Existing buildings' operation and maintenance

Existing buildings’ operation and maintenance: renovation project of Chow Yei Ching Building at the University of Hong Kong

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Sun Xiaonuan* and Stephen LAU SiuYu School of Architecture, The University of Hong Kong, Hong Kong, China

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Abstract

Keywords: existing building; operation and maintenance; energy consumption saving retrofit; energy audit; measurement and verification; facility improvement measures (FIM) * Corresponding author. [email protected]

Received 29 November 2012; revised 24 November 2013; accepted 13 January 2014

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1 INTRODUCTION With the rapid development of urbanization, China’s building energy consumption increased year by year, which has risen to .30% of the whole energy consumption. The energy consumption of existing buildings cannot be ignored. Due to obsolete equipment and construction, as well as architectural forms, thermal performance and engineering equipment problems, existing buildings cause a serious waste of resources and energy. Most of the existing buildings now need to be updated to save energy. According to the China Energy Conservation Association Committee’s statistical service, the existing building area in China is .43 billion m2, of which only 5% can achieve green building standards (http://www.cabr.com.cn/InfoViewer.aspx?BizMainClass= 2&BizSubClass=1&RowGuid=2189). These green building standards are based on the three-star green building certification system in China. This research introduced a scientific methodology of the energy audit (EA) before and after the retrofit. Existing buildings’ operation and maintenance has large influence and potential to the whole energy-efficiency process. From the research perspective, the retrofit of existing building need to solve three key issues that are EA and energy-saving potential assessment before the retrofit; choosing the most optimized transformation measures; measurement and verification after the retrofit. [1]. Hong Kong’s climate is subtropical, tending toward temperate for nearly half of the year. July, August and September are the

hottest months with high humidity, which are the highest energy consumption period. According to the data from the Hong Kong Observatory, there was an average rise of 0.128C per decade from 1885 to 2009. The final energy consumption of the buildings can be affected by rising temperatures as it will reduce energy consumption for heating and raise demand for cooling [2, 3]. The energy consumption of buildings in Hong Kong especially in summer is so high because of the high density of the buildings and high energy consumption in the summer. So, the retrofit of the existing buildings in Hong Kong plays a crucial role to reduce the energy consumption. This paper aims to find a typical and scientific methodology to do the retrofits to reduce the energy consumption especially for the cooling system in summer.

2 DESCRIPTION OF THE PROJECT The University of Hong Kong (HKU) has contracted with Siemens Limited Hong Kong (SLHK), with project management assistance from Eco-Tech International (ETI), to provide support for Leadership in Energy and Environmental Design (LEED) for Existing Buildings: Operations and Maintenance (EB:OM) certification for the Chow Yei Ching (CYC) Building. With a concerted effort, the building has a chance of achieving the gold certification objective. This research that based on the real retrofit project of CYC Building at HKU will present more practical experience and 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

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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 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.

S. Xiaonuan and S.L. SiuYu

In fact, a list of issues violating the energy conservation principles, such as those outlined in the ASHRAE Standard 100-2006 [4], was identified after the walk-through assessment as discussed in the following subsections.

2.1 Scope of the EA According to Figures 1 and 2, EA flow chart that described in the article EA of an educational building in a hot summer climate [5], the EA process includes several tasks. The first task is to define the scope of the EA, including the areas to be audited, the audit sophistication level and the savings anticipated. In this study, CYC Building is selected to be implemented with EA. The building was built in 1993 and now it is a multipurpose academic building, which comprises offices, lecture rooms and different types of laboratory. It has a total of 13 floors from LG4/F to its highest 8/F. The total floor area is 13 168 m2.

2.2 Form EA team With many technical and funding problems, building owners need a professional team to manage the whole project. One of the most effective ways is to employ a third party which is called energy service company (ESCO) to operate. The ESCO will promise the energy efficiency of the project and profits that will come from the retrofits to the building owners. This ESCO can reduce the risk of the project, and it can also overcome the technical hurdles and finally achieve the goal of energy saving. In the contract, the ESCO reported a guarantee of energy savings that can be translated into profits. If the real energy savings are less than the guaranteed energy savings after the retrofits, the ESCO will bear the part which does not achieve the guaranteed energy savings. In this project, SLHK has promised 30% energy savings after retrofits of CYC Building. Because this study has a research dimension, the team was formed by the following parties:

Figure 1. CYC Building.

Figure 2. The location of CYC Building.

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

The O&M personnel is a research team which is made with researchers whose area is the green building operation and maintenance, and the author is one of the members of this research team. The tasks of the O&M personnel include taking measurements


(a) SLHK whose main duty was to ensure the implementation of the whole project objectives. (b) The HKU includes Estate office, electrical/electronic technician 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.

Existing buildings’ operation and maintenance

before and after each retrofit, giving advice of the appropriate technologies, making plan according to the existing buildings’ operation and maintenance in LEED and so on Figure 3.

3 INFORMATION COLLECTING PROCESS BEFORE THE RETROFIT

† FIM1: chilled water plant upgrading and optimization. † FIM2: building management system (BMS) upgrading and with energy monitor and controlling (EMC). † FIM3: lighting retrofits. † FIM4: window film. † FIM5: solar panel. † FIM6: green roof with condensate recycling. † 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 2009, the energy requirement for CYC Building was met as following (Figure 4 and Table 1):

There are many facility improvement measures (FIMs) after the literature review such as the lighting retrofits, the fac¸ade retrofits and so on. According to the condition and characteristic of the CYC Building, the following FIMs are proposed by the ESCO from the existing popular FIMs through literature review:

3.2 Building information and site measurements before renovation

Figure 3. Team formation.

In conducting a study of this type, it is essential that the existing conditions be precisely established as a baseline for the evaluation of any potential system improvements. Relevant factors were identified and assessed through a systems approach in an 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


† Electricity: 3 742 860 kWh at a total cost of HKD4 695 048 (HKD1.254/kWh). † For this estimated 13 178 m2 facility, this equates to energy cost of $356.3/m2.

After proposing these eight FIMs, the ESCO conducts the computer simulation to evaluate how much energy can be saved after the retrofits. The results are shown in Table 2. In this table, the wind turbine is not applicable in Hong Kong because of the high density of the Hong Kong Island, and there is not enough wind resource. The solar panel is also not applicable because of the climate conditions of Hong Kong, it need a long 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. According to Table 2, the total energy saving is 1 256 259 kWh per annum which translates to approximately reduction in 853 tons of CO2 emission per annum. Total project cost: HKD16 419 350.00. 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, energysaving amount, the building information etc. The detailed and complete description and analysis will be presented in Section 4.


Table 1. Base-year electricity consumption (data from Estate Office of the HKU). Month

Electricity consumption

January 2009 February 2009 March 2009 April 2009 May 2009 June 2009 July 2009 August 2009 September 2009 October 2009 November 2009 December 2009 Total

Electricity fee (maximum demand tariff ), $

kVA consumption

kWh consumption

kVA charge

kWh charge

Total charge

779 863 992 801 1016 1309 980 1102 1070 1242 1218 814

208 980 224 400 258 280 275 740 324 240 384 660 371 210 400 820 418 230 349 380 296 280 230 640 3 742 860

$33 552 $37 115 $42 540 $34 294 $43 586 $55 893 $42 063 $47 196 $45 833 $53 099 $52 057 $35 044

$237 639 $250 787 $288 642 $316 097 $359 699 $427 920 $409 721 $442 864 $461 169 $389 294 $332 032 $256 913 Total

$271 191 $287 902 $331 181 $350 391 $403 285 $483 813 $451 784 $490 060 $507 002 $442 393 $384 089 $291 957 $4 695 048

No

FIM

Estimated existing consumption (kWh)

Estimated postretrofit consumption (kWh)

Annual electricity savings (kWh)

Percentage of savings (%)

Annual electricity savings (HKD)

1

Chilled water plant upgrading BMS upgrading Lighting retrofits Window film Solar panels Green roof Micro-wind turbine Elevators updating Total

1 749 705

1 013 392

736 313

42

923 631

604 291

390 562

374 296

273 239

2 3 4 5 6 7 8

123 355 213 729 59 242 2373 20 189 N/A 101 057 1 256 259

† Building occupancy patterns. † Building environmental conditions that include temperature, humidity, ventilation and CO2. † Building envelope that refers to the exterior walls, windows/ doors and roof. † Mechanical and electrical systems that refers to the chiller plant, air handling unit [AHU and precooling air unit (PAU)], ventilation fans, fan coil units (FCUs), lighting system, lift system and power quality system. 3.2.1 Building occupancy patterns The building is in occupied by 700 staffs from 8:30 am to 7:00 pm Monday to Friday and from 8:30 am to 12:30 pm on Saturday. The occupancy of the building is summarized in Table 3. 3.2.2 Building environmental conditions The building’s environmental conditions are measured and listed in Table 4. 3.2.3 Building envelope ‘Exterior walls’: The walls consist of 150-mm thick concrete block with face brick exterior.

396


35

27

154 737 267 162 74 312 2976 25 325 N/A 126 767 1 574 911

Project cost (HKD)

Simple payback (years)

7 973 670

8.6

1 060 970 1 717 710 585 000 388 000 706 000 188 000 3 800 000 16 419 350

6.9 7.4 7.9 130 27.9 N/A 30.0

‘Windows/doors’: The windows consist of a combination of single pane glass with aluminum frame. Window areas of facing different directions: (calculated by the elevations of CYC Building) † † † † † †

North: 440 m2. South: 388 m2. West: 80 m2. East: 80 m2. Doors: there are open exits at G/F and LG4/F. Roof: the roof construction consists of 150-mm thick concrete block, and the total surface area of roof floor is 1013 m2 (Figure 5).

3.2.4 Mechanical and electrical systems ‘Chiller plant’: Building cooling is provided by a chiller plant located at the roof floor. The chiller plant consists of four aircooled 180-ton chillers, four primary chilled-water pumps and three secondary chilled-water pumps. The chiller plant was installed with Honeywell BMS, it was found that some of the sensors such as temperature sensors and flow sensors are malfunction, the chiller plant cannot be


Table 2. Investment budget and return cycle (data from Estate Office of the HKU).


Table 3. CYC Building full occupancy schedule. Area

M-F begin

M-F end

Sat begin

R/F and UR/F plant rooms 8/F laboratories 7/F lecture room, offices, laboratories 6/F lecture room, offices, laboratories 5/F lecture room, offices, laboratories 4/F lecture room, offices, laboratories 3/F lecture room, offices, laboratories 2/F offices, laboratories 1/F laboratories G/F lecture theatre LG1/F lecture theatre LG2/F laboratories LG301,A,B workshop/store, office, store room LG 302 hydraulic laboratory LG 303 technician room LG 4/F plant rooms

On request 9:00 am 9:00 am 9:00 am 9:00 am 9:00 am 9:00 am 9:00 am 9:00 am 9:00 am 9:00 am 9:00 am 9:00 am 8:00 am 9:00 am On request

8:00 pm 8:00 pm 8:00 pm 8:00 pm 8:00 pm 8:00 pm 8:00 pm 8:00 pm 5:00 pm 5:00 pm 8:00 pm 8:00 pm 8:30 pm 8:00 pm

On request On request On request On request On request On request On request On request On request On request On request On request 8:00 am On request On request

Sun begin

8:30 pm

Sun end

Estimated hours/week 4 66 66 66 66 66 66 66 66 40 40 66 66 75 66 4

4 DATA ANALYSIS AND FIMs PROPOSAL 4.1 Electricity distribution 4.1.1 Chiller plant consumption The building consumption can be divided into two groups, one is weather sensitive and the other is non-weather sensitive. Chiller plant consumption is sensitive to the weather, the higher the temperature/humidity, the higher the plant power required to provide cooling. The consumption profile is fluctuated throughout the year depends on the weather. Apart from chiller plant, other loadings in the building are non-weather sensitive and are relative stable throughout the year. From the on-site measurement, the monthly constant load is 166 MWh. By subtracting this constant load, the annual chiller plant consumption profile can be obtained (Table 7). 4.1.2 Air-side equipment—AHU, PAU, VF, FCU, split unit With reasonable assumption of operating hours, the consumption of the air-side equipment can be obtained as shown in Table 8. 4.1.3 Lighting system With the reasonable assumption of the operating hours, the electricity consumption of the existing lighting system can be obtained. The annual electricity consumption is 604 291 kWh, which is approximately equal to 16.1% of the building consumption. 4.1.4 Lift system With the estimation of the existing maintenance contractor, the annual consumption of the lifts in CYC Building is approximately equal to 10% of the building consumption. The annual consumption is 374 296 kWh.



operated fully automatically. We found some of the temperature readings in the BMS were manually input or in error condition (Figure 6). Air handling unit (AHU and PAU: precooling air handling unit): There are totally 23 of AHUs and 9 of PAU serving the building. With the supplied chilled water from the chiller plant, the AHUs provide cooling to each floor. The problem is the temperature controls of the AHU and PHU that are being done by standalone electronic controller. No connection to the BMS (Figure 7). Ventilation fans. There are totally 36 ventilation fans serving the building. All the ventilation fans are being individually controlled by the Honeywell BMS for start and stop control according to the preset time schedule (Figure 8). Fan coil units. There are totally 270 FCUs installed at different 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 schedule. The temperature controls of FCUs are done by conventional thermostat. Lighting system. Various types of lighting fixtures were installed throughout the whole building. Most of them are T8 tubes. All lighting fixtures are controlled by conventional timers according to the preset time schedule (Table 5). Lift system. There are totally four lifts installed in the CYC Building. One of them is service lift. The lift schedule is as given below (Table 6). 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 very good condition, the power factor is 0.98 (Figure 9). So after the survey of the mechanical and electrical systems, many weak points of the system can be found. The detailed retrofits plan will be described in the Section 4.

Sat end


Table 4. The building’s environmental conditions. CYC Building environmental conditions Temperature set point (8C) Measured temperature (8C) Humidity set point Measured humidity (%) CO2 set point Measured CO2 (ppm)

8/F lift lobby Room 803 Room 806 Room 807 8/F toilet 8/F staircase 1 8/F staircase 2 7/F lift lobby 7/F staircase 1 7/F staircase 2 6/F corridor Room 601C Room 603 Room 604 Room 611 Room 613 Room 615 5/F corridor Room 508 Room 510 Room 516 Room 522 4/F corridor Room 402 Room 409 Room 416 Room 420 Room 429 Room 430 3/F corridor Room 306 Room 312 Room 318 Room 326 Room 328 2/F corridor Room 205 1/F corridor G/F lift lobby G/F LT lobby G/F sitting area G/F outdoor LG1/F lift lobby LG1/F LT lobby LG1/F sitting area LG2/F lift lobby LG3/F lift lobby

24 24 24 24 N/A N/A N/A 24 N/A N/A 24 24 24 24 24 24 24 24 24 24 24 24 24 24 24 24 24 24 24 24 24 24 24 24 24 24 24 24 24 24 24 24 24 24 24 24 24

25.2 25.3 25.8 25.0 25.2 25.2 25.2 25.1 25.1 25.8 25.1 23.8 24.6 24.2 23.6 23.5 23.3 24.1 24.0 23.8 23.8 24.0 25.1 23.8 24.3 23.4 23.4 23.6 23.6 23.9 23.2 23.3 23.5 23.5 23.7 23.8 23.8 24.2 24.9 24.0 25.9 26.0 24.9 24.3 25.3 24.5 24.2

Figure 5. Building envelope.

398


N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A

52.3 49.9 43.7 48.5 52.0 78.5 79.7 60.1 78.5 81.7 52.4 53.5 52.3 52.0 55.0 57.0 56.7 60.5 64.9 64.5 60.4 62.2 56.4 57.9 59.1 63.3 67.3 65.5 68.6 53.4 54.8 59.7 60.2 60.2 60.5 49.8 49.2 49.5 66.0 68.7 66.0 80.0 59.0 68.0 62.5 49.5 54.1

N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A

521 696 696 262 650 742 495 543 482 391 520 585 500 497 501 514 559 564 542 516 601 690 617 741 715 605 664 674 681 586 676 648 673 604 611 496 488 646 572 507 546 448 613 575 588 469 572


Area


Table 5. Lighting schedule. Wattage

Key specification

Total

3 18 W

Recess mounted luminaire with parabolic mirror and parabolic lamellas Recess mounted luminaire with parabolic mirror and parabolic lamellas Recess mounted luminaire with parabolic mirror and parabolic lamellas Recess mounted down light 12 V recess down light c/w aluminum silver, bright anodized reflector Single-tube batten Single-tube batten Single-tube batten c/w Prismatic controller Single-tube batten c/w prismatic controller Total enclosed single-tube flameproof fluorescent fitting clear perspex exit sign with one number of self-contained and maintained E-light unit c/w charger and battery for 2 h operation Low bay ceiling-mounted luminaire c/w, aluminum reflector and wire guard Low bay ceiling-mounted luminaire c/w, aluminum reflector and wire guard Pendant mounted luminaire at 2600 mm AFFL Single-tube batten with high impact resistance, vacuum-formed acrylic cover Wall-mounted up-down light Ceiling-mounted luminaire Ceiling-mounted luminaire Batten lamp holder w/red light Suspended ceiling-mounted luminaire Semi-recessed luminaire Wall uplight c/w protection glass Wall-mounted outdoor luminaire at 2500 mm AFFL

211

3 36 W 2 36 W 1 100 W 1 50 W 1 18 W 1 36 W 1 18 W 1 36 W 1 36 W

Figure 6. Chiller plant of CYC Building.

1 18 W

1 250 W and 1 150 W 2 36 W 1 36 W 2 R95,100 W,E27 1 21 W 1 36 W 1 40 W 1 85 W 1 85 W 1 300 W 1 18 W

Figure 7. Air handling units.

93 102 16 6 277 34 130 1 83

34 13 824 10 6 10 45 1 13 1 3 15

Table 6. Lift system. Lift no.

Type

Speed (m/s)

Duty (kg)

Floor served

1

Passenger

2

1250

2 3 4

Passenger Passenger Passenger

2 2 2

1250 1250 1800

LG3, LG1, G, 1, 3, 5, 7 (total 7 stops) G, 1 –11 (total 12 stops) G, 1 –11 (total 12 stops) G, 1 –11 (total 12 stops)

4.1.5 Other system Apart from the consumption of the chiller plant, air-side equipment, 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

Figure 8. Ventilation fans.

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 efficiency 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


1 250 W

392


Figure 10. Consumption file.

Figure 9. Capacity banks in switch room.

Chiller plant electricity consumption (kWh) Months

CYC Building

January 2009 February 2009 March 2009 April 2009 May 2009 June 2009 July 2009 August 2009 September 2009 October 2009 November 2009 December 2009 Total

2986 5508 46 649 46 948 78 857 128 226 126 930 130 310 156 770 104 569 77 440 13 599 918 793

Table 8. Chiller plant consumption. Equipment

Annual consumption (kWh)

AHU PAU VF FCU Split unit

152 802 67 663 183 141 146 189 59 227

for a well-designed all-variable speed plant, however, the efficiency should be about COP ¼ 5.0 (i.e. 1.35 kW/ton). The existing chilled water plant consists of four 180 tons Carrier air-cooled chillers, which will be replaced by two 300 tons water-cooled chillers equipped with variable-speed drivers. The existing chilled water plant uses a constant volume primary loop and a secondary variable flow pumping system to supply 88C chilled water 24/7 throughout the year. An alternative design to the existing independent air-cooled

400


4.2.2 Building management system upgrading with energy monitor and controlling The degree of interest in intelligent building is increasing. Building owners and facilities managers demand a sophisticated building energy management with complete build-in functions of optimization programs. 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 the chilled-water system, it is proposed to replace the existing Honeywell Excel 5000 series with Siemens APOGEE system. For the air-side system, the existing AHUs electronic P1 controller will be replaced by Siemens APOGEE direct digital controller. The following savings will be applied † Adaptive control † Demand control ventilation


Table 7. Chiller plant consumption.

decoupled primary– secondary system is the variable primary flow design. The chillers will have modulating valves installed on the 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 allow optimal variable flow on each chiller without producing inadequate or excessive water flow rates. The new chillers will be factory equipped with local controls designed to respond efficiently to varying flow. The new plant condenser water system will include new highperformance cooling towers and variable-speed condenser water pumps designed to minimize energy consumption and demand. The condenser system is designed to work optimally with the variable speed chillers. Also, two new premium efficiency cooling towers will be installed. In the designing of a high-performance chilled water plant, every component must be evaluated for maximum energy efficiency as stand alone and as an integral part of the full system efficiency. At last, it is also proposed to install Siemens APOGEE system for the chiller plant control. The APOGEE system will utilize the proprietary Siemens Chiller Plant Optimization Programming.


† Start and stop time optimization † Supply air temperature reset At last, it is also proposed to install power meters and feedback to the APOGEE System to all major power supply branches of the electric system in CYC Building. Siemens APOGEE System incorporate with the Energy Monitoring and Controlling system provides a comprehensive approach for energy management.

Figure 12. Comparison of T8 and LED.

Figure 11. Chiller performance comparison.



4.2.3 Lighting retrofits Currently in CYC Building, 90% of the general lightings are using florescent tubes. These lighting may be improved and total lighting power can be reduced by a retrofit project. Since lighting systems represent an internal heat gain to the building, any 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 hydraulic 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.

4.2.4 Window film As discussed above, large areas of window are installed as building envelope at CYC Building. The window is of single pane type and the shading coefficient is 0.91. The large value of shading coefficient results in large amount of heat can be transferred by sunlight from the station. Both south and north sides of the building are installed with large areas of window. At the west and east sides, the window areas are comparatively small. However, there is a composite building which is very close to the east side of CYC Building and, hence, it blocks a lot of sunlight from outside (Figure 12). In summer, heat gain to the building is very high from the outside through the window, especially in the afternoon time.


According to the analysis, it is proposed to install 3M NV-35 window film at the north, south and west sides of the CYC Building. The total area of the window film is 843 m2 (9080 square foot). The author also tested the performance of 3M NV-35 window film, and it improves the shading coefficient by reducing the solar transmission through the window. If it is set as 100% solar transmission through the existing windows (not the real value of solar transmission), the solar transmission is only 44% of the 100% with the window film (Figures 13 and 14; Table 9). 4.2.5 Green roof A green roof is a roof of a building that is partially or completely covered with vegetation and soil, or growing medium, planted

5 MEASUREMENT AND VERIFICATION AFTER THE RETROFITS 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 practice 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 performance. 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 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 retrofits, 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 appropriate plan will be made to reduce the energy consumption.

6 CONCLUSION

Figure 14. Measurement of the solar transmission.

Table 9. Measurement data of the window film. Measurement

3M window film

Existing window

Indoor temperature (8C) Indoor relative humidity (%) Solar transmission (%)

26.1 46.4 44

27.9 43.9 100

402


This paper studied how to measure and compare the energy consumption and indoor environment quality before and after the renovation. It has also pointed that, in the whole project, EA is the crucial part which is a process to detect operating problems, improve occupants comfort and optimize energy use of existing buildings. In addition, it also identified the opportunities for energy conservation measures. This research introduced a scientific methodology to complete the EA before and after the retrofit. The first task was to define the scope of the EA, including the areas to be audited, the audit sophistication level and the savings anticipated. The


Figure 13. Location of the composite building.

over a waterproofing membrane. Also known as ‘living roofs’, green roofs serve several purposes for a building, such as absorbing rainwater, providing insulation, creating a habitat for wildlife, and helping to lower urban air temperature and combat the heat island effect. By considering the condition of the existing building information, it is suggested to build a green roof at the area just above the concourse. The total area of the suggested green roof is 2400 m2.


Table 10. The overview of M&V of IPMVP1. How savings are calculate

Typical application

A. Partially measured retrofit isolation Savings are determined by partial field measurement of the energy use of the system(s) to which an ECM was applied, separate from the energy use of the rest of the 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. B. Retrofit isolation Savings are determined by field measurement of the energy use of the systems to which the ECM was applied, separate from the energy use of the rest of the facility. Short-term or continuous measurements are taken throughout the postretrofit period.

Engineering calculations using short term or continuous postretrofit measurements and stipulations.

Lighting retrofit where power draw is measured periodically. Operating hours of the lights are assumed to be one half hour per day longer than store open hours.

Engineering calculations using short-term or continuous measurements.

Application of controls to vary the load on a constant speed pump using a variable-speed drive. Electricity use is measured by a kWh meter installed on the electrical supply to the pump motor. In the base year, this meter is in place for a week to verify constant loading. The meter is in place throughout the postretrofit period to track variations in energy use. Multifaceted energy management program affecting many systems in a building. Energy use is measured by the gas and electric utility meters for a 12-month base-year period and throughout the postretrofit period.

C. Whole facility Savings are determined by measuring energy use at the whole facility level. Short-term or continuous measurements are taken throughout the postretrofit period. D. Calibrated simulation Savings are determined through simulation of the energy use of components or the whole facility. Simulation routines must be demonstrated to adequately model actual energy performance measured in the facility. This option usually requires considerable skill in calibrated simulation.

Analysis of whole facility utility meter or submeter data using techniques from simple comparison to regression analysis.

Energy use simulation, calibrated with hourly or monthly utility billing data and/or end use metering.

Table 11. Selection of M&V methods. FIM

M&V methods

Chilled water upgrading BMS upgrading Lighting retrofits Window film Green roof The whole project

Option B Option A Option A Option A Option A Option C þ D

Table 12. Future task by the author. Time

Future task by the author

1 September 2013 to 31 December 2013: 4 months

Take measurement after the retrofits and make the model to do computer simulations; conduct field work; compile site information. Task: compile measurement data before and after the retrofits; draw graphs and build numerical site models; compile detailed data and conduct preliminary data analysis. Task: conduct data trend analysis and regression analysis, take measurement and verification after the renovation.

1 January 2014 to 30 June 2014: 6 months

1 July 2014 to 31 December 2014: 6 months

Multifaceted energy management program affecting many systems in a building but where no base-year data are available. Postretrofit period energy use is measured by the gas and electric utility meters. Base-year energy use is determined by simulation using a model calibrated by the postretrofit period utility data.

second step is to form EA team. Next is to estimate time frame and the budget, collect building information and conduct site measurements before renovation. The information refers to the building occupancy patterns, building environmental conditions, building envelope and mechanical and electrical systems. The following step is to analyze collected data information and propose FIMs. After the retrofits of the project, measurement and verification are also conducted in this research.

ACKNOWLEDGEMENTS Thanks to Estate Office of the University of Hong Kong for giving a lot of data. Also thanks to Siemens Limited Hong Kong to give a lot of help in this study.

REFERENCES [1] Eskin N, Turkmen H. Analysis of annual heating and cooling energy requirements for office buildings in different climates in Turkey. Energy Build 2008;40:763 –73.



M&V option


[2] Ebinger J, Vergara W. Cimate Impacts on Energy Systems: Key Issues for Energy Sector Adaptation. The World Bank. 2010. [3] Landsberg HE. The Urban Climate (Google eBook). Academic Press, 1981, 275. [4] ASHRAE, ANSI/ASHRAE Standard 100 – 2006. Energy Conservation in Existing Building. American Society of Heating, Refrigerating and Air-Conditioning Engineers Inc., 2006.

[5] Alajmi A. Energy audit of an educational building in a hot summer climate. Energy Build. 2011;47:122– 30. [6] EVO (Efficiency Valuation Organization). M&V by International Performance Measurement and Verification Protocol (IPMVP). [7] USGBC. LEED for Existing Buildings Reference Guide, U.S. Green Building Council.


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