ASHRAE Journal - February 2013 - S11

Feature

Photo 1: Durbar Hall with new AHUs installed.

suspended using special anchor fasteners embedded in
the rocky ceiling, which was porous at places (Photo 1).
• The outdoor units had to be located far away from the
indoor air-handling units, involving extensive refrigerant piping and careful sizing to ensure oil return to the
compressors. A total of 736 ft (224 m) was the measured
length of the piping, including a 230 ft (70 m) ‘U’ loop with
one arm of 66 ft (20 m) and a second arm of 49 ft (15 m).
• Some ductwork had to cross through 4 ft (1.2 m) thick
stone walls, and openings had to be made using wire
saw cutters.
New Banquet Hall and Kitchen
• A total of 64 tons (225 kW) for the banquet hall was installed. This area was completely redeveloped, is almost
two floors below the ground level, and has surrounding
stone walls that are 4 ft (1.2 m) thick.
• The kitchen had a double height, so the kitchen ventilation
equipment was planned to be installed at the mezzanine
level by casting a slab.
• The challenge was to provide for intake of fresh air and
exhaust of stale kitchen air.
• Being at a lower level and very high at the center, an innovative and integrated air-conditioning system was needed.
• The selected system was required to be well-integrated
aesthetically, as the hall was voluminous with traditional
interiors and arches.
• The kitchen had a very specific exhaust requirement. The
exhaust point was very close to the open patio of the owner’s residence, so care had to be taken to ensure that the
kitchen exhaust does not have any objectionable odors.
Guest Rooms & Presidential Suites
• A total of 44 ton (155 kW) VRF units were installed for
the six guest rooms and six presidential suites. The tariff
for these rooms was to be in the range of $400 to $800,
therefore, the comfort level and environment needed to
be commensurate with the high tariff.
Proposed HVAC System
The HVAC system that was installed consisted of a total 256 hp
(191 kW) VRF outdoor units that were integrated with a variety
S11

of indoor units, including some ductable and cassettes, standard
air-handling units for treated fresh air supply and special small
duct high velocity air handlers with round flexible ducts and
special 2 in. (50 mm) circular air outlets.
The outdoor units of 16 hp (12 kW) each in six modules; two
of 32 hp (24 kW) feed the newly created banquet hall and rooms,
while four of 48 hp (36 kW) feed the existing Durbar Hall, Galleria
restaurant as well as a part of the new banquet hall and guest rooms.
Durbar Hall
• A 48 hp (36 kW) VRF system connecting three AHUs of 15
tons (53 kW) each, and another 48 hp (36 kW) VRF system
connecting the remaining two AHUs of 15 tons (53 kW)
and five AHUs of 3 tons (11 kW) for the Galleria restaurant
was installed.
• Apart from the other benefits of this selected combination of VRF systems, it also enabled the air-cooled
condensers to be located far away from Durbar Hall,
thereby reducing the earlier noise level of 85 dBA near
the owner’s residence.
• By shifting the DX outdoor units, which had been placed
in the corridor, we facilitated the space to be converted
into premium rooms with a picturesque view. This retrofit
has generated an additional income of approximately
Rs.10.8 million (US$216,000) per annum from the six new
rooms created.
• The selected digital VRF system has a full load COP. In
addition, the digital scroll technology has a very high
Integrated part load value (IPLV).
• Hence, power consumption was reduced from 1.35 kW/
ton (5 kW/kW) (with the old reciprocating compressors) to
0.85 kW/ton (3 kW/kW) (with scroll compressors). Because
of this energy efficient retrofit, there is a direct saving in
the power bill to the tune of Rs.540,000 (US$10,800) per
annum.
• The old DX system used R-22, which has been replaced
with the eco-friendly R-410A.
• This shifting of outdoor units became possible due to the
electronic expansion valve (EEV) kits.
Lower New Banquet Hall
• Catered by three different systems: two of 48 hp (36 kW)
and one of 32 hp (24 kW).
• Indoor unit location was
a challenge that was met
by using small duct, high
velocity indoor units.
• The indoor units are installed at the mezzanine
level on both sides of the
banquet hall.
• Supply and return air
ducts are taken to the
lower level, and flexible
sound attenuator tubing
is connected to the supply Photo 2: Two inch round supply
air duct (Photo 2).
air outlets blend with interior.
February 2013

ASHRAE Journal - February 2013

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