MECHANICALVENTILATION
AND AIR CONDITIONING
SYSTEM
DESIGN CRITERIA
Maritime Facility Centre
Prepared by
Abans Engineering Pvt Ltd
128, Airport Road,
Ratmalana
ABANS ENGINEERING PVT LTD.
128 AIRPORT ROAD,
RATMALANA
1 Introduction
This report covers the design criteria for the design of MVAC system for the proposed high rise
office complex of Maritime Facility Centre, Port Authority.
This provides information on the overview, referred standards, assumptions made, design
concept for the proposed MVAC Systems of this project.
2 Overview
In accordance with the tender documents a centralized chilled water system with water cooled
chillers is proposed for the premises to maintain the human comfort criteria stipulated below
in this document with referenced to the specified standards.
Inverter type split units are also proposed for spaces such as panel room, generator room,
driver’s rest room, security room etc.
Building also facilitate with centralized toilet exhaust system for public toilet area in each floor.
Two fire staircases are proposed to have two separate staircase pressurization systems to
facilitate escape during a fire situation.
Automatic control and monitoring of all the MVAC equipment will generally be carried
out via Direct Digital Control (DDC) system which will be fully integrated with the
BMS.
Special attention has been made to maintain the noise and vibration created from the MVAC
equipment within the permitted values.
3 MECHANICAL VENTILATION & AIR CONDITIONING SYSTEM
Reference Standards
ASHRAE
- American Society of Heating Refrigeration and Air Conditioning Engineers
SMACNA
- Sheet Metal and Air Conditioning Contractor's National Association
AMCA
- Air Moving and Conditioning Association
ARI
- Air Conditioning and Refrigeration Institute
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ABANS ENGINEERING PVT LTD.
128 AIRPORT ROAD,
RATMALANA
Design Criteria
3.2.1 Outdoor Design Criteria
Item
Design Temperature
Summer Ambient
34 ºC DB/ 70 % RH
3.2.2 Indoor Design Conditions
Description
Summer
Notes
Offices/ Meeting Rooms
24°C db
55±5% *
Entrance Lobby/Lift lobbies
24°C db
55±5% *
Server Rooms
22°C db
50±5% *
Auditorium
24°C db
55±5% *
Cafeteria/ Dining
24°C db
55±5% *
Library
24°C db
55±5% *
Electrical Panel Room
24°C db
55±5% *
Equipment room
30°C db
55±5% *
Security Room
24°C db
55±5% *
*No direct humidity control is provided other than incidental de-humidification as part of the
cooling process.
3.2.3 Ventilation Air Provision
Fresh air requirement will be based on the Ashrae standard 62.1.
Toilet exhaust
- 10ACH
3.2.4 Population Densities
Description
Occupancy
Offices – open plan1
Based on the furniture layout
Auditorium
1m2/person
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ABANS ENGINEERING PVT LTD.
128 AIRPORT ROAD,
RATMALANA
Entrance Lobby
12m2/person
Lift Lobby
6m2/person
Canteen
2m2/person
Library
5m2/person
Shop
3m2/person
Meeting Room
2m2/person
3.2.5 Fabric Performance
Fabric
Criteria
Glazing U-value
5.4 W/m2 K 1
Glazing – Shading Coefficient
0.8
Wall U –Value
2.4 W/m2 K 2
Roof U –Value
2.7 W/m2 K 2
3.2.6 Cooling Load Densities
Description
Lighting
Equipment
Offices-Open
12 W/m²
100 W/person
Lobbies and Corridoor
12 W/m²
-
Server Rooms
12 W/m2
250W/m2
Auditorium
15 W/m2
-
Meeting room
12 W/m2
300W
Electrical panel room
12 W/m²
250W/m2
Shop
12 W/m²
-
Canteen
12 W/m²
15W/person
Library
12 W/m²
100W
3.2.7 Infiltration Rates
EntranceLobby – 0.5 ACH
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ABANS ENGINEERING PVT LTD.
128 AIRPORT ROAD,
RATMALANA
MVAC System Description
Centralized chilled water system proposed with two no’s of 550TR water cooled centrifugal
chillers and two no’s of water cooled 275TR VFD single screw chillers. The Chillers shall be
installed in the chiller plant room at 18th floor level of the building. The units shall be controlled
via DDC type microprocessors and shall circulate chilled water through the piping network to
AHUs and Fan Coil Units in the building.
Chilled water distribution system shall circulate chilled water through the piping network to
Fan Coil Units and AHUs in building. Variable primary pumping system with 6 no’s of VFD
driven centrifugal pumps, shall be used for the chilled water supply. The chilled water circuit
will operate in chilled water temperature of 7 oC supply and 12 oC return. The pump speed
shall be varied according to the building load. Bypass arrangement with suitable control valves
shall be installed to maintain the minimum flow rate through the chiller.
6 no’s of Variable speed centrifugal pumps will be used for condenser water distribution
between chillers and cooling towers.
Two-way motorized valves installed at the chilled water line adjacent to the AHU and fan coil
unit shall maintain chilled water flow rate through units according to cooling load requirement
of the space.
The chilled water pumps and condenser water pumps shall be installed in the chiller plant
room. 4 no’s of cooling towers shall be installed on the 19th floor.
The chilled water piping system for AHUs and FCUs in each floor shall be connected to the two
main chilled riser pipes in each service duct as show in the layout drawing. The AHUs shall be
installed in the AHU rooms in each floor. Conditioned air to the required space shall be
supplied through the ceiling diffusers and grills. Return air shall be directed to the return air
ducts through return air diffuser/bar grills and return air plenum. Variable air volume (VAV)
units are connected to the AHU ducting where individual temperature control of the spaces
are needed. VFD fan will control the air flow to the spaces according to the DP sensor reading
installed in the air supply duct.
Fresh air to the building shall be supplied by using two fresh air AHUs comprises with energy
recovery wheel, installed in the 17th floor. Fresh air supply duct shall be connected to the AHUs
on each floor. Exhaust air shall be drawn from the return ducts and directed to the energy
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ABANS ENGINEERING PVT LTD.
128 AIRPORT ROAD,
RATMALANA
recovery unit of the FAHU. Required quantity of fresh air is provided by Demand Control
Ventilation (DCV) System, and is calculated based on the Return air C02 level.
Building also facilitate with centralized toilet exhaust system for public toilet area in each floor.
System comprises a separate fan for each toilet block and a centralized fans for duty standby
operation.
Two fire staircases are proposed to have two separate staircase pressurization systems to
facilitate escape during a fire situation.
All electrical power panel in every AHU room and chiller plant room shall be supplied by the
air conditioning and ventilation contractor including cabling, switch gears etc. and panel shall
be BMS compatible.
In case of an alarm by fire detection system of the building, AC system shall be switched off
automatically and necessary provision shall be provided by the MVAC contractor.
Acoustic and vibration treatment, where required, shall be provided for the Air-conditioning
and ventilation equipment, ducting, piping etc. The system shall be acoustically treated to a
permissible noise level in respective areas.
3.3.1 Central Chiller System
Selected chiller efficiency for 550TR chiller - 0.554 kW/RT.
Selected chiller efficiency for 275TR chiller - 0.566 kW/RT.
A primary only chilled water system were selected for better energy saving than
primary – secondary system
The cooling towers are selected with condenser water leaving at 30 0C and condenser
water entering at 350 C to the cooling tower.
3.3.2 Air Distribution System
Primary energy recovery type air handling units are used to pretreat the fresh air for
the office floors and the common spaces, while exhausting cold air from the conditioned
spaces.
CO2 sensors and motorized dampers used at the each individual AHUs’ to control the
fresh air intake based on the occupancy in the respective areas.
Cooling coils were selected with face velocity <= 2.5 m/s.
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ABANS ENGINEERING PVT LTD.
128 AIRPORT ROAD,
RATMALANA
All the AHU duct were sized maintaining duct pressure loss <=0.9 Pa/m
3.3.3 Mechanical Ventilation System
Toilet Ventilation:
Design of the ventilation shall be 10 air changes per hour for the office toilets
Make-up air will be drawn through the door undercut/ fitted to the door louver.
The exhaust air fans shall be sized in such a way to create negative pressure within the
toilet area with respect to the air conditioned space.
Kitchen Ventilation:
Kitchen hood extract through using hood extract fan (motor outside the air stream).
Before the extract fan, Electro Static Precipitator (ESP) shall install to remove the oil
and after the fan shall install carbon activate filter to remove odor and the smoke.
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