Pilot study report : The Liberty Tower of Meiji University · 1.1.5 Principal objectives To...

IEA ECBCS Annex 35 : HybVent

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Pilot study report :

The Liberty Tower of Meiji University Tokyo, Japan

1 GENERAL INFORMATION 1.1.1 Report date

February 2002

1.1.2 Principal researchers Shinsuke Kato 4-6-1 Komaba, Meguro, Tokyo 153-8505, Japan Tel: +81-3-5452-6431 Fax: +81-3-5452-6432 e-Mail: [email protected] Tomoyuki Chikamoto 2-1-3 Koraku, Bunkyo, Tokyo 112-8565, Japan Tel: +81-3-3813-3361 Fax: +81-3817-7072 e-Mail: [email protected]

Pilot study report : The Liberty Tower of Meiji University

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1.1.3 Other participants 1.1.4 Project title

A study on features of the hybrid ventilation of the Liberty Tower of Meiji University.

1.1.5 Principal objectives To validate the design features of the building in respect to the Hybrid ventilation principles of the following: - Energy saving and improvement of IAQ from utilization of hybrid air-conditioning during day-time - Energy saving and improvement of IAQ by night purge. - Increase of ventilation rate by wind floor. - Reinforcement to existing 2000 automatic measurement points data used in the BEMS.

1.1.6 Start date / End date 1999-2000

1.1.7 Number of man-hours Man-hours for evaluations and reporting is approx. 1000.

1.1.8 Project approach Nothing in particular.

1.1.9 Building selection Nothing in particular.

1.1.10 References Nothing in particular.

1.1.11 Comments During design phase, Liberty Tower of Meiji University, a high-rise building located at the center of Tokyo Metropolitan area, several testing methods were applied to ensure the effectiveness of the various components used in the principle of hybrid ventilation system design. Its special design feature is the “wind-floor”, whereby the central core is planned to induce natural ventilation for every floor by creating stack-effect. Other measures are also taken to improve the quality of indoor environment including the use of natural ventilation windows controlled automatically, automatic outdoor air intake, and a proper building environment and energy management system that takes advantage of the optimum outdoor air quality and temperature to cut energy consumption costs of the building.

2 TEST SITE DESCRIPTION 2.1 Geographic information

2.1.1 Location Chiyoda, Tokyo, Japan located at Latitude; Latitude; 35° 42’N. Longitude; 139°46’E.

2.1.2 Elevation (height above sea level) 12 m.

2.1.3 Terrain; Site plan Flat, surrounded by buildings much lower (refer aerial view).

2.1.4 Orientation The building is oriented with its main-axis at North-South direction and its main facade facing east.

2.1.5 Comments Nothing in particular.


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2.2 Climate information (Summary) The climate data of the Tokyo Meteorological Agency (Otemachi) is available, which covers the air temperature, humidity, insolation, precipitation and the wind speed and direction. The weather data shown in this report was standardized from 1980 to 1995. These data are also measured at the Liberty Tower.

2.2.1 Location of meteorological station The Tokyo Meteorological Agency is sited at 35°41’N 139°46’E, and the height of anemometer is 74.5 m. However, with these data, the result of wind speed is calculated, and 6.5m height wind speed is shown in this report.

2.2.2 % frequency wind speed versus wind direction The frequency versus wind direction, which was measured on the site, is shown below. The mean wind speed on the site was 1.9 m/s.

WIND DISTRIBUTION CHART FREQUENCY VERSUS WIND DIRECTION

0

100

200

300

400

500

Ｎ

Ｓ

EW

(O ut door tem p. : over 20 OC )

0

500

1000

1500

2000

2500

3000

3500

4000

4500

5000

0 1 2 3 4 5 6 7 8 9 10W ind velocity (m /s)

Frequency （hour）


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2.2.3 Air temperature

The following shows monthly average, maximum and minimum air temperature. The average air temperature is 16.1 oC. Design conditions for summer and winter are 33.4 °C and -0.2 °C respectively.

OUTDOOR TEMPERATURE ON THIS SITE

FREQUENCY OF OUTDOOR TEMPERATURE ON THIS SITE

CLIMOGRAPH

2.2.4 Degree day information 1600 heating degree days (18°C baseline) and 230 cooling degree days (24 °C baseline) in Tokyo.

0

5

10

15

20

25

30

35

1 2 3 4 5 6 7 8 9 10 11 12month

outd

oor t

emp

(℃)

minmaxave

O ct

Nov

Dec

JanFeb

JunSep

JulAug

M ar

Apr

M ay

-10

0

10

20

30

40 50 60 70 80 90

H um idity （％）

Temperature （℃）

0

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450

-20

-18

-16

-14

-12

-10

-8

-6

-4

-2 0 2 4 6 8

10

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16

18

20

22

24

26

28

30

32

34

36

38

40

Tem perature （℃）

Frequ

ency （hour/month）

DecNovOctSepAugJulJunMayAprMarFebJan


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MONTHLY HEATING DEGREE DAYS

MONTHLY COOLING DEGREE DAYS

2.2.5 Daylight / insolation The total hours of sunlight was 1,983 hours, and the total insolation was 4,486 MJ/m 2 (total diffuse solar radiation is 1,953 MJ/m 2 and total direct solar radiation is 2,533 MJ/m 2)

MONTHLY HORIZONTAL SOLAR RADIATION 0

100

200

300

400

500

600

Jan Feb M ar Apr M ay Jun Jul Aug Sep O ct Nov Dec

（ＭＪ／㎡）

D iffuse solar radiation

Direct solar radiation

0

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600

700


Ｄ24-24

0

5

10

15

20

25

30

35

（day）

C ooling degree days days

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600

700


Ｄ18-18

0

5

10

15

20

25

30

35

（day

）

Heating degree days days


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TOTAL HOURS OF SUNLIGHT

2.2.6 Cloud factor Cloud factor in every hour is measured. It is rainy season from June to July, and mostly clears in winter. In mid season (from April to May and from September to October), there are a lot of days when it cleared up.

2.2.7 Relative humidity & precipitation Relative humidity is around 70%RH in summer and around 50%RH in winter. The design %RH is 54% RH in summer and 36%RH in winter. The total precipitation is 915 mm.

PRECIPITATION

2.2.8 Barometric pressure Unknown.

2.2.9 Soil temperature Unknown.

2.2.10 Other meteorological parameters None.


0

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100

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300

350

400


Precipitation （mm/month）

0

50

100

150

200

250


（hour）


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3 BUILDING DESCRIPTION 3.1 General description

3.1.1 Building name The Liberty Tower of Meiji University.

3.1.2 Building type Educational Institution (Lecture rooms, offices, restaurant and library).

3.1.3 History A new construction.

3.1.4 Design philosophy for IAQ and thermal comfort, energy efficiency and other issues of concern Liberty Tower of Meiji University is 23 stories high-rise building located at the center of Tokyo metropolitan area. Its special design feature is the “wind-floor”, with its central core planned to induce natural ventilation for floors below using the principle of the stack-effect. (Refer diagram) Automatically controlled natural ventilation windows using state of the art building environment and energy management system, allows outdoor air intake at optimum conditions and in term cut down energy consumption of the building. The building shape was designed to take optimum advantage of the solar geometry and building codes and regulations. The insulation values(U-values in W/m2K) of the various components of the building are: external wall(1.65); glazing(4.81); roof(0.75); basement floor and ground(0.46). The following methods were adopted in the design process: - Thermal dynamic simulations on natural ventilation by STREAM - Hour by hour air conditioning system simulation by HASP/ACLD/ACSS - Hour by hour thermal comfort simulation by PMV-3d



3.2 Building geometry & materials 3.2.1 Plan

The building is oriented with its main-axis at North-South direction and its main facade facing east. Its special design feature is the “wind-floor”, with its central core planned to induce natural ventilation for floors below using the principle of the stack-effect.

8

FL TYPICAL LECTURE FLOOR

Memorial library

L

New library Library entrance

Lecture rooms

Refresh space

N

iberty hall (300

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OOR PLAN (1st FLOOR)

WIND FLOO (18th FLOOR

0 10 20 3

Entrance hall

L (

Plaza

Mechanical Room

M/R

ecture room300 person)
Lecture room(300 person)
R )

0

Rounge

M/R

Wind fence

40 (m)


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3.2.2 Elevation See fromt page.

3.2.3 Building form 118.95 m (RF Level), 110.87 m (PHF Level). 23 floors and 3 basement floors.

3.2.4 Volume 256,697 m3.


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3.2.5 Floor area & materials GFA 59,011 (office: 2,324 m2, lecture room: 14,165 m2, gymnasium: 1,690 m2, restaurant: 841 m2, rounge, hall: 2,553 m2, library: 7,111 m2, car parking: 5,934 m2, others: 24,393 m2) NFA Approx. 40,000 m2

Insulation values (U-values in W/m2K) - exterior wall (1.65) - Glazing (4.81) - Roof (0.75) - Basement floor and ground (0.46) Insulation layers of the top slab and crawlspace are 50 mm in thickness, and U-values are 0.55 W/m2K.

3.2.6 Ceiling height Floor height is kept at 4.35m; Ceiling height in room is kept at 3.0m and a raised floor of 0.1m is being adopted.

3.2.7 Facades (external walls) The external wall consists of tile curtain wall with 30 mm thickness insulation. The U-value is estimated 1.2 W/m2K.

3.2.8 Windows The total area of windows is approx. 4,000 m2. External shading: None. Shading control: Internal blinds are controlled by intensity of direct solar radiation on vertical plane. The U-value is estimated 3.6 W/m2K.

3.2.9 External doors or hatches North 0 m2

, south 4 m2, west 8 m2, east 50 m2.

3.2.10 Number, volume and layout of rooms 3.2.11 Attic, basement, crawlspace 3.2.12 Interior walls, including moveable partitions 3.2.13 Interior doors and devices 3.2.14 Stairwells

Number of stairwells: 6 Size of stairwells: each 15 m2

3.2.15 Service risers Number of elevator shafts: 11 Size of elevator shafts: each 9 m2 Rubbish chutes: None


3.3 Air leakage data (type, location and crack length for each component) The air leakage test is scarcely applicable because of the building size.


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3.3.1 Doors 3.3.2 Windows 3.3.3 Ventilation openings & stacks 3.3.4 Chimneys & flues 3.3.5 Communicating walls, such as cavity walls 3.3.6 Structural joints: sole-plate, ceilings, corners, skirting boards, vapour and air barrier

treatments 3.3.7 Service routes: plumbing outlets, drains, electrical outlets, etc. 3.3.8 Other air leakage zones such as stairwells & service risers 3.3.9 Background leakage 3.3.10 Neutral pressure level 3.3.11 Comments

3.4 Wind pressure coefficients 3.5 Space heating

Heating and cooling are provided. The single duct VAV system is applied and 2 air handling units on every floor are installed. The system, which combines wind induced natural ventilation with the usual mechanical air-conditioning system

HYBRID NATURAL VENTILATION AND A/C SYSTEM The main heating/cooling plant is 2 electric heating-tower-turbo chillers for heating/cooling (each capacity is 1400 kW, HCFC-123) and screw chiller for cooling (211 kW, HCFC-134a). Heat storage tanks (capacity of heating/cooling switching at season tank is 3600 m3 and all year cooling tank is 500 m3) are set for energy saving and peak cut of electricity. The supply/return temperature is 46/38 °C for heating and 6/14 °C for cooling. The natural ventilation mode is not active for heating duration.

3.6 Ventilation 3.6.1 Ventilation principle

Ventilation principle is natural ventilation in combination with stuck driven forces and cross ventilation. The plan utilizes center core formed by escalator space between 1st and 17th floor, a major means of mass transit of students, as a course of airflow for natural ventilation, called “wind core”. The wind core (escalator void) also causes the stack effect, which promotes the natural ventilation. Above the wind core, on 18th level, the “wind floor” is planned to induce the natural ventilation for every floor. Near the opening on 18th floor, wind fence is set to prevent the outdoor air passing through the wind floor from disturbing smooth exhaust through the opening on the top of the center core. It maintains steady condition in the natural ventilation system, regardless of wind direction.

VAV

Air Handling Unit(Middle season:all fresh air conditioner)

Lecture Room

NaturalVentilation Conditioned Air

To each Class RoomReturned Air

EscalatorHall

Fresh Air

Exhausted AirFrom each Class Room

To Wind Floor (18th level)

Motor Damper


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On 18th floor, there are openings to exhaust the air, which passes through 4 wind paths designed toward 4 different directions, and is led to outside the building. The airflow of the wind floor on 18th level was simulated by CFD, and found that the outdoor air flows on the wind floor at a speed without declining. Therefor the wind floor creates driving force for ventilation that stimulates air intake via perimeter counter units and exhaust through the opening at the top of wind core. As the wind floor open to 4 directions, the driving force is expected to be stable through the year with regardless of wind direction. It adapts natural ventilation with air-conditioning system, then occupant zone air climate are kept comfortably by passive natural ventilation power and active minimum air-conditioning power.

3.6.2 Components

NATURAL VENTILATION SYSTEM WIND FLOOR ON 18TH LEVEL TYPICAL FLOOR PLAN WIND FLOOR PLAN

Lecture Rooms

Escalator

Refresh SpaceWC WC

M/RM/R

Wind is exhausted at the top of EscalatorWind is exhausted at the top of Escalator(Wind floor on 18th level)(Wind floor on 18th level)

エスカレーター縦穴を上昇してきた気流は風穴階（１８Ｆ）開口より屋外へ排気

Wind fence

Exhaust opening on the top of escalator void

Wind pass through

on this floor

Wind fence

Exhausted air from

Escalator hole


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WIND FLOOR INCREASES VENTILATION RATE BY 30%

3.6.2.1 Fresh air inlets DETAIL OF THE WINDOW Each room of occupancy has ventilation opto introduce outdoor cool air. The intake awhich conditioned air also passes through tcoming into the rooms via the ventilation olectures using audiovisual sets such as OHPare installed inside window counter units pautomatically controlled. Switching of the openings depends on sevehumidity between interior (occupancy roomnatural ventilation is operated only when itsystem can be used to remove heat and pollof several openings is possible and is remo

11.4 12.213.5

5.5 4.0

4.6

0

5

10

15

20

N N E N N W S

Ventilation rate(times/

h)

w ith w ind floorw ithout w indow floor

Air flow on the wind floor

Results by Simulation

Top of theEscalator

sunshade by pent roof

perimeter counter

Window (single glass)

ventilation opening

AUTOMATICALLY CONTROLLED VENTILATION WINDOW

enings under the glazed windows along perimeter zone ir is led to the wind core through a return path duct in o return. Details of the windows allow natural airflow penings even when blind screens are shut down during . These openings, with traps to obstruct outer noise,

reventing accidents and mischief when the operation is

ral factors, such as comparison of temperature and s) and exterior, rain condition and wind velocity, then

is found to be effective considering these factors. The utants from the rooms during nights, while switching tely controlled by the central monitoring room.

This photo shows the case of maintenancepanel opened.

Automatically controlledVentilation opening


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3.6.2.2 Fans Natural ventilation without ny fan assistance, is induced by wind core and wind floor.

3.6.2.3 Heat recovery Natural ventilation system used for daytime and night time cooling, therefore it does not need any heat recovery system.

3.6.2.4 Filtration No filtration.

3.6.2.5 Ducts No duct.

3.6.2.6 Room supply & extract devices

Concerning air supply inlets, see AUTOMATICALLY CONTROLLED VENTILATION WINDOW at chapter 3.6.2.1.Outlets for natural ventilation are set at the slit of the ceiling light, which are also used for exhaust openings of air-conditioning system.

3.6.2.7 Air exhaust outlets See WIND FLOOR ON 18TH LEVEL at chapter 3.6.2.

3.6.3 Frequency of operation, duration of operating cycle Hybrid ventilation is active during air-conditioning period, 8 am to 10 pm. In night time, night time cooling mode in operative automatically.

3.6.4 Balancing report 3.6.5 Ventilation rate (outdoor airflow supplied by system)

Ventilation rate of outdoor airflow supplied by natural ventilation is around 5-10 times per hour. Outdoor airflow rate comes from air-conditioning system is controlled by measuring indoor CO2 density (minimum 0 times per hour, and maximum 5 times per hour).

3.6.6 Any recirculation between rooms due to HVAC system 3.6.7 Space cooling

See chapter 3.5.


3.7 Internal loads 3.7.1 Pattern of occupancy

Hours of occupancy : 14 hours (8:00 to 22:00) Number of occupants and m2 /person : approx. 8000 occupants and 2.0 m2 /person in lecture room, however actual number of occupants changes according to the lecture, season, time etc.

Exhaust opening

Supply opening for air conditioning

Supply opening for natural ventilationsystem


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3.7.2 Lighting Lighting gain is approx.25 W/ m 2 . Lighting is controlled by illuminance sensors which is for usage of natural lighting.

3.7.3 Other internal gains Personal computers and plazma display monitors, both are not always used.

3.8 Control system and control strategy for ventilation and space conditioning 3.8.1 Type of system

The control system is BEMS (Building Energy Management System).

3.8.2 Parameters monitored Dry-bulb temperature, relative humidity, both are indoor and outdoor, precipitation, wind speed, and wind direction.

3.8.3 Sensors Dry-bulb temperature sensors, set at indoor wall, and humidity sensors, set in return duct of every air handling unit, contorol VAV unit and two-way valve of water supplied for air handling unit. External dry-bulb temperature sensors, relative humidity sensor, anemometer, precipitation meter and pyrheliometer placed on/above the roof for monitoring the outdoor conditions by BEMS, and control the all automatically controlled inlets and outlets for natural ventilation with motors. Manually operated inlets are also installed, which can be opened by the occupants during the over time period on holidays and on crisis.

3.8.4 Control strategy & internal design conditions Night cooling by ventilation is activated if the external temperature is under 28 ºC and over 10 ºC during none occupied hours. During night cooling each inlet and outlet are opened automatically with monitoring the outside temperature and room temperature. The inlets and outlets are opened if the external temperature is under 22 ºC and over 18 ºC. During day time cooling each inlet and outlet are also opened automatically with monitoring the outside temperature and room temperature. If rain is falling and/or the wind speed is higher than 10 m/s, all ventilation windows are closed. Winter: - Wholly heating by HVAC system - Constant supply temperature Summer: - Centrally controlled night cooling - On moderate day, ventilation for daytime cooling with mechanical air-conditioning system - Fully automatic - Inlets and outlets closed at high temperature, high wind speed or rainfall - Natural ventilation mode turns on when enthalpy of outdoor air is less than indoor - At daytime cooling, the excessive air-conditioning load, which could not be removed by natural ventilation, is removed with the air-conditioning system. Middle season: - Centrally controlled daytime cooling with mechanical air-conditioning system and night cooling - Fully automatic - Inlets and outlets closed at high temperature, high wind speed or rainfall - Natural ventilation mode turns on when enthalpy of outdoor air is less than indoor


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-At daytime cooling, the excessive air-conditioning load, which could not be removed by natural ventilation, is removed with the air-conditioning system.

SENSORS

3.9 Pollutant sources 3.9.1 Interior sources

None.

3.9.2 Exterior sources Some external pollution comes from road in the lower part of the building.

3.10 Furniture, interior fittings 3.11 Costs

3.11.1 Building Around 17 EURO €/m2 for additional automatically controlled windows.

3.11.2 Plant 3.11.3 Control system

Around 3 EURO €/m2 for additional automatically operation system in BEMS.

3.12 Monitoring programme 3.12.1 Measurement objectives The measurement performed for the indoor environment and energy saving effect is mentioned hereinafter. The full scale field measurements were carried out in order to evaluate the effect of the natural ventilation / Hybrid Ventilation. The chief measurement objectives are as follows. (1) Short term measurement The short term detailed measurements were undertaken October 9 to 11 of 1999, which is the middle season in Japan. Objectives of the measurement are as follows: 1) Inspection of air exchange rates of the natural ventilation. 2) Inspection of the indoor thermal comfort. (2) Long term measurement The long term measurement through the year under the normal operation is beeing carried on since December 1998. It is automatically recorded (every 10 minutes) by over 2000 points sensors of building energy management system. In this measurement, energy consumption of each building equipment (heat pump, air handling unit, pump, lighting and consent etc.), temperature, humidity and velocity of each room and air handling unit (see figure 10) and outdoor conditions. Objectives of the measurement are as follows:

Anemometer,State of natural ventilation window (open or close),Integrated time while windows are open

T H

T

T

HOutdoor

Solar radiationRainfall

Wind speed at exhaust opening

Thermometer

T

H Hygrometer

V

Anemometer

Wind speed & direction

V

V

VV

V

COdensity

2

T

These data (total 2000 points) are recorded automatically every 10 minutes


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1) Inspection of the realities of the hybrid air-conditioning system 2) Inspection of energy saving effect both at each time and all year round

3.12.2 Parameters to be measured, Measured plan Parameters to be measured are shown in the following tables. (1) Short term measurement

ITEM EQUIPMENT USED Vertical temperature distribution (indoor) Cu-Co thermo-couple placed at different heights and

locations in the room recorded using thermal-duct E200 machine, which is multi points data logger. Globe temperature was measured inside a 100mm diameter copper sphere.

Globe temperature (indoor) Globe temperature was measured inside a 100mm diameter copper sphere.

Indoor velocity distribution 3D ultra-sonic wind anemometer, thermister velocimeter

PMV, Predicted Mean Vote (indoor) PMV meter. Velocity on 18th floor 3D ultra-sonic wind anemometer, thermister

velocimeter Air change rate Multi gas monitor Convective heat transfer rate Thermal mannequin Indoor Air quality Sample is being collected and analysed using

GC/MS method. Questioner survey

(2) Long term measurement

ITEM EQUIPMENT USED Outdoor temperature Thermostats are set in the room. Measured data are

informed by BEMS. Outdoor humidity Hygrometers are set in the duct. Measured data are

informed by BEMS. Velocity at ventilated inlets (room) Wind velocity sensors around ventilation openings

near the openings under the window in each room set at 14 points per floor, which is used for estimating airflow rate all year round. Measured data are informed by BEMS.

Velocity at ventilated outlets (on 18th floor) Wind velocity sensors around exhaust openings of each 4 direction, which is also used for estimating airflow rate all year round. Measured data are informed by BEMS.

Energy consumption by Air handling units, heat sources, pumps etc.

Measured data are informed by BEMS.

Operating time of Air handling units, heat sources, pumps etc.


Air change rate by air handling unit Anemometers are set in the duct. Measured data are informed by BEMS.

Cooling load by air handling units, heat sources



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3.12.3 Parameters analysis See chapter 3.12.2.

MEASURED ROOMS

MEASURED POINTS

18階風穴

最高高さ119.5m

Room 1121 (12F)

Room 1111 (11F)

Room 1071 (7F)

Room 1061 (6F)

Room 1118

4th Meeting Room(6F)


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THERMAL MANNEQUIN

3.13 Results from monitoring programme 3.13.1 Distributions of air flow rates through air inlets 3.13.2 Decline of indoor air flow rates 3.13.3 Air exchange rates The air change rate, irrespective of the wind direction, effect of opening/closing of the wind floor at 18th level, the north facing Room 1061, at the 6th floor, the air change rate was observed to be 0.5-0.7 times/hour with the wind-floor closed, this increased tremendously 6-10 folds to 4.6-5.5 times/hour when the wind floor was opened. South facing 4th Conference room of the same floor read 1.1times/hour and 3.7times/hour respectively, apparent 3 times greater when the wind floor is opened. The north facing Room1111 on the 11th floor, nevertheless read a contradictory of 3.2times/hour when the wind floor is closed to 2.1-2.4times/hour when the wind floor is opened, however, the difference is quite insignificant. With respect to the location of the room (North-South) in the building, the air-change rate for Room1061 of 6th floor on the northern side, with the wind floor opened, read 4.6-5.5 times/hour compared to 3.7times/hour for the 4th Conference Room on the opposite side. The North facing room enjoyed better air-change. When the wind floor was closed, the South facing 4th Conference Room however has an air-change rate of 1.1times/hour compared to 0.5-0.7 times/hour on its counter part, difference was small but the Southern side this time enjoyed better air change. On the 11th floor, when the wind floor was opened, the north facing Room1111 read 2.1-2.4times/hour for the air-change rate compared to 3.0times/hour for Room 1118 on the southern side. The air-change rate with respect to the height inside the building with the wind floor opened, the north facing Room1061 on the 6th floor read 4.6-5.5 times/hour compared to 2.1-2.4 times/hour for Room1111 on the 11th floor. The floors at the lower level enjoyed more air-change. This in term reversed when the wind floor was closed with reading of 0.5-0.7 for Room1061 compared to 3.2 times/hour for Room1111, the upper floor enjoyed greater air-change rate. For the South facing rooms, when the wind floor was opened, the 4th Conference Room on the 6th floor read 3.7 times/hour for the air-change rate, Room1118 on the 11th floor at 3.0 times/hour, the lower floor enjoyed greater air-change rate.


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Air exchange rate is also evaluated by BMS data (long-term measurement).

VENTILATED WINDOW OPENING TIME PER YEAR On all floors, ventilated windows are open for a long time, and hybrid ventilation system functions effectively in this building. (In Japan, normal open time of window in normal building, which adapts natural ventilation system, is about 500~600 hour per year.)

OUTSIDE TEMPERATURE ON REPRESENTATIVE DAY IN MIDDLE SEASON

AIR FLOW RATE ON REPRESENTATIVE DAY IN MIDDLE SEASON Airflow rate is about 3~5 times per hour in this building.

0

200

400

600

800

1,000

1,200

1,400

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1,800

B3F

B1F

2F

4F

6F

8F

10F

12F

14F

16F

18F

20F

22F

23F

時間

/年

2000/3

2000/2

2000/1

1999/12

1999/11

1999/10

1999/9

1999/8

1999/7

1999/6

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1999/4

Hour/year

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2:00

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22:00

1999/5/17 1999/5/18 　 1999/5/19

（℃

自然換気有効ﾅｲﾄﾊﾟーｼﾞ

有効

空調時間帯

Night parge is effective

Day-time natural ventilation is effective

Time of air conditioning system functions

0

1

2

3

4

5

6

0:00

5:00

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21:00

2:00

7:00

12:00

17:00

22:00

1999/5/17 1999/5/18 1999/5/19

（回

／時

間）

換気回数３～５回/時

運用上の禁止条件等による

降雨

Air flow rate is 3~5 times per hour

RainingNatural ventilation is prohibited in operation


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3.13.4 Indoor air temperature under natural ventilation Room 1061 under normal condition, apparent temperature rises from 6:00 am onwards and drops from 4:00 in the afternoon. As much as 3 oC vertical room temperature difference was observed near the perimeter zone at around 6:00 in the morning. The temperature at 5cm above ground read at 17 oC under the influence of the in-flowing outdoor air, slightly lower than the floor temperature itself. Temperature in the middle of the room varied within the range of 1 oC. The cool outdoor air was allowed in at night to cool down the room temperature and in term achieved the ”Night-Purge” effect. With the Natural Ventilation windows shut, temperature in the room at different height changed very little, temperature range is relatively small.

VERTICAL INDOOR AIR DISTRIBUTION WITHOUT NATURAL VENTILATION (room 1071)

VERTICAL INDOOR AIR DISTRIBUTION WITH NATURAL VENTILATION (room 1061)

22 23 24 25 26 20 21 22 23 24 22 23 24 25 26 20 21 22 23 24

3

2.5

2

1.5

1

0.5

0

Temp[OC]

Height[m] Perimeter Interior zone

1)10/10-18 3)10/11-6 4)10/11-15 2)10/11-0

Temp[OC] 22 23 24 25 26 19 20 21 22 23 21 22 23 24 25 2617 18 19 20 21

3

2.5

2

1.5

1

0.5

0

Height[m] Perimeter Interior zone

1)10/10-18 3)10/11-6 4)10/11-15 2)10/11-0


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VERTICAL INDOOR AIR DISTRIBUTION WITHOUT NATURAL VENTILATION (room 1071)

VERTICAL INDOOR AIR DISTRIBUTION WITH NATURAL VENTILATION (room 1061)

3.13.5 Marginal conditions for the natural ventilation During the short-term experiment, it was a little hot weather condition, and the stuck effect seems too be underestimated. The air velocity near the Natural Ventilation windows at the floor read at 0.48m/s and dropped to 0.17m/s near the leg of the chair at 1.5m away from the windows. When the wind floor was opened, PMV (MET=1.2,CLO=0.7) was in the range of +0.5~-0.5, showing that comfort level was achieved. The Thermal Mannequin model showed that heat transfer rate was greatest at the foot at 11.32, followed by the right hand at 7.36 and 0.66 at around the head zone. The result from the VOC reading shown 79.5*10-6(g/m3) in the outdoor air, and this was shown to affect the air quality inside the room when natural ventilation was used. The stair core was shown to have greatest concentration at 325.2*10-6 (g/m3). When the outside wind is weak, it was found to be unpractical in the assessment of the wind volume of the openings at the wind floor level. The measurement done on the 17th October, showed when the wind was blowing from the North, the wind was entering the building from the north and the west and flowed out on the Eastern and southern sides of the building. The in-flowing air volume measured 62000 m3/h, out-flowing at 73000 m3/h, a difference of 11000 m3/h, which can be attributed to the air raised through the escalator core.

18

21

24

27

9:30 15:30 21:30 3:30 9:30

床面 5cm10cm 50cm150cm 天井面

Floor

Ceilin

Heigh

Temperatur

Time

1 5

1 8

2 1

2 4

2 7

9 :3 0 1 5 :3 0 2 1 :3 0 3 :3 0 9 :3 0

時刻

温度

[℃]

自然換気給気床面

5c m 1 0 c m

5 0 c m 1 5 0 c m

天井面

Time

Temperatur

Heigh

Ceiling

Floor Inlet of NV


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3.13.6 Energy Conservation caused by Hybrid Ventilation The following data shows the airflow rate by natural ventilation and supplied air by air-conditioning system in room. The cooling load changes time by time according to the lectures, the number of attendance etc. In addition, cooling ability by natural ventilation changes time by time. The air conditioning system supplements lack of cooling ability to maintain indoor environment and comfort.

AMOUNT OF SUPPLIED AIR BY AHU/NV ON REPRESENTATIVE DAY IN MIDDLE SEASON AMOUNT OF COOLING LOAD REDUCED BY AHU/NV ON REPRESENTATIVE DAY IN MIDDLE

SEASON

3.13.7 Annual energy consumption The following drawing shows result of annual energy for removing cooling load of this building from April 1999 to November 1999, such as fans in air handling units, heat sources, pumps for carrying cold water from heat source from AHU. Total annual energy for cooling load was 415 MJ/m2, which is 17% reduction by natural ventilation using hybrid ventilation system.

0

2000

4000

6000

8000

10000

0:00

2:00

4:00

6:00

8:00

10:00

12:00

14:00

16:00

18:00

20:00

22:00

1999/5/18

（m3/h、空

調機１台

あたり風

量）

室内負荷除去のため、補完的に空調によって導入する外気量

自然換気による外気導入量→空調機ﾌｧﾝ動力の削減

補完的に空調を導入し、空調負荷削減と自然換気利用率の向上

空調風量

空調負荷削減

Natural ventilation was effective all day long and removed the cooling load, though cooling load was changable. Air conditioning system supplemented the lack of cooling ability. Fan power of air handling unit was reduced by natural ventilation.

Air flow rate (m3/h)

Amount of supplied air by air handling unit Air flow rate by atural ventilation

0

10

20

30

40

50

60

0:00

2:00

4:00

6:00

8:00

10:00

12:00

14:00

16:00

18:00

20:00

22:00

1999/5/18

（W/㎡)

空調による除去熱量算定

換気による除去熱量算定

補完的に空調し、空調負荷削減

換気により空調負荷の１／２を削減

Removed cooling load by AHU Removed cooling load by NV

50% of the cooling load was removed by natural ventilation. If this building did not adapt hybrid ventilation, most of the cooling load could not be removed by natural ventilation, therefore, energy consumption by air-conditioning system would increase.


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ENERGY CONSUMPTION FOR REMOVING COOLING LOAD

3.14 Lessons Learned The most significant problem of the system was that inlet located under the glazed windows along perimeter zone. It leads the uncomfort for the occupant sitting near the window, because occupants’ feet become cold. In addition, the air induced by natural ventilation came to occupant zone directly, then it was mixed with the air supplied from ceiling inlet by air conditioning system. With this condition, the air by natural ventilation, which is a little high and humid, will revolt the occupant.

HYBRID VENTILATION SYSTEM AT LIBERTY TOWER OF MEIJI To remove this problem, a new type of hybrid ventilation system was proposed at IDE (Institute of Developing Economies, JETRO) by us (contact person: Dr. Tomoyuki Chikamoto, [email protected]).

HYBRID VENTILATION SYSTEM AT IDE

0

10

20

30

40

50

60

70

80

90

4 5 6 7 8 9 10 11 月

冷房

用ｴﾈﾙｷﾞー

消費

量(M

J/月

㎡)

自然換気による削減量

空調機動力

空調熱源

17％減

17% of annual cooling energy was reduced by natural ventilation using hybrid ventilation system

Reduced by NV

Heat source AHU energy

month

Energy consumption for removing cooling load (MJ/month/m2)

タスク域から熱上昇

清涼な新鮮空気

アンビエント域

タスク域

SA (給気)

レタンパスを通して廊下へ排気→エスカレーター吹き抜けを通し風穴階へ

温熱的にも空気質的にも快適

タスク域からの汚染質

RA (還気)VAV

Ambient Zone

Task Zone

Mixing with air by AHUand NV Air conditioned air

Natural ventilation air

Heat fromTask Zone

Supply fan unitfor Ambient Zone

Fresh air

Ambient Zone

Task Zone

CH C

EA (Exhaust Air)

OA (Outside Air)

Personal supply outlet for Task Zone(D air to human body)irect supply of fresh

Effective exhaustion ofheat and pollutant

CH COA

Personal AC system for Task Zone

Higher temp.upply jets

Under-floor AC systemfor Ambient Zone

20℃

22℃22℃

28℃26℃

High IAQ andthermal comfort

Pollutant fromTask Zone

26℃

30℃


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With this system, excess cooling load and pollutant from task zone are exhausted by natural ventilation effectively. And task zone is amended for the comfort by conditioned air supplied from the floor and personal inlet unit. Another major problem at this building is pressure loss between the room and corridor (that is wind core). The air from room to wind core is led through return path ducts in which conditioned air also passes through to return. In these pass duct, smoke and fire dumpers, which prevent smoke and fire extension, are set. The limitation of the size of pass duct and these smoke and fire dumpers lead to large loss of pressure and lead to decrease of air flow rate.

3.15 Conclusions With this hybrid ventilation system at the beginning, the Liberty Tower of Meiji University has adopted a lot of energy saving methods. With these nethods, primary energy consumption of whole building became 1587 MJ/year/m2, which is 40 % decrease from standard building. These results were evaluated and we got the Prize of IBEC (Institute for Building environment and Energy Conservation)and the Prize of SHASE (The Society of Heating, Air-conditioning and Sanitary Engineers of Japan), both are most typical prize for energy saving design and building in Japan.

0

500

1000

1500

2000

2500

3000

Standard M easures ResultsPrimary energy consumption ［MＪ/year㎡]

Others

Kitchen

EV

Outlet

Ligh

AHU

Pumps

Heat source (others)

Heat Source(thermal strage)

15871647

2696

40%

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