance rating
(79) in comparison to the other attributes within
the mandate Thermal Performance. This result is
not surprising because air temperature has
Table 4. Rating of basic attributes relevant to each performance mandate
Basic attributes
Air Temperature
Relative Humidity
Mean Radiant Temperature
Air Velocity
Illuminance level
Daylight factor
Daylight Glare Index
View to outside
Background noise level
Speech privacy
Speech intelligibility
Sound insulation quality
Problem of echo
Ventilation rate
Amount of air pollutants
Odor in office
Air temperature
Relative humidity
Way-finding performance
Occupancy density
Provision for disabled
Structural stability
Building Envelope integrity
Interior system integrity
Building maintainability
Fire integrity
Escape time
Emergency evacuation plan
Utility provisions & protections during emergency
Design for control of ingress & egress
Security measures after normal operating hours
10
Mean
79
66
71
70
88
81
64
62
51
66
54
67
64
86
69
78
88
72
81
81
61
89
57
72
89
84
81
89
80
78
83
Standard deviation
25
33
32
33
7
22
35
35
37
34
37
31
35
13
33
28
7
30
19
21
37
3
33
28
7
20
25
5
25
26
18
Olanipekun et al.; CJAST, 22(6): 1-19, 2017; Article no.CJAST.33904
Table 5. Rating of features relevant to each performance mandate
Basic attributes
VAV with individual control
Sensor control (body heat +movement)
Occupancy sensor
Day-lighting systems
Sun-shading features on façade
Operable windows
CO2 sensors to control fresh air intake
Centralized waste & human cleaning System
Flexibility in workplace transfiguration
Availability of social meeting area
Quality of Public Address (PA) system
Leakage detection system
Personal safety/ Evacuation kits
Alarm activation system
Intruder sensors
Mean
79
76
63
52
59
78
61
70
56
65
57
74
79
74
74
Standard deviation
22
24
33
36
37
24
34
30
36
33
35
29
25
29
30
Table 6. Basic attributes and features identified within each performance mandate
Performance
mandate
Thermal
Performance
Visual
Performance
Acoustics
Performance
IAQ
Performance
Top basic attribute
Mean
Standard
deviation
Air
79
25
Temperature
Illuminance
88
7
level
Daylight factor
81
22
Sound
67
31
insulation
quality
Air temperature
88
7
Spatial
Performance
Ventilation rate
Way-finding
performance
86
81
13
19
81
21
Building
Integrity
Occupancy
density
Structural
stability
89
3
87
7
Safety &
Security
Building
maintainability
Emergency
evacuation plan
89
5
The top basic attribute within Visual Performance
is illuminance level with a mean importance
rating of 63 and this makes sense because
adequate lighting for visibility and carrying out of
tasks is the predominant indicator of visual
comfort in the office setting. If there is
inadequate illuminance and, if conduction of
tasks is impaired, it would cause major
VAV
Top feature
Mean
Standard
deviation
79
22
Occupancy
sensor
63
33
Quality of PA
system
57
35
Operable
windows
78
24
Availability of
social meeting
area
65
33
Leakage
detection
system
74
29
Personal
safety
79
25
dissatisfaction among the occupants, even if
other lighting criteria are fulfilled. Thus, this
explains why illuminance is rated the most
important. It is not unbelievable to note that
sound insulation quality is considered the most
important attributes of Acoustic Performance
in the modern workplace with a mean rating of
57. Sound insulation quality of the office
11
Olanipekun et al.; CJAST, 22(6): 1-19, 2017; Article no.CJAST.33904
evacuation plan here refers to the ability of the
building to have successfully planned for the
evacuation of the workers during emergency
cases. The lesson from the collapse of World
Trade Centre in the 9/11 terrorist attack where
the steel structure of the building was unable to
withstand the immense heat caused by the
sudden explosion has increased the awareness
of the building community in this aspect. In order
to give real time warning to occupants
instantaneously at the time of emergencies and
intrusion, an efficient and effective alarm
activation system is highly desired to improve
the safety and security performance of the
building as rated by the experts. This would
alert the occupants so that they can be
prepared to evacuate the building in time of
emergencies.
encompasses the efficiency in isolation and
blockage of unwanted noise sources and it has a
direct impact on provision for speech privacy.
This is probably why this attribute is given the
highest importance rating for its contribution to
Acoustic Performance of a building. A Public
Address (PA) system of good quality is also
considered to be the most desirable feature in
the building that can serve to enhance the
acoustic performance of the workplace.
Considering unforeseen events especially, a
good PA system which allows announcements to
be made in time, coherently and clearly without
interference is certainly an inevitable feature in
the building. Way finding performance and
occupancy density are rated to be the most
important attributes of Spatial Performance of a
building which are probably not unexpected as
the workers in the building love to work in a
place that is not rowdy and easily work around in
their office.
Generally, it is noted that the standard deviations
of the top basic attributes and features within
each mandate are comparatively smaller than
that of the other variables within the
corresponding mandate. Hence, the variability of
the ratings is not that great, i.e. in other words,
the distribution of ratings for the top attributes
and features is not overly diverse and dispersed,
indicating a good degree of agreement in the
experts’ judgments for placing the highest priority
on these parameters.
Air temperature has been identified to be the
most significant attribute of Indoor Air Quality in
a workplace by the experts. On the other hand,
it is of great interest to note that operable
window is considered the most highly desired
feature to enhance the indoor air quality in an
office building. In Nigeria for instance, most of
the windows are just 50% operable but it is
recommendable to make the windows in office
buildings to be 100% operable (louver).
4.2.2 Analysis of top ten basic attributes and
features among all the performance
mandates
The structural stability of the building is without
doubt the most important attribute of Building
Integrity at a mean rating of 89. The ability of the
building to withstand the structural load and
stresses over the building’s lifespan is of great
importance as it makes the safety of the
occupants assured. In addition to this, the
emphasis on the structural stability of the
building in the event of terrorist attacks is
reinforced in the aftermath of the 911 attacks
made on the World Trade Centre.
Leakage
detection system, on the other hand, has been
identified as the most desirable feature with a
VAS of 74 to enhance Building Integrity in a
building. This type of system can be used for
enabling plant and equipment to be monitored
for leakage to avoid hazardous effect on the
occupants and damage to the environment as
well as office property.
Almost half of the top ten basic attributes singled
out are stratified under the Safety& Security
performance mandate, showing a strong concern
and need for proper precautions in the case of a
disaster. These four attributes are emergency
evacuation plan (89), fire integrity (84), and
security measures after closing hours (83) and
escape time (81). Likewise for the list of top ten
features, survey respondents found the alarm
activation system (83) and in-building repeater
system (74) for the purpose of safety and
security in a building most desirable. The
increasing concern for safety & security is not
unfounded, especially with heightened building
security and continued awareness of safety
issues creating a raised level of anxiety in most
people.
It is evident from Table 4.6 that emergency
evacuation plan is rated to be the most important
attributes of Safety & Security performance of
the building at mean rating of 89. Emergency
Among the top ten basic attributes, only two of
them fall under the category of Building Integrity
as reflected in Table 7. The attributes are,
namely, structural stability (89) and building
12
Olanipekun et al.; CJAST, 22(6): 1-19, 2017; Article no.CJAST.33904
Table 7. Top ten attributes and features identified among all seven performance mandates
Top ten basic attributes
Emergency evacuation plan
Structural stability
Air temperature
Illuminance level
Building maintainability
Ventilation rate
Fire integrity
Security measures after closing hours
Escape time taken occupant
Occupancy density
Way finding performance
Daylight factor
Top ten features
Personal safety/evacuation kits for building occupants
Variable air volume with individual control
Operable window
Sensor based on body heat and movement
Leakage detection system
Alarm activation system
Intruder sensor
Centralized waste and human cleaning system
Availability of social meeting area
Occupancy sensor
Mean importance
rating
89
89
88
88
87
86
84
83
81
81
81
81
Mean desirability
rating
79
79
78
76
74
74
74
70
65
63
Performance
mandate
Safety & Security
Building integrity
IAQ performance
Visual performance
Building Integrity
IAQ performance
Safety and security
Safety and security
Safety and security
Spatial performance
Spatial performance
Visual performance
Performance
mandate
Safety &security
Thermal
IAQ performance
Thermal
Building integrity
Safety and security
Safety and security
IAQ performance
Spatial performance
Visual
for movement of clean air that is free from
pollutants and smell and yet at the same time
does not compromise with the habits of some of
the occupants.
maintainability (87) respectively, in descending
order of mean importance ratings. The emphasis
on building integrity is expected. The question of
upgrading current building codes in the face of
the World Trade Center (WTC) collapse has
touched off a debate in the design, construction,
and real estate communities that will impact
facility management operations across the
country. As such, the results from this survey
have amply demonstrated this increased
awareness of the structural performance of our
built environment.
The two basic attributes from the top-ten list
which are related to the Visual Performance with
reference to Table 7, it is observed that the
survey respondents perceived illuminance level
(88) and daylight factor (81) to be the two most
important factors in Visual performance,
indicating the severe need for workable
environment with good sight. On the other hand,
under the list of the top ten features, one of
which fall under the category of Visual
performance mandate. This feature is occupancy
sensor (63). The desirability for this feature in a
building reiterates the need for work under good
lighted environment to improve work level and
speed.
On the one hand, the two basic attributes from
the top-ten list which are related to the Indoor Air
Quality (IAQ) Performance with reference to
Table 7, it is observed that the survey
respondents perceived air temperature (88) and
ventilation rate (86) to be the two most important
factors in IAQ performance, showing the severe
need for less temperate and well ventilated work
environment. On the other hand, under the list of
the top ten features, two of which fall under the
category of IAQ performance mandate. These
two features are operable window (72) and
centralized waste and human cleaning
system (70). The desirability for these two
features in a building further reiterates the need
The two basic attributes from the top-ten list
which are related to the Spatial Performance
with reference to Table 7, it is observed that the
survey respondents perceived way finding
performance (81) and occupancy density (81) to
be the two most important factors in Spatial
performance, indicating that workers like to be
13
Olanipekun et al.; CJAST, 22(6): 1-19, 2017; Article no.CJAST.33904
few in their offices and be able to move around
at the same time with ease. On the other hand,
under the list of the top ten features, one of
which fall under the category of Spatial
performance mandate. This feature is availability
of social meeting area (65). The desirability for
this feature in a building reiterates the need for
having all the workers together at a meeting
place during meetings for discussing of important
issues. Although the basic attributes of Thermal
Performance did not appear under the top ten
basic attribute list (See Table 7), survey
respondents expressed the desirability of some
of these features under the top ten features list.
Survey respondents found VAV with individual
control (79) and sensor based on body heat
and movement (76) to be the two most
desirable features under Thermal Performance
Mandate.
Although there was little agreement among the
experts in their overall individual pair- wise
ratings of the performance mandates with a low
coefficient of agreement u=0.12, the results of
the test of significance showed that the ratings
could not have occurred by chance. Hence this
indicate that there is still a degree of consensus
among the experts as they did not assign the
ratings randomly. Further analysis showed that
there is significant agreement on the overall
importance of certain mandates over another in
total building performance. The results of the
Tukey Kramer test showed that the overall
importance ratings between certain pairs of
performance mandates are significantly different,
indicating that there is reason to conclude that
one performance mandate is significantly more
important than another in total building
performance.
It is noted that neither attribute nor feature under
the respective top ten lists is related to Acoustics
Performance Mandate. This means that the
majority of building professionals generally place
less emphasis on acoustical performance in an
office building. As discussed, this might be as a
result of its comparison to other performance
mandates, acoustics performance is perceived to
play a smaller role in total building performance.
However as emphasized previously, it must be
emphasized that acoustic performance of a
building must still be within acceptable level.
Otherwise this would become a source of
problem and one of major concern in building
performance assessment if annoyances and
complaints are invoked.
The results showed that Safety & Security is
without doubt the most important performance
mandate with respect to the other mandates
in its contribution towards total building
performance. This is followed by IAQ
Performance,
Building
integrity,
Thermal
performance, Spatial Performance, Visual
performance, and lastly Acoustic Performance.
These results corroborate with the results
obtained from the content analysis where
IAQ Performance and Safety and Security were
ranked the first and second. Thermal and Spatial
performance were only ranked number four and
five on the list.
The relevance and desirability of the basic
attributes and features within each performance
mandate are also evaluated and the top basic
attribute and feature within each performance
mandate are identified and discussed. One
sample t test was also conducted to bring out the
attributes and features that are not rated
significantly important or desirable so that they
may be removed. The results revealed that
almost 50% of the top basic attributes and
features among the performance mandates
are stratified under Safety & Security. This
further affirms that Safety & Security is of great
important in a high performance building.
The results showed that in the content analysis
of the responses from the open-ended interview,
IAQ Performance and Safety and Security
Performance were the
most
frequently
mentioned concepts in a high performance
building. This was followed by Thermal
Performance, Spatial performance, Building
Integrity Visual performance and then Acoustic
Performance. The frequency of mentions was
used as an indicator of the significance of a
performance mandate in a high performance
building. Although IAQ Performance, Safety and
Security and Thermal Performance were ranked
in the first, second and third place respectively,
their frequency of mentions differs very
marginally,
at
16%,
14%
and
9%
correspondingly. As such, the results indicate
that these three mandates are considered to be
the more important factors in a high performance
building.
The results of the Tukey Kramer Procedure are
generated by PHStat2 in Microsoft Excel based
on the above statistical inputs. Table 8 lists the
pairs of mandates that are identified by the
statistical procedure to be significantly different
from each other in terms of its general
importance in total building performance.
14
Olanipekun et al.; CJAST, 22(6): 1-19, 2017; Article no.CJAST.33904
Table 8 shows that Safety & Security is
significantly
more
relevant
than
Visual
Performance, Acoustic Performance, Spatial
Performance and Building Integrity in total
building performance. In addition, it is noted that
the disparity in absolute difference between
Safety & Security and Building Integrity is not
very big at 45.
The result justifies greater
priority to be allocated to Safety & Security
performance of the building with respect to the
other four mandates in total building
performance evaluation. It also further confirms
the findings from previous section where Safety
& Security has been shown to receive
comparatively higher mean importance ratings
than other mandates.
On the whole, the results shows that Safety &
Security, Building integrity and IAQ are the
three most relevant performance mandates in
a high performance building especially with
respect to Visual Performance,
Acoustic
Performance and Spatial Performance.
4.3 Developing
a
Total
Building
Performance
Framework
for
Assessing Office Buildings
As the performance of a mandate is dependent
on the corresponding performance of those
relevant attributes and features, the Overall
Weighted Attribute Score and Overall Weighted
Feature Score were used to determine the
performance index of each mandate. These two
constituent scores of each mandate were
totalled and divided by the maximum total
score which sums up to 100 for both categories
to arrive at the performance index for the
respective mandate. In cases where the Overall
Weighted Feature Score is equivalent to 0, only
the Overall Weighted Attribute Score is divided
by the maximum total score (120) to determine
the performance index.
Table 8. Pairs of mandates identified to be
significantly different in overall importance
Performance mandates
Thermal to Visual
Thermal to Acoustics
Thermal to Spatial
Visual to IAQ
Visual to Building Integrity
Visual to Safety & Security
Acoustics to IAQ
Acoustics to Building Integrity
Acoustics to Safety & Security
IAQ to Spatial
Spatial to Building Integrity
Spatial to Safety & Security
Building Integrity to Safety &
Security
Absolute
difference
12
17
1
30
29
74
35
34
79
19
18
63
The performance index is the ratio of aggregated
overall weighted scores of both attributes and
features to the maximum total score and the
maximum value of the index is 1. The
performance index derived serves as an
indicator of the level of performance achieved by
each mandate hence the higher the index, the
better the performance of a particular mandate. It
is useful to derive individual performance index
for each mandate so that the performance of
each mandate can be examined separately to
identify problems which may exist in each
mandate.
45
It is also seen from the table that Building
integrity is significantly more relevant than Visual
Performance, Acoustic Performance and Spatial
Performance in total building performance. The
absolute difference between the overall
importance rating of Building integrity and the
three mandates are rather large in magnitude.
This result shows that greater emphasis is
placed on Building integrity over Visual
Performance, Acoustic Performance and Spatial
performance in total building performance
evaluation. Likewise, it can be inferred from the
results that IAQ is graded to be more
significantly relevant than Visual Performance,
Acoustics Performance and Spatial Performance
by the experts in a high performance building.
This illustrates that in a high performance
building, IAQ would be given a greater relative
priority over these three mandates.
As mentioned, the maximum value of a
performance index is 1. This indicates that all
attributes within the mandate are performing at
the optimum/maximum level with an Overall
Weighted Attribute Score of 100 and all the
desirable features identified are present in the
building with an Overall Weighted Feature
Score of 20. On the other hand, when optimum/
maximum performance is achieved by all
attributes but no features are present in the
building, the corresponding performance index
achieved will be 100/120 ≈ 0.8. If all the
attributes have just met the minimum acceptable
thresholds but there are no features present,
then the performance index will be 50/120≈40.
The lowest value of the performance index is 15
Olanipekun et al.; CJAST, 22(6): 1-19, 2017; Article no.CJAST.33904
0.4 and this corresponds to the failure of all
attributes within the mandate with an Overall
Weighted Attribute Score of -50. The Overall
Weighted Feature Score is not included because
the prerequisite of meeting the basic
requirements of the attributes has not been met.
Thus the performance index is derived by taking
-50/120 ≈ -0.4.
weighted performance indices of all seven
mandates to arrive at the TBP index is proposed
as follow in Equation 1.
Hence,
TBP Index =
13.36ð+12.57ŋ+12.46Ɣ+15.34ω+12.38ɸ+15.
58φ+18.30ψ
(1)
It is assumed that Total Building Performance
can be assessed by aggregating the individual
performances of the seven mandates as the
satisfactory performance of the seven mandates
is the determinant of the overall building
performance. As the role each mandate plays
in the contribution towards total building
performance
varies,
the weights of the
performance mandates must be factored in to
reflect the relative importance of each mandate.
In view of this, a linear function to integrate the
Where:
ð= Thermal Performance,
ŋ= Visual Performance,
Ɣ= Acoustic Performance,
ω= Indoor Air Quality,
ɸ= Spatial Performance,
φ= Building Integrity, and
ψ= Safety and Security.
Table 9. Mean performance mandates and acoustic performance
Φ* Ɣ
Ɣ* φ
*Ɣ
ω*Ɣ
Ψ* Ɣ
Ð* Ɣ
Ŋ* Ɣ
Architects
31.67
63.33
54.44
42.5
61.94
57.22
38.89
Builders
36.67
28.33
69.17
33.33
57.5
53.33
71.67
Estate surveyors
22.92
60
49.17
51.25
73.54
50.83
42.29
Mechanical engineers
23.33
78.33
58.33
43.33
71.67
28.33
46.67
Table 10. Weight of all the performance mandates against acoustic performance by
professionals
Φ* Ɣ
Ɣ* φ
*Ɣ
ω*Ɣ
Ψ* Ɣ
Ð* Ɣ
Ŋ* Ɣ
Architects
9.05%
18.10%
15.56%
12.14%
17.70%
16.35%
11.11%
Builders
10.48%
8.10%
19.76%
9.52%
16.43%
15.24%
20.48%
Estate surveyors
6.55%
17.14%
14.05%
14.64%
21.01%
14.52%
12.08%
Table 11. Mean score of each mandate in
relation to their weight
ψ
φ
ω
ð
ŋ
Ɣ
ɸ
Mean score
64.04
54.54
53.69
46.77
44.01
43.62
43.33
% Contribution
18.30
15.58
15.34
13.36
12.57
12.46
12.38
Mechanical engineers
6.67%
22.38%
16.67%
12.38%
20.48%
8.10%
13.33%
The above function is based on the assumption
that the individual performances of the seven
mandates can be assessed independently and
aggregated linearly to evaluate the total building
performance. The individual performances of the
seven mandates are measured by the
performance index obtained for each mandate.
The values of the performance indices of the
seven mandates are substituted into the
proposed function to derive the TBP index.
Hence the magnitude of the performance indices
will affect the result of the TBP index.
Rank
1
2
3
4
5
6
7
16
Olanipekun et al.; CJAST, 22(6): 1-19, 2017; Article no.CJAST.33904
B. Building A has all attributes performing at
optimum level except for thermal comfort with
PPD at 22% which is only marginally below the
minimum acceptable value of 20%. Building B on
the other hand, has all attributes performing
within the acceptable range but just meeting
the threshold level. In this case, it is reasonable
to conclude that Building A is on the whole a
better building than Building B despite not
meeting all stipulated acceptable performance
requirements because
the deviation of
performance from the acceptable limits is
marginal.
It is also assumed that total building performance
can be measured along a linear scale where a
value of 100 represents the maximum TBP index
achievable. The lowest TBP index derivable is 40 where all the seven performance mandates
have failed corresponding to the failure of all 38
attributes with calculated values at the extreme
limits. In this case, the performance index is -0.4
for each mandate which is the lowest possible
index as mentioned earlier. If all 38 attributes just
fulfilled the minimum acceptable requirements
corresponding to a score of 50 each (with no
features present), the performance index of each
mandate is approximately 0.4 and the TBP index
derived is 40.
5. CONCLUSION
It is noted that it might be possible for a building
that does not have all the attributes meeting the
acceptable criteria to have a higher TBP index
than another which has all the attributes meeting
the acceptable criteria. This scenario is possible
in the event that one building has most attributes
achieving optimum performance and a few
performing poorly outside the acceptable range
but on the average still achieved a very high TBP
index. On the other hand, another building that
meets all the criteria albeit just marginally will
achieve a lower TBP index in comparison. In this
case, it is difficult to tell from the TBP index at
first glance which building is better than another
if the definition of a good building is one that has
at least met all the acceptable requirements, i.e.
the performance of all attributes are within the
stipulated acceptable range.
The weights of the seven performance mandates
computed from experts’ ratings reflect the
relative importance of each mandate in total
building performance. Performance indices were
also derived for the seven performance
mandates which served as an indication of the
performance level of each mandate in the
assessed building. The performance index of
each mandate was taken from the aggregation of
Overall Weighted Attribute Score and Overall
Weighted Feature Score. The weighted
performance indices of the seven mandates
were then substituted into the above function to
derive the overall TBP index which serves as an
indicator of overall building performance. The
maximum value of the TBP index was 100 and
the lowest value was -40 which corresponds to
the failure of all attributes, with measured values
at the extreme limits. The proposed TBP
assessment framework provides an opportunity
for important performance requirements of office
buildings to be assessed comprehensively along
a common set of performance dimensions. This
assessment framework ensures the total needs
of a building to be examined together in an
integrated manner which does not result in
promotion of a single performance area at the
expense of another.
However, it is presumed that most buildings are
deemed to meet the acceptable requirements
and even if not, should not deviate from the
acceptable limits too drastically because of
codes, standards and guidelines in place for
compliance. Assuming that this holds true, then
the higher the TBP index the better a building
because it is very unlikely to have a building that
has many attributes performing exceptionally
well and some performing extremely poorly. This
is further supported by the fact that the attributes
within each mandate are usually interdependent,
so the performance of one attribute is likely to
have an impact on the performance of another.
Secondly, the assessment framework is not only
capable of assessing the current capability of the
occupied building in use, it can also be used
for periodic check-ups, troubleshooting when
problems occurs as well as an aid to
building operation and maintenance.
In view of the above considerations, it is
justifiable to say that a building with a higher
TBP index is better than another with a lower
TBP index even if the one with the higher TBP
index has a few attributes performing slightly
outside the acceptable limits. For example, say
Building A has a higher TBP index than Building
Thirdly, as professionals in different disciplines
working in different organizations tend to see
the same problem from different viewpoints,
it is beneficial to be able to integrate these
viewpoints in a systematic manner which would
17
Olanipekun et al.; CJAST, 22(6): 1-19, 2017; Article no.CJAST.33904
serve as invaluable information. The expert
survey conducted makes it possible to take
advantage of the vast body of knowledge and
expertise created in a variety of separate
disciplines and enable different priorities to be
focused on different performance issues in the
building.
5.
6.
Lastly, the TBP index can be used to evaluate
and compare building performance. It can be
used to facilitate the benchmarking of total
building performance of office buildings in
Nigeria and thus may pave the way to the
development of a labelling system.
7.
8.
6. IMPLICATIONS OF THE STUDY
The findings of this study implies that the
government should demand for TBP index of
office buildings before issuing building permits
for the construction of office buildings in Nigeria.
This is necessitated by the need for security of
buildings, especially in the wake of terrorists’
attacks that are targeting office buildings. Also,
the construction professionals that are involved
in building design are required to incorporate the
analysis of buildings for total building
performance during the function analysis of
buildings at the conceptual design stage.
9.
10.
11.
COMPETING INTERESTS
Authors have declared
interests exist.
that
no
competing
12.
REFERENCES
1.
2.
3.
4.
Larsson N, Macias M. Overview of the
SBTool assessment frame work. UPM
Spain, April; 2012.
Leaman A. Post-Occupancy evaluation:
Building use studies; 2004.
Available:www.usablebuildings.co.uk
(Accessed 12 October, 2012)
Loftness V. et al. Critical frameworks for
building evaluation. In Preiser, W.F.G. Ed.
Total Building Performance, Systems
Integration, and Levels of Measurement
and Assessment in Building Evaluation.
Plenum Press, New York. 1990;149-166.
Jiun NGC. Development of total building
performance (TBP) assessment system
for office buildings. An M.Sc. Thesis
Submitted
to
the
Department
of
Building, National University of Singapore;
2005.
13.
14.
15.
16.
18
Hartkopf VH, Loftness VE, Mill PAD. The
Concept of total building performance and
building diagnostics. In G. Davis, Ed.
Building
Performance:
Function,
Preservation and Rehabilitation. ASTM
STP 901, in American Society for Testing
and Materials, Philadelphia. 1986;5-22.
Building Research Advisory Board.
Building Diagnostics. National Academy
press, Washington; 1985.
Anderson G, Barrett P. Development of a
post-occupancy building model. In. Barrett,
P. (Ed), Facilities Management: Research
Directions, RICS, London; 1993.
Aronoff S, Kaplan A. Total workplace
performance:
Rethinking
the
office
environment. WDL Publications, Ottawa,
Canada; 1995.
ASHRAE
Fundamentals
Handbook:
American Society of Heating, Refrigerating
and Air-conditioning Engineers Atlanta;
1993.
Ang G. et al. A systematic approach to
define client expectations of total building
performance during the pre-design stage.
In the proceedings of CIB World Building
Congress (CLI 26). Wellington: CIB; 2001.
Okolie KC. Performance evaluation of
buildings in educational institutions: A case
of universities in South East Nigeria. A
PhD Thesis Submitted to the Department
of Construction Management, Nelson
Mandela Metropolitan University, South
Africa; 2011.
Ajibola KO. Energy optimization in a warm
humid climate – A case study of some
health facilities in Ile – Ife, Nigeria.
Renewable Energy. 1993;3(1):39-44.
Ajibola K. An appraisal of thermal comfort
in warm, humid climate: A case study of
student housing at Obafemi Awolowo
University, Ile-Ife. Journal of Renewable
Energy. 1995;5(III):2278-2282.
Olanipekun EA. An appraisal of energy
conservation practices in some selected
buildings at Obafemi Awolowo University,
Ile-Ife. An Unpublished M.Sc Thesis
Submitted to the Department of Building,
Obafemi Awolowo University, Ile-Ife; 2002.
Adunola AO. Adaptive thermal comfort in
residential buildings in ibadan metropolis.
Unpublished Ph.D. Thesis Submitted to
the Department of Architecture, Obafemi
Awolowo University, Ile-Ife; 2011.
Agunbiade WL. Effects of building
ventilation
on
the
reproductive
Olanipekun et al.; CJAST, 22(6): 1-19, 2017; Article no.CJAST.33904
impact of the work environment on
performance of female rabbits in humid
productivity.
Architectural
Research
tropics. A PhD Thesis submitted to the
Centres Consortium Inc, Washington D.C;
Department of Agricultural Engineering,
1985.
Obafemi Awolowo University, Ile-Ife;
25. Douglas J. Building performance and
2011.
its relevance to facilities management.
17. Akinbami JFK. An analysis of demand and
Facilities. 1996;4(3/4):3-32.
supply of electricity and the green house
gases emission of the Nigeria power 26. ASHRAE Standard 90.1: Energy standard
for buildings except low rise residential
industry. Unpublished Ph.D. Thesis
buildings. American Society of Heating,
Submitted
to
the
Department
of
Refrigerating and Air – Conditioning
Technology Planning and Development
Engineers, Atlanta, Georgia; 2001.
Unit, Obafemi Awolowo University, Ile-Ife;
27. Barrett
P,
Baldry
D.
Facilities
2003.
management: Towards best practice.
18. Williams B. Editorial: What Performance.
Blackwell Publishing, Oxford; 2003.
Property Management. 1993;11:13.
19. Gajendran T. An integrated approach 28. Becker F. The total workplace: Facilities
management and the elastic organization.
to assess facilities performance. an
Van Nostrand Reinhold, New York; 1990.
Unpublished Ph.D thesis submitted to
the Department of Building, National 29. Burns R. Introduction to research
methods. Longman, Frenchs Forest, NSW;
University of Singapore; 2000.
1994.
20. Preiser WFE. Applying the performance
concept to post-occupancy evaluation, 30. Cliff M, Butler R. The performance and
cost-in-use of buildings: A new approach.
International
Journal
of
Facilities
BRE
Report:
Building
Research
Management. 1997;1(4):179-184.
Establishment. Garston; 1995.
21. Preiser WFE, et al. Post occupancy
evaluation. Van Nostrand Reinhold, New 31. Oladapo AA. An evaluation of the
maintenance management of the staff
York; 1988.
housing estates of selected first generation
22. Bruhns H, Isaacs N. Building quality
universities in Southwestern, Nigeria. An
assessment. In Baird, G. et. al. (Ed).
unpublished PhD Thesis Submitted to the
Building Evaluation Techniques, Mc Graw
Department of Building, Obafemi Awolowo
Hill, USA; 1996.
University, Ile-Ife; 2004.
23. Davis G. et al. ORBIT-2 organizations,
buildings and information technology, 32. Shenzhen: Renewable energy resources
and a greener future, a review of
Harbinger, Norwark; 1985.
quantitative approaches to intelligent
24. Zeisel J. Building purpose: The key to
building
assessment.
China;
2006;
measuring building effectiveness. In M.E.
VIII(6):2.
Dolden and R.J. Robertson Ed. The
_________________________________________________________________________________
© 2017 Olanipekun et al.; This is an Open Access article distributed under the terms of the Creative Commons Attribution
License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any
medium, provided the original work is properly cited.
Peer-review history:
The peer review history for this paper can be accessed here:
http://sciencedomain.org/review-history/20391
19