Technical Guidelines

for

Connection to District Cooling System

2012 Edition
(as at 30.08.2012)
Technical Guidelines for Connection to DCS EMSD

Contents
Page
1 Interpretation 1
2 Introduction 2
2.1 Scope 2
2.2 Purpose 2
3 Application for DCS Connection 3
3.1 Application Procedure 3
3.2 Handover date for EMSD's installation 3
4 District Cooling Services Specification 5
4.1 Supply Temperature 5
4.2 Supply Quality 5
4.3 Supply Capacity 5
5 General DCS Connection Design Guidelines 6
5.1 General 6
5.2 Connection between the DCS Network and Substation 6
5.3 Substation Location 7
5.4 Typical Substation 7
5.5 Building Requirements for Substation 9
5.6 Access to Substation 10
5.7 Building Services Requirements for Substation 11
5.8 Provision of Building Services Equipment and Services during Installation 12
6 Compatibility of Design of the Primary and Secondary Sides 13
6.1 Equipment to be Installed in Secondary Side by EMSD Inside Substation 13
6.2 Equipment to be Installed in Secondary Side by the Consumer 13
6.3 Recommendations to Ensure Compatibility 13
6.4 Consequences 14
7 Testing and Commissioning and Handover of Substation 15
7.1 Hydrostatic Pressure Testing 15
7.2 Flushing and Cleaning 15
8 Interfaces during Operation and Maintenance 16
8.1 Access for O&M and Data Reading 16
8.2 Water Treatment 16
8.3 Meter and Metering 16
Appendix A – Fundamentals of DCS 17
a) Principle 17
b) Key components 17
Appendix B - Recommendations to Secondary Side System 19
1) Air Handling and Terminal Units 19
2) Mixing Valve at the Secondary Side 20
3) Secondary Chilled Water Pump Control 21
4) Operation of Heat Exchanger 21
Technical Guidelines for Connection to DCS EMSD

Appendix C 22
Appendix D 26
Technical Guidelines for Connection to DCS EMSD

Figures
Fig. A1 – Elements of a District Cooling System
Fig. B1 – Air Handling and Terminal Units
Fig. B2 – Mixing Valve at Secondary Side
Fig. C1 – Gernal Arrangment on Construction of Substation
Fig. C2 – DDC Control Schematic Diagram in Substation
Fig. C3 – Typical Layout of Substation of Two Heat Exchangers
Fig. C4 – Tyipcal Layout of Substation of Three Heat Exchangers

Table
Table 5.1 – Reference Schedule of Number of Heat Exchangers vs Cooling Capacity of the Building
Table D1 – Buidling and Building Services Provisions of Substations for Different Cooling Capacities
Technical Guidelines for Connection to DCS

1 Interpretation

“contracted cooling capacity” means the maximum designed cooling capacity required for
providing district cooling services to the building as determined by the consumer of the
building and agreed by Electrical and Mechanical Services Department (EMSD) on the approval
of the application for connecting the building to the services;

“consumer” means a person who is approved under the Ordinance as a consumer of district
cooling services supplied to the building;

“consumer installation” means the installation of chilled water system of the central air-
conditioning system through the secondary side of each heat exchanger outside the substation
including the interfacing pipes inside the substation by the consumer;

“district cooling services (DCServ)” means the supply of chilled water for air-conditioning
purposes by a district cooling system vested in and maintained by the Government, and the
provision of other related services;

“district cooling system (DCS)” means a system in which chilled water is distributed from one
or more central chiller plants to buildings through a network of pipes for air-conditioning in, or
provision of other related services to, the building;

“meter” means a device owned by the Government and maintained by EMSD or an operator
for the purpose of measuring the actual cooling capacity required, and the actual cooling
energy consumed, in respect of the DCServ provided to a consumer;

"normal operating conditions” means the consumer’s cooling demand for DCServ is greater
than 10%, but not more than 100%, of contracted cooling capacity;

“operator” means a person who has entered into a contract or management agreement with
the Government for the management, operation and maintenance of a DCS;

“substation” means the site within the boundary of building in which the heat exchangers, the
chilled water pipes, meter and other associated equipment required by DCServ.

2012 EDITION (as at 30.08.2012) Page 1 EMSD

Technical Guidelines for Connection to DCS

2 Introduction
2.1 Scope

This “Technical Guidelines for Connection to District Cooling System” (hereinafter termed as
“Guidelines") is to address the general principles to be applied to the design and installation
works required for connection to DCS, including the provisions of substation located at ground
floor or basement level of the building concerned.

2.2 Purpose

The objectives of this Guidelines are to ensure that all the design and installation requirements
for connection to DCS and the substations provided by the consumers are designed to the
same standard, and fully comply with the relevant requirements of government departments,
utilities, telephone companies, and other authorities as required, and those requirements of the
operator.
Other than the statutory requirements, this Guidelines is to be read in conjunction with other
relevant ordinances, regulations and codes of practice published by HKSAR Government. In
case, there are discrepancies between the requirements stipulated herein and the other
ordinances, regulations and codes of practice, the more stringent requirement should prevail.

2012 EDITION (as at 30.08.2012) Page 2 EMSD

Technical Guidelines for Connection to DCS

3 Application for DCS Connection

3.1 Application Procedure

Any party who wishes to apply for the DCServ shall complete and sign an Initial Application
Form at preliminary design stage and an Application Form at later detailed design stage. The
maximum designed cooling capacity will form the contracted cooling capacity once the
application was accepted by EMSD.
Upon receipt of an application, EMSD or the operator
 May require additional information to be submitted by the applicant
 Shall advise the applicant of the connection scheme and technical requirements
The procedure shall include but not limited to the following:
 Information submission by the consumer, including completed application form,
cooling demand calculation methods, secondary side water-side drawings & etc.
 EMSD or the operator will review the information submitted by the consumer
 Discussion on the design of substation and interfaces. On the substation detailed
layout drawings, EMSD or the operator will suggest possible location of DCServ lead-in
chilled water pipe and control cable to the consumer
 Confirmation of the cooling demand, substation location, trench location, works
programme & service commencement date
 For any such non-standard connections on top of the standard provision, the consumer
shall provide relevant information to EMSD or the operator for consideration and
approval. The supply, installation and maintenance of such additional facilities and
equipment shall be carried out by the consumer at his own cost
 Preparation of construction drawings by the consumer. The substation layout plans
prepared by the consumer should be submitted to EMSD or the operator for
agreement. The submitted drawings should be in both hardcopy and softcopy format.
The softcopy should be in “.dwg” format and compatible with either one of the latest
three AutoCAD® versions
 The consumer must submit the detailed layout drawing incorporating the finalized pipe
trench and exact position of interface services together with the works programme for
agreement by EMSD or the operator prior to installation
 Construction of the substation, trench excavation, backfilling by the consumer
 After join inspection with satisfaction, the substation will be taken over by EMSD for
the installation of heat exchangers and related facilities in the substation. Before
testing and commissioning of the heat exchangers and related facilities, consumer shall
submit pressure test report and treatment details and report to EMSD
 Issuance of handover completion report by the consumer to EMSD or the operator
after testing and commissioning
 EMSD or the operator will commence the operation and maintenance of the substation

3.2 Handover date for EMSD's installation

EMSD or the operator shall agree with the consumer on a handover date of the substation such
that EMSD can install the equipment on time. The handover date is normally five (5) months
before the target chilled water supply date. After taking possession of the substation, EMSD
will install the heat exchangers including chilled water pipes and accessories within substation.
The consumer shall complete all the required testing and commissioning works of consumer
installation and EMSD will coordinate with the consumer for testing and commissioning of heat
exchangers and this is normally one month before the target chilled water supply date. Once

2012 EDITION (as at 30.08.2012) Page 3 EMSD

Technical Guidelines for Connection to DCS

the chilled water supply of DCServ commences, the consumer is required to pay for the DCServ
charge onwards.

2012 EDITION (as at 30.08.2012) Page 4 EMSD

Technical Guidelines for Connection to DCS

4 District Cooling Services Specification

4.1 Supply Temperature

4.1.1 EMSD or the operator shall normally operate the DCS to supply chilled water at
primary side of heat exchanger, measured at 30-minute interval, at Design Primary
Supply Temperature of 5ºC  1ºC under normal operating conditions and the return
temperature on consumer side shall normally be maintained at 14ºC.

4.2 Supply Quality

4.2.1 EMSD or the operator shall exercise reasonable care and skill to provide the consumer
with an uninterrupted supply within the Design Primary Supply Temperature on a 24
hourly basis under normal operating conditions.
4.2.2 EMSD or the operator shall use its best efforts to prevent any interruption in the
provision of DCServ and to minimize the duration of any such interruption. EMSD or
the operator shall notify the consumer as soon as practicable by telephone if there is
unexpected significant change in the operating status of DCServ or if any interruption
is expected to occur.
4.2.3 DCServ may be interrupted or may deviate from the Design Primary Supply
Temperature as specified in clause 4.1.1, but not limited to, the following
circumstances:-
a) When EMSD or the operator takes necessary actions for safety reasons;
b) When EMSD or the operator makes improvements or carries out maintenance,
repairs or works;
c) When matters outside the control of EMSD or the operator causes it do so; or
d) Faults in the consumer installation.

4.3 Supply Capacity

4.3.1 EMSD or the operator shall use its best efforts to provide the consumer the required
cooling capacity under normal operating conditions at all times provided that the
consumer shall always maintain the chilled water return temperature at 14ºC.

2012 EDITION (as at 30.08.2012) Page 5 EMSD

Technical Guidelines for Connection to DCS

5 General DCS Connection Design Guidelines

General design criteria are established in this Guidelines so that the consumer can provide the
basic requirements for the substation for the interface with DCServ during building design.
5.1 General

5.1.1 The consumer shall at its own cost provide and construct the substation in
accordance with the plans and specifications agreed by EMSD. Such plans and
specifications shall not be altered without the approval in writing by EMSD or the
operator. The consumer shall ensure that the substation shall only be used for plant
and equipment linked to the provision of DCServ within the consumer's site
boundary.
5.1.2 The consumer shall at its own cost maintain the trench and cover for pipework
installation and substation within the consumer's site boundary inclusive of building
structure, infrastructure, building services and general cleanliness within the
substation.

5.2 Connection between the DCS Network and Substation

5.2.1 Valve Chamber

5.2.1.1 The consumer's isolation valve chamber is to be assigned by EMSD, subject to
negotiations with other relevant government departments.
5.2.1.2 The consumer's isolation valve chamber that serves as a main switch to separate
the chilled water network and individual consumer, shall be built, operated and
maintained by EMSD. It is normally located outside the periphery of consumer's site
boundary and shall be easily accessible for daily operation and emergency isolation
of the pipework.

5.2.2 Pipes & trenches within site boundary

5.2.2.1 Only DCServ pipes & valves are to be built, operated and maintained by EMSD.
5.2.2.2 For the avoidance of doubt, other facilities and infrastructure for connection within
the site boundary, such as, but not limited to pipe trenches, thrust blocks (if any),
backfilling, protection and covers within site boundary are built, operated and
maintained by the consumer. The routing and size are to be mutually agreed by
the consumer and EMSD. However, a minimum clearance of 1.5m from DCServ
pipeline shall be reserved from the ground level and other utilities.
5.2.2.3 The cross-sectional areas of pipe trenches should not be reduced by ground beams
or other civil/building structures. The invert level of pipe trenches at the boundary
of the substation should be coordinated with EMSD. If ground beams are present
at the boundary of the substation, the clearance under the beams should be
considered. Trench should be built with bedding with at least 100mm of
compacted sand and the depth required should take into account of the gradient
requirement of the pipes to be laid. Pipe trench should be allowed to lay three nos.
of chilled water pipes at same level and 2 nos. of cable duct at each side of trench
(total 4 nos.). Bends should always be avoided. Unless agreed by EMSD, bends
should not exceed 4 nos. for each pipe run to limit the friction loss. Vertical bend
(e.g. “U” & “/\” bend) shall be avoided to prevent from dirt and air accumulated. If
these bends will be used for pipes, drain valve and air vent with valve pit with
adequate maintenance space shall be provided.
5.2.2.4 Bell hole with the minimum size of 2000mm width and 800mm depth shall be
provided at the welding joint of DCServ pipe. The bell hole shall be backfilled with
sand by the consumer.
5.2.2.5 Draw pit(s) for minimum size of 1100mm(W)x1100mm(L)x1500mm(H) for 4 nos. of
uPVC cable duct for control cables shall be provided by the consumer if necessary.
5.2.2.6 Pipes will be direct buried and shall be backfilled with sand by the consumer.

2012 EDITION (as at 30.08.2012) Page 6 EMSD

Technical Guidelines for Connection to DCS

5.2.2.7 Trench width and depth for different cooling capacity should refer to Table D1 in
Appendix D.
5.2.2.8 General arrangement on construction of substation should refer to Fig. C1 in
Appendix C.

5.3 Substation Location

5.3.1 In order to reduce the pipe length, minimize pipe routing space and risk of water
leakage, the substation shall be located as close as possible to the consumer's
isolation valve chamber located outside the periphery of consumer's site boundary
feeding chilled water to the substation. The substation shall preferably be located as
the periphery of the building to ensure ease of installation and operation and
maintenance. In normal case, only one substation should be provided for the
consumer.
5.3.2 For ease of moving heavy equipment, the substation shall be located in ground floor
(road level) or at basement 1 (one level below road level). In any case, the top level of
the substation (including the pipe top level) is limited at or below +10mPD.
Protection shall be provided for the DCServ pipe if the pipe will be installed above
ground and shall be approved by EMSD before installation.
5.3.3 The exact location shall be agreed with the consumer and EMSD.

5.4 Typical Substation

In general, all equipment installed in the primary side and secondary side of heat
exchanger including heat exchanger itself within substation are to be supplied,
installed, operated and maintained by EMSD. Details shall refer to Fig. C1 and Fig.
C2 in Appendix C.

5.4.1 Layout
5.4.1.1 Typical substation layout and dimensions for two heat exchangers and three heat
exchangers are indicated in Fig. C3 and Fig. C4 in Appendix C and Table. D1 in
Appendix D. The layout and table show the minimum dimensions which is subject
to the change in according to EMSD’s comments and suggestions.

5.4.2 Substation Dimension

5.4.2.1 The substation should be planned in accordance with the maximum designed
cooling capacity. The cooling load calculation method, secondary side water-side
schematic and assumptions of the building shall be submitted to EMSD in the
application form as described in Section 3.1 for review and approval. This can
ensure that adequate cooling capacity is reserved for the consumer.
5.4.2.2 The dimensions of the substation are dependent on the maximum designed
cooling capacity. The indicative dimensions are listed in Table D1 in Appendix D.
The table shows the required minimum dimensions which is subject to change due
to site conditions and/or comment from EMSD or the operator.

2012 EDITION (as at 30.08.2012) Page 7 EMSD

Technical Guidelines for Connection to DCS

5.4.3 Heat Exchanger

5.4.3.1 Adequate numbers of heat exchangers will be installed inside the substation
depending on the maximum designed cooling capacity by the consumer (see Table
5.1 below).

Cooling Capacity (kW) Heat Exchangers

(no. x kW)
100 2 x 60
200 2 x 120
300 2 x 180
400 2 x 240
500 2 x 300
1000 2 x 600
2500 2 x 1500
5000 2 x 3000
7500 2 x 4500
10000 3 x 4000
12500 3 x 5000
15000 3 x 6000
20000 3 x 8000
24000 4 x 7200

Table – 5.1 Reference Schedule of Number of Heat Exchangers vs Cooling

Capacity of the Building

5.4.3.2 The number of heat exchangers and necessary components to be provided by

EMSD in the substation will be determined by EMSD as the standard provision.
5.4.3.3 The following general criteria of heat exchanger are used for the design of
consumer installation by the consumer:
a) The supply water temperature on the primary chilled water side is 5 ± 1°C
b) Secondary return chilled water temperature should be at 14°C
c) Close temperature approach, within 1°C, is adopted for the heat exchanger
d) Maximum working pressure of 16 bar
e) Pressure drop across heat exchanger at rated flowrate : 5m
f) Minimum flow rate at secondary side of each of heat exchanger is 20% of its
nominal flow rate
5.4.3.4 If the consumer’s cooling demand for DCServ is less than 10% of contracted
cooling capacity, additional smaller heat exchanger(s) may be requested to cater
the low load conditions. The consumer shall provide relevant information for
EMSD’s consideration and approval. The consumer shall provide larger size of
substation for installation of additional heat exchanger(s).

5.4.4 Interfacing for Metering

5.4.4.1 EMSD will only provide one set of metering device in the substation as the
standard provision. These metering devices are to measure and record the chilled
water capacity and consumption information at primary side. All these metering
devices should be supplied, installed, operated and maintained by EMSD. Adequate
pipe run shall be reserved for these metering devices to allow accurate
measurement.

2012 EDITION (as at 30.08.2012) Page 8 EMSD

Technical Guidelines for Connection to DCS

5.5 Building Requirements for Substation

All these building provisions should be provided and maintained by the consumer.
The detail requirements of the building provision are described in the following
section.

5.5.1 General Requirements

5.5.1.1 All substations should comply with all applicable statutory requirements.
5.5.1.2 For the substation on ground level, they should be directly accessible from open air
(non-covered area) at all times. The permanent access to the substation should be
of adequate height, width and of sufficient strength to withstand the combined
weight of the equipment and the conveying vehicle during installation and
subsequent operation and maintenance.
5.5.1.3 For DCServ substation location exposing to the risk of flooding such as near an
inclined road, slope and sea front, anti-flooding provisions should be built to
prevent flooding of the substation. Kerb at doors should be constructed after
delivery of heat exchangers by EMSD. Ground level substation should be at least
150mm higher than the outside (pavement) level to reduce the risk of flooding.
5.5.1.4 Sufficient space for delivery access should be allowed for equipment delivery for
installation, maintenance and replacement with all leveled ground.
5.5.1.5 Minimum clear headroom of different cooling capacity (excluding any lifting hook)
should be referred to Table D1 in Appendix D inside the substation to install the
heat exchanger and relevant equipment.
5.5.1.6 Permanent hoisting facilities should be provided for each heat exchanger within
the substation for delivery, installation, maintenance and replacement.
5.5.1.7 For special circumstances, the consumer should obtain EMSD prior agreement on
building requirement.
5.5.1.8 The substation shall be solely for the DCServ equipment and building services
serving only the substation. Other utilities, equipment, control panel and system
not intended for DCServ shall not be installed within the substation.

5.5.2 Additional Requirements for Substation Location other than Ground level
5.5.2.1 The substation should be directly accessible from the open air at ground level by a
shared staircase.
5.5.2.2 Emergency exit route diagram should be provided in the substation.
5.5.2.3 Enough access leading from street level to the substation should be provided for
equipment delivery.
5.5.2.4 Curb to be provided if necessary, provision (i.e. height of curb) subject to specific
site condition / location.

5.5.3 Equipment Dimensions, Weights and Operational Space

5.5.3.1 The clearances and operating areas required around the equipment have been
considered with due consideration for future operation, maintenance and upgrade.
5.5.3.2 In general, the minimum clearance required around the heat exchangers are:-
a) 1000mm on the back side
b) 1500mm between side wall and heat exchanger
c) 1500mm between each heat exchanger
The above dimensions given are measured from plinth to plinth and subject to final
approval by EMSD.

2012 EDITION (as at 30.08.2012) Page 9 EMSD

Technical Guidelines for Connection to DCS

5.5.4 Foundation/ Plinth

5.5.4.1 The heat exchanger foundation/ plinth to be provided by the consumer should be
capable of supporting equipment load. The dimensions of the equipment plinth
should be considered as well as plinth level with finished floor level. The indicative
dimensions are listed in Table D1 in Appendix D.
5.5.4.2 The foundation should be capable of supporting a maximum static plus dynamic
load per equipment. The minimum cover between the finished floor level with
proper design for the reinforcement bar of the plinth should be considered. The
floor surface should be flat and within a proper tolerance. The structural floor
loading should be designed of at least 20kPa.

5.5.5 Door requirement

5.5.5.1 Doors with secured key lock should be provided to EMSD or the operator for the
substation and should be available during the handover of the substation to EMSD
or the operator. Only EMSD or the operator has the key to the substation once the
substation is handed over to EMSD or the operator for installation. The door width
and height should be enough for equipment delivery. The door fire resisting period
(FRP) should be the same as the fire compartment as required in the Code of
Practice for Fire Resisting Construction issued by Building Department.

5.5.6 Internal Finishing

5.5.6.1 Substation shall have finished painted walls and oil resistant non-slip finished floors.

5.6 Access to Substation

5.6.1 Chilled water lead-in pipes

5.6.1.1 The substation shall require an aperture sufficient for the chilled water lead-in
pipes and control ducts. The location, size and level of the required aperture will
depend on the tap-off location, entry level and chilled water lead-in pipe diameter.
The details of these requirements shall be provided by EMSD or the operator.
5.6.1.2 EMSD shall provide the pipe with puddle flange for the consumer to install when
the chilled water lead-in pipes penetrate through consumer's building. The water
stop for uPVC control cable duct shall be provided and installed by the consumer.
To avoid doubt, consumer shall be responsible for the water proofing and pipe seal
and shall be maintained by the consumer.
5.6.1.3 Builder’s works drawings for the slab opening(s), aperture(s) and other associated
details for the DCServ pipe penetrations shall be agreed by EMSD or the operator
prior to the works commencement.

5.6.2 Delivery
5.6.2.1 The minimum loading of the route for delivery of the equipment should be
sufficient to support the equipment weight and the delivery equipment.
5.6.2.2 EMSD shall deliver the equipment to the substation. The consumer shall provide all
necessary support for the delivery of the equipment during installation and
operation and also the subsequent replacement due to maintenance issue.
5.6.2.3 Hoisting equipment shall be provided for the installation work and future operation
and maintenance. The size of the hoisting equipment shall be able to lift all the
heat exchangers and valves inside substation. Details shall be agreed during
coordination on site.

2012 EDITION (as at 30.08.2012) Page 10 EMSD

Technical Guidelines for Connection to DCS

5.7 Building Services Requirements for Substation

The building services provision inside the substation should include mechanical
ventilation, fire services provision, plumbing & drainage, electrical services and
telecommunication. All these building services provision should be provided and
maintained by the consumer, including all the subsequent utilities costs such as
electricity cost, water cost, telecom cost, etc. The detail requirements of the building
services provision are described in the following section.
5.7.1 Mechanical Ventilation System
5.7.1.1 The substation should be adequately ventilated with a fixed ventilation system.
5.7.1.2 The height of the ventilation outlet to free air should be minimum 2.5m above
street level. The air outlet stream should be directed away from personnel on the
footpath nearby.
5.7.1.3 Effective inlet louvre area should be considered and determined. Filter shall be
provided and maintained by the consumer at the supply inlet.
5.7.1.4 The air duct should be painted in white colour with exhaust air direction labels in
black painted on the air duct.
5.7.1.5 The mechanical ventilation system should be provided by the consumer to maintain
a proper indoor plantroom condition. Both ducted and non-ducted ventilation
systems are acceptable.
5.7.1.6 The mechanical ventilation fan(s) are needed to control by a temperature sensing
device to avoid unnecessary operation.
5.7.1.7 The supply and exhaust fans, if installed, should be switched on simultaneously.
5.7.1.8 The noise level generated by the ventilation system should comply with
requirements of the Noise Control Ordinance.

5.7.2 Plumbing and Drainage Services

5.7.2.1 The plumbing and drainage services should comply with requirements of Building
Ordinance.
5.7.2.2 Minimum size for floor drain should be 100 mm for proper floor wash down and
drainage as standard permanent provision. Discharge point should be available
prior to testing and commissioning of the DCServ equipment.
5.7.2.3 One cleansing trough with faucet of 32mm water inlet point should be provided as
standard permanent provision and should be available prior to testing and
commissioning of the DCServ equipment.
5.7.2.4 The substation floor slope shall also be designed to follow the Best Engineering
Practice, in order to ensure proper water drainage.
5.7.2.5 A pit with sump pump shall be provided inside the substation. An automatic and
manual switch for operation of sump pump shall be provided.
5.7.2.6 A high water level sensor with control panel inside the substation shall be provided
to raise a flooding alarm with flashing light at the door of substation. The flooding
signal shall be transmitted to the main control panel of building. The consumer
shall provide a repeated signal to EMSD’s DDC panel in the substation.

5.7.3 Fire Services

5.7.3.1 The fire services provision should comply with the statutory requirements of Fire
Services Department (FSD). In general, heat detectors and fire extinguishers should
be provided in the substation. The exact fire services provision should be subject to
the approval by FSD.

2012 EDITION (as at 30.08.2012) Page 11 EMSD

Technical Guidelines for Connection to DCS

5.7.4 Lighting System

5.7.4.1 Illumination inside the substation should be average 200 lux measured on the floor
of the substation.
5.7.4.2 The adjacent lighting fittings should be fed from different circuits of the
distribution board such that illumination inside the substation will not be totally
lost when one lighting circuit is tripped.
5.7.4.3 Twin fluorescent batten fittings for 1.2m energy efficient T5 fluorescent tube
should be used.
5.7.4.4 Battery operated fixed fluorescent lighting and exit sign should be provided to
enable a safe exit to be made from the substation in the event of loss of power
supply.
5.7.4.5 The provision of emergency lighting of 2 lux measured on the floor should be
provided in accordance of the Code of Practice for Minimum Fire Services
Installations and Equipment issued by FSD.

5.7.5 Power Supply System

5.7.5.1 The power supply to the substation should be cabled by the consumer. The
distribution board should be located near the main access door and should house a
32A 4-pole main switch together with an adequate number of final circuits
protected by miniature circuit breaker (MCB) for lighting installation, small power,
ventilation and metering/control equipment. It shall have IP rating of IP 54 and be
supplied with preferably back-up power supply. Sufficient number of 13A single
phase socket outlets should be provided for general maintenance.
5.7.5.2 The power requirement for EMSD's instrumentation & control and other
accessories shall be provided in each substation near EMSD's DDC panel by the
consumer.

5.7.6 Telecom Facilities

5.7.6.1 One telephone/data outlet completed with 25mm diameter conduit should be
provided and connected to the TBE Room of the building. Mobile signal shall be
covered inside the substation.

5.7.7 Earthing
5.7.7.1 Earthing terminal connecting to the main earthing terminal of the building should
be provided inside the substation.
5.7.7.2 Earthing should be provided to all electrical equipment including, but not limited to,
lighting fixtures per the Code of Practice for Electricity (Wiring) Regulations issued
by EMSD.

5.8 Provision of Building Services Equipment and Services during Installation

The following temporary facilities/services shall be provided by the consumer during

installation period to facilitate the installation of heat exchangers and other DCServ
equipment. Further coordination with EMSD shall be required before works
commencement.
a) Power supply
b) Plumbing and drainage
c) Fire services provision
d) Security for the substation and storage area
e) Storage area for DCServ pipe, equipment and tools.

2012 EDITION (as at 30.08.2012) Page 12 EMSD

Technical Guidelines for Connection to DCS

6 Compatibility of Design of the Primary and Secondary Sides

6.1 Equipment to be Installed in Secondary Side by EMSD Inside Substation

6.1.1 Temperature and pressure sensors and gauges of the supply and return lines on the
secondary side to be supplied, installed and maintained by EMSD.
6.1.2 Strainers, pressure relief valves, dismantling joints (or flexible bellows), drain pipes
and air vent inside the substation to be supplied, installed and maintained by EMSD
for operational, safety and maintenance purposes.
6.1.3 Temporary flushing by-pass connection to be installed on the secondary side pipes by
EMSD for flushing the secondary circuit inside the substation without passing water
through heat exchangers.

6.2 Equipment to be Installed in Secondary Side by the Consumer

6.2.1 Industrial grade automatic air vents at all the high points of the consumer’s internal
chilled water system.
6.2.2 Chilled water treatment system including manual feed chemicals, dosing pot with
necessary rust inhibitors and biocides with sufficient quantity necessary for testing,
commissioning and operation. A specialized water treatment company shall handle
the water treatment system.

6.3 Recommendations to Ensure Compatibility

To ensure the systems are compatible, some recommendations are stated below and detailed in
Appendix A and B.
6.3.1 All terminal equipment such as air handling units, fan coil units etc. shall be designed
to
a) Supply Temperature = 6°C ± 1°C
b) Return Temperature = 14°C
6.3.2 Variable speed secondary chilled water pumps are recommended for the internal
distribution of the consumer’s chilled water system or other mean which the
consumer considers it can efficiently control secondary chilled water. Operation of
variable speed secondary chilled water pumps shall be combined with internal
distribution of the consumer side chilled water system based on 2 way valves with
modulating actuator for each AHU and FCU. Varying the consumer’s side chilled
water flow is required to maintain the differential temperature across the substation
heat exchanger and achieve the desired delta T.
6.3.3 Modulating valves shall be installed at the bypass pipe between the chilled water
supply and return lines of the consumer’s secondary circuit. If the secondary side
(consumer side) chilled water return temperature is below 14 °C, the modulating
valve shall operate and enable re-circulating of chilled water to enable the chilled
water return temperature to the heat exchanger as high as practical.
6.3.4 If two heat exchangers are installed inside the substation, one of the heat exchanger
shall be closed by using the motorized valve of consumer side when the
instantaneous cooling capacity is less than 50% of the maximum designed cooling
capacity. If three heat exchangers are installed, one of the heat exchanger shall be
closed by using motorized valve of consumer side when the instantaneous cooling
capacity is less than 2/3 of the maximum designed cooling capacity. Another heat
exchanger shall be further closed when the cooling load is dropped to 1/3 of the
maximum designed cooling capacity. Same principle shall be applied to additional
heat exchangers.

2012 EDITION (as at 30.08.2012) Page 13 EMSD

Technical Guidelines for Connection to DCS

6.4 Consequences

If the consumer’s secondary chilled water return temperature is lower than 14°C,
EMSD will incur additional pumping costs and significant loss of chiller capacity at the
DCS plants. Consequently, the reliability and service level of supply cannot be
guaranteed as a result of the consumer in the system inability to comply with return
temperature requirement.

2012 EDITION (as at 30.08.2012) Page 14 EMSD

Technical Guidelines for Connection to DCS

7 Testing and Commissioning and Handover of Substation

7.1 Hydrostatic Pressure Testing

The consumer will be responsible for filling their internal chilled water system at
initial start of the commissioning and any make-up water requirement during the
operation of the plant.
Pressure test of the consumer internal chilled water pipe work hydraulically at a
minimum of 1.5 x system working pressure for the internal distribution piping for a
period of not less than 4 hours without any drop in pressure to ensure that the
pipes are free from leak. The results of hydrostatic test report shall be submitted to
EMSD or the operator for approval.

7.2 Flushing and Cleaning

The consumer shall perform a complete and thorough flushing of the internal
chilled water piping network using cleaning chemicals and potable water as
recommended by the water treatment specialist of the consumer to ensure that at
the time of supply of DCServ, the consumer’s piping system is full of clean water
and is clear from unwanted debris. To achieve that, the consumer has to install a
temporary bypass at consumer installation for the purpose of circulating water
through the internal network. Consumer side cleaning method, flushing and
chemical treatment details shall be submitted to EMSD or the operator for review
and obtain approval, prior to commencement of each activity.

EMSD will install a temporary bypass at each heat exchanger for performing a
complete and thorough flushing of the chilled water piping of secondary side of
heat exchangers inside the substation. The heat exchangers and interfacing valves
with consumer installation will be isolated during flushing.

The consumer shall submit flushing and cleaning method and water treatment
report to EMSD for approval before supply of DCServ. The purpose of this
approval is to ensure that the flushing and cleaning has no adverse effect on the
heat exchangers. However EMSD or the operator’s review and agreement shall not
relieve the consumer of the responsibility of ensuring industry standard procedures
for flushing, cleaning and passivation of secondary side piping and associated
works.

2012 EDITION (as at 30.08.2012) Page 15 EMSD

Technical Guidelines for Connection to DCS

8 Interfaces during Operation and Maintenance

8.1 Access for O&M and Data Reading

8.1.1 Adequate space accessible without any obstruction for data taking, maintenance and
replacement should be allowed in the substation to accommodate the following
equipment which is to be supplied, installed, operated and maintained by EMSD or
the operator.
8.1.2 The substation should be locked to keep out unauthorized personnel and only EMSD
or the operator has the key to the substation.
8.1.3 The personnel access shall be freely accessible by EMSD or the operator 24 hours a
day to conduct operation and maintenance and inspection so as to ensure
continuous and reliable supply of chilled water.
8.1.4 The consumer shall make request with EMSD or the operator for access the
substation for routine maintenance and inspection of their installations or equipment.
8.1.5 For the avoidance of doubt, should there be any civil and/or builder's work required
for DCS within the site boundary, the consumer shall provide suitably sized access
such as but not limited to repair access and subsequent make good at no cost to
EMSD or the operator.

8.2 Water Treatment

8.2.1 In a closed water loop with minimal make-up water requirements, chemical water
treatment is normally used to neutralization of corrosive properties and control of
scaling in heat exchangers. The consumer is responsible to provide adequate water
treatment in the secondary circuit of the heat exchanger.
8.2.2 The consumer shall submit water treatment report for the secondary side to EMSD or
the operator on a monthly basis.

8.3 Meter and Metering

8.3.1 EMSD will provide one set of metering device as mentioned in Section 5.4.4 in the
substation as the standard provision.
8.3.2 The metering equipment shall be supplied, installed and maintained by EMSD.
8.3.3 EMSD or the operator will deliver the best efforts to maintain the meter to record the
energy usage by the consumer in good order from time to time. However, if there is
power interruption from consumer side and the meter fails to record the energy
consumption during the period, EMSD or the operator have the right to make a
reasonable estimation on energy usage during the period based on the historical data.
The estimation amount will be noted in the consumer invoice for record.
8.3.4 In order to maintain the accurate energy metering, regular validation of meter
accuracy will be performed by EMSD or the operator. During the validation period of
about half-a-hour to one hour, the metering function will be suspended. Therefore,
EMSD or the operator will also make a reasonable estimation on energy usage during
the period based on the historical data. The estimation amount will be noted in the
consumer invoice for record.
8.3.5 If the meter shall for any reason become faulty or inaccurate beyond the accuracy
permissible limits, EMSD or operator shall as soon as possible procure the service,
repair, re-calibration or replacement of such meter as appropriate. If the consumer
disputes the accuracy of the meter, the consumer may request EMSD to have the
meter tested and calibrated by an independent testing agency. EMSD or the
operator may charge for this service if the meter is found to operate within the
permissible limits.

2012 EDITION (as at 30.08.2012) Page 16 EMSD

 Appendix A – Fundamentals of DCS
a) Principle

District cooling is a system in which chilled water is distributed in pipes from a central chiller
plant to multiple buildings through a network of underground pipes for space air-conditioning
in the buildings. The cooling and heat rejection is provided from the central chiller plant. A DCS
contains three major elements: the cooling source, distribution system, and substations.

Consumer Building

Cooling Source
(DCS Plantroom )

Consumer Heat Exchanger

Substation (Inside Building)

To/From other
consumers
Distribution System

Fig. A1 – Elements of a District Cooling System

The cooling source is generally equipped with electrical compressor driven chillers which
generate chilled water to cope with the cooling demand. Chilled water is distributed by variable
speed pumps which creating a pressure differential between the supply and return pipes of the
distribution system. The interface between the DCS and the building air-conditioning system is
the substations.

b) Key components

(i) DCS Plants

Chilled water for KTD sites is generated from the Northern and Southern DCS Plants
where equipped with electric driven seawater-cooled chillers to serve the north and
south portion of the KTD respectively. These two DCS Plants comprise chillers, chilled
water pumps, controls, power supply and supporting facilities.
Since the chilled water flow rate is high, variable speed pumping system will be
adopted in order to optimize the energy consumption. Variable speed pumps will
distribute chilled water to the DCServ distribution network and then to the
substations according to the load profile.

(ii) Distribution Network

Chilled water is distributed from the cooling sources to the substations through
supply pipes and is then returned after extracting heat from the building’s air-
conditioning load. Variable speed pumps housed in the Northern and Southern DCS
Plants distribute the chilled water by creating a differential pressure (DP) between
the supply and return lines. The pump head is selected to overcome the flow
2012 EDITION (as at 30.08.2012) Page 17 EMSD
 resistance in the supply and return lines plus the differential pressure in the
substation at the critical node of the system. Control valves, sized for a large flow
operating range responsive to the variations in the demand for cooling in the
building, governs the amount of water that flows through each substation at KTD.

(iii) DCServ Consumer Substation

The substation will be built within the lot boundary of the consumer building to
convey cooling energy from DCS to the chilled water system of that building. The
DCServ consumer substation is designed for indirect connection between the DCS
distribution network and the building chilled water system through multiple
(minimum two nos.) heat exchangers.
Indirect connection is chosen instead of direct one because,
 The head loss at the substation can be determined in a simple manner for calculating
the required system pumping pressure.
 Cross contamination between the DCServ loop and the building loop is avoided.
Primary chilled water system owned by EMSD is protected from interventions in the
buildings.
 Clear demarcation of system boundary for system liability and maintenance
responsibility.

Chilled water pipes from the DCS distribution network are connected to the plate type heat
exchangers installed inside the substation. The heat exchanger together with the pipework
inside the substation will be provided by EMSD.
The designed chilled water supply and return temperatures at the primary chilled water side at
the substation for KTD DCServ under normal operating conditions are,
 Supply Temperature = 5°C ± 1°C
 Return Temperature = 13°C
The designed chilled water supply and return temperatures at the building chilled water side
under normal operating conditions are,
 Supply Temperature = 6°C ± 1°C
 Return Temperature = 14°C
(1°C temperature rise through heat exchanger as recommended by manufacturer)
Both EMSD or the operator and the consumer have the obligations to fulfill the design
conditions to ensure energy efficiency and all consumers are supplied with quality chilled water
according to the design.

2012 EDITION (as at 30.08.2012) Page 18 EMSD

 Appendix B - Recommendations to Secondary Side System

1) Air Handling and Terminal Units

It is necessary to:
 Use variable flow chilled water system and two way equal percentage control valves for all
air handling units and fan coil units and the control valve shall be capable of controlling
flow through full range of expected turn-down and through full range of expected
differential pressure across the valve;
 Fit all air handling units, fan coils units and main branches with double regulating
balancing valves with self-sealing test point used for chilled water flow measurement as
required during balancing and commissioning;
 Install strainers on all air handling unit supply chilled water pipe;
 Test, adjust and balance the hydraulic system to make sure that the chilled water
requirement of each fan coil unit and air handling unit is met, preferably the testing and
balancing shall be carried out by a specialized third party commissioning firm; and
 Operate the AHU/FCU chilled water valve with reference to the Return Air Temperature of
the AHU/FCU. Since Return Air Temperature represents the actual heat load from the
building, controlling the chilled water valve with reference to Return Air Temperature
sensor instead of either Supply Air Temperature or Off-Coil Temperature will save energy
and maintain the return water temperature comparatively on higher side.
 The chilled water modulating valve shall be closed when AHU fan’s status is off. This shall
be added in the PLC/DDC programme logic as an interlock to operate the PID loop of
modulating valve. The chilled water valve shall modulate based on the set point when the
status of machine is “ON” and follow the PID logic.

Fig. B1 – Air Handling and Terminal Units

2012 EDITION (as at 30.08.2012) Page 19 EMSD

 2) Mixing Valve at the Secondary Side

 It is recommended to install a modulating control valve between the chilled water supply
and return lines of the secondary circuit. Modulating control valve shall be interfaced with
the chilled water return temperature on the secondary side (consumer’s side) to maintain
the return temperature at 14 °C.
 Only two way control valves shall be selected and installed to ensure that the variable
chilled water flow technical design principle works properly at the consumer side
throughout the year, especially in achieving the expected chilled water return temperature.
 If the secondary side (consumer’s side) chilled water return temperature is below 14 °C, the
modulating bypass valve shall operate and it shall be capable of re-circulating up to 2/3 of
the full secondary side design flow to enable the chilled water return temperature to EMSD
heat exchanger to be maintained as high as practical.

at 6°C ± 1°C

at 14°C

Fig. B2 – Mixing Valve at Secondary Side

2012 EDITION (as at 30.08.2012) Page 20 EMSD

 3) Secondary Chilled Water Pump Control

 Consumer side chilled water pumps shall be controlled based on the Differential Pressure
Transmitters (DPT) installed at the consumer’s side of the chilled water system (these works
on the consumer’s side of heat exchangers are the responsibility of the consumer).
 It is recommended to use an industrial grade DPT located across the hydraulically far end of
the chilled water pipes for each building if the secondary circuit serving more than one
building, secondary pump frequency/speed shall be controlled based on the input from
DPT(s) sensor.

4) Operation of Heat Exchanger

 The modulating valve on primary side of heat exchanger will be commanded to fully close
if the modulating valve on secondary side of consumer installation is in fully closed position.
 To have better control and enhancing energy efficiency of DCS chiller plant, it is
recommended that if two heat exchangers are installed inside the substation, one of the
heat exchanger shall be closed by using the motorized valve of consumer side when the
instantaneous cooling capacity is less than 50% of the maximum designed cooling capacity.
If three heat exchangers are installed, one of the heat exchanger shall be closed by using
motorized valve of consumer side when the instantaneous cooling capacity is less than 2/3
of the maximum designed cooling capacity. Another heat exchanger shall be further
closed when the cooling load is dropped to 1/3 of the maximum designed cooling capacity.
Same principle shall be applied to additional heat exchangers.

2012 EDITION (as at 30.08.2012) Page 21 EMSD

Appendix C

Fig. C1 – General Arragement on Constuction of Substation

2012 EDITION (as at 30.08.2012) Page 22 EMSD

 Fig. C2 – Control Schematic Diagram in Substation

2012 EDITION (as at 30.08.2012) Page 23 EMSD

 Fig. C3 – Typical Layout of Substation of Two Heat Exchangers

2012 EDITION (as at 30.08.2012) Page 24 EMSD

 Fig. C4 – Typical Layout of Substation of Three Heat Exchangers

2012 EDITION (as at 30.08.2012) Page 25 EMSD

Appendix D

Substation Cooling Heat Exchanger Operating Weight PHE size Clear Room Size Floor Drain Ventilation Flow Cleasing trough Hoisting Hook Lead-in Trench Width Lighting Lighting Fixture
FS Provision
Type Capacity (kW) (no x kW) (each PHE)(kg) (L x W x H)(mm) (L x W x H)(mm) (no. & size) Rate (ACH/hr) with fauet (kg) service pipes (WxH)mm (Lux) IP

1 100 2x60 1000 800x400x1300 7000x4500x3000 1 x Φ100 Heat Detector & FE 6 1 x Φ32 1000 Φ80 2600x950 200 IP 54

2 200 2x120 1100 700x480x2400 7000x4500x3500 1 x Φ100 Heat Detector & FE 6 1 x Φ32 1500 Φ80 2600x950 200 IP 54

3 300 2x180 1250 1100x480x2400 7000x4500x3500 1 x Φ100 Heat Detector & FE 6 1 x Φ32 1500 Φ100 2800x950 200 IP 54

4 400 2x240 1350 1100x480x2400 7000x4500x3500 1 x Φ100 Heat Detector & FE 6 1 x Φ32 1500 Φ100 2800x950 200 IP 54

5 500 2x300 1450 1200x610x2400 7000x5000x3500 1 x Φ100 Heat Detector & FE 6 1 x Φ32 1500 Φ125 2900x950 200 IP 54

6 1000 2x600 2200 1410x610x2400 7000x5000x3500 1 x Φ100 Heat Detector & FE 6 1 x Φ32 2500 Φ150 3000x1050 200 IP 54

7 2500 2x1500 3750 2600x610x2400 8000x7000x3500 1 x Φ100 Heat Detector & FE 6 1 x Φ32 4000 Φ200 3200x1100 200 IP 54

8 5000 2x3000 7500 3300x770x2700 8000x8500x4200 1 x Φ100 Heat Detector & FE 6 1 x Φ32 8000 Φ300 3500x1200 200 IP 54

9 7500 2x4500 10250 5300x770x2700 8500x10000x4200 1 x Φ100 Heat Detector & FE 6 1 x Φ32 10500 Φ350 3700x1350 200 IP 54

10 10000 3x4000 9500 4800x770x2700 8500x11500x4200 2 x Φ100 Heat Detector & FE 6 1 x Φ32 10000 Φ400 3800x1400 200 IP 54

11 12500 3x5000 13400 5300x770x3300 9000x12500x4500 2 x Φ100 Heat Detector & FE 6 1 x Φ32 14000 Φ500 4200x1500 200 IP 54

12 15000 3x6000 16300 5300x970x3300 9500x12500x4500 2 x Φ100 Heat Detector & FE 6 1 x Φ32 17000 Φ500 4200x1500 200 IP 54

13 20000 3x8000 19900 6250x970x3300 10000x12500x4500 2 x Φ100 Heat Detector & FE 6 1 x Φ32 20000 Φ600 4500x1500 200 IP 54

14 24000 4x7200 19000 6000x970x3300 10000x16500x4500 2 x Φ100 Heat Detector & FE 6 1 x Φ32 19500 Φ700 4800x1600 200 IP 54

Table D1 – Building and Building Services Provisions of Substations for Different Cooling Capacities

2012 EDITION (as at 30.08.2012) Page 26 EMSD