Characteristics of the High-rise building sector

Table 2.3-5 Surveys of high-rise office building in HANOI - 2014 to 2016

OC CA VP CE

Total Floor 19, 1250sqm.

Central air Daikin VRV-II

Total Floor 23 , 1195 sqm.

Center air Toshiba

Total Floor 27, 614 sqm

Central air Chiller Total Floor 27 , 788 sqm Chiller center system

Daikin office: 12^th floor Use: 4 74Ui; 1

TR-76Ui

Vinaline office: 14^th floor Use: 3 TR-74Ui

Himlam office: 23^th floor Use: 5 74Ui; 1

TR-76Ui

ThuDo office: 22^th floor Use: 1 74Ui; 1

TR-76Ui

Vinaconex office: 23^th

Use: 3 TR-74Ui CEO office: 5^th floor Use: 4 74Ui; 1

TR-76Ui

PV VN VA TD

Total Floor 26 , 2099.2 sqm

Central air Carrier Chiller and VRV

Total Floor 27, 1550sqm

Central air Daikin VRV III Total Floor 27 , 788 sqm

Chiller center system TID TOWER Fujitsu VRV systerm

PVI ivestment office 24^th Use: 7 74Ui; 1

TR-76Ui

PVI insurance office 22^th Use: 6 75Ui; 1

TR-76Ui

VNPT project deverloper 7^th floor

Use: 5 74Ui; 1 TR-76Ui

VINACONEX project deverlopment division 4^th

floor Use: 5 TR-74Ui

Floor 7^th 2 TR-76Ui Floor 8^th 2 TR-76Ui Floor 12^th 2 TR-76Ui

Table 2.3-6 Surveys of high-rise office building in Ho Chi Minh City-2014 to 2015

LI CT RE ET

Total Floor 34 , 700 sqm Water Chiller

Total Floor 23 , 1178

Water cooler Chiller sqm Total Floor 23 , 880 sqm Total Floor 17 , 1400 sqm

Observation in Floor 25

LIM office heat quater Searefico floor 14th User: Temperature, CO2,

Humidity, lighting, MRT.. None contact None contact

Table 2.3-7. Buildings Overview of target buildings for investigation

Building CA CE OC PV VN

Total stories 23 27 19 25 27

Gloss area [m2] 28000 22518 34640 61400 40000

Typical floor [m2] 981-1265 834 12245 2090 1520

Net floor area 823 644 940.2 1684 873 (1237)

Total space AC

[m2] 18929 13910.4 17863.8 42100 21825

Celling height [m] 2.65 2.65 2.65 2.7 2.7

Investigated area

[m2] 239 (507.6) 415 662+115, 542 392

Investigated

occupants 36 40 54 152 35

AC systerm Individual Central Individual Individual +

central Individual Ownership Private Corporate Corporate Corporate Government

Age(yr) 2010 2009 2002 2013 2009

BMS system yes yes yes yes yes

Façade double glass brick + singer

glass concrete +

singer glass double glass brick + singer glass

Electric capacity 2000+1600KVA 16000KVAx2 2500KVAx2

Occupants density 100% 90% 77% 65% 80%

2.4.1. Building envelope

The window to wall ratio varied from 48.6% to 88.6%. However, it was also often found that the U-value of the external wall was approximately 2.2–3 W/m2 in most high-rise buildings because the envelope was based on a concrete material.

Table 2.4-1. Building Envelope properties

Characteristics CA CE OC PV VN

U-value wall 2.22 2.92 2.43 - 3.02

WWR 74.6% 48.6% 61% 88.6 46.2%

SC 0.36 - 0.55 0.26 0.56

U-value glass 1.62 - 5.6 0.78 -

Glass trade CSG - AGC AGC -

2.4.2. Typical HVAC

Office building occupancy schedules could vary widely. Many buildings were occupied from approximately 8:00 am to 6:00 pm. Other buildings were occupied by some personnel as early as 6:30 am to timings as late as 7:00 pm. Certain tenants may require night work schedules, usually not extending beyond 10:00 p.m. Given project deadlines, individual offices or cubicles could be occupied at any time and during any day.

Table 2.4-2 shows the results of the observation studies for office building occupancy schedules and air-conditioning thermal set points in the summer. When the building manager controlled an entire HVAC system by BMS, the system schedule and the set-point temperature for the outdoor unit were fixed, while there were other variables that were different from each other. The indoor schedule was controlled by occupancy and it could vary from day to day. The indoor setting temperature was slightly different in each building during the summer season.

Office buildings usually included both peripheral and interior zone spaces. The peripheral zones frequently have large window areas and may be considered as subdivided. These zones have variable loads due to the changing weather and sun position and they typically require cooling in the summer.

Table 2.4-2 Schedule of HVAC on summer time

summer Turn ON Turn OFF Occupant Manage

Building outdoor unit indoor unit outdoor unit indoor unit O setting B setting

CA 8:00 8:00 19:00 26 ˚C 27 ˚C

CE 7:00 N/A N/A 25 ˚C 25 ˚C

OC 7:00 8:00 17:00 25 ˚C 18 ˚C

PV 7:30 N/A 17:00 26 ˚C 26 ˚C

VN 7:30 8:00 17:00 25 ˚C 25 ˚C

However, high-rise office buildings in Hanoi use central chiller cooling towers or VRV heat pumps. In areas where the system was not installed for a perimeter zone, it implied that the thermal zone between them could not be separately controlled.

2.4.3. Lighting

All the buildings used artificial lighting, day lighting was not used often during the investigation period, and the indoor blinds were always closed. The general lighting system typically had the highest consumption of energy in an office building and it typically consisted of recessed fluorescent fixtures using T10 technology.

The results from observations in five high-rise office buildings in Hanoi indicated that the typical lighting system was the fluorescent type lighting system. The lighting systems were designed in grids and were allocated evenly. There were very limited desk lamps and they were not used as part of the lighting. Decorative lights appeared only in the reception area and were very limited.

2.4.4. Typical construction and building materials

Structural building forms and materials used in high-rise buildings in Vietnam grow slowly when compared to those used in other countries, and are typically characterized by bearing structures and building materials. The construction of high-rise buildings from areas in the North to South consists of mostly structural reinforced concrete frames.

As shown in five case studies, the oldest building was constructed in 2002 and the newest building was constructed is 2013 by using the same technologies. This problem was not due to the lack of knowledge in applying new technologies or using new materials, but

due to the inability to produce material that met elf-construction standards under the new method.

However, the building stoke report by international consultants indicated that most high-rise buildings used techniques based on reinforced concrete structures. The area of a typical floor ranged from 1000 to 2000 m2. The ceiling height ranged from 2.6 to 2.7 m, and the slab height ranged from 3.3 to 3.6 m. The plenum space height depended on ME systems.