STUDY ON EFFECTS OF AUTOMATIC CONTROLLED EXTERNAL VENETIAN BLINDS AND ELECTRICAL HEATABLE DOUBLE

GLAZING IN THE OFFICE BUILDING

Takefumi Yokota 1†, Fumio Nohara 1, Mutsuo Honma 1, Takaharu Kawase 2, Takashi Inoue 3and Masashi Momota4

1 NIKKEN SEKKEI LTD.

2 Department of Architecture & Design, Chiba University 3 Department of Architecture, Tokyo University of Science

4 Department of Architecture, Tokyo Denki University ABSTRACT Motorized sun-controlled louvers and electrically heated glasses are installed in NIKKEN SEKKEI Tokyo Bldg. A lot of highly effective equipment systems are set up in this building. In this research, these energy conservation systems are measured and analyzed. This report explains the specification of the building, equipments, and the window system. . As a result, it was confirmed that the exterior blinds and a heat generating double glazing was effective in keeping thermal environment comfortable and saving energy. KEYWORDS Perimeterless, Solar shading, Daylighting, anti-condensation, Energy-saving 1. INTRODUCTION The NIKKEN SEKKI Tokyo Building is one element of the I-Garden redevelopment zone Iidabashi, Chiyodaku. The zone intended to form an urban garden, surrounded by greenly, in which cluster of high-rise buildings stand amid rich foliage. This is medium-high-rise building, with 14 floors above ground. It shares attributes of height, wall boundary line and ground floor setback with two adjacent buildings, forming consistent row. The main purpose of the building is to serve as the headquarters for NIKKEN SEKKEI LTD. It also had to satisfy the additional design condition of being able to accommodate other office tenants. The first floor has an exhibition galley, and the second floor contains consultation area and meeting rooms. Offices occupy the third floor to the thirteenth floor. The fourteenth floor has a multi-purpose studio and a lounge． The basic approach, affecting all aspects of the building was that, as the office building that the design company would use for itself, it should adopt a no-frills design in its plan and exterior, equipment and detailing. Nevertheless the building incorporates the latest innovative technology. It also stands as product of innovative but proven technologies. Rather

† Corresponding Author: Tel: + 813 5226 3030 , Fax: +813 5226 3038 E-mail address: yokota@nikken.co.jp

Figure 1 NIKKEN SEKKEI Tokyo Building

than an effort to produce something special for company’s own building, they are intended to serve as a prototype for general office building in the future. One of the design concept is “response to the external environment,” which inspires an array of systems and details that link the interior to natural ventilation and light. The east and west façades have extensive glazed surfaces, which make the most of the site’s characteristics by securing board and far-reaching views. These sides are the façades facing road, so they are the sides that express the character of the building. The balcony eaves on each floor emphasize the horizontal lines, which cast shadows. The only vertical lines are narrow, sharp mullions, which are inconspicuous. The major feature of the building is the motorized blinds mounted on the exterior. They are computer controlled, and provide further emphasis for the horizontal lines.

1.1 Development of the new external blinds The site for the NIKKEN SEKKEI Tokyo Building has long east and west sides, while the north and south sides have views restricted by adjacent buildings. The plan to open good views though extensive gazing on the east and west side was prompted by the formed of site. However, those sides are strongly impacted by sunshine making it challenge to reduce the thermal load. The external blinds are effective means of daylight control. They are already well-proven technology in Europe, where they have been demonstrated to save energy and distribute reflected sunlight into deeper building interiors. However, they had not been used to good effect in Japan before, so new product had to be developed. The main design aims were increased strength, to resist high wind load, and refined appearance. The aluminum slats, a new design, are hollow, extruded members. They can be used normally in wind speeds of up to 25 m/s. For safety, a wind sensor detect when wind speeds exceed 15m/s, at which time the blinds are automatically lowered into storage at each floor level. They are motorized and computer controlled so these slats’ angle and up down are adjust to the incident sunlight. In ordinary building operation, the external blinds are extending to cover the entire glazed area. The blinds set the appearance of the building apart from the standard glazed office building, with the shadow cast by the horizontal slats creating a unique three-dimensional image.

1.2 Revolutionary openings in a prototype for the next generation of office buildings In addition to the external blinds, the openings on the east and west sides are protected by balcony

Table 1 Specification of NIKKEN SEKKI Tokyo Building

Location Iidabasshi,Chiyoda-ku,TokyoSite Area 2,853.00m2

Building Area 1,497.75m2

Total Floor Area 20,580.88m2

Structure S,SRC,RCFloors 14 stories

+1 basement floor+1 penthouse

Building Height SGL+66.0mParking Capacity 42 carsConstruction period September 2001 to March 2003

Figure 2 Section of the window system

eaves, multi-pane heating glass, natural ventilation in an innovative design. The combination of external blinds with multipane heating glass is a key characteristic of the building, as it eliminates the need for perimeter air conditioning system. Fan coil units or airflow fans are often installed in perimeter areas. But they are not installed in this building. Multi-pane heating glass has a thicker air layer (t=12mm) than ordinary double-glazing. A planner-heating element heats the inner glass layer, giving it high insulation, and preventing cold draft and condensation. The power required for heating is slight, and power need only be supplied for short period. The perimeter-less openings, build around the external blinds and the multi-pane heating glass are a superior system well suited for general use in tenant office buildings. Such measures are particularly useful where site conditions of impose east-west façades. So we report verification of energy savings effects and operational trials in this paper.

1.3 Window system components This window system is build up by three components. The first component is motorized external Venetian blend. This slats angle and up down is automatic controlled. And new slats design, which is made of hollow aluminum, is strong enough not to be destroyed by typhoon. The second component is multi-pane heating glass. It has a thicker air layer (t=12mm) than ordinary double-glazing. An invisible thin metal planner heating elements is heated by electricity and keep whole glass uniformly same temperature so can prevent cold draft ，cold radiation. The third component is automatic control system. This system is a newly developed open network system, which has LON WORKS servers on each floor. Motion detective sensors can dimmer lights and ambient light photo sensor controls lightings and proper illuminance control. 2. OUTLINE OF MEASUREMENT Thermometers, a PMV meter, a pyranometer were in West perimeter (Fig.2) and measurements were taken at 5-minutes intervals.

2.1 Comparative measurement of external venetian blinds and internal venetian blinds To compare shading performance of solar radiation external venetian blinds and internal venetian blinds, actually installed internal venetian blinds in the west perimeter. One of the internal venetian blinds is white and the other is gray (Fig.5).

Figure 3 Automatic slats’ angle control

Integrated each floor controller （（（（BACnet/LON GW））））Cooperative control : Air-Conditioning & Lighting & Blind

Building roof unit [Machine floor]

Measurement Equipment

MachineController

ExothermicGlass

controller

ExternalBlind

Controller

DDC(AHU)

Floor controller[Touch panel operation]

[OS : Windows CE]

IcontLighting

LON

Icont

BACnet(TCP/IP)

Accident prevention

control panel

Office LAN OA terminal

OA LAN

Security systemcontrol panel

OA LAN

Router

Router

Printer

BMS server

Data server

HIM(PC)

Web server

RouterOA LAN

Fire WallInternet

Office LANOA terminal

Each floorB1F～～～～14F

IcontSubstation

facility

IcontPrimary

heat source

IcontSecondary heat source

Integrated each floor controller （（（（BACnet/LON GW））））Cooperative control : Air-Conditioning & Lighting & Blind

Building roof unit [Machine floor]

Measurement Equipment

MachineController

ExothermicGlass

controller

ExternalBlind

Controller

DDC(AHU)

Floor controller[Touch panel operation]

[OS : Windows CE]

IcontLighting

LON

Icont

BACnet(TCP/IP)

Accident prevention

control panel

Office LAN OA terminal

OA LAN

Security systemcontrol panel

OA LAN

Router

Router

Printer

BMS server

Data server

HIM(PC)

Web server

RouterOA LAN

Fire WallInternet

Office LANOA terminal

Each floorB1F～～～～14F

IcontSubstation

facility

IcontPrimary

heat source

IcontSecondary heat source

Figure 4. Automatic control system with Floor Icont

Figure 6 Slats enclosing control (2004.09.19)

2.2 Measurement of Thermal comfort at slats enclosing control Usually these external blinds were controlled slats angle. In this Experiment, we rolled down the slats by automatic schedule control and measure thermal environment. The external blinds system can rolled slats down top of the pericounter and full height view can be got. Time zone of roll down control is from 8:00 a.m. to 12: 30 a.m. on the west side and from 12:00 p.m. to 8:00 p.m. on the east side in order to avoid direct sunlight.

2.3 Measurement of Thermal comfort of multi-pane heating glass We measured surface temperature of multi-pane heating glass and PMV at the night of winter, when we switched on or switched off to inspect an effect of thermal comfort improvement.

3. INSPECTION RESULTS OF THE EFFECTIVENESS OF THE WINDOW SYSTEM

3.1 Automatic controlled external venetian blinds Fig.5 is a thermograph photo when solar energy was peak. It shows that external venetian blinds can shade sunlight effectively so surface temperature was 29.8 degree C. But internal gray venetian blind’s surface temperature was 40.1 degree C and it was about 10 degrees high than external blinds.

Roll-down control is effective for improvement of a view from the window. We compared thermal environments when slats were controlled by only angle and by roll-down control. Fig.6 shows a photo and thermograph of roll-down control. Fig.7 shows a photo and thermograph of automatic slats’ angle control. This west side windows’ slats were roll-down controlled for 8:00 ~ 12:30. By comparison of thermograph photos at 12:30 and 15:30,if schedule was set appropriately, the roll-down control could keep thermal comfortability and could improve view from windows. Fig.8 shows change of temperatures before roll-down control was installed and after. Solar radiation power was almost same before and after. For 8:00~11:00, window surface

Figure 5 Comparative measurement of external venetian blinds and internal venetian blinds

Figure 7 Slats Angle control (2004.09.19)

temperture was 1~2 degrees higher than before roll-down control was installed. But for 11:00 ~12:30, temperature difference of the window was expanded to about 4 degree. After those experiments, roll-down control schedule was changed 8:00~11:00 in west side.

3.2 Inspection results of Multi-pane heating glass Fig.10 shows window temperature and PMV when switched on and switched off. Out air temperature was about 5degree but inner window surface temperature was about 18 degree C by high insulation ratio of multi-pane glass. When the switch was turn on and the electric current of 50W/m2 flowed to the window, surface temperature of the window rose approximately 4 degrees. In this case PMV was improved to -0.1 from -0.5. A thermostat that installed upper side of inner glass controls multi-pane heating glass. So the thermostat indicates lower temperature than the average temperature of glass because metal sash causes thermal bridge. After those measurements, to keep average temperature of inner glass surface approximately 20 degree C, set point of temperature was changed 19 degree C to 15 degree C. Fig.11 shows set point, thermostat vale and center temperature of glass. After modifying set point temperature, the electric energy was reduced substantially.

4. ENERGY CONSUMPTIONS Fig. 12 shows solar power and lighting power ratio in west perimeter. The first line of lighting power was decreasing when solar power was increasing. The second line and the third line of lighting power is flatter than that of first line. Fig.12 shows that lighting power ratio of perimeter is lower 14% than lighting power ratio of interior. Interior lighting power ratio decreased to approximately 60% by appropriate luminous intensity control. External blinds roll-down control can decrease perimeter lighting power, Fig.14 shows that the effect was about 8%. Fig.15 shows the correlation diagram of the amount of solar radiation power and cooling loads

Figure 8 Window Surface Temperature

17.017.018.018.0

19.019.0

20.020.0

21.021.0

22.022.0

23.023.0

24.024.025.025.0

17.017.018.018.0

19.019.0

20.020.0

21.021.0

22.022.0

23.023.0

24.024.025.025.0

18:30 18:30 18:30 18:30 (Switched OFF)(Switched OFF)(Switched OFF)(Switched OFF)　　　　 19:30 19:30 19:30 19:30 (Switch ON)(Switch ON)(Switch ON)(Switch ON)

11118888℃℃℃℃ 22222222℃℃℃℃

17.017.018.018.0

19.019.0

20.020.0

21.021.0

22.022.0

23.023.0

24.024.025.025.0

17.017.018.018.0

19.019.0

20.020.0

21.021.0

22. 022.0

23.023.0

24.024.025.025.0

18:30 18:30 18:30 18:30 (Switched OFF)(Switched OFF)(Switched OFF)(Switched OFF)　　　　 19:30 19:30 19:30 19:30 (Switch ON)(Switch ON)(Switch ON)(Switch ON)

11118888℃℃℃℃ 22222222℃℃℃℃

Figure 9 Window Surface Temperature of

Multi-pane heating glass (Thermograph photo)

-1.5

-1

-0.5

0

0.5

1

18:00 18:10 18:20 18:30 18:40 18:50 19:00 19:10 19:20 19:30 19:40 19:50 20:000

5

10

15

20

25[PMV] [℃]

Outdoor Temp PMV

Indoor Temp(Perimeter）Winodow Surface Temp　(Indoor)

Switched　ON [50W/㎡]

Figure 10. Window Surface Temperature of

Multi-pane heating glass(Graph)

0

10

20

30

2004.11. 2004.12. 2005.1. 2005.2. 2005.3.

0

25

50

75[℃] [kWh/d]

SetpointSetpointSetpointSetpoint

Electric power of Multi-paneElectric power of Multi-paneElectric power of Multi-paneElectric power of Multi-paneheating glass (5F)heating glass (5F)heating glass (5F)heating glass (5F)2004200420042004 ....11111111～～～～2005200520052005....03030303

Outdoor TempOutdoor TempOutdoor TempOutdoor Temp

Window SurfaceWindow SurfaceWindow SurfaceWindow SurfaceTemp(Thermostat)Temp(Thermostat)Temp(Thermostat)Temp(Thermostat)

Electric power of Multi-paneElectric power of Multi-paneElectric power of Multi-paneElectric power of Multi-paneheating glass (5F)heating glass (5F)heating glass (5F)heating glass (5F)2003200320032003 ....11111111～～～～2004200420042004....03030303

Window SurfaceWindow SurfaceWindow SurfaceWindow SurfaceTemp(Center)Temp(Center)Temp(Center)Temp(Center)

Figure 11 Running Condition of Multi-pane heating

glass (2004 year)

Figure 12 Correlation of window surface solar power and lighting power ratio (2004.04~2005.03)

of perimeter and cooling loads of interior. Because the external blinds shade solar radiation appropriately, when the amount of solar radiation power increased, cooling load increased loosely.

5. SIMULATOIONS OF REDUCTOIN EFFECT OF COOLING LOAD AND LIGHTING POWER

5.1 Method of simulations We improved dynamic thermal load calculation program “HASP-L” in order to simulate effect of automatic external blinds and multi-pane heating glass. Standard Model has inner Venetian blinds and single 8mm glass without lighting control. Model of the NIKKEN SEKKI BUILDING has automatic external blinds, multi-pane heating glass and optimal control of artificial lighting and daylighting. Table 1 shows conditions of simulation. Out air

01020304050607080

Lig

hting

pow

er

ratio[%

]

West Primeter Interior

14％

1430[kWh/annual］ 5.8[W/㎡］ 5590[kWh/annual］ 7.5[W/㎡］

Sep

Mar

Feb

Jan

Dec

Nov

Oct

Aug

Jul

Jun

May

Apr

Sep

Mar

Feb

Jan

Dec

Nov

Oct

Aug

Jul

Jun

May

Apr

Figure 13 Monthly Lighting power ratio (2004.04~2005.03)

0

20

40

60

80

Lig

hting

pow

er

ratio[%

]

0

20

40

60

80

8:00 9:00 10:00 11:00 12:00 13:00 14:00 15:00 16:00 17:00Time

①Before:External blinds roll-down control2003.09.06～2003.10.31

West Primeter

East Primeter

①Before:External blinds roll-down control2003.09.06～2003.10.31

②After:External blinds roll-down control　2004.09.06～2004.10.31

８％

②After:External blinds roll-down control　2004.09.06～2004.10.31

Figure 14. Lighting power ratio by External blinds roll-down control

0

40

80

120

160

200

0 200 400 600 800

Solar radiation power　on the west window[W/㎡]

Coolin

g　Load

[W/㎡

]

0 200 400 600 800

Interior

0 200 400 600 800

West Perimeter+InteriorWest Perimeter

Figure 15 Correlation of window surface solar power and Cooling Load (2004.04~2005.03)

quantity are smaller than general settings, but it decided from the actual operational result. Table 2 shows physical properties value of the window system.

5.2 Result of energy-saving effect Correlation diagrams of insolation and cooling loads are shown in Fig.19. Influence of the amount of insolation has appeared with the standard model building remarkably. Measurement result and the simulation result of the NIKKEN SEKKEI Tokyo building shows that Influence of the amount of insolation to cooling load is smaller than the standard model building. Total air-conditioning load of this building is as many as 45% fewer than the standard model in perimeter zone (Fig.18). This comparison proves that external blind is effective to the cutoff of solar radiation and multi-pane heating glass has high insulation. And Fig.18 shows that control of daylight utilization is effective in energy decrease of lighting.

Table 1 Conditions for Simulations Content Value

Dayｓ　of　A..C.　stop National holidays & 12/30.～1/3Weekday 8:00～22:00

Saterday・Sunday 8:00～20:00① 25.5～26.0℃　40～60％RH②　 25.0～25.5℃　40～60％RH③　 24.0～24.5℃　40～60％RH

AC-1(East）：3.5m3/m2hAC-2(West)：2.8m3/m2h

Running schdule

Room air condition

※①：Jun～Sep　②：Apr,May,Oct,Nov,Dec　③：Jan,Feb,Mar

Out Air(Average of running rusults)

Table 2 Performance of glasses

SCR SCC

4.9 0.26 0.262.0 0.60 0.092.0 0.07 0.07

FL8㎜+Internal white venetian blind

Sade factorOver all heat transfer

coefficient

[W/㎡K]

Multi-pane heating glassExternal blind and multi-pane heating glass

Classification

0

40

80

120

160

200

0 200 400 600 800Solar radiation power　on the west window[W/㎡]

Coolin

g　Load

[W/㎡

]

0 200 400 600 800 0 200 400 600 800

Simulation　results ofNIKKEN SEKKEI Tokyo BuilingModel

Simulation　results ofStandard Office Builing Model

Actual survey ofNIKKEN SEKKEI Tokyo Builing5F West Primeter

Figure 16 Correlation of window surface solar power and Cooling Load

Simulation results and Actual survey (2004.04~2005.03)

External blind andmulti-pane heating glass

Daylighting control

Internal venetian blinds+FL8mm

Annual SimulationsAnnual SimulationsAnnual SimulationsAnnual Simulations

Annual actual surveyAnnual actual surveyAnnual actual surveyAnnual actual survey

Power Consumption ofLighting [MWh/a]

Heatingload

[GJ/a]

Cooling load[GJ/a]

88.6

65.8

55.9

337.5 504.2 100%96.965.5

92.4288.3 424.1 84.1%

4.3

6.936.5 80.1

28.2

287.9 62.9 397.3

0.3

(summer) (intermediate) (winter)

100%

74.3%

Figure 17 Simulation results and Actual survey (2004.04~2005.03)

Total zone of 5th floor (Area 1,000m2)

6. CONCLUSION The combination of external blind and multi-pane heating glass is beneficial to the energy conservation of air conditioning in NIKKEN SEKKEI Tokyo Building. Especially external Blind can cut off the influence of solar radiation, it is possible to keep air conditioning environment comfortably. Roll-down control is effective for improvement of a view from the window and If control schedule is set appropriately, it can decrease perimeter lighting power. This study proved that the window system can make comfortable environment and reduce energy consumption simultaneously and is able to actualize the perimeterless air conditioning system.

7. REFERENCES 1. Yokota et al. (2005), Study on the Performance Assessment of an Energy Efficient Building Part 1~4，

Summaries of Technical Papers of Annual Meeting, SHASE 2. Ueda et al. (2004), Effect of External Blinds and Exothermic Double Glazing in an Office Building，

Summaries of Technical Papers of Annual Meeting, Architectural institute of Japan

72.6

38.1

31.6

125.9

26.9

187.6 771.9 100%431.5

87.1

10.356.0

266.2 419.6 54.4%352.3

29.2

261.2 82.3

34.1

406.8

100%

52.5%

Annual SimulationsAnnual SimulationsAnnual SimulationsAnnual SimulationsPower Consumption of

Lighting [MWh/a]Heating

load[GJ/a]

Cooling load[GJ/a]

(summer) (intermediate) (winter)

External blind andmulti-pane heating glass

Daylighting control

Internal venetian blinds+FL8mm

Annual actual surveyAnnual actual surveyAnnual actual surveyAnnual actual survey

Figure 18 Simulation results and Actual survey (2004.04~2005.03)

West perimeter zone of 5th floor (Area 110m2)