Existing buildings’ operation and

maintenance: renovation project of Chow Yei

Ching Building at the University of Hong Kong
..............................................................................................................................................................

Sun Xiaonuan* and Stephen LAU SiuYu

School of Architecture, The University of Hong Kong, Hong Kong, China
.............................................................................................................................................
Abstract
Existing buildings’ operation and maintenance is the key part of improving the buildings’ performance
and energy consumption saving. Being different from the new building, existing buildings’ retrofits have

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many difficulties and challenges. This paper is based on a real project at the University of Hong Kong, and
studies the process of the retrofits and energy audit for the existing buildings. It also studies how to
optimize the operation and maintenance of the building and how to measure and verify the results after
the retrofits.

Keywords: existing building; operation and maintenance; energy consumption saving retrofit; energy
audit; measurement and verification; facility improvement measures (FIM)
* Corresponding author.
sunxiaonuan@gmail.com Received 29 November 2012; revised 24 November 2013; accepted 13 January 2014
................................................................................................................................................................................

1 INTRODUCTION hottest months with high humidity, which are the highest energy
consumption period. According to the data from the Hong Kong
With the rapid development of urbanization, China’s building Observatory, there was an average rise of 0.128C per decade from
energy consumption increased year by year, which has risen to 1885 to 2009. The final energy consumption of the buildings can
.30% of the whole energy consumption. The energy consump- be affected by rising temperatures as it will reduce energy con-
tion of existing buildings cannot be ignored. Due to obsolete sumption for heating and raise demand for cooling [2, 3]. The
equipment and construction, as well as architectural forms, energy consumption of buildings in Hong Kong especially in
thermal performance and engineering equipment problems, exist- summer is so high because of the high density of the buildings
ing buildings cause a serious waste of resources and energy. Most and high energy consumption in the summer. So, the retrofit of
of the existing buildings now need to be updated to save energy. the existing buildings in Hong Kong plays a crucial role to reduce
According to the China Energy Conservation Association the energy consumption. This paper aims to find a typical and
Committee’s statistical service, the existing building area in China scientific methodology to do the retrofits to reduce the energy
is .43 billion m2, of which only 5% can achieve green building consumption especially for the cooling system in summer.
standards (http://www.cabr.com.cn/InfoViewer.aspx?BizMainClass=
2&BizSubClass=1&RowGuid=2189). These green building stan-
dards are based on the three-star green building certification system 2 DESCRIPTION OF THE PROJECT
in China. This research introduced a scientific methodology of the
energy audit (EA) before and after the retrofit. The University of Hong Kong (HKU) has contracted with Siemens
Existing buildings’ operation and maintenance has large in- Limited Hong Kong (SLHK), with project management assistance
fluence and potential to the whole energy-efficiency process. from Eco-Tech International (ETI), to provide support for
From the research perspective, the retrofit of existing building Leadership in Energy and Environmental Design (LEED) for Existing
need to solve three key issues that are EA and energy-saving po- Buildings: Operations and Maintenance (EB:OM) certification for
tential assessment before the retrofit; choosing the most opti- the Chow Yei Ching (CYC) Building. With a concerted effort, the
mized transformation measures; measurement and verification building has a chance of achieving the gold certification objective.
after the retrofit. [1]. This research that based on the real retrofit project of CYC
Hong Kong’s climate is subtropical, tending toward temperate Building at HKU will present more practical experience and
for nearly half of the year. July, August and September are the methodology.

International Journal of Low-Carbon Technologies 2015, 10, 393– 404

# The Author 2014. Published by Oxford University Press.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0/), which
permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited.
doi:10.1093/ijlct/ctu008 Advance Access Publication 10 July 2014 393
S. Xiaonuan and S.L. SiuYu

In fact, a list of issues violating the energy conservation prin- 2.2 Form EA team
ciples, such as those outlined in the ASHRAE Standard With many technical and funding problems, building owners
100-2006 [4], was identified after the walk-through assessment need a professional team to manage the whole project. One of
as discussed in the following subsections. the most effective ways is to employ a third party which is called
energy service company (ESCO) to operate.
2.1 Scope of the EA The ESCO will promise the energy efficiency of the project
According to Figures 1 and 2, EA flow chart that described in the and profits that will come from the retrofits to the building
article EA of an educational building in a hot summer climate owners. This ESCO can reduce the risk of the project, and it can
[5], the EA process includes several tasks. The first task is to also overcome the technical hurdles and finally achieve the goal
define the scope of the EA, including the areas to be audited, the of energy saving. In the contract, the ESCO reported a guarantee
audit sophistication level and the savings anticipated. of energy savings that can be translated into profits. If the real
In this study, CYC Building is selected to be implemented with energy savings are less than the guaranteed energy savings after
EA. The building was built in 1993 and now it is a multipurpose the retrofits, the ESCO will bear the part which does not achieve
the guaranteed energy savings. In this project, SLHK has pro-

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academic building, which comprises offices, lecture rooms and
different types of laboratory. It has a total of 13 floors from LG4/F mised 30% energy savings after retrofits of CYC Building.
to its highest 8/F. The total floor area is 13 168 m2. Because this study has a research dimension, the team was
formed by the following parties:

(a) SLHK whose main duty was to ensure the implementation

of the whole project objectives.
(b) The HKU includes Estate office, electrical/electronic techni-
cian to follow the energy measurements and supervise
future implementation.
(c) Operation and Maintenance (O&M) personnel to provide
input and implement any recommendation.
(d) LEED-EBOM consultant to ensure the achievement of the
gold certification.

The O&M personnel is a research team which is made with

researchers whose area is the green building operation and mainten-
ance, and the author is one of the members of this research team.
Figure 1. CYC Building. The tasks of the O&M personnel include taking measurements

Figure 2. The location of CYC Building.

394 International Journal of Low-Carbon Technologies 2015, 10, 393–404

 Existing buildings’ operation and maintenance

before and after each retrofit, giving advice of the appropriate tech- † FIM1: chilled water plant upgrading and optimization.
nologies, making plan according to the existing buildings’ operation † FIM2: building management system (BMS) upgrading and
and maintenance in LEED and so on Figure 3. with energy monitor and controlling (EMC).
† FIM3: lighting retrofits.
† FIM4: window film.
† FIM5: solar panel.
3 INFORMATION COLLECTING PROCESS † FIM6: green roof with condensate recycling.
BEFORE THE RETROFIT † FIM7: micro-wind turbine.
† FIM8: variable-voltage variable-frequency systems for elevators.
3.1 Budget and Payback
During the 12-month period from January 2009 to December After proposing these eight FIMs, the ESCO conducts the com-
2009, the energy requirement for CYC Building was met as fol- puter simulation to evaluate how much energy can be saved
lowing (Figure 4 and Table 1): after the retrofits. The results are shown in Table 2.
In this table, the wind turbine is not applicable in Hong Kong

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† Electricity: 3 742 860 kWh at a total cost of HKD4 695 048 because of the high density of the Hong Kong Island, and there is
(HKD1.254/kWh). not enough wind resource. The solar panel is also not applicable
† For this estimated 13 178 m2 facility, this equates to energy because of the climate conditions of Hong Kong, it need a long
cost of $356.3/m2. payback of 130 years. However, the life span of photovoltaic is at
most 30 years. So, this payback year is more than its life span.
There are many facility improvement measures (FIMs) after According to Table 2, the total energy saving is 1 256 259 kWh
the literature review such as the lighting retrofits, the façade ret- per annum which translates to approximately reduction in 853
rofits and so on. According to the condition and characteristic tons of CO2 emission per annum.
of the CYC Building, the following FIMs are proposed by the Total project cost: HKD16 419 350.00.
ESCO from the existing popular FIMs through literature review: Annual guaranteed savings: HKD1 574 911.00.
Percentage of total saving: 34%.
After the computer simulation of the energy saving of each
FIM and the total energy saving of the proposed FIMs, we should
select the appropriate ones according to the payback, energy-
saving amount, the building information etc. The detailed and
complete description and analysis will be presented in Section 4.

3.2 Building information and site measurements

before renovation
In conducting a study of this type, it is essential that the existing
conditions be precisely established as a baseline for the evalu-
ation of any potential system improvements. Relevant factors
were identified and assessed through a systems approach in an
Figure 3. Team formation. effort to develop potential FIMs, as outlined below.

Figure 4. Monthly electric profile of CYC Building.

International Journal of Low-Carbon Technologies 2015, 10, 393– 404 395

S. Xiaonuan and S.L. SiuYu

Table 1. Base-year electricity consumption (data from Estate Office of the HKU).
Month Electricity consumption Electricity fee (maximum demand tariff ), $

kVA consumption kWh consumption kVA charge kWh charge Total charge

January 2009 779 208 980 $33 552 $237 639 $271 191
February 2009 863 224 400 $37 115 $250 787 $287 902
March 2009 992 258 280 $42 540 $288 642 $331 181
April 2009 801 275 740 $34 294 $316 097 $350 391
May 2009 1016 324 240 $43 586 $359 699 $403 285
June 2009 1309 384 660 $55 893 $427 920 $483 813
July 2009 980 371 210 $42 063 $409 721 $451 784
August 2009 1102 400 820 $47 196 $442 864 $490 060
September 2009 1070 418 230 $45 833 $461 169 $507 002
October 2009 1242 349 380 $53 099 $389 294 $442 393
November 2009 1218 296 280 $52 057 $332 032 $384 089

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December 2009 814 230 640 $35 044 $256 913 $291 957
Total 3 742 860 Total $4 695 048

Table 2. Investment budget and return cycle (data from Estate Office of the HKU).
No FIM Estimated existing Estimated Annual Percentage Annual electricity Project cost Simple
consumption postretrofit electricity of savings savings (HKD) (HKD) payback
(kWh) consumption (kWh) savings (kWh) (%) (years)

1 Chilled water plant 1 749 705 1 013 392 736 313 42 923 631 7 973 670 8.6
upgrading
2 BMS upgrading 123 355 154 737 1 060 970 6.9
3 Lighting retrofits 604 291 390 562 213 729 35 267 162 1 717 710 7.4
4 Window film 59 242 74 312 585 000 7.9
5 Solar panels 2373 2976 388 000 130
6 Green roof 20 189 25 325 706 000 27.9
7 Micro-wind turbine N/A N/A 188 000 N/A
8 Elevators updating 374 296 273 239 101 057 27 126 767 3 800 000 30.0
Total 1 256 259 1 574 911 16 419 350

† Building occupancy patterns. ‘Windows/doors’: The windows consist of a combination of

† Building environmental conditions that include temperature, single pane glass with aluminum frame. Window areas of facing
humidity, ventilation and CO2. different directions: (calculated by the elevations of CYC
† Building envelope that refers to the exterior walls, windows/ Building)
doors and roof.
† Mechanical and electrical systems that refers to the chiller † North: 440 m2.
plant, air handling unit [AHU and precooling air unit † South: 388 m2.
(PAU)], ventilation fans, fan coil units (FCUs), lighting † West: 80 m2.
system, lift system and power quality system. † East: 80 m2.
† Doors: there are open exits at G/F and LG4/F.
3.2.1 Building occupancy patterns † Roof: the roof construction consists of 150-mm thick con-
The building is in occupied by 700 staffs from 8:30 am to 7:00 crete block, and the total surface area of roof floor is
pm Monday to Friday and from 8:30 am to 12:30 pm on Saturday. 1013 m2 (Figure 5).
The occupancy of the building is summarized in Table 3.
3.2.4 Mechanical and electrical systems
3.2.2 Building environmental conditions ‘Chiller plant’: Building cooling is provided by a chiller plant
The building’s environmental conditions are measured and located at the roof floor. The chiller plant consists of four air-
listed in Table 4. cooled 180-ton chillers, four primary chilled-water pumps and
three secondary chilled-water pumps.
3.2.3 Building envelope The chiller plant was installed with Honeywell BMS, it was
‘Exterior walls’: The walls consist of 150-mm thick concrete found that some of the sensors such as temperature sensors
block with face brick exterior. and flow sensors are malfunction, the chiller plant cannot be

396 International Journal of Low-Carbon Technologies 2015, 10, 393–404

 Existing buildings’ operation and maintenance

Table 3. CYC Building full occupancy schedule.

Area M-F begin M-F end Sat begin Sat end Sun begin Sun end Estimated hours/week

R/F and UR/F plant rooms On request 4

8/F laboratories 9:00 am 8:00 pm On request 66
7/F lecture room, offices, laboratories 9:00 am 8:00 pm On request 66
6/F lecture room, offices, laboratories 9:00 am 8:00 pm On request 66
5/F lecture room, offices, laboratories 9:00 am 8:00 pm On request 66
4/F lecture room, offices, laboratories 9:00 am 8:00 pm On request 66
3/F lecture room, offices, laboratories 9:00 am 8:00 pm On request 66
2/F offices, laboratories 9:00 am 8:00 pm On request 66
1/F laboratories 9:00 am 8:00 pm On request 66
G/F lecture theatre 9:00 am 5:00 pm On request 40
LG1/F lecture theatre 9:00 am 5:00 pm On request 40
LG2/F laboratories 9:00 am 8:00 pm On request 66
LG301,A,B workshop/store, office, store room 9:00 am 8:00 pm On request 66

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LG 302 hydraulic laboratory 8:00 am 8:30 pm 8:00 am 8:30 pm 75
LG 303 technician room 9:00 am 8:00 pm On request 66
LG 4/F plant rooms On request On request 4

operated fully automatically. We found some of the temperature 4 DATA ANALYSIS AND FIMs PROPOSAL
readings in the BMS were manually input or in error condition
(Figure 6). 4.1 Electricity distribution
Air handling unit (AHU and PAU: precooling air handling 4.1.1 Chiller plant consumption
unit): There are totally 23 of AHUs and 9 of PAU serving the The building consumption can be divided into two groups, one
building. With the supplied chilled water from the chiller plant, is weather sensitive and the other is non-weather sensitive.
the AHUs provide cooling to each floor. Chiller plant consumption is sensitive to the weather, the
The problem is the temperature controls of the AHU and higher the temperature/humidity, the higher the plant power
PHU that are being done by standalone electronic controller. No required to provide cooling. The consumption profile is fluctu-
connection to the BMS (Figure 7). ated throughout the year depends on the weather. Apart from
Ventilation fans. There are totally 36 ventilation fans serving chiller plant, other loadings in the building are non-weather sen-
the building. All the ventilation fans are being individually con- sitive and are relative stable throughout the year. From the
trolled by the Honeywell BMS for start and stop control accord- on-site measurement, the monthly constant load is 166 MWh.
ing to the preset time schedule (Figure 8). By subtracting this constant load, the annual chiller plant con-
Fan coil units. There are totally 270 FCUs installed at different sumption profile can be obtained (Table 7).
area of each floor with the supplied air from the AHU and
PAU. All the FCUs are being zone controlled by the Honeywell
BMS for start and stop control according to the preset time 4.1.2 Air-side equipment—AHU, PAU, VF, FCU, split unit
schedule. With reasonable assumption of operating hours, the consump-
The temperature controls of FCUs are done by conventional tion of the air-side equipment can be obtained as shown in
thermostat. Table 8.
Lighting system. Various types of lighting fixtures were in-
stalled throughout the whole building. Most of them are T8
4.1.3 Lighting system
tubes. All lighting fixtures are controlled by conventional timers
With the reasonable assumption of the operating hours, the elec-
according to the preset time schedule (Table 5).
tricity consumption of the existing lighting system can be
Lift system. There are totally four lifts installed in the CYC
obtained.
Building. One of them is service lift.
The annual electricity consumption is 604 291 kWh, which is
The lift schedule is as given below (Table 6).
approximately equal to 16.1% of the building consumption.
Power quality system. To eliminate the effect of harmonic, the
University had already installed capacitor banks for power factor
improvement. During the site visit, the power quality was in 4.1.4 Lift system
very good condition, the power factor is 0.98 (Figure 9). With the estimation of the existing maintenance contractor, the
So after the survey of the mechanical and electrical systems, annual consumption of the lifts in CYC Building is approxi-
many weak points of the system can be found. The detailed ret- mately equal to 10% of the building consumption. The annual
rofits plan will be described in the Section 4. consumption is 374 296 kWh.

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S. Xiaonuan and S.L. SiuYu

Table 4. The building’s environmental conditions.

CYC Building environmental conditions

Area Temperature set point (8C) Measured temperature (8C) Humidity set point Measured humidity (%) CO2 set point Measured CO2 (ppm)

8/F lift lobby 24 25.2 N/A 52.3 N/A 521

Room 803 24 25.3 N/A 49.9 N/A 696
Room 806 24 25.8 N/A 43.7 N/A 696
Room 807 24 25.0 N/A 48.5 N/A 262
8/F toilet N/A 25.2 N/A 52.0 N/A 650
8/F staircase 1 N/A 25.2 N/A 78.5 N/A 742
8/F staircase 2 N/A 25.2 N/A 79.7 N/A 495
7/F lift lobby 24 25.1 N/A 60.1 N/A 543
7/F staircase 1 N/A 25.1 N/A 78.5 N/A 482
7/F staircase 2 N/A 25.8 N/A 81.7 N/A 391
6/F corridor 24 25.1 N/A 52.4 N/A 520
Room 601C 24 23.8 N/A 53.5 N/A 585

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Room 603 24 24.6 N/A 52.3 N/A 500
Room 604 24 24.2 N/A 52.0 N/A 497
Room 611 24 23.6 N/A 55.0 N/A 501
Room 613 24 23.5 N/A 57.0 N/A 514
Room 615 24 23.3 N/A 56.7 N/A 559
5/F corridor 24 24.1 N/A 60.5 N/A 564
Room 508 24 24.0 N/A 64.9 N/A 542
Room 510 24 23.8 N/A 64.5 N/A 516
Room 516 24 23.8 N/A 60.4 N/A 601
Room 522 24 24.0 N/A 62.2 N/A 690
4/F corridor 24 25.1 N/A 56.4 N/A 617
Room 402 24 23.8 N/A 57.9 N/A 741
Room 409 24 24.3 N/A 59.1 N/A 715
Room 416 24 23.4 N/A 63.3 N/A 605
Room 420 24 23.4 N/A 67.3 N/A 664
Room 429 24 23.6 N/A 65.5 N/A 674
Room 430 24 23.6 N/A 68.6 N/A 681
3/F corridor 24 23.9 N/A 53.4 N/A 586
Room 306 24 23.2 N/A 54.8 N/A 676
Room 312 24 23.3 N/A 59.7 N/A 648
Room 318 24 23.5 N/A 60.2 N/A 673
Room 326 24 23.5 N/A 60.2 N/A 604
Room 328 24 23.7 N/A 60.5 N/A 611
2/F corridor 24 23.8 N/A 49.8 N/A 496
Room 205 24 23.8 N/A 49.2 N/A 488
1/F corridor 24 24.2 N/A 49.5 N/A 646
G/F lift lobby 24 24.9 N/A 66.0 N/A 572
G/F LT lobby 24 24.0 N/A 68.7 N/A 507
G/F sitting area 24 25.9 N/A 66.0 N/A 546
G/F outdoor 24 26.0 N/A 80.0 N/A 448
LG1/F lift lobby 24 24.9 N/A 59.0 N/A 613
LG1/F LT lobby 24 24.3 N/A 68.0 N/A 575
LG1/F sitting area 24 25.3 N/A 62.5 N/A 588
LG2/F lift lobby 24 24.5 N/A 49.5 N/A 469
LG3/F lift lobby 24 24.2 N/A 54.1 N/A 572

Figure 5. Building envelope.

398 International Journal of Low-Carbon Technologies 2015, 10, 393–404

 Existing buildings’ operation and maintenance

Table 5. Lighting schedule.

Wattage Key specification Total

3  18 W Recess mounted luminaire with parabolic mirror 211

and parabolic lamellas
3  36 W Recess mounted luminaire with parabolic mirror 392
and parabolic lamellas
2  36 W Recess mounted luminaire with parabolic mirror 93
and parabolic lamellas
1  100 W Recess mounted down light 102
1  50 W 12 V recess down light c/w aluminum silver, bright 16
anodized reflector
1  18 W Single-tube batten 6
1  36 W Single-tube batten 277
1  18 W Single-tube batten c/w Prismatic controller 34
1  36 W Single-tube batten c/w prismatic controller 130

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1  36 W Total enclosed single-tube flameproof fluorescent 1
fitting
1  18 W clear perspex exit sign with one number of 83
Figure 6. Chiller plant of CYC Building. self-contained and maintained E-light unit c/w
charger and battery for 2 h operation
1  250 W Low bay ceiling-mounted luminaire c/w, 34
aluminum reflector and wire guard
1  250 W and Low bay ceiling-mounted luminaire c/w, 13
1  150 W aluminum reflector and wire guard
2  36 W Pendant mounted luminaire at 2600 mm AFFL 824
1  36 W Single-tube batten with high impact resistance, 10
vacuum-formed acrylic cover
2  R95,100 W,E27 Wall-mounted up-down light 6
1  21 W Ceiling-mounted luminaire 10
1  36 W Ceiling-mounted luminaire 45
1  40 W Batten lamp holder w/red light 1
1  85 W Suspended ceiling-mounted luminaire 13
1  85 W Semi-recessed luminaire 1
1  300 W Wall uplight c/w protection glass 3
1  18 W Wall-mounted outdoor luminaire at 2500 mm 15
AFFL

Figure 7. Air handling units. Table 6. Lift system.

Lift no. Type Speed (m/s) Duty (kg) Floor served

1 Passenger 2 1250 LG3, LG1, G, 1, 3, 5, 7

(total 7 stops)
2 Passenger 2 1250 G, 1 –11 (total 12 stops)
3 Passenger 2 1250 G, 1 –11 (total 12 stops)
4 Passenger 2 1800 G, 1 –11 (total 12 stops)

4.1.5 Other system

Apart from the consumption of the chiller plant, air-side equip-
ment, lighting system and lift system, other consumption is
11% of the total building.
The summary of consumption profile is as below (Figure 10).

4.2 Facility improvement measures

4.2.1 Chiller water plant upgrading and optimization
Chiller plant consumption is 24% of the total consumption. As
discussed above, the existing system is low efficient and the effi-
Figure 8. Ventilation fans. ciency of the existing plant is about COP ¼ 2.6 (i.e. 0.7 kW/ton);

International Journal of Low-Carbon Technologies 2015, 10, 393– 404 399

S. Xiaonuan and S.L. SiuYu

Figure 10. Consumption file.

decoupled primary– secondary system is the variable primary

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flow design.
The chillers will have modulating valves installed on the
Figure 9. Capacity banks in switch room. chiller entering chilled-water piping to automatically balance
flows on each chiller. A differential pressure transducer will be
field installed across each chiller evaporator barrel, which will
Table 7. Chiller plant consumption. allow optimal variable flow on each chiller without producing
inadequate or excessive water flow rates. The new chillers will be
Chiller plant electricity consumption (kWh)
factory equipped with local controls designed to respond effi-
Months CYC Building ciently to varying flow.
The new plant condenser water system will include new high-
January 2009 2986
February 2009 5508 performance cooling towers and variable-speed condenser water
March 2009 46 649 pumps designed to minimize energy consumption and demand.
April 2009 46 948 The condenser system is designed to work optimally with the
May 2009 78 857 variable speed chillers.
June 2009 128 226
Also, two new premium efficiency cooling towers will be in-
July 2009 126 930
August 2009 130 310 stalled. In the designing of a high-performance chilled water
September 2009 156 770 plant, every component must be evaluated for maximum energy
October 2009 104 569 efficiency as stand alone and as an integral part of the full system
November 2009 77 440 efficiency.
December 2009 13 599
At last, it is also proposed to install Siemens APOGEE system
Total 918 793
for the chiller plant control. The APOGEE system will utilize the
proprietary Siemens Chiller Plant Optimization Programming.

Table 8. Chiller plant consumption.

4.2.2 Building management system upgrading with energy
Equipment Annual monitor and controlling
consumption (kWh)
The degree of interest in intelligent building is increasing.
AHU 152 802 Building owners and facilities managers demand a sophisticated
PAU 67 663 building energy management with complete build-in functions
VF 183 141 of optimization programs.
FCU 146 189
Split unit 59 227
In this project, it is proposed to install Siemens APOGEE in
three major areas that refer to chilled-water system, air-side
system and metering system.
for a well-designed all-variable speed plant, however, the efficiency For the chilled-water system, it is proposed to replace the
should be about COP ¼ 5.0 (i.e. 1.35 kW/ton). existing Honeywell Excel 5000 series with Siemens APOGEE
The existing chilled water plant consists of four 180 tons system.
Carrier air-cooled chillers, which will be replaced by two 300 For the air-side system, the existing AHUs electronic P1 con-
tons water-cooled chillers equipped with variable-speed drivers. troller will be replaced by Siemens APOGEE direct digital con-
The existing chilled water plant uses a constant volume troller. The following savings will be applied
primary loop and a secondary variable flow pumping system to
supply 88C chilled water 24/7 throughout the year. An † Adaptive control
alternative design to the existing independent air-cooled † Demand control ventilation

400 International Journal of Low-Carbon Technologies 2015, 10, 393–404

 Existing buildings’ operation and maintenance

† Start and stop time optimization 4.2.4 Window film

† Supply air temperature reset As discussed above, large areas of window are installed as build-
ing envelope at CYC Building. The window is of single pane type
At last, it is also proposed to install power meters and feedback and the shading coefficient is 0.91. The large value of shading
to the APOGEE System to all major power supply branches of coefficient results in large amount of heat can be transferred by
the electric system in CYC Building. Siemens APOGEE System sunlight from the station.
incorporate with the Energy Monitoring and Controlling system Both south and north sides of the building are installed with
provides a comprehensive approach for energy management. large areas of window. At the west and east sides, the window
areas are comparatively small. However, there is a composite
4.2.3 Lighting retrofits building which is very close to the east side of CYC Building
Currently in CYC Building, 90% of the general lightings are and, hence, it blocks a lot of sunlight from outside (Figure 12).
using florescent tubes. These lighting may be improved and total In summer, heat gain to the building is very high from the
lighting power can be reduced by a retrofit project. Since lighting outside through the window, especially in the afternoon time.
systems represent an internal heat gain to the building, any

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savings in lighting energy will reduce the internal heat gain as
well which can result in a decreased cooling load for the cooling
system.
Light-emitting diode (LED), a semiconductor light source, is
considered as the ultimate general lighting solution due to a low
power consumption, high efficiency and long life span.
All the general lighting in the main area (except plant rooms)
will be replaced, these areas cover offices, laboratories, lecture
theaters, lift lobbies, corridors, staircases, loading bay and hy-
draulic laboratory.
The required light level on work surface is 150l. The author
has conducted measurement before the lighting retrofits and
found LED can provide the same light level as florescent.
However, the luminous efficacy (lm/W) of LED is higher. As
shown in the Figure 11, we tested 30 T8 tubes and 30 LED tubes,
and we found that LED saves more electricity to achieve the
same light level. The wattage of two LED tubes is 35 W, and that
of two T8 tubes is 67 W. Figure 12. Comparison of T8 and LED.

Figure 11. Chiller performance comparison.

International Journal of Low-Carbon Technologies 2015, 10, 393– 404 401

S. Xiaonuan and S.L. SiuYu

According to the analysis, it is proposed to install 3M NV-35 over a waterproofing membrane. Also known as ‘living roofs’,
window film at the north, south and west sides of the CYC green roofs serve several purposes for a building, such as absorb-
Building. The total area of the window film is 843 m2 (9080 ing rainwater, providing insulation, creating a habitat for wild-
square foot). life, and helping to lower urban air temperature and combat the
The author also tested the performance of 3M NV-35 window heat island effect.
film, and it improves the shading coefficient by reducing the solar By considering the condition of the existing building informa-
transmission through the window. If it is set as 100% solar trans- tion, it is suggested to build a green roof at the area just above the
mission through the existing windows (not the real value of solar concourse. The total area of the suggested green roof is 2400 m2.
transmission), the solar transmission is only 44% of the 100%
with the window film (Figures 13 and 14; Table 9).
5 MEASUREMENT AND VERIFICATION
4.2.5 Green roof AFTER THE RETROFITS
A green roof is a roof of a building that is partially or completely

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covered with vegetation and soil, or growing medium, planted After the retrofits of the CYC Building, how to measure and
verify each FIM becomes a key problem.
The International Performance Measurement and Verification
Protocol (IPMVP) [6] provides an overview of current best prac-
tice techniques available for verifying results of energy efficiency,
water efficiency and renewable energy projects. It may also be
used by facility operators to assess and improve facility perform-
ance. Energy conservation measures covered herein include fuel
saving measures, water efficiency measures, load shifting and
energy reductions through installation or retrofit of equipment
and/or modification of operating procedures. The IPMVP is
being integrated into the US Green Building Council’s [7] LEED
rating system, which is rapidly becoming the National Green
Building design standard. So, we choose IPMVP as the protocol
Figure 13. Location of the composite building.
of M&V. The overview of M&Voptions is as below (Table 10).
After the retrofits of CYC Building, M&V methods of each
FIM are selected as shown in Table 11.
All the retrofits will be finished in July 2013 and, after the ret-
rofits, we will conduct 1-year testing. The schedule of the future
work after the retrofits is shown in Table 12.
After confirming the detailed measurement plans for the
thermal and lighting environments of the CYC Building, the
data for 1 year after all retrofits will be traced and record. If
the performance is out of expectation, detailed measurements
and research will be conducted to find the problems, and appro-
priate plan will be made to reduce the energy consumption.

6 CONCLUSION
This paper studied how to measure and compare the energy
consumption and indoor environment quality before and after
Figure 14. Measurement of the solar transmission. the renovation. It has also pointed that, in the whole project, EA
is the crucial part which is a process to detect operating pro-
blems, improve occupants comfort and optimize energy use of
Table 9. Measurement data of the window film. existing buildings. In addition, it also identified the opportun-
Measurement 3M window film Existing window
ities for energy conservation measures.
This research introduced a scientific methodology to com-
Indoor temperature (8C) 26.1 27.9 plete the EA before and after the retrofit. The first task was to
Indoor relative humidity (%) 46.4 43.9
define the scope of the EA, including the areas to be audited, the
Solar transmission (%) 44 100
audit sophistication level and the savings anticipated. The

402 International Journal of Low-Carbon Technologies 2015, 10, 393–404

 Existing buildings’ operation and maintenance

Table 10. The overview of M&V of IPMVP1.

M&V option How savings are calculate Typical application

A. Partially measured retrofit isolation Engineering calculations using short Lighting retrofit where power draw is measured
Savings are determined by partial field measurement of term or continuous postretrofit periodically. Operating hours of the lights are assumed
the energy use of the system(s) to which an ECM was measurements and stipulations. to be one half hour per day longer than store open
applied, separate from the energy use of the rest of the hours.
facility. Measurements may be either short term or
continuous.
Partial measurement means that some but not all
parameter(s) may be stipulated, if the total impact of
possible stipulation error(s) is not significant to the
resultant savings. Careful review of ECM design and
installation will ensure that stipulated values fairly
represent the probable actual value. Stipulations should
be shown in the M&V plan along with analysis.

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B. Retrofit isolation Engineering calculations using Application of controls to vary the load on a constant
Savings are determined by field measurement of the short-term or continuous speed pump using a variable-speed drive. Electricity use
energy use of the systems to which the ECM was applied, measurements. is measured by a kWh meter installed on the electrical
separate from the energy use of the rest of the facility. supply to the pump motor. In the base year, this meter is
Short-term or continuous measurements are taken in place for a week to verify constant loading. The meter
throughout the postretrofit period. is in place throughout the postretrofit period to track
variations in energy use.
C. Whole facility Analysis of whole facility utility meter Multifaceted energy management program affecting
Savings are determined by measuring energy use at the or submeter data using techniques from many systems in a building. Energy use is measured by
whole facility level. Short-term or continuous simple comparison to regression analysis. the gas and electric utility meters for a 12-month
measurements are taken throughout the postretrofit base-year period and throughout the postretrofit period.
period.
D. Calibrated simulation Energy use simulation, calibrated with Multifaceted energy management program affecting
Savings are determined through simulation of the energy hourly or monthly utility billing data many systems in a building but where no base-year data
use of components or the whole facility. Simulation and/or end use metering. are available. Postretrofit period energy use is measured
routines must be demonstrated to adequately model by the gas and electric utility meters. Base-year energy
actual energy performance measured in the facility. This use is determined by simulation using a model calibrated
option usually requires considerable skill in calibrated by the postretrofit period utility data.
simulation.

second step is to form EA team. Next is to estimate time frame

Table 11. Selection of M&V methods.
and the budget, collect building information and conduct site
FIM M&V methods measurements before renovation. The information refers to the
Chilled water upgrading Option B
building occupancy patterns, building environmental condi-
BMS upgrading Option A tions, building envelope and mechanical and electrical systems.
Lighting retrofits Option A The following step is to analyze collected data information and
Window film Option A propose FIMs. After the retrofits of the project, measurement
Green roof Option A and verification are also conducted in this research.
The whole project Option C þ D

Table 12. Future task by the author.

ACKNOWLEDGEMENTS
Time Future task by the author Thanks to Estate Office of the University of Hong Kong for
1 September 2013 to 31 Take measurement after the retrofits and make
giving a lot of data. Also thanks to Siemens Limited Hong Kong
December 2013: 4 months the model to do computer simulations; to give a lot of help in this study.
conduct field work; compile site information.
1 January 2014 to 30 June Task: compile measurement data before and
2014: 6 months after the retrofits; draw graphs and build
numerical site models; compile detailed data REFERENCES
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1 July 2014 to 31 December Task: conduct data trend analysis and
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