Group Project: Air Conditioning System Replacement in Hong Kong

This group project focuses on the replacement of a central air conditioning system in a commercial building located in Hong Kong. The project addresses the need for a new system due to the existing one's age and frequent breakdowns. The project's scope includes disassembling the old system, designing and installing a new central air conditioning system, and providing a warranty. The project adheres to specific design specifications, including requirements for the compressor, condenser, evaporator, and other components. Constraints such as tenant disruption and noise levels are considered. The project also includes a detailed breakdown of group roles, meeting proceedings, and design proposals, including the selection of a water-cooled chiller. The project evaluation and recommendations for improvement are also included, along with project development records, references, and schematic drawings of the central air conditioning system.

Group Project 1
GROUP PROJECT IN THE CONSTRUCTION INDUSTRY
Name
Course
Professor
University
City/state
Date

Group Project 2
Table of Contents
1. Task 1.................................................................................................................................................2
1.1. Task 1.1: Group roles and activities.........................................................................................2
1.2. Task 1.2: Specifications based on Constraints.........................................................................4
1.2.1. Requirements of the Central Air Conditioning System........................................................5
1.2.2. Products...............................................................................................................................8
1.3. Initial proposals.......................................................................................................................11
1.3.1. Proposal 1..........................................................................................................................11
1.3.2. Proposal 2..........................................................................................................................13
1.3.3. Comparison of the existing and proposed systems.............................................................15
2. Task 2...............................................................................................................................................16
2.1. Task 2.1: Evidence of project development...........................................................................16
2.2. Task 2.2: Final design proposal that meets the desired specifications.................................20
2.2.1. Essential Design Specifications.........................................................................................21
2.2.2. Water-cooled chiller...........................................................................................................21
3. Task 3...............................................................................................................................................27
3.1. Task 3.1: Project evaluation and recommendations for improvement................................27
3.1.1. Proposal 3..........................................................................................................................27
4. Task 4...............................................................................................................................................29
4.1. Task 4.1: Project development records..................................................................................29
References................................................................................................................................................33

Group Project 3
1. Task 1
1.1. Task 1.1: Group roles and activities
Project members: Chan Nai Tat, Wong Wai and Chan Ming
First Group Meeting (#1)
Date: June 5, 2017
Time: 2:30 P.M.
Venue: TBA
Members present:
Chan Nai Tat
Wong Wai
Chan Ming
Meeting agenda:
1. Deliberation on the project goals and objectives
2. Role of each group member in relation to the project
3. Scope of work for each group member
4. Expected code of conduct for all group members
Meeting proceedings:
1. Group structure
Team leader – Chan Nai Tat
Team member – Wong Wai
Team member – Chan Ming
2. Responsibilities
Chan Nai Tat (team leader) – responsible for tendering process, prepare project program, track
progress of the project and provide guidance on way forward, ensure collaboration and
cooperation of members, resolve any disputes between members and call for meetings.
Wong Wai (team member) – responsible for establishing the desired specifications for various
components and processes of the project, develop necessary drawings, prepare relevant
documents, compile reports, write minutes during meetings and keep records of all ongoing
activities.
Chan Ming (team member) – responsible for carrying out site survey, facilitating coordination
with subcontractors and coordinating and monitoring works performed by subcontractors on site.
3. Project plan discussion

Group Project 4
Project background: this project is about replacement work of a central air conditioning
system in a commercial building located in Central, Hong Kong. The building was constructed in
1976 and its air-conditioning system had been in use for about two decades. The system was
experiencing frequent breakdowns probably because it was outdated and therefore it could not
meet the required air conditioning levels and standards. The need for replacing the old air-
conditioning system with a new central-air conditioning system was inevitable and that is why
owners and operators of the building created this contract. The key parameters that were
paramount when implementing this project included: energy efficiency, environmental
conservation, cost, quality, project delivery (time), and compliance with or adherence to the
relevant codes, standards and laws. The client wanted a cost-effective and durable central air-
conditioning system that operates quietly, consumes less energy, provides cleaner air and ensures
that the desired indoor comfort is attained.
Estimated project duration: 3 – 6 months
Project budget: HK$10 million
Next Group Meeting (#2)
Date: June 8, 2017
Time: 2:30 P.M.
Venue: TBA
1.2. Task 1.2: Specifications based on Constraints
Project: Replacement of a Central Air-Conditioning System of a Commercial Building
Project Name: Replacement of a Central Air-Conditioning System at Alexandra House in
Central, Hog Hong
Brief Descriptions: the specific requirements of the project are to replace existing air
conditioning system of the commercial building with a new one that is more efficient in terms of
performance, resource utilization and environmental impact.
Scope of Work
Disassembling and removing the existing air conditioning system from the plant room (including
the compressor, condenser, evaporator and thermal expansion valve).
Designing and installing a new central air conditioning system in the plant room.
Testing and commissioning the installed central air conditioning system.
Providing one year warranty period of repair and maintenance work for the installed central air
conditioning system.
Essential Design Specifications

Group Project 5
The contractor is responsible for the inclusive design of the central air conditioning
system. This entails ensuring structural stability, proper sizing and compatibility of all
components of the system (compressor, condenser, evaporator and thermal expansion valve) and
correct installation. All these processes are to be carried out in compliance with the stated
performance requirements and relevant building codes, standards and regulations.
The contractor is expected to coordinate and collaborate with other key participants in the
project and ensure that he collects all useful data and submits and shares all relevant data,
calculations, information and documents for the Architect to approve at every stage of the
project.
The contractor is expected to design and install the central air conditioning system
through strict adherence to the stipulated design specifications, project budget and project
duration.
1.2.1. Requirements of the Central Air Conditioning System
1.2.1.1. General Requirements
The requirements stated in this section are in concurrence with the general provisions
provided in the contract, including: conditions of the contract, general conditions, supplementary
conditions, and contract drawings.
1.2.1.2. Scope
Provide computer controlled central air conditioning system with adequate capacity to
cool the building to the desired temperature level. The system’s schematic drawings, layout and
operation should be in accordance with the drawings and specifications provided in the relevant
contract documents. The main components of the air conditioning system that should be
provided include, but not limited to: compressor, condenser, evaporator, thermal expansion
valve, filters, electrical power control panel and connections, system control hardware and
software and manufacturer manual.
1.2.1.3. Delivery and Handling
All components should be delivered on site ready for installation. The manufacturer
should ensure that the components packed are the ones ordered for. The components should be
packaged depending on how they will be installed. For example, the condenser package should
contain the condenser itself and other units needed for its installation.
All vulnerable components should be provided with proper protective covering so as to
ensure their safety during shipment from the manufacturer to the site. Any open ends or nozzles
have to be fitted using plastic enclosures.
Shipment should be done using recommended trucks by the manufacturer. If there are
any wide loads, relevant transportation regulations must be followed.
Once delivered on site, the components shall be handled and stored in accordance with
the manufacturer’s guidelines.
1.2.1.4. Starters and wiring
Component mounted starter board should be provided. The board should also have a
metal nameplate showing identification numbers of the manufacturer, serial number, phase amp,
maximum full load amp and voltage.

Group Project 6
1.2.1.5. Control interface
Every component should have an integrated control unit that will be connected to the
component on site to ensure accurate and continuous monitoring and control of the component’s
operation.
1.2.1.6. Installation
All components should be installed to enable efficient operation, and easy and safe
maintenance. Grease fittings should be fixed directly to bearings except if the bearings are not
easily reached. In cases where bearings are not easily reached or visible, the contractor shall have
to provide reachable extensions to lubrication fittings of the bearings. The arrangement of the
entire system should be in accordance with the specified physical layout. The valves should be
strategically located to enable isolation and removal of any component without having to
completely drain the liquid or refrigerant circuits.
1.2.1.7. Finish
All components should be factory painted according to the recommendations of the
manufacturer for those that are exposed to the environment of industry activity. If necessary, the
components shall also be painted on site by following the architect’s instructions.
1.2.1.8. Service tools and sideboard
Complete set of apparatuses and tools for maintenance and servicing of the system in
metal sideboard with appropriate tagging should also be provided.
Contract duration: 90 – 180 days
Contract cost: HK$10 million
1.2.1.9. Standard drawing
Schematic drawing of the central air conditioning system (chiller) is as shown in Figure 1 and 2
below
Figure 1: Schematic drawing of water-cooled chiller

Group Project 7
Figure 2: Schematic drawing of the central air conditioning system
1.2.1.10. Constraints
Throughout the construction period, tenants of the building should not be affected. This
means that the air conditioning system should not stop working and the contractor should
provide adequate cool air for supply in the building. Noises emanating from ongoing
construction activities should not cause disturbance to the tenants. Also, transportation of
materials and equipment to the site should only be done from 10:00 A.M. to 11:00 A.M., 1:00
P.M. to 2:30 P.M. or during the night starting from 7:00 P.M.
1.2.1.11. Project acceptance
The project shall be accepted by following the acceptance criteria provided in various
relevant standards. These include: BEEO – Building Energy Efficiency Ordinance (the
Ordinance), General Specification for Air-Conditioning Refrigeration, Ventilation and Central
Monitoring & Control System Installation, Building Energy Codes and the Code of Practice for
Energy Efficiency of Air Conditioning Installations.

Group Project 8
1.2.2. Products
1.2.2.1. Manufacturers
All components supplied shall only be accepted if they are from the specified
manufacturer, meet the minimum industry standards, comply with the specifications provided in
the contract documents and meet the stipulated performance requirements. But if there is any
other alternative component used that is not from the specified manufacturer, it will be the
responsibility of the mechanical contractor to coordinate with the general contractor and other
relevant subcontractors to ensure that appropriate installation process is followed so that there is
appropriate compatibility between all the components installed. The alternative components
should also conform to the following requirements: meet the minimum industry standards,
comply with the specifications provided in the contract documents and meet the stipulated
performance requirements. During coordination for this purpose, the following factors shall be
considered: structural supports and integrity of the components; size, layout and sturdiness of the
condenser, evaporator, compressor and expansion valve; connection points and size of
connection pipes; electrical power supplies, electrical supply pipe sizes and overcurrent shields;
site noises during installation; and any other physical constraints.
Any costs incurred by consultants, the general contractor and subcontractors when
changing the building provisions so as to accommodate the alternative components shall be paid
by the mechanical contractor.
The manufacturer selected for this project should be a company specialized in the design
and production of the specified components and products and is required to have a minimum
experience of 5 years, manufacturing and supplying central air conditioning systems that is
specified in the contract documents.
1.2.2.2. General
Description:
Design, install, test, commission and maintain a factory assembled central air
conditioning system as specified and validated in the drawings. The whole system entails, but not
limited to: water-cooled shell & tube condenser, shell & tube type evaporator (including blower
or air handler and evaporator coil), hermetic screw compressor, expansion valve, electrical
supply panel, supply and return pipes, refrigerant circuits, refrigerant, wiring cables, operating
and safety controls, system control hardware and software, etc. The components should have all
the specified performance characteristics and relevant security features.
Operating characteristics:
The central air conditioning system should have the capacity to provide high and low
ambient temperature control options and operate with the ambient temperature ranging from -10
°C to 25 °C. The system should be able to vary its working capacity so as to adjust cooling
capacity depending on cooling load.
Sideboard:
Structural elements, component panels, structural bases of heavy equipment and control
boxes should be made of factory coated galvanized steel. Exposed steel panel should be painted
with seared powder paint so as to pass the 500-hour salt spray check.

Group Project 9
Shipping:
Each component i.e. compressor, evaporator, condenser and others, should be shipped in
one assembled piece ready for installation. All the necessary pipe connections and wiring should
be completed in the factory. In cases where a component is shipped in different pieces, the
manufacturer shall provide all the necessary materials and labour to assemble it on site.
1.2.2.3. Condenser
The condenser shall be water-cooled shell & tube condenser with a minimum capacity of
650 tons. Its steel shell shall house large copper tubes of thickness 0.75 inches and brazed into
perforated plates. The fans for the condenser should be quieter and made of glass fiber reinforced
blades and its aluminium hub shall be corrosion resistant. The fan shall be driven by 3 phase
A.C. motors of high efficiency and proper insulation and current protection. The insulation
should be factory-applied and appropriate adhesives should be applied at relevant locations, as
specified in the contract documents. The condenser’s maximum thermal conductivity shall be
0.25 at a mean temperature of 15°, with a maximum allowable pressure of 30 bar on the
refrigerant side. The refrigerant outlet should have a shut-off valve to enable refrigerant
connection. The end covers of the condenser should be detachable to enable easy cleaning.
1.2.2.4. Evaporator
The required evaporator for this project is shell & tube type evaporator, also referred to as
chiller. The evaporator is flooded type with 4 cooling or refrigerant circuits and a cooling
capacity of up to 2500 kW. The evaporator shall comprise of several large tubes interleaved in
the shell and it can use different HFC (hydrofluorocarbon) and HCFC (hydrochlorofluorocarbon)
refrigerants. Its tube bundles should be removable to facilitate easy cleaning and maintenance.
The evaporator should be made of high quality materials that meet industry standards. Heat
transfer pipes should be made of copper; body, flange, water connections, tube sheet, header and
refrigerant should be made of carbon steel; bolts should be made of steel alloys; baffles should
be made of materials that are resistant to corrosion; and gaskets should be neoprene or asbestos
free. The evaporator should have desired water inlet & outlet connections and branches. It must
be tested for leakage at a pressure of 30 bar and it should also meet all relevant safety
requirements. The images below are different schematic diagrams of the evaporator.
1.2.2.5. Compressor
The compressor used in this project shall be an independent hermetic screw compressor with
two helical rotors (male and female rotors built in the piston). The compressor shall be driven by
a 3 phase alternating current (AC) electric motor with appropriate rating and comprising of the
following units: receiver tank with a minimum capacity of 20,000 liters and fitted with drain
valve, pressure gauge and safety valves; suction filter; pressure relief valve; drain valve;
automatic pressure switch; starter for motor; non return valve and oil sight glass. The
compressor’s maximum noise level should be 50 dB when working at normal load and it has to
be designed for nonstop operation and should be fitted with stainless steel valves, aluminium
cooler tubes and cast iron piston. Other important units of the compressor are:
1.2.2.6. Air dryer
The integrated air dryer should have a moisture trap with manual and automatic drain. It
should also have a hot gas by-pass valve for maintaining an even pressure dew point to the
setpoint and prevent freezing when it is operating under un-load run mode. This component

Group Project 10
should supply compressed air to the system in accordance with the relevant building codes in
Hong Kong.
1.2.2.7. Pre filter
The pre filter should be able to remove foreign substances, including oil, dirt and other solid
particles, from the air as stated in the specifications.
1.2.2.8. Control panel
This component is used for accurate and continuous monitoring of data and regulate
performance of the compressor based on the feedback it receives. The features that the control
panel should contain include: phase sequence and failure protection relays, starting load
protection, overload trip, and oil discharge or high air temperature trip.
1.2.2.9. Others
Other components needed for connecting and operation of the compressor include: power
supply, circuit breaker, switches, cables, pipes, hoses ad connectors.
1.2.2.10. Power control panel
The power control panel should be factory wired and installed, powder coated steel
sideboards with hinged, lockable, latched and ring sealed external doors furnished with wind
struts to facilitate safer servicing. The contractor should also provide the following: main power
connections, motor contactors, compressor starters, factory wiring and current overloads. The
power control panel should also have an access door to the control chamber.
1.2.2.11. Single point power
Power connecting to the central air conditioning system should be single point, driven by 3
phase A.C. of the specified voltage. Incoming single point connections should be done by
terminal block connections for compressor interconnecting wiring and field connection. Separate
external protection should also be provided and all wiring works should be in accordance with
the requirements of local building codes.
1.2.2.12. Control transformer
Power panel should be provided with a factory wired and fixed control transformer to supply
all the required system control voltage from the power supply’s main. The line voltage used by
the transformer on the primary and secondary side should be one specified in the documents.
1.2.2.13. Power factor
The equipment supplied should have the specified power factor modification capacitors so as
to retain a displacement power factor of 95% at every load capacity or condition. In case the
supplied power factory modification capacitors are not factory wired and fixed, it will be the
responsibility of the installing contractor to meet any cost incurred in furnishing and installing
these capacitors.
The electrical system enclosure should have a short circuit withstanding rate of 600, 640 and
720V: 40,000.
All unprotected power wiring cables should be channeled through ultra violet stabilized,
liquid-light, non-metallic conduits.
All components supplied should not exceed specified MCA (maximum circuit ampacity). If
there are any deviations regarding MCA, it will be the responsibility of the mechanical

Group Project 11
contractor to meet additional costs associated with modification of the components to ensure that
they meet the specified MCA.
1.2.2.14. Acoustic data
Acoustical sound pressure or power level data should be provided in dB (decibels) at the
specified 8 octave band center frequencies. The sound pressure or power level should be
provided at cooling load of 25%, 50%, 75% and 100%. At any of these cooling loads, the
components supplied should not exceed the specified sound pressure or power level. If there is
any deviation regarding sound pressure or power level of the components supplied, it will be the
responsibility of the mechanical contractor to meet the associated additional costs of reducing the
data to the required level.
The diagram in Figure 3 below shows the general layout of the central air conditioning
system that shall be provided in this project
Figure 3: Simplified layout of the system
1.3. Initial proposals
1.3.1. Proposal 1
1.3.1.1. Introduction
Alexandra House is a 37-storey commercial building of Grade A, located in Central district
of Hong Kong. The building was constructed about 40 years ago but remains one of the
spectacular office buildings in Central, Hong Kong. Notable tenants of the building include:
Deacons, Otto e Mezzo Bombana, Richards Butler, Linklaters and Christie’s. The building is
owned by Hongkong Land. The existing air conditioning system of the building has been in use
for many years and its performance and efficiency was decreasing due to aging. Other factors
such as energy efficiency, thermal comfort, changing occupant comfort needs and environmental
impacts of air conditioning systems also prompted need to replace the existing system. We
proposed to replace the existing air conditioning system with a 700 tons York YD air conditioner
that is more energy efficient and meets the desired performance requirements.

Group Project 12
1.3.1.2. Objectives of Proposal 1
The objectives of this proposal are: maximize performance of the air conditioning system,
reduce operation cost of the system, reduce downtimes and emergency calls, increase reliability
of the air conditioning system, automate and streamline system monitoring and control, use
environmentally friendly refrigerant (HFC-134a) that has no phase out date and causes zero
depletion of ozone layer, maintain desirable indoor room temperature, and reduce energy
consumption and bills.
1.3.1.3. Description of existing air conditioning system
The components of existing central air conditioning system are housed in a plant room. The
system is interconnected with ducts that supply cool air to all rooms in the building depending on
the indoor thermal comfort needs of the occupants. The existing system has a total cooling
capacity of 600 tons. This means that it can remove approximately 7.2 x 106 (600 x 12,000)
British Thermal Units (BTU) of heat in one hour. Below are some of the details of the existing
central air conditioning system at Alexandra House.
Existing equipment Model Max.
duty
capacity
Quantity Location
600 tons central air conditioning
system
York YK
chiller
10,000
kW
1 Plant room
1.3.1.4. Description of proposed air conditioning system
The existing air conditioning system shall be replaced with the proposed central air
conditioning system. The new system has a total cooling capacity of 700 tons, meaning that the
system can remove approximately 8.4 x 106 (700 x 12,000) BTU per hour. The system will be
installed in the same location of the existing system. This new system has a greater performance
and resource efficiency. The table below contains some details of the proposed system
Existing equipment Model Max.
duty
capacity
Quantity Location
700 tons central air conditioning
system
York YD
chiller
15,000
kW
1 Plant room
1.3.1.5. Energy analysis of new air conditioning system
Energy efficiency has become a very crucial factor in modern buildings not only in Hong
Kong but across the world. This is due to the environmental, social and economic impacts of
energy. For this reason, various proposals of the air conditioning systems of the buildings have
been assessed based on their energy consumption and efficiency. This has been done by
determining annual operating costs of the systems using their seasonal energy efficiency ratio
(SEER) values. Systems with higher SEER values consume less energy (Consumer Reports,
2017). According to AHRI (Air Conditioning, Heating, and Refrigeration Institute), SEER is
calculated by dividing total cooling capacity of the system during normal operation period (not
exceeding 1 year) by total electrical power input during the same period (Air-Conditioning,
Heating, and Refrigeration Institute, 2012).