FMT302: Chiller Plant Operation and Maintenance Analysis

This report examines the operation and maintenance of a chiller plant in a 25-story commercial building in Singapore, focusing on improving efficiency and addressing challenges. It analyzes issues like contaminated tubes, non-condensable gases, low refrigerant charges, and incorrect cooling tower operation. The report explores building control strategies, including building automation systems, energy management, and space management. Furthermore, it delves into the application of smart analytics, highlighting automated notifications, fault detection diagnostics, and operation monitoring to optimize building performance. The report emphasizes the importance of electrical and mechanical equipment performance efficiency, and the impact of lighting control on energy consumption. This assessment provides a comprehensive overview of strategies to enhance the performance of building services.

Running Head: OPERATION AND MAINTENANCE OF BUILDING SERVICES
Operation and Maintenance of Building Services
Name
Institutional affiliation

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INTRODUCTION
This assessment paper examines the operation status of chillers in a 25-storey commercial
development comprising of a six-storey retail podium and an office block with two basement
levels situated in Singapore downtown by evaluating the challenges in improving the current
efficiency performance of chilled water cooling plant, and also suitable preventive maintenance
practices.
b)
The chillers are machines that remove heat from a liquid through an absorption refrigeration
cycle and vapor-compression. This liquid is then circulated through the heat exchanger to cool
the equipment. The type of centralized air-conditioning system in the chiller plant is water-
cooled where chilled water is distributed to heat exchangers which cool the air in the various
spaces. In this 25-storey commercial development comprising of a six-storey retail podium and
an office block with two basement levels, there are 4 number chiller plants, 4 number chiller
water pumps, 4 number condenser water pump, 2 number cooling towers, average peak building
load of 1,460RT, the total cooling capacity of 2,200RT, and the system efficiency 0.84kW/RT.
The three major characteristics of an efficient chiller water cooling plant include contaminated
tube, non-condensable gas present, low refrigerant charge, incorrect cooling tower operation, and
irregular water flow to chiller. The challenges faced in improving plant performance efficiency
are discussed below:
Fouled or Contaminated Tube
Research shows that one of the biggest potential obstacles to the performance of chillers desired
is the efficiency of heat transfer. The optimal performance and maintaining chiller plant

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efficiency are directly related to the ability of the chiller to transfer heat and this starts with
having a clean condenser tubes and clean evaporator. The efficiency of the chiller water cooling
plant deteriorates as tubes become contaminated or fouled especially when contaminants, scale,
sludge, algae, or mud accumulate on the waterside surface of the heat-transfer surfaces (Zheng,
Watt, & Wang, 2016). The rate of system contamination depends on the type of the system
which can either be closed or open and also the water temperature, cleanliness, and quality. If the
tubes of the chiller become plugged or coated with biological growth, sludge, or scale, the ability
to transfer heat significantly drop.
All chiller makeup and circulating water contains contaminants. Chemical treatment of water
assist in preventing the accumulation of contaminants on the surfaces of heat transfer. The wrong
concentration or chemicals that are too high can damage the internal components. It is still
important to perform a cleaning of condenser tubes of the chiller water cooling plant using brush
even with suitable water treatment program (Thangavelu, Myat, & Khambadkone, 2017). The
annual cleaning can eliminate accumulation of loose materials, biological growth, and sludge.
Presence of Non-condensable Gas
The presence of non-condensable gas in the condenser tubes of the chiller water cooling plant
introduces additional thermal resistance at the condenser which can substantially lower the
energy efficiency of the plant. The addition of thermal resistance caused by presence of non-
condensable gas in the condenser tube arises, deriving from a diffusion process of vapor in the
non-condensable gas layer that tends to concentrate near the condensing surface, being conveyed
by the centripetal force of vapor towards the tubes (Xiupeng, Guanglin, & Kusiak, 2014). It is
clear that a small quantity of non-condensable gas causes huge damage since they are not

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distributed uniformly inside the internal volume of condenser tube, but collect close to the
surface where condensation is occurring.
Low Refrigerant Charge
Chilled water cooling plant operates in an optimal condition if the system is charged fully with a
particular amount of refrigerant. Refrigerant leakage or poor field maintenance causes low level
of charge leading into a higher operating cost and a lower thermal performance. For every chilled
plant, a particular amount of refrigerant is need to charge the system to function in optimal
conditions at the section pressure and design discharge (Chao, Meng, & Qiang, 2014). Small
variations possible because of the negligence of the installers may not significantly affect the
performance of the system. Nevertheless, Serious degradation of performance may occur when
the charge level if below a particular limit. Frequent system maintenance can locate and correct
the problem. However, the problem may persist for a longer duration in many cases due to no or
poor maintenance resulting in higher energy usage and lower system performance.
Research shows that maximum energy efficiency and cooling capacity occur near to the
condition of full-charge. Exceedingly overcharging or undercharging the system result in
decrease in both energy efficiency ratio and capacity, and the impact on capacity for low charge
is stronger compared to the overcharge condition (Seshadri, Rysanek, & Schlueter, 2019). Low
refrigerant charge can also cause overheating of the compressor since the compressor will have a
tendency of picking up the slack. Refrigerant generally dissipates and absorbs thermal energy so
as to bring cool air into the building. The refrigerant charge must be in at the correct level so as
to make majority of the electrical energy so as to reduce energy costs over time.
Incorrect Cooling Tower Operation

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The five factors that determine the performance of a cooling tower in chiller water cooling plant
include airflow rate, water-flow rate, wet-bulb temperature, cold water temperature, and hot
water temperature. The operation of cooling tower determines the operating efficiency of the
chiller plant in most cases. Towers that are not in good condition, operated wrongly, and poorly
maintained prevent peak efficiency operation of chillers (Chun-Wei, Cheng-Wen, & Chia-Yon,
2010). Generally situated on the roof of the building, cooling towers normally suffer from being
out of mind and out of sight. Given the environment in which cooling towers operate in,
performing proper maintenance is specifically significant. Cooling towers are exposed to the
elements and are perfect gatherers of debris, leaves, and dirt that can clog water and air passages
(Tirmizi, Siddiqui, & Gandhidasan, 201). Also, the moist and warm environment in which the
cooling towers operate in promotes biological growth that can clog spray nozzle and minimize
the efficiency of heat transfer. Proper operation of cooling towers require regular schedule
inspection of towers and repairs.
c) (i)
Some of the methods of improving building system operation and equipment performance
include lighting control, mechanical and electrical equipment performance efficiency, the
sequence of equipment operation, and building control strategies.
Building Control Strategies
Some of the building control strategies that can be adopted to improve the building system
operation and equipment include use of building automation system, optimization of operational
efficiencies, energy management of submetering,
Building Automation System

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Building automation is a building control strategy involving monitoring and control of electrical
and mechanical equipment of the building such as security systems, power systems, lighting, and
ventilation through computer control. The Building automation is composed of hardware and
software configured in a categorized way using protocols like Profibus and C-Bus and is
generally implemented in large projects with extensive electrical, HVAC, and mechanical
systems (Zong & Wang, 2011). The systems linked to the building automation system represent
40% of the energy usage in the building and if the lighting system is included, then the energy
usage is 70%.
Energy Management and Submetering
Energy management and submetering is also a building control strategy and involves energy
management through allocating energy usage and cost to specific spaces. The submetering
system is based on energy verification, monitoring, and management based on high frequency,
finer spatial resolution, and predictive indicators (Zhiqiang & Salazar, 2020). This enables
regular energy analysis based on predictive results that incorporate operating schedule,
occupancy, and outdoor temperature.
Space Management
The management of space in the building is also a significant strategy for building control. The
management of space provides tenants and developers with an increased understanding of how
space is utilized and who is using the spaces specifically, support agile working environment,
real-estate management, and planning (Wilson, Rogelio, & Pedro, 2018). Understanding the
utilization of space enables an evolved understanding of the energy use of the building which

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will encourage not just making spaces more energy-efficient, but also making the spaces more
spatially efficient.
Electrical and Mechanical Equipment Performance Efficiency
Extended Equipment Lifecycle
The electrical and mechanical equipment performance efficiency influences the equipment
performance by extending the lifecycle of the equipment. Optimized performance efficiency of
the equipment enables performance issues to be diagnosed and detected early before the
equipment can fully fail to operate (Blum, 2014). By improving the performance efficiency of
the chiller plant system through schedule maintenance, the lifecycle of the equipment can be
extended hence improving the equipment performance and building system operation.
Improved Energy Usage
The electrical and mechanical equipment performance efficiency affects the energy usage of the
building hence improving the operation of the building system. The efficient operation of the
chiller plant system, the energy usage in the building will greatly be reduced. The efficiency of
the chiller plant system and other electrical systems ensure reduced energy consumption by
implementing energy-efficient practices such as improvement of compressor and heat exchange
technology hence improving building system operation and equipment performance (Togashi &
Miyata, Development of building thermal environment emulator to evaluate the performance of
the HVAC system operation, 2019).
Better Productivity, Comfort, and Health for Building Occupancy

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The electrical and mechanical equipment performance efficiency influences the equipment
performance by ensuring better productivity, comfort, and health of the building. The
performance efficiency of the chiller plant system provides occupants comfort by cooling and
heating the building.
Reduced Cost of Operation and Replacement Equipment
The electrical and mechanical equipment performance efficiency affects the building system
operation by reducing the cost of operating the equipment or replacing the equipment with a new
one which the building tenants will have to incur. The efficient performance of the chiller plant
system reduces energy consumption through the identification of any defect in the equipment
hence reducing the cost of operating the equipment and operation of the building (Togashi &
Miyata, Development of building thermal environment emulator to evaluate the performance of
the HVAC system operation, 2019).
Lighting Control
Lighting control plays a significant role in improving the operation of the building system by
regulating the energy consumption of the building. One of the most common types of lighting
control is the occupancy sensor which switches off the lighting of a room or area if the place
remains unoccupied to prevent wastage of energy. The use of energy-saving light fittings and
effective lighting maintenance programs both increase lighting efficiency and reduce energy
consumption hence improving the building system operation (Hicks & Thomas, 2013).
c) (ii)
Smart analytics can be used to improve building operations through the implementation of
various approaches and techniques to attain them. Smart analytics provides substantial data that

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can be used in the optimization of the energy performance and removal of any inefficiencies in
the building. Some of how smart analytics can be harnessed to improve building operations
include:
Automated notifications and alerts
The smart analytics is significant in critical management of building operations where remote
monitoring where remote monitoring is possible from miles away. Smart analytics can be used to
integrate with the open system to allow the occupant to receive notifications and alerts through
automation (Rocha, Siddiqui, & Stadler, 2015). For instance, mart analytics in the building can
send a notification to the occupant in case of fire since it incorporates a fire alarm system which
monitors smoke and heat levels in the building.
Fault Detection
Diagnostics and fault detection for predicting cost and energy saving are significant elements in
the smart analytics of the building. The smart analytics of the building can analyze the
maintenance, and energy, comfort levels, and track performance at periodic intervals through a
computer-based control system. This enables the occupants to proactive building maintenance
while ensuring continuous energy efficiency (Burroughs, 2017). For instance, if the system
efficiency of the chiller plant system is not 0.84kW/RT, then the fault will be detected by the
smart analytics from the data collected.
Operation Monitoring
The smart analytics of the building assist in providing data that can be used in lowering the
operation and maintenance costs. Sensor data from meters, electric plug, HVAC, occupancy, and

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lighting are significant but the power of smart analytics depends on the provision of an integrated
view of all these individual components.
Energy Performance
The application of smart analytics increases the actions taken in ensuring consistency in the
performance of equipment. The smart analytics indicates new insights into energy consumption
and system performance of the building through collecting data from different equipment,
systems, and facilities (Pickering, Hossain, & French, 2018). For instance, is the cost of energy
used in lighting and pump operation increases above normal, the smart analytics data will
indicate so and corrective actions can be taken to determine the cause of the high cost of certain
electricity units and faulty equipment.
CONCLUSION
The major aspects of operation and maintenance of building services discussed in this paper
include challenges in improving the current performance efficiency of chilled water cooling,
improvement of building system operations and equipment performance, and smart analytics
used to improve the building operations.

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