Performance Indicators for Water Supply in Buildings
M. LOURENÇO1, A. SILVA-AFONSO2, C. PIMENTEL-RODRIGUES3
1Multiprojectar Engineering, Vagos, PORTUGAL
2RISCO, Department of Civil Engineering, University of Aveiro, Aveiro, PORTUGAL
3ANQIP – Portuguese Association for Quality and Efficiency in Building Services,
Operational Centre of the University of Aveiro, Aveiro,
PORTUGAL
Abstract: - Drinking water is a vital resource for the population’s quality of life and health. The satisfaction of
their needs is increasingly demanding, essentially associated with the growth of the population's income and the
possibility of improvements in terms of comfort, quality, and safety at lower costs. However, despite the
accuracy of engineering design, the functional performance of the building's water networks does not always
match the expectations because it can be subjected to failures, which can compromise other infrastructures and
cause a lot of inconvenience to the residents or users. In this case, we can say that the water supply system is no
longer reliable. In the study presented in this article, profiles were developed that make easier the assessment of
the reliability of the installation, specifying key aspects involved, which may be called performance indicators.
The indicators combined in a balanced way according to their importance make it possible to translate the
relevant aspects regarding the operation of the water supply systems in the building and their reliability. In this
sense, it is expected to contribute to the improvement and durability of building installations, regarding the
water supply's performance, security, and quality.
Key-Words: - building, durability, functional performance, quality, reliability, water supply in buildings,
performance indicators, water supply security
Received: October 25, 2021. Revised: August 5, 2022. Accepted: September 11, 2022. Published: October 4, 2022.
1 Introduction
Currently, there is a growing trend in the standard of
living of the population, as a result of the increased
markets offer in all areas, competitive edges and
consumer demands in which, in many cases, quality
is the preferred criterion. The building water supply
systems, which seek to respond to the need to ensure
the supply of drinking water for human
consumption, also follow this trend [1,2].
In the construction of water supply networks in
buildings sought comfort and security at the lowest
cost. But several factors can influence these
purposes, resulting in technical conditions of the
installations, conditions of use, and economic and
environmental conditions [3-5].
A large number of problems and discomforts
detected in buildings are related to the malfunction
of the water networks and may, ultimately,
compromise the health and welfare of the occupants
[6]. Thus, it is considered important to have
mechanisms that allow assigning a confidence level
to the behavior of the water supply systems,
examining whether it can be more or less reliable
[7].
This evaluation is not simple, because the design
of the system depends on factors that are variable in
each case, such as the architectural characteristics of
the building and the water pressure available in the
public network. Other important aspects that can
affect reliability are the materials and equipment
used, the sizing of the system components, the
construction practices, and the maintenance
performed.
To facilitate this assessment is proposed the
creation of performance indicators that can quantify
levels of security for each variable that can affect
the operation of the water supply system. These
variables, when properly combined, according to
their degree of importance, can provide significant
information about the reliability of the system. In
summary, it is intended to identify and detail the
variables which can affect, with greater or lesser
complexity, the behavior of the water supply system
in buildings.
The use of performance indicators has already
been used in some countries, such as Saudi Arabia
or Hong Kong, to evaluate the construction of
buildings as a whole in these specific countries
[8,9]. Indeed, over the last few years, several
authors have sought to establish Key Performance
Indicators (KPIs) for general application in
buildings, in the construction or use phases, but few
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of these works have focused on building
installations [10-14]. In the bibliography can be
found proposals for KPIs applications in the energy
field (or HVAC) [15-17], but there are practically
no specific references to performance indicators for
hydraulic networks in buildings. It should be noted
that some authors focus on special buildings, such
as hotels, commercial buildings, or industrial
buildings, and others propose more complex
approaches, such as models based, for example, on
an artificial neural network [18-19],
The performance indicators proposed in this
article were developed based on Portuguese practice
and regulations, but insofar as they follow European
directives, they are directly applicable in a broader
scope. It is easy to realize that the proposed
methodology can be easily adapted to different
realities.
In this paper, no formula is proposed to weight
these indicators, with a view to a final valuation of
the installation, given that the weight to be
attributed to each indicator may depend on specific
circumstances, such as the priority on the comfort of
users, the search for a low maintenance network, the
existence of other specific construction control
mechanisms, etc.
2 Concept of Reliability
In general, reliability is the degree of trust which is
attributed to a system in operation, placed in a
particular environment for a while, without failure
occurrence. A reliable system is synonymous with a
robust system, insofar as it can overcome barriers
and in which it can be trusted, being free of errors
and with predictable results [7-20,21].
But, there always is a probability of happenings
undesirables in the operation of the system,
designated as failures. In other words, failure is
defined as the consequence of the combined action
of several factors random and unpredictable
associated with the system, as well as the influence
of the environment in which it operates.
It is perceivable that the reliability of a system
decreases with the period of operation. However,
the operation period is not always measured in units
of time. Other units may be considered, such as
distance traveled, shifts/operating cycles, or a
combination of these two measures.
The reliability theory is not more than a set of
ideas, models, or methods intended to estimate the
occurrence of problems. The objective is to
contribute to obtaining optimization solutions that
increase the probability of survival of a system,
related to the lifetime of its components and
equipment [7-20,21].
The first applications for mathematics models
about reliability were observed in the maintenance
machines, from the decades 30 and 40, but it should
be noted that was essentially in the II Mundial War
period that the reliability theory was developed, to
respond to the need to improve military technology.
However, in the 50s, were developed some other
aspects of reliability, for example, life tests
performed on electronic equipment, missiles, and
aircraft, providing information about the problems
associated.
From 1955 emerged the initial reliability models
for the lifetime of equipment and processes in
solving maintenance problems. In the decade of 70,
the safety of nuclear reactors spurred greater
attention to reliability problems and, in the 80s, the
attention was put on the security of computer
networks. In the 90s, were traced new guidelines for
the investigation of reliability, influenced by physics
and differential geometry.
In the present century, there are already models
for analysis and application in numerous fields, such
as mechanical and electronic equipment, but also in
systems more complex, such as public electricity
networks, and public telecommunication drainage,
among others [7-20,21].
3 Factors Affecting the Performance
of the Water Supply in Buildings
The water supply to a building can be done by
connecting to a public or private source, through a
system formed by a set of pipes, fittings, and
equipment that enable the distribution of water for
each user device called the internal network of the
building, which enables the supply of water for each
user device. This internal distribution network can
become more or less complex, depending on the
needs that are intended to be met concerning the
available resources. It can include building
reservoirs, water treatment, pumping systems, and
sanitary hot water production, for example.
Based on the conviction that any water supply
network in buildings can fail, there is an interest in
assessing its reliability, as the unpredictable failures,
internal or external to the building, as well as the
time required for its resolution, can significantly
affect the health and life quality of users. It is
necessary to discover the potential causes and try to
minimize faults in the future, to get contribute to
better performance.
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One good performance of the network is a result
of several factors. The continuity of their functions
exercise at optimized conditions, depends on the
knowledge of information that can help to keep this
objective, or, at worst, anticipate and solve problems
that eventually may arise and possibly provide your
solution timely, avoiding damages.
The existence of failures is the result of how the
system was built and causes inconsistencies in its
proper functioning, which can be permanent,
temporary, or intermittent. The constant repetition
of an occurrence provides indications for the
development of methods to avoid or make them
bearable. In addition, it is known that the durability
of the networks is limited and, therefore, it is
necessary, as much as possible, to preserve their
stability, acting on its maintenance and control [20-
22].
In the first stage, it is important to conceive the
building network properly and, in a manner,
technically correct, through the development of a
project that, knowing the architectural
characteristics of the building and the availability of
pressures in the public network, provided by the
water authority, will lead to a more or less complex
network. The selection of the right materials and the
development of a good design and correct sizing are
extremely relevant, subsequently affecting the
conditions of comfort, durability, and operation [6].
Moreover, the compatibility of the solutions
envisaged in the project with other building services
is essential, lest they arouse changes during the
construction phase that could interfere with the
expected performances. In the construction stage,
they need good construction practices, particularly
as regards the correct installation or assembly of
materials, fittings, equipment, and devices.
With time, the installations will be degraded
naturally. As such, inspection routines become
necessary, enabling to correct possible
deteriorations or detection the impending of failures
that, even allowing continued operation of the
system, affect the operating conditions (case, for
example, of small water leaks). Thus, preventive
repair or timely maintenance operations should be
carried out, without harming consumers or causing
any damage with associated costs. For example, if
there are reservoirs in the building, its periodic
inspection is extremely important, for reasons of
public health.
However, it is observed with a frequency that
these building installations exhibit pathologies
associated to project errors, construction errors, or
lack of control and maintenance, causing discomfort
and inconveniences affecting the quality of life of
the inhabitants or users, or even their health, often
with high repair costs.
4 Performance Indicators. Definition
and Characterization
A building's water supply network is a set of pipes,
connections, equipment, and devices. Knowing that
internal and external factors can affect its
performance, the analysis of its reliability is not
simple. To facilitate this assessment, it is important
to specify factors that identify and characterize the
main aspects involved, which can be called
performance indicators.
A performance indicator should be understood as
a measure of a quantitative assessment of the
efficiency or effectiveness of the performance of the
various constitutive elements and factors associated
with a given system. Efficiency assesses the extent
to which available resources are optimally used for
system operation.
Effectiveness assesses the extent to which
management objectives, specifically and
realistically, are met. Each indicator contributes to
the quantification of a given parameter in a given
context and for a given period. Thus, it makes it
possible to simplify the analysis of the fulfillment of
a certain objective and to verify its evolution over
time. Indicators are usually expressed as
relationships between variables and can be
dimensionless (expressed in %) or intensive (eg
€/m3).
Although the information inherent to each
indicator may be relevant when examined
individually, they must be considered together,
considering the objectives to be achieved and the
context in which they are inserted, to obtain more
adequate results in the global assessment of the
performance of a given system. Together, the
indicators combined in a balanced way according to
their importance can translate the relevant aspects of
the functioning of building water networks and their
reliability.
5 Performance Indicators for Water
Supply in Buildings
To quantify the functional performance of a water
supply network in a building, it is proposed some
performance indicators that evaluate individually
each of its parts, according to certain criteria. The
following criteria are relatively exhaustive but can
be reduced or adapted on a case-by-case basis.
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- Indicator of Available Resources [IAR]: related
to the availability/suitability of service pressure
in the public network, provides information
about the relationship between the resources
available and needed. May condition the greater
or lesser complexity of the building network.
- Indicator of Human Resources [IHR]: translates
information about the qualifications/training of
professionals, interconnected to the main stages
that the installation goes through in its life
cycle: design, construction, and use (inspection
and maintenance).
- Indicator of Infrastructures [II]: represents
information on the degree of complexity of the
water supply network, regardless of the
adequacy of its design to the available
resources, as well as its ability to respond to the
continuity of supply, even with less
performance, in case of failures occurrence.
- Indicator of Maintenance of the Infrastructures
[IMI]: reveals information about the way how
are implemented the recommendations or good
practices of inspection and maintenance of the
installation.
- Indicator of Malfunctions [IM]: provides
information on the performance of the network
components and the location of failures
occurrence.
- Indicator of Quality of the Service [IQS]: gives
information on the quality of service provided,
whether by the efficiency of the repair of
malfunctions or by the impact which this cause
on the consumption, reflecting the number of
supply interruptions during a certain period.
- Indicator of Costs/Investments [ICI]: provides
information about the investments made in the
installation, regarding the improvement of the
systems, as well the maintenance costs, when
the networks have more than 5 years in
operation.
5.1 Criteria for the Performance Indicators
The water supply network is a complex system. To
simplify its performance analysis, the proposed
indicators are subdivided into several criteria,
properly identified, as shown in Table 1:
Table 1. Performance Indicators and their criteria
Performance indicators and their criteria
Criteria
identification
1
C1.1
2
C2.1
3
C3.1
C3.2
C3.3
C3.4
C3.5
C3.6
4
C4.1
C4.2
C4.3
C4.4
5
C5.1
C5.2
C5.3
C5.4
6
C6.1
C6.2
C6.3
C6.4
C6.5
7
C7.1
5.2 Indicator of Available Resources
The resources that a public network provides are
flow rates and pressures and the conception of the
building network must be adequate to the conditions
of supply of these resources. It is assumed that water
distributed through the public network meets the
quality requirements established in the applicable
legislation, so this factor will not be considered in
the present indicator.
Flow and pressure are not independent, since
excessive consumption in the public network
implies high-pressure losses, reducing the residual
pressures available. Thus, in order not to make the
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analysis too complex, the present indicator will only
consider the "pressure" resource for the required
flow rate. It should be noted that the possibility of a
non-constant supply, with interruptions, will be
analyzed within the scope of indicator C3.1 and not
in the present indicator.
The pressure available on the local public
network is crucial for the design of the water supply
system, making it more or less complex. As
previously mentioned, for each new request for a
connection for water supply, the public network can
be affected by the service pressure it can provide, so
there must be an assumed responsibility of the water
authority, to guarantee satisfactory values over time.
For reasons of comfort and durability of
materials, it is generally recommended that the
pressures in the devices are between 150 kPa and
300 kPa [23]. However, according to the technical
codes of some countries (such as the Portuguese
regulation [24]), the pressures could vary between
50 kPa and 600 kPa. The European standard EN
806-3:2006 considers a domain more restricted,
between 100 kPa and 500 kPa [25].
The service pressure insufficiency, typically
related to architectural conditions (number of floors
to supply), may require the placement of reservoirs
and pumping systems, which, in case of failures, can
compromise building network performance. On
another side, if the service pressures are too high
(due to the existence of basements in the building,
for example), it may be necessary to install
pressure-reducing valves or equivalent devices. The
solutions for the reduction of pressures can also
generate failures and compromise the longevity of
the network.
Thus, given the data provided by the operator of
the public system, specifically the pressures
(maximum and minimum) available in the public
network measured at the site, and the pressure
needed to supply the building, by the project, the
criteria listed in Table 2 are adopted.
Table 2. IAR: Criterion C1.1
Indicator of Available Resource - IAR
Identification
Availability / Suitability of pressure in the public network
C1.1
This Indicates the service pressure in the public network is properly to
supply the installation needs.
This indicates the maximum pressure of the public network is higher,
exceeding 500 kPa which involves the need for a pressure-reducing
device.
This indicates the service pressure available at the public network is
insufficient to satisfy the needs of the installations considering a direct
supply.
It should be noted that to check the minimum
pressure the devices must be considered the
available service pressure, while, to check the
maximum pressure, must be considered the static
pressure at the site. The criteria indicated in the next
table are adjusted to the European Standards but can
be easily adapted to other standards [26].
5.3 Indicators of Human Resources
In countries where there are degrees of professional
qualifications (like Portugal), this indicator can be
considered, as, in principle, it should be reflected in
the quality of the installation. The professional
qualifications, somehow, can translate into the
adoption of solutions and materials, as well as the
implementation of good construction practices,
inspection, and maintenance. The training is
relevant and requires constant updating, according
to new techniques, equipment, systems, and
constructive solutions that arise in the market, as
well the experience in the working activity, where
can be developed knowledge about the "know-how"
to tasks run, allowing a continuous quality
improvement of the final works.
At the project stage, the adequate choice of the
materials and systems for the building network and
a correct definition of the hydraulic performance,
contribute to the intended operating conditions. In
Portugal, the civil engineers registered in the
Portuguese Engineers Order can subscribe projects
of water building network projects, with the levels
of effective members, senior members, and
counselor members.
At the construction stage, the good functioning
of the installation is associated with a good practice
mounting, so special attention must be paid to the
quality of the work, through the qualification of
installers who perform these tasks, which can be
certified or not, as well as their work experience. In
Portugal, for example, there is a certification
association for plumbers, called ANQIP (National
Association for Quality in Building Services).
At the control and maintenance stage, is essential
that the network operation and durability are
ensured through periodic inspections and
maintenance of all its elements. Thus, as in the
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construction phase, the plumbers' qualifications and
experience should be contemplated in this criterion.
Although this indicator must be adjusted to the
specific reality of each country, the experience of
design engineers and plumbers for each stage of the
installation can be defined in a simplified way based
on time intervals: [0-5 years], [> 5- 10 years] and [>
10 years]. Table 3 reflects a possible configuration
of this indicator for the Portuguese reality.
To validate the criteria, it is suggested the
submission of declarations of professional
associations, or educational/training certificates, as
well as professional curricula.
Table 3. Criterion C2.1 and their sub-criteria
Indicator of Human Resources - IHR
Identification
Qualification / Training of personnel
assigned to the project, construction,
control, and maintenance
C2.1
Design
C2.1.1
Professional Category or Level
C2.1.1.1
Professional Experience
C2.1.1.2
Construction
C2.1.2
Certified Installer
C2.1.2.1
Professional Experience
C2.1.2.2
Control and Maintenance
C2.1.3
Uncertified Installer
C2.1.3.1
Professional Experience
C2.1.3.2
5.4 Indicator of Infrastructures
A system with several alternatives of operation is
undoubtedly more complex and prone to failure
occur. However, it can respond more efficiently to
counteract the occurrence of localized problems
without interruption of operation.
a) Water reserve infrastructures
If the existence of a reservoir in the building is
imposed, although the system becomes more
complex, it can have the advantage of guaranteeing
the water supply for a certain period in case of
failure in the public network.
In this way, Tank Capacity Reserve [RCT] is
defined as the period, measured in days, in which
users of the building can use their volume in case of
failure of the supply from the public network,
corresponding to the relationship between the useful
volume of the tank and the average daily
consumption expected in the building.
In Europe, taking to account that the uptake is
150 liters of water per day, which can be considered
an average value, then to the residential sector is
obtained:
The useful volume is measured in liters. The
number of users depends essentially on the
characteristics of the building but can vary
significantly in similar buildings. In the case of
residential buildings, it is proposed to quantify the
number of consumers according to the type of
building, as shown in Table 4.
Table 4. Conventional Number of occupants
according to the type of building unit
Conventional Number of occupants according to the type of
building unit
Typology of the building
(according to the number
of bedrooms “n”)
T0
T1
T2
T3
...Tn
Number of occupants
2
2
3
4
...n+1
In the case of non-residential buildings, there are
other known criteria for estimating the number of
occupants. Per capita consumption in these
buildings must be adequate for the intended use.
If there is a reservoir in the building system, the
following criteria and sub-criteria are considered
(Table 5):
Table 5. Criterion C3.1 and his sub-criterion
C3.1 – System Water Reserve
Identification
Reserve Capacity of tank
C3.1.1
Reserve Capacity of tank ≤ ½ day
½ day < Reserve Capacity of tank ≤ 1 day
Reserve Capacity of tank > 1 day.
It should be noted that limits are established for
the maximum volume of tanks in the regulations of
some countries, so as not to exceed a maximum
retention period, for reasons of water quality.
b) Pumping system and complementary
infrastructures
The imposition of the existence of pumping systems
in the building is related to the fact that the pressure
available in the public network is insufficient for the
desired use conditions. To suppress this problem, it
is necessary to install pressurization or lifting
equipment which, in case of failure, can
compromise the water distribution. As such, the
redundancy of pumps, though, for example, the
doubling of groups, with one generally remaining in
reserve, is an advantage, since, in addition to the
possibility of having a complementary supply of
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water at an exceptional peak of consumption, it can
ensure continuity of normal water supply in case of
service pump failure.
Moreover, the functioning of the pumps depends
in general on the electric energy. However, can exist
failures of the electricity supply, and without an
energy source, the equipment doesn´t work and,
consequently, the water distribution is
compromised. So, the pump operation can be
ensured by the existence of others energy supply
alternatives, such as generators.
Then, in case of the existence of a pumping
system, it is assumed (Table 6):
Table 6. Criteria C3.2 and their sub-criteria
C3.2 – Pumping system and
interconnected systems
Identification
Reserve the pumping system
C3.2.1
Pumping system without reserve
Pumping system with 50% of the
reserve
Pumping system with 100% of the
reserve
Reserve of supply energy
C3.2.2
Existence of an alternative energy
supply system
No existence of an alternative energy
supply system
c) Water heating infrastructures or equipment
The distribution of hot water is generally considered
one of the minimum comfort requirements in
buildings, especially in the residential sector. To
meet this requirement, buildings must have at least
one device for producing sanitary hot water (SHW).
However, when there are failures in its operation,
the heating of the water is naturally compromised,
so it is relevant the existence of other equipment,
complementary or not, for the production of SHW
(for example, solar panels), to minimize the impact
of eventual deficiencies in the operation of the main
equipment.
Thus, if sanitary water heating equipment is
available, the sub-criterion of the following table
(Table 7) can be considered:
Table 7. Criterion C3.3 and his sub-criterion
C3.3 – System water heating
Identification
Amount of heating sanitary water
equipment
C3.3.1
1 sanitary hot water equipment
2 sanitary hot water equipment
> 2 sanitary hot water equipment
d) Unitary head losses
The length and diameter of the pipes, as well as
their accessories, equipment, and valves, lead to
more or fewer pressure losses. The water pressure in
the most unfavorable use device concerning the
entry point may have fewer comfort conditions, with
greater variations in pressure heads [27].
In this criterion, the head losses calculated in the
design phase can be considered in the installation
phase but, in the construction and control, and
maintenance phases, the actual head losses can be
measured with a pressure gauge. When the analyses
are cumulative, the value of the head loss measured
on site should be considered, as it is more real.
In this way, the reference values inherent to the
criterion are shown in the next table (Table 8):
Table 8. Criterion C3.4
C3.4 – Unit Load Loss
Reference values:
Unitary head loss average < 0.05 m/m
0.05 < Unitary head loss average ≤ 0.1 m/m
Unitary head loss average > 0.1 m/m
e) Sectioning of the network
The building network is made up of branches and as
long as the sectioning valves are strategically
positioned, it is possible to localize failures (and
carry out the respective repairs), without
compromising the overall functioning of the
network, as long as the failures are local.
This criterion can be defined as a sectioning
index of the network [SN]:
(2)
According to the exposed, the criterion
considered is shown in the next table (Table 9):
Table 9. Criterion C3.5
C3.5 –Network sectioning
Network Sectioning Index < 1
Network Sectioning Index ≥ 1
f) Devices density
The total number of devices in the building
installation can make the system more or less
complex (and more or less subject to failures),
affecting network performance. Thus, the sub-
criterion indicated in Table 10 is assumed:
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Table 10. Criterion C3.6 and his sub-criterion
C3.6 – Devices Density
Identification
Total Amount of use devices in the
building installation of water distribution
C3.6.1
< 10 devices
11 to 20 devices
21 a 30 devices
> 30 devices
5.5 Indicator of Infrastructures Maintenance
The early detection of possible problems in the
network allows for its timely resolution, without
higher costs and discomfort to the users. Those
problems could translate, besides the supply cuts,
situations that can damage other infrastructures.
Therefore, the inspection frequency and
maintenance of the infrastructures of the building
network is a factor to take into account in this
performance indicator. During the network
operation, the maintenance/inspection processes that
are verified should be registered, for example, the
date that the process was made, the operation type
and network components involved, identification
and professional category involved, etc.
a) Maintenance of Water Reserve System
The inspection, maintenance, and cleaning of the
reservoir components are important, as regards their
conservation state and the quality of the water
consumed. A stationary water reserve for long
periods can compromise the water quality for
human consumption.
In that way, in the case of the existence of tanks,
are assumed the Table 11 criteria and sub-criteria:
Table 11. Criterion C4.1 and their sub-criteria
C4.1 – Maintenance of water reserve system
Identification
Maintenance/Cleaning of the system
components of the tank:
C4.1.1
Cleaning frequency of filters
C4.1.1.1
No one time per semester
1 time per semester
2 times per semester
> 2 times per semester
Cleaning frequency and sanitation of the
tank
C4.1.1.2
No one time per year
1 time per year
> 1 time per year
Maintenance Frequency of control unit of
the tank levels
C4.1.1.3
No one time per year
C4.1 – Maintenance of water reserve system
Identification
1 time per year
2 times per year
> 2 times per year
Inspection of system components of the tank:
C4.1.2
Inspection frequency of the filters
C4.1.2.1
No one time per semester
1 time per semester
2 times per semester
> 2 times per semester
Inspection frequency of the tank
C4.1.2.2
No one time per year
1 time per year
2 times per year
> 2 times per year
Inspection frequency of control unit of the
tank levels
C4.1.2.3
No one time per semester
1 time per semester
2 times per semester
> 2 times per semester
Equipment of treatment and disinfection /
Monitoring of water quality of reservoirs:
C4.1.3
Inspection frequency of treatments
equipment of water
C4.1.3.1
No one time per month
1 time per month
> 1 time per month
Maintenance frequency of treatments
equipment
C4.1.3.2
No one time per month
1 time per month
> 1 time per month
All the sub-criteria presented inherent to the water
reserve system, depending on the frequency that is
executed by the competent professionals. This frequency
should be correctly registered during the operation of the
network.
b) Maintenance of pumping system and
complementary infrastructures
In the case of the existence of pumping equipment,
as well as other complementary infrastructures, is
considered good practice its periodic inspection and
maintenance, to evaluate the conservation state and
functional performance, that way to detect timely
possible damages that can occur and repair them,
without major impacts on the building network
performance (Table 12).
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Table 12. Criterion C4.2 and their sub-criteria
C4.2 – Maintenance of pumping system
and complementary infrastructures
Identification
Inspection frequency of pumping system
C4.2.1
No one time per year
1 time per year
> 1 time per year
Calibration frequency of pressure switches
C4.2.2
No one time per year
1 time per year
2 times per year
3 times per year
> 3 times per year
Inspection frequency of normal system of
electric energy supply
C4.2.3
No one time per year
1 time per year
> 1 time per year
Inspection frequency of alternative system
of energy supply
C4.2.4
No one time per year
1 time per year
> 1 time per year
c) Maintenance of water heating systems
The good functional performance of the domestic
hot water heating system implies frequent inspection
and maintenance, according to the manufacturer's
recommendations, to increase the probability of
continuing an efficient hot water supply.
Thus, is established the criterion shown in the
next table (Table 13). It assumes that the inspection
frequency should be registered:
Table 13. Criterion C4.3
C4.3 – Maintenance of system water
heating
Identification
Inspection frequency of SHW system
C4.3.1
No one time per year
1 time per year
> 1 time per year
d) Maintenance of the building network
The periodic inspection of the building network can
check the conservation and cleaning state of the
components system (pipes, accessories, devices,
etc.), alerting to failures eventually at the occur
eminency. The criterion and sub-criterion are shown
in Table 14.
Table 14. Criterion C4.4 and his sub-criterion
C4.4 – Maintenance of network building
distribution of water
Identification
Inspection frequency of pipes, accessories,
and devices
C4.4.1
No one time per year
1 time per year
> 1 time per year
The frequency and the components involved
should be registered.
5.6 Indicator of Malfunctions
In case of failures, the occurrence should be
registered, with detection date, failure type, and
cause. When analyzing the individual criteria of this
indicator, it's possible to evaluate which elements
can compromise the system and, if it is justified,
proceed to its preventive substitution, to improve the
reliability of the system.
Moreover, the complete stop of water
distribution in the system implies a repair as quickly
as possible, knowing that the discovery of the
problem source is not always immediate. Therefore,
based on the malfunction’s history, is possible to
establish a priority order of checks, investigate their
provenance and minimize the repair time.
So, during the network operation, the
malfunctions which occur and their frequency
should be registered. This register should include
detection, malfunction type, affected elements in the
network, identification, and professional category
involved, among others.
a) Failures of the Water Reserve System
In case of the existence of a water reserve cistern,
when detected the occurrence of its failures should
naturally be registered. The criterion adopted is
shown in the next table (Table 15):
Table 15. Criterion C5.1 and his sub-criterion
C5.1 – Failures of the water reserve
system
Identification
Occurrence frequency of failures in the
water reserve system
C5.1.1
No one malfunctions per year
1 or 2 malfunctions per year
3 or 5 malfunctions per year
>5 malfunctions per year
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b) Failures of the pumping system or
complementary infrastructures
In case of the existence of a pumping system and
complementary infrastructures (such as expansion
tanks, pressure gauges, etc.), the occurrence of
failures should also be registered. In the fowling
table it is assumed (Table 16):
Table 16. Criterion C5.2 and their sub-criteria
C5.2 – Failures of the pumping system or
complementary infrastructures
Identification
Occurrence frequency of failures in the
pumping system
C5.2.1
No one malfunctions per year
1 or 2 malfunctions per year
3 or 5 malfunctions per year
>5 malfunctions per year
Occurrence frequency of failures in
complementary infrastructures of the
pumping system
C5.2.2
No one malfunctions per year
1 or 2 malfunctions per year
3 or 5 malfunctions per year
>5 malfunctions per year
Occurrence frequency of failures in the
normal supply of energy
C5.2.3
No one malfunctions per year
1 or 2 malfunctions per year
3 or 5 malfunctions per year
>5 malfunctions per year
Occurrence frequency of failures in the
alternative supply of energy to the pumping
system
C5.2.4
No one malfunctions per year
1 or 2 malfunctions per year
3 or 5 malfunctions per year
>5 malfunctions per year
c) Failures of the water heating system
In the case of the existence of system water heating,
is also indispensable to consider the register of the
failures detected. Thus, it is proposed the criterion
indicated in the table (Table 17):
Table 17. Criterion C5.3 and their sub-criteria
C5.3 – Failures of the system water heating
Identification
Occurrence frequency of failures in the
systems heating water
C5.3.1
No one malfunctions per year
1 or 2 malfunctions per year
3 or 5 malfunctions per year
>5 malfunctions per year
d) Failures in the water distribution components
The failures occurrence of the water distribution
components, correctly registered, is related to the
sub-criterion indicated in Table 18:
Table 18. Criterion C5.4 and his sub-criterion
C5.4 – Failures of network building
distribution of water
Identification
Occurrence frequency of failures in the
pipes, accessories, and devices
C5.4.1
No one malfunctions per year
1 or 2 malfunctions per year
3 or 5 malfunctions per year
>5 malfunctions per year
5.7 Indicator of Quality Service
Sometimes, the repairs of equipment failures
(pumps, heating water equipment, pipes, devices,
etc.) are inconclusive, so the malfunctions quickly
reappear by the same motive.
In this way, it is important to verify the quality of
the services provided, evaluating, for example, the
frequency of water interruptions that can be
attributed to failures or inaccuracies in the provision
of these repair services.
a) Repair Efficiency of the Water Reserve System
In the case of tank existence in the building
network, this criterion is related to repeated faults
frequency in the reserve system (Table 19):
Table 19. Criterion C6.1 and his sub-criterion
C6.1 – Repair efficiency of the water
reserve system
Identification
Occurrence Frequency of repeated faults in
the water reserve system
C6.1.1
No one repeated malfunction per year
1 repeated malfunction per year
2 repeated malfunctions per year
>2 repeated malfunctions per year
b) Repair efficiency of the pumping system and
complementary infrastructures
This criterion is subdivided as shown in the next
table (Table 20):
Table 20. Criteria 6.2 and his sub-criteria
C6.2 – Repair Efficiency of the pumping
system and complementary parts
Identification
Occurrence frequency of repeated faults in
the pumping system
C6.2.1
No one repeated malfunction per year
1 repeated malfunction per year
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2 repeated malfunctions per year
>2 repeated malfunctions per year
Occurrence frequency of repeated faults in
complementary infrastructures of the
pumping system
C6.2.2
No one repeated malfunction per year
1 repeated malfunction per year
2 repeated malfunctions per year
>2 repeated malfunctions per year
Occurrence frequency of repeated faults in
the normal supply of energy
C6.2.3
No one repeated malfunction per year
1 repeated malfunction per year
2 repeated malfunctions per year
>2 repeated malfunctions per year
Occurrence frequency of repeated faults in
the alternative supply energy to the pumping
system
C6.2.4
No one repeated malfunction per year
1 repeated malfunction per year
2 repeated malfunctions per year
>2 repeated malfunctions per year
c) Repair efficiency of the water heating system
In the case of a sanitary water heating system, the
next table (Table 21) is applied:
Table 21. Criterion C6.3 and his sub-criterion
C6.3 – Repair efficiency of the system
sanitary water heating
Identification
Occurrence Frequency of repeated faults in
the system sanitary water heating
C6.3.1
No one repeated malfunction per year
1 repeated malfunction per year
2 repeated malfunctions per year
>2 repeated malfunctions per year
d) Repair efficiency in the building distribution
network
To check the repair efficiency in the building
distribution network of the building is adopted the
next criterion (Table 22):
Table 22. Criterion C6.4 and his sub-criterion
C6.4 – Repair efficiency in the building
distribution network
Identification
Occurrence Frequency of repeated faults in the
pipes, accessories, and devices
C6.4.1
No one repeated malfunction per year
1 repeated malfunction per year
2 repeated malfunctions per year
>2 repeated malfunctions per year
e) Interruptions of water supply
The interruptions of water supply can have more or
less impact on the consumption, according to the
period in which occur the fault water.
It is suggested the analysis by periods, assuming
periods of higher consumption, normal
consumption, and lower consumption during the
day. (Table 23).
Table 23. Criterion C6.5 and their sub-criteria
C6.5 – Interruptions of water supply
Identification
Occurrence frequency of water interruptions
during established periods:
C6.5.1
07h00 – 9h00: Higher Consumption period
C6.5.1.1
0 interruption per year
1 to 2 interruptions per year
2 to 5 interruptions per year
> 5 interruptions per year
09h00 – 11h00: Normal Consumption period
C6.5.1.2
0 interruption per year
1 to 2 interruptions per year
2 to 5 interruptions per year
> 5 interruptions per year
11h00 – 14h00: Higher Consumption period
C6.5.1.3
0 interruption per year
1 to 2 interruptions per year
2 to 5 interruptions per year
> 5 interruptions per year
14h00 – 18h00: Normal Consumption period
C6.5.1.4
0 interruption per year
1 to 2 interruptions per year
2 to 5 interruptions per year
> 5 interruptions per year
18h00 – 23h00: Higher Consumption period
C6.5.1.5
0 interruption per year
1 to 2 interruptions per year
2 to 5 interruptions per year
> 5 interruptions per year
23h00 – 7h00: Lower Consumption period
C6.5.1.6
0 interruption per year
1 to 2 interruptions per year
2 to 5 interruptions per year
> 5 interruptions per year
In this context, it is assumed that the
interruptions of water supply should be registered
according to the schedule established, as well as the
date of occurrence.
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5.8 Indicator of Costs/ Investments
The investments are related to the initial cost of the
building water supply system.
In this context, the following investments are
accounted for:
- investments in improvements in the system
water reserve
- investments in improvements in the pumping
system and complementary infrastructures
- investments in improvements in the water
heating system
- investments in improvements of pipes,
accessories, and devices
- investments in the maintenance contracts for the
installations
Thus, attending to the initial cost of building
installation can be defined as the criterion, as shown
in the next formula:
(3)
6 Conclusion
Building water networks are one of the most
important building infrastructures, in terms of the
comfort and health of their users or occupants. Thus,
consumers have the best expectations regarding
their operational behavior.
However, when the systems are not meeting the
requested requirements, they can cause interruptions
or damage to the building and the constraint
provided can be severe, either by cuts in the water
supply or by repair costs. In this sense, it is
important to contribute to the improvement and
durability of building installations, concerning the
performance and guarantee of the quality of the
water supply, through a methodology for assessing
the reliability of the network.
But, is not possible to establish one simple
evaluation, since the system is constituted of a set of
elements which, depending on architectural
conditions of edifications and the water service
pressure available at the public network, can
become a complex system. In addition, other aspects
can be conditioners, such as the applied materials,
the design of the network, the correct dimensions,
the good construction practices, and the
maintenance.
Therefore, to simplify this objective, it is
proposed, similar to what already exists in some
countries in relation, for example, to public
networks, the creation of performance indices that
can quantify the efficiency or effectiveness and the
security levels of each of the variables necessary for
the functioning of building networks.
These variables, when examined individually,
may reflect only a partial aspect and not a view of
the entire building water system, about its
performance. However, when combined using a
mathematical model, weighted according to their
specific degrees of importance, the variables can
reveal important information for the reliability of
the global system.
After the performance indicators have been
characterized, a model can be developed that allows,
in a certain way, to quantify the performance of the
networks and classify their reliability, capable of
contributing to predicting, monitoring, and
improving the operability of the networks.
Although there are already many references
regarding the application of KPIs in different
building services or different types of buildings,
there is no previous research in the scope of the
development of specific performance factors for the
water supply in buildings. Given the growing
importance of efficient water management in all
sectors, for reasons of sustainability or scarcity of
the resource, it is considered that this article can
contribute to the promotion and development of
future studies in this area, such as, for example, the
development of mathematical models to weight the
performance factors according to the degree of
importance attributed to each one. The development
of performance factors for drainage in buildings is
also a proposal for future research in this context.
References:
[1] Van der Schee, W., 2009. Water Systems in
high-rise residential buildings. Guidelines for
design and Construction, in Proc. 36th
International Symposium of CIB W062 Water
Supply and Drainage for Buildings, 7-9
September 2009, Dusseldorf, Germany, 85-
104.
[2] Ichikawa, N., 2009. Trends in and Recent
Research into Direct Water Supply Systems in
Japan, in Proc. 36th International Symposium
of CIB W062 Water Supply and Drainage for
Buildings, 7-9 September 2009, Dusseldorf,
Germany, 10-26.
[3] Silva-Afonso A. 2014. The bathroom of the
future: its contribution to sustainability, in
Proc. 41st International Symposium of CIB
W062 Water Supply and Drainage for
Buildings, 8-10 September 2014, S. Paulo,
Brazil, 519-530.
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[4] Silva-Afonso, A., Pimentel-Rodrigues, C.
2014. Water Policy for Buildings: A
Portuguese Perspective. in K Adeyeye (Eds.)
Water Efficiency in Buildings: Theory and
Practice. John Wiley & Sons, 42–55.
[5] Silva-Afonso, A.; Pimentel-Rodrigues, C.;
Kanoun-Boulé, M.; Almeida, J. 2017. Toilets:
past, present and future". In Proc. 43rd
International Symposium of CIB W062 Water
Supply and Drainage for Buildings, 23-25
August 2017, Haarlem, Netherlands, 421-430.
[6] Silva-Afonso, A. 2008. Certificação de
qualidade das instalações hidráulicas e
sanitárias: Uma necessidade em Portugal, in
Proc. GESCON 2008 – Fórum Internacional de
Gestão da Construção 11-12 December 2008,
Oporto, Portugal, 162-169 (Portuguese).
[7] O’Connor, P. and Kleyner, A. 2013. Practical
Reliability Engineering. John Wiley and Sons,
Ltd., 2012. 512 p.
[8] Elshakour, H. et al. 2013, Indicators for
measuring the performance of building
construction companies in Kingdom of Saudi
Arabia, Journal of King Saud University -
Engineering Sciences 25, 125-134.
[9] Yeung, J. et al. 2008, Establishing quantitative
indicators for measuring the partnering
performance of construction projects in Hong
Kong, Construction Management and
Economics 26:3, 277-301.
[10] Ahmad, S. et al. 2016. A review of
performance measurement for successful
concurrent construction, in Proc. 29th World
Congress International Project Management
Association, 28 September – 1 October 2015,
Westin Playa Bonita, Panama,447-454.
[11] Jahangirian, M. et al. 2017, Key performance
indicators for successful simulation projects,
Journal of the Operational Research Society
68:7, 747-765.
[12] Rodrigues, M et al. 2011, Building envelope
anomalies: a visual survey methodology,
Construction Building Materials 25:5, 2741-
2750.
[13] Kylili, A. et al. 2016, Key performance
indicators (KPIs) approach in buildings
renovation for the sustainability of the built
environment: a review, Renewable, and
Sustainable Energy Reviews, 56, 906-915.
[14] Han, L. et al. 2020, System-level key
performance indicators for building
performance evaluation, Energy and Buildings,
209, 109703.
[15] Zhichao, T. and Xing, S. 2022, Proposing
energy performance indicators to identify
energy-wasting operations on big time-series
data, Energy and Buildings, 269, 112244.
[16] Ghahfarrokhi, K. et al. 2020, Key performance
indicators regarding user comfort for buildings
energy consumption management, in Proc.
International Conference on Energy and
Environment Research, ICEER 2020, 14-18
September 2020, Porto, Portugal.
[17] Crespi, G. et al. 2022, Innovative metrics to
evaluate HVAC systems performances for
meeting contemporary loads in buildings,
Energy Reports, Volume 8, 9221-9231.
[18] Maya, M. et al. 2021, Develop an artificial
neural network (ANN) model to predict
construction projects performance in Syria.
Journal of King Saud University – Engineering
Sciences, (online) doi.org/10.1016/j.jksues.
[19] Fernando, D. et al. 2018, Key performance
indicators for measuring the performance of
facilities management services in hotel
buildings: a literature review, In Proc 7 World
Construction Symposium, June 2018,
Colombo, Sri Lanka.
[20] Woods, D. 2006. Resilience Engineering:
Concepts and Precepts. Taylor & Francis, Ltd.,
2006. 416 p.
[21] Provan, D. et al. 2020, Safety II professionals:
How resilience engineering can transform
safety practice, Reliability Engineering &
System Safety 195, 106740.
[22] Mokssit, et al. 2018, Building a methodology
for assessing service quality under intermittent
domestic water supply, Water 10: 1164.
[23] Silva-Afonso, A. et al. 2008, Economic design
of water distribution systems in buildings,
Engineering Optimization, Taylors & Francis,
London, U.K., Volume 40:8, pp. 749-766.
[24] PORTUGAL 1995, Regulamento Geral dos
Sistemas Públicos e Prediais de Distribuição de
Água e de Drenagem de Águas Residuais –
Decreto Regulamentar n.º 23/95, Imprensa
Nacional, Lisbon (portuguese).
[25] CEN, EN 806-3: 2006, Specifications for
installations inside buildings conveying water
for human consumption – Part 3: Pipe sizing –
Simplified method. European Committee for
Standardization. Brussels, Belgium.
[26] Pimentel-Rodrigues, C. Silva-Afonso, A. 2014,
The need to rethink the design criteria for
water supply in buildings in light of the
implementation of water efficiency measures,
in Proc. Symposium CIB W062 2014 – Water
Supply and Drainage for Buildings. S. Paulo,
Brazil, 8 - 10 Sept.
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Volume 18, 2022
[27] Silva-Afonso, A., Pimentel-Rodrigues, C.
2016, Rethinking the sizing criteria in the
water supply for buildings”, In Proc. of the
symposium CIB W062 2016 – Water Supply
and Drainage for Buildings. Kosice, Slovakia,
29 Aug - 1 Sept.
Contribution of Individual Authors to the
Creation of a Scientific Article (Ghostwriting
Policy)
-Mary Lourenço developed the conceptualization of
the text and wrote the original draft.
-Armando Silva-Afonso was responsible for
defining the methodology of research and
supervising and validating the final text.
-Carla Pimentel-Rodrigues collaborated in the
research and validation and was responsible for
writing (reviewing and editing) the final text.
Creative Commons Attribution License 4.0
(Attribution 4.0 International, CC BY 4.0)
This article is published under the terms of the
Creative Commons Attribution License 4.0
https://creativecommons.org/licenses/by/4.0/deed.en
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