Energy Conservation
for Office Buildings
Major points, measures, and successful cases of energy conservation for office buildings

The Energy Conservation Center, Japan

Introduction

The first commitment period of Kyoto Protocol started in FY2008,
which requires us to achieve a target of reducing greenhouse gas
emissions to 6% below the base year (FY1990) levels by FY2012.
Approximately 87% of the greenhouse gas is comprised of carbon
dioxide (CO2) from energy consumption. The CO2 emissions havebeen significantly growing especially in commercial businesssectors and enhancement of drastic measures has become anurgent need.
This brochure is intended for owners of office buildings andpersons in charge of energy conservation promotion or energy
facility management, explaining the points, measures and the caseexamples of energy conservation based on our investigation data.
We hope that you will find the information taking account ofcharacteristics in energy consumption particularly seen in officebuilding operations helpful for your activities toward better energy
conservation practices.

Contents

1．Characteristics of Energy Consumption in Office Buildings ............................2
1.1 Energy Consumption in Office Buildings by Departments ......................................2
1.2 Energy Consumption in Office Buildings by Usage ...............................................3
1.3 Energy Intensity of Office Buildings by Type .........................................................4
1.4 Energy Intensity of Office Buildings by Scale ........................................................5
1.5 Correlation of Energy Consumption in Office Buildings .........................................5

2．Major Points for Energy Conservation in Office Buildings ..........................8
3．Check Points for Energy Conservation Measures in Office Buildings .........10
4．Successful Cases of Energy Conservation Measures in Office Buildings .....12
5．Effective Tools and Techniques for Promoting Energy Conservation by Improved Operation ...18

1.Characteristics of Energy Consumption in Office Buildings
１．
１ Energy Consumption in Office Buildings by Departments
Types of office buildings become diversified as the scale gets larger; with larger area ratio of spaces
other than general office use, including shops, etc. Taking an office building with a total floor spaceapproximately 35 thousand square meters as an example, the graphs below show the area ratio and theenergy consumption ratio, each by departments.
“Rentable ratio” (Area of general offices/Total floor space) is often used as an index to describe the typeof an office building. In this example, the rentable ratio is 52.6% of the “office-dedicated space”. Also,
note that “office-common space” indicates elevator halls, restrooms, etc. in office floors.
Area ratio by department
Parking area
15.5%

Restaurants-common
0.8%
Restaurants
0.8%
Shops
0.7%

Common area
10.1%

Office-Dedicated52.6%

Office-common
19.4%

The values in the below graph indicate the ratio of the primary energy of fuel, heat, and electricity,
consumed by air conditioning load, lightings, outlets, ventilation, and etc. The smaller graph indicatesthe consumption ratio of the office-dedicated department. The energy of the common space means theprimary energy consumed at the facilities for the power receiving and transforming equipment,
heat-distribution equipment, warehouses, and machine rooms. In addition, the energy of the officecommon space means the primary energy consumed at restrooms, elevators, meeting rooms, lounges,
reception rooms, etc.
Energy consumption ratio by department
Parking area
6.8%
Common area
23.2%
Restaurants-common
0.3%
Restaurants
2.7%
Shops
0.4%

Office-Dedicated60.2%

Office-common
6.4%

Air conditioning
28%

Outlet32%

Lighting
40%

1. Characteristics of Energy Consumption in Office Buildings2１．
2 Energy Consumption in Office Buildings by Usage
With energy management in buildings, it is essential to understand the status of energy consumption;
where and how much energy is being used. The below table describes the classifications of energy
usage, and the below graph shows the energy consumption ratio of a tenant building with a rentableratio of more than 60% (with heat source), which is classified according to the items and details of thetable.
Energy consumption structure
Energy usage classification
Item
Heat source
Heat
distribution

Major energy-consuming equipment

DetailHeat source main body

Chiller, water chiller/heater, boiler, etc.

Auxiliary machine’s power

Cooling water pump, cooling tower, chilled/hot water primary pump, etc.

Water distribution

Chilled/hot water secondary pump

Air distribution

Air conditioning unit, fan coil unit, etc.

Hot water supply Heat source main body Boiler, circulation pump, electric water heater, etc.
Lighting, outlet

PowerLighting

Lighting fixture

OutletOffice equipment, etc.

Ventilation

Fans in parking, etc.

Water supply/drainage
Elevating machine

OthersElevator, escalator, etc
Transformer loss, power of shops, etc.

OthersWater supply/
drainage

Lifting pump, etc.

ElevatingmachineOthersVentilation

Power

Heat source
equipment

Heat source

Heat source
auxiliary machine

OutletLighting Outlet

Water
distribution

Hot water supply

Heat-distribution
Air distribution

Lighting

Hot water
supply3

1. Characteristics of Energy Consumption in Office Buildings

１．
3 Energy Intensity of Office Buildings by TypeThe below graph indicates the energyintensity* (mid-value of the data group) by energy use derived byextracting 120 valid data whose energy consumption structure can be analyzed, and classified into
government office, company-owned building, and tenant building, based on our investigation data ofoffice buildings. As to tenant buildings, a stratified data by rentable ratio (rentable space ratio) is shown.
* Energy intensity: A value calculated by dividing the amount of energy use by production volume or a value strongly related to the building’s total floor space andamount of other energy use.

As a result, the following became clear.
(1) The operation period of air conditioning, indoor temperature, lights-out, and etc. in government
offices are strictly controlled compared to general office buildings, and these efforts for energy
conservation are demonstrated as intensity.
Note that areas which are not regularly used including assembly halls, etc. are also included in thespace.
(2) Since most DHC (District Heating and Cooling) buildings are ultra-high/high rise buildings in themetropolitan areas, those structure with unopenable windows leads to longer air conditioning
operation hours. Also with many tenants with longer working hours due to business characteristics,
the intensity seems to be larger.
(3) It seems that smaller rentable ratio means larger. This may be due to higher area ratio of shops (otherthan offices) with large energy consumption.
Energy/Total floor space
Energy intensity of office buildings by types

Energy/Air-conditioned floor space
Energy/Total floor space-Parking floor space
Heat source

Office building classification (Floor space of general office/Total floor space)

Government office(All heat source)

Auxiliary machine
Water distribution
Air heat distribution

Company-ownedbuilding(All heat source)

Hot water supply
Lighting
OutletVentilation
Water supply/drainage power

60% or more
(With heat source)

Elevating machine
Others60% or more
(DHC)

40% or more andbelow 60%
(With heat source)

40% or more andbelow 60% (DHC)

Below 40%
(All heat source)(Average value ofthe total floor space)

Energy intensity (MJ/m2 per year)* Mid-value means the value placed in the middle when the data is aligned in descending order of value.

1. Characteristics of Energy Consumption in Office Buildings

4１．
4 Energy Intensity of Office Buildings by Scale
The below graph indicates the energy intensity (mid-value of the data group) by office’s scale derived by
excluding the data of government offices and classified by area scale, based on our investigation data ofoffice buildings.
As a result, it seems that larger scale means larger intensity. This may be due to water transfer power
associated with the verticalization of buildings and increased energy of elevating machines.
Energy intensity of office buildings by scale

Energy/Total floor space
Energy/Air-conditioned floor space
Energy/Total floor space-Parking floor space

Office building classification (Total floor space)

Heat source
Auxiliary machine
Water distribution
Air heat distribution
Hot water supply
Lighting
OutletVentilation
Water supply/drainage power
Elevating machine
Othersor moreEnergy intensity (MJ/m2 per year)* Mid-value means the value placed in the middle when the data is aligned in descending order of value.

１．
5 Correlation of Energy Consumption in Office Buildings
The below graph indicates the correlation of the total floor space and the annual gross energy
consumption of the tenant building with rentable ratio of 40% or more, based on our investigation dataof office buildings. It is clear from the graph that the total floor space has a high correlation with theannual gross energy consumption. Also, DHC (District Heating and Cooling) buildings have higher
correlation than the heat source-owned buildings.

Annual energy consumption (thousand GJ/year)

Correlation graph of the total floor space and energy use(primary energy converted value)

38 thousand m2 in average
Total floor space (thousand m2), Total number of data: 80

5

1. Characteristics of Energy Consumption in Office Buildings

Correlation of air conditioning energy consumption with total floor space

As to the relation of air conditioning energy and the scale (total floor space), “heat source(chiller/auxiliary machine) + heat distribution energy (pump/fan)” has higher correlation than the heatsource energy consumption. Thus, when managing the intensity of air conditioning, the key is to manage“heat source + heat distribution energy”.
Correlation of lighting/outlet energy consumption with total floor space

In general, lighting and outlet are measured together by a wattmeter (for accounting purpose, etc.) in
office buildings. As shown in the graph, correlation is higher when the lighting energy is separated,compared to the bulk data. This may be due to the difference in the scale between the lighting and theoutlet load, since the later depends on the installation condition of the OA equipments in offices, etc.
Thus, from the view point of energy management, we consider that lighting and outlet should bemeasured by individual wattmeters.

With rentable ratio of 60% or more
DHC

Annual energy consumption(thousand GJ/year)

Annual energy consumption(thousand GJ/year)

Heat source-owned building

23 thousand m2 in average

83 thousand m2 in average

Total floor space (thousand m2), Number of data: 20

Total floor space (thousand m2), Number of data: 9

Total floor space (thousand m )2

23 thousand m2 in average
Total floor space (thousand m )2

As to the correlation with the total floor space, “heat source + heattransfer energy” has higher correlation than the “heat sourceenergy” .

Heat source+ heat transfer energy consumption(thousand GJ/year)

Heat source energy consumption(thousand GJ/year)

83 thousand m2 in average
Total floor space (thousand m )2Lighting outlet energy consumption(thousand GJ/year)

Lighting energy consumption(thousand GJ/year)

23 thousand m2 in average

23 thousand m2 in average
Total floor space (thousand m )2

83 thousand m2 in average
Total floor space (thousand m )2

83 thousand m2 in average
Total floor space (thousand m2)

2

Lighting outlet energy consumption(thousand GJ/year)

Total floor space (thousand m )DHCLighting energy consumption(thousand GJ/year)

23 thousand m2 in average

Heat source+ heat transfer energy consumption(thousand GJ/year)

Heat source energy consumption(thousand GJ/year)

Heat source-owned building

83 thousand m2 in average
Total floor space (thousand m2)

Both usages have high correlation with the total floor space.

1. Characteristics of Energy Consumption in Office Buildings6With rentable ratio of 40% or more and below 60%
DHC
Annual energy consumption(thousand GJ/year)

Annual energy consumption(thousand GJ/year)

Heat source-owned building

58 thousand m2
in average

30 thousand m2 in average

Total floor space (thousand m2), Number of data: 40

Total floor space (thousand m2), Number of data: 11

Total floor space (thousand m )2Heat source+ heat transfer energy consumption(thousand GJ/year)

Heat source energy consumption(thousand GJ/year)

58 thousand m2 in average
Total floor space (thousand m2)

30 thousand m2 in average
Total floor space (thousand m2)“Heat source + heat transfer energy” and “lighting energy" havehigh correlation with the total floor space.

58 thousand m2 in average
Total floor space (thousand m2)

58 thousand m2 in average
Total floor space (thousand m2)

Lighting outlet energy consumption(thousand GJ/year)

30 thousand m2 in average

30 thousand m2 in average
Total floor space (thousand m2)

Lighting outlet energy consumption(thousand GJ/year)

Lighting energy consumption(thousand GJ/year)

Total floor space (thousand m2)

DHC

Lighting energy consumption(thousand GJ/year)

30 thousand m2 in average

Heat source+ heat transfer energy consumption(thousand GJ/year)

Heat source energy consumption(thousand GJ/year)

Heat source-owned building

58 thousand m2 in average
Total floor space (thousand m2)

The correlation is lower than the DHC buildings with rentable ratioof 60% or more. This may be due to the usages of shops (otherthan offices) and IT related businesses which affect the amount ofenergy consumption.

1. Characteristics of Energy Consumption in Office Buildings

2.Major Points for Energy Conservation in Office Buildings
As to office buildings, several points for energy conservation can be extracted from the trends in energy
consumption according to time zone.
Though keeping track of energy by electricity, fuel, or the combination of these two, or by consumption
structure classification is the best way, information analysis can also be realized only with the total
amount of electricity. The following describes the major points for energy conservation based on theenergy consumption characteristics of the four time zones.

Classificationof time zone
①Time before the start of business②Operation time
③Overtime④Non-used time (nighttime/holidays)

Electric energy
or amount of heat or gas consumption

Time before
the start of business

Energy consumption characteristics of this time zone

Since this is the time zone for starting
businesses, a large amount of energy isconsumed for air conditioning warm-ups.
Energy consumption of this time zone reaches
the maximum in the winter. Also, as employers
arrive at the office to be in time for the start ofbusiness, lighting/outlet load increases sharply
during this time zone.

No.

Major energy conservation measures for this time zone

1

When the trend of the intermediate season with low heat load is similar to those of summer and winter, operation startingtime of the air conditioning should be delayed.

2

At operation starting time of the air conditioning for cooling/heating, outside air intake should be stopped to reduce loads.

3

The blinds on the east side of the building should be closed at the end of the business hours to reduce solar load in the next morning.

4

Night-purge should be used before dawn of the cooling season to eliminate the heats storaged in the building frame, roomloads during night time, and solar radiant load during holidays, in order to alleviate air conditioning load.

5

Install a through-flow boiler, etc.which requires less warm-up time, and delay the operation starting time for heating.

2. Major Points for Energy Conservation in Office Buildings

Operation
１．
4

Energy consumption characteristics of this time zone

④

time

This is the time zone in which the energy consumption is
the highest in a day. The peak demand is recorded in thesummer. Thus, users’ actions for energy conservation
greatly affect the amount of consumption. Also, due tothe difference in the air conditioning load according toseasons, management of the facility’s operation
efficiency is the essential point for energy conservation.

No.

0：00

①

②

③

6：00

12：00

18：00

④

24：00

Major energy conservation measures for this time zone

1

Employees should be lightly dressed in the summertime, and the indoor temperature should be adjusted appropriately.

2

Lightings in offices should be turned off while the users are taking a lunch break.

3

According to the difference in the load by seasons, operation management to enhance overall energy efficiency of theequipments including air conditioning/heat source equipments and auxiliary machines should be conducted.

4Management of CO2 concentration and adjustment of minimum outside air intake should be carried out, and outside air
intake controls including CO2 sensor etc. should be employed at the time of the retrofit.

5High-efficiency heat source equipment, variable air volume system, and variable water volume system should be installed at thetime of the retrofit. It should be installed by dividing the number of units for the optimum capacity to enable efficient operation.

Over
１．
4 time(By referring to the temperature setting recommended by the government.)

Energy consumption characteristics of this time zone④

Energy consumption decreases gradually compared tothe time zone before the start of business.Limited
partitions and management of the facility’s operation
efficiency is the essential points for energy conservation
during this time zone, since air
conditioning/lighting/outlet load is partial during theovertime.

0：00

No.

①

②

③

6：00

12：00

18：00

④

24：00

Major energy conservation measures for this time zone

1

Lightings in the office should only be turned on in a zone where employees stay working, and the partitions should be limited.

2

Lightings in the common area should be turned on partially.

3

Heat source equipment operation should be turned off before end of office hours to use the heat inside the equipment in an
effective way. (Only the pump should be operated to fully use the heat inside the heat source equipment and the piping.)

4

Effective operation should be carried out by selecting equipments which can operate in limited partitions, etc. (When the
air conditioning and the heat pump are installed in the same zone.)

5

Switch the power of the hot water supplier and warm-water cleaning toilets in floors without any employer left to night mode.

Non-used
１．
4

Energy consumption characteristics of this time zone④

time (night time/holidays)

①

②

③

6：00

12：00

18：00

④

Since this time zone does not include working hours, general air conditioning and most of
the lightings are turned off, resulting in an extremely low energy consumption compared to
daytime. However, as it is referred to as a “base load", amount of energy consumption ofthis time zone is consumed 24hours /7days. Thus, energy conservation will be very
effective during this time zone.
0：00

No.

9

24：00

Major energy conservation measures for this time zone1

Confirm whether lightings and ventilation are necessary by making a tour of inspection at midnight to eliminate waste.

2

Consolidate the load of electrical transformers, and reduce the number of operating transformers to cut down iron loss (no-load loss).

3

Reduce the number of elevators in operation.

4

Turn off the vending machines at night time by timer control.

5

Renew transformers to high-efficiency top runner transformers to minimize loss.

2. Major Points for Energy Conservation in Office Buildings

3.Check Points for Energy Conservation Measures in Office Buildings

1

Energy conservation measures by users
Energy conservation measures by users are carried out by the users and correspond to users’ efforts aswell as elimination of waste including “appropriate adjustment of room temperatures”, “lights-off during
lunch break”, etc. These actions to minimize load are the first step towards energy conservation measures.

Classification
Management
Air
conditioning

Hot water supply

Lighting/
electricity

Architecture
Elevating machine

2

Major energy conservation measures

Result◎

Maintain organizations for promoting energy conservation.
Adjust the indoor temperature appropriately. (Refer to the temperature setting recommended by the government.)
Use outside air cooling in the intermediate season and winter.

Case
example◎Case
example○1
2

Stop the hot water supply during the seasons other than winter.

◎

Stop the circulation pump during the time zone with less usage.

○

Turn off the lights in unused rooms.

◎

Turn off the lights during lunch break.

◎Turn off the vending machines at night time.

◎

Manage the blinds of the east side of the building to reduce cooling load in the morning.

○

Adjust the number of elevators in operation on Saturdays, holidays, and night time.

◎

Energy conservation measures by operations
Energy conservation measures by operation are to operate the current facility efficiently, and to rationalize
the use of energy, such as “tuning of equipment/system”. The measures are the basic of the energy
management in which energy conservation is promoted without imposing a burden to users.

ClassificationAir
conditioning/hot
water supply

Major energy conservation measures

Result○Adjust the air ratio of the boiler and combustion equipment.

○

Maintain adequate boiler blowdown and water quality.
Case
exampleManage the setting of the chiller’s outlet temperature and the efficiency of the combination of the auxiliary machine and distribution power. 3○

Adjust the number of the distribution pumps, according to the cooling/heating load.

◎
Case
example◎Case
example◎Case
example6 7Turn off the heat source equipment before the end of operation time to use the heat inside the equipment and the piping effectively.

○

Conduct bypass operation of the total heat exchanger while the outside air cooling is available.

◎

Case
example◎Manage the cooling water temperature for the chillers to enhance efficiency of them.
Airconditioning

Manage CO2 concentration level to enable minimum ouside air intake.
Stop outside air intake at the time of starting cooling/heating.

Shorten the warm-up time of the air conditioning.
Lighting/
electricity

4
5

Case
example8○

Manage the load ratio of the transformers and adjust the balance of them correlation.

○

Review the temperature setting of the electric room to rduce cooling load and ventilation power.

○

3. Check Points for Energy Conservation Measures in Office Buildings

103Energy conservation measuresby investments which are collectable in a short term
In general, energy conservation measures by investments which are collectable in a short term mean
measures in which investments can be collected in three to five years by cost reduction due to the result ofenergy conservation. Even though the measures are the same, a payback year is different from theoperation type of the building. Generally, a payback year is shorter when the efficiency of the current facility
is poor, or with measures including inverterization of the pumps/fans whose operation times are long.

ClassificationAir
conditioning

Air conditioning/
hot water supply
Ventilation
Water supply/hotwater supply
Lighting/
electricity

4

Major energy conservation measures

ResultInstall an inverter to the blower to adjust wind volume.

◎

Install an inverter to the pump to realize operation according to the pressure and flow volume.

◎

Exchange the filling material of the cooling tower depending on the clogging status.

○◎

Enhance thermal insulation of the steam valve, piping, etc.
Case
exampleInstall sensors to the ventilation equipment of the parking area to control start-stop and wind volume. 10○

Employ water-saving top and equipment.

○

Install imitation sound generation devices to ladies restrooms.

○

Subdivide the lighting circuits put it together the operations○

Exchange the stabilizer of the existing lighting fixtures to an inverter type.

◎

Energy conservation measures by retrofits
Energy conservation measures by retrofits are to introduce high-efficient equipments and systems at thetime of a large-scale renovation work owing to the aging of facilities. Major measures are mentioned in thecreation guideline for mid-and-long term plan in the Act on the Rational Use of Energy (Energy
Conservation Act) as the subject to be discussed.

ClassificationAir
conditioning

hot water supply

Lighting/
electricity

11

Major energy conservation measures

ResultEnhance the efficiency at the time of partial load by appropriate adjustment of the heat source capacity and the number of units.

◎

Introduce variable air volume system and variable water volume system. (VAV, VWV)◎

Employ CO2 sensor system for outside air intake.

◎

Employ total heat exchanger.

○

Employ free-cooling for the cool demand during the intermediate and winter season.

○

Introduce BEMS to enhance overall efficiency of the air conditioning equipments.

○

Consider introducing a local type hot water supply.

○

Renew to high-efficiency lighting fixtures.

◎

Employ high-efficiency transformers and equalize the loads.

◎

Renew condenser/reactor to low-loss type.

○

3. Check Points for Energy Conservation Measures in Office Buildings

4.Successful Cases of Energy Conservation Measures in Office Buildings
Case
exampleBy changing the room temperature setting forcoolingfrom 26°C to 28°C, chilled water thermal
quantity of the DHC reduced approximately 11%.

Consumed thermal quantity of DHC (MJ/h)

1

Set the indoor temperature setting to energy conservation mode.
(Summer: 28°C, Winter: 20°C)

Summer26°C to 28°C

Changes in consumed thermal quantity
by raising the room temperature by 2˚C
FY2004 (Room temperature setting: 26°C)
FY2005 (Room temperature setting: 28°C)

From the “TuBE Guidebook” (Created in March, 2006)

Fan

Air conditioning

Use natural cooling by outside air during theintermediate season. When the outside air damperis broadened from 20% to 100% while employing
outside air cooling, consumed thermal quantity of
the DHC resulted in 10% energy conservation.

Fan

Outsideair
Office2

Outside air cooling

Air conditioning

Case
exampleOfficeOutside air enthalpy [kJ/kg]

OutsideairConsumed thermal quantity of DHC (MJ/h)

OA Damper opening: 20%
OA Damper opening: 100%

Damper opening: 20%

Damper opening: 100%

From the “TuBE Manual” (Created in March, 2006)
Outside air enthalpy [kJ/kg]

4. Successful Cases of Energy Conservation Measures in Office Buildings

12

3

Setting change of the chilled/hot
water outlet temperature
When the chilled water outlet temperature ischanged from 8°C to 11°C during the intermediateseason, COP of the chilled/hot water generator
enhanced from 0.60 to 0.75, and resulted in 20%
energy conservation.

COP vs.outside air enthalpy

COP of 11°C (10/4)

COP

Case
exampleCOP of 8°C (10/5)

Outside air enthalpy (kJ/kg [DA])Gas consumption by hot water temperature
Gas consumption (m3/h)

When the hot water outlet temperature is changed
from 55°C to 45°C during early winter, the averagegas consumption of the chilled/hot water generator
decreased from 47.0 to 42.5 m3/h, and resulted in
10% energy conservation.

Outside air enthalpy (kJ/kg [DA])Total consumption of hot water and chilled water gas: 45°C
Total consumption of hot water and chilled water gas: 55°C

Case
example4

Setting change of the coolingwater temperature

From the “TuBE Manual” (Created in March, 2008)

When the cooling water inlet temperature is changed from 28°C to
25°C during the intermediate season, the cooling water temperatureof the chilled/hot water generator dropped about 3°C, and resulted inenhanced output by 16%
Cooling water: 28°C and above,
Chilled water outlet temperature: 7-8°C

Chiller output (GJ/h)

Chiller output (GJ/h)Cooling water: 25°C and below,
Chilled water outlet temperature: 7-8°C

Gas input (GJ/h)

Gas input (GJ/h)
From the “TuBE Manual” (Created in March, 2008)

4. Successful Cases of Energy Conservation Measures in Office Buildings

CO2 concentration (ppm)

5

Reduction ofoutside air volume
By reducing the outside air volume by
23%, from 2,373 m3/h to 1,819 m3/h,
chilled water thermal quantity reduced
approximately 12% to 10 MJ/h. However, it
should be adjusted to be below 1,000 ppm
by monitoring CO2 concentration.

Transition of CO2 concentration

Thermal quantity consumption (MJ/h)

Case
exampleFrom the “TuBE Manual” (Created in March, 2008)

8/29
9/4

8/30
9/5

8/31
9/6

9/7

CO2 concentration with outside air damper opening by 50% (2,393m3/h)
CO2 concentration with outside air damper opening by 30% (1,819m3/h)
From the “TuBE Manual” (Created in March, 2008)

6

Outside air enthalpy (kJ/kg)
Outside air volume 2,373 m3/h
Outside air volume 1,819 m3/hLine (Outside air volume) 2,373 m3/hLine (Outside air volume) 1,819 m3/h

8/28
9/3

Case
exampleComparison of the outside air enthalpyof the chilled water thermal quantity consumption
by changing the outside air volume

Convert the verification results to below 1,000 ppm.
Increase outsideair volume to 2,130 m3/h;(1100 - 400)/(1000 - 400) = 1.17 times.
Chilled water thermal quantity will be reduced by
8.5 MJ/h; (10 MJ/h)/1.17 = 8.5 MJ/h.
Thus, when the outside air enthalpy is 72 kJ/kg,
chilled water thermal quantity reduced by 10%.

Cutback on outside air load by changing
the start order of the air conditionings (cooling)
Reduction on outside air load of the outside air conditioner on activation (From June to September)
CO2 concentration starts to rise from about 8:30; when employees begin to arrive, and reaches thesetting value of 900 ppm in about 10:00 which is after hour and a half. Thus, until 8:30, outside air
conditioner and perimeter air conditioner can be operated with outside air blocked.
Operate the interior air conditioner (for cooling only) which requires less consume power and nooutside air intake and the perimeter air conditioner firstly, and then start the outside air conditioner
at 8:30 to reduce outside air load.
Reduced thermal quantity by blocking outside air during activation (From June to September): 185
GJ
3.2% reduction compared to the chilled water load from June to September, 5786 GJ (Outside air
cooling is used in May and October)Air conditioning system of the standard floor
Perimeter air conditioning

NE system

Interior air conditioning
Interior x 8 units

Outsideair conditioniner
2.2kW
Perimeter air conditioner
3.7kW

Perimeter air conditioner
3.7kW

Outside air conditioniner
2.2kW
Outside air conditioner
Interior x 8 units

SW system

4. Successful Cases of Energy Conservation Measures in Office BuildingsRoom temperature of SW-related in the 14th floor

Perimeter AHU
Outside air conditioner

Time

High-story chilled water, chilled/hot water thermal quantity and interior AHU

Interior AHU

Time

CO2 concentration of SW-related in the 14th floor and outside air coolingCase
example7

Time

Stop outside air intake on warm-up and cool-down periods
The graph below shows an example of the trend in thermal quantity for heating in a building without
warm-up control. It is clear that the load gets especially high during an hour required for warm-up
the air conditioning.
Energy conservation can be enhanced by blocking the outside air-intake during warm-up andcool-down periods.
Classificationof time zone
①Time before the start of businessElectric energy
or amount of heator gas consumption②Operation time
③Overtime④Non-used time (nighttime/holidays)

Usage amount of steam (2007/1/22-1/28)

1/22

1/23

1/24

1/25

1/26

1/27

1/28

From the “TuBE Manual” (Created in March, 2008)

4. Successful Cases of Energy Conservation Measures in Office Buildings

Case
example8

Improvement of air conditioning activation time (Cut-down on warm-up time)
The time reach to the appropriate temperature (setting or control temrature), varies the season,
peak time, light-load season, and the chilled/hot water temperature. It leads to enhanced energy
conservation by adjusting the air conditioning activation (operation) time according to the air
conditioning load status.

Temperature change during air conditioning activation (Cooling operation)
Reduced operation time

Temperature [°C]

Temperature [°C]

Air conditioning operation waste timeAirconditioning
operation
contract timeTarget control
point

Indoor setting
temperatureAir
conditioning
operation
contract timeTarget control
point

Indoor setting
temperature
Indoor temperature
variation

Indoor temperature
variation

Operation start
time before theadjustment

Time

Time
Air conditioning
Business start time
operation start time

Air conditioning
Business start time
operation start time

The annual consumption power of thevariable pressure control was 50% ofthat of the constant pressure control,
resulting in enhanced energy
conservation.
The reason is because of decreased
water flow, the piping resistancedecreases as well.
This is effective if operation hours withload ratio about 50% is frequently.

Flow volume/ electric energy
Constant pressure
Constant pressure

Electric energy (kW)9Power reduction by leveraging
the difference in secondary
pump control method

Variable pressure,2 units in operation
Variable pressure power

Variable pressure,number of units controlled

Constant pressure power calculation formula

Variable pressure power calculation formula

Load flow (m3/h)

Relation between load flow/power
INV 1 constant pressure control power

Power (kW)Case
exampleFrom the “TuBE Manual” (Created in March, 2008)

Constant pressure control power

Variable pressure control power

Load flow (m3/h)
From the “TuBE Manual” (Created in March, 2008)

4. Successful Cases of Energy Conservation Measures in Office Buildings

Case
example10Intermittent operation of the ventilation fan in the parking area
As to the three patterns provided as the intermittent operation schedule of the ventilation fan in
the parking area, accumulated electric energy of each pattern is measured.
As a result, by the difference in intermittent operation methods, mode 3 shown in the below
figure had 50% difference in electric energy consumption, compared to mode 1. Indoor CO andCO2 concentration maintain the environmental standard.
Accumulated electric energy
consumption (Wh)Electricity diagram of the ventilation fan in the parking area
Mode 1: Accumulated electric energy of the day (11/12)
Mode 2: Accumulated electric energy of the day 80 kW (11/11)
Mode 3: Accumulated electric energy of the day 55 kW (11/13)

Time

Environment of the level ground parking areaTime
11/11 (Tue.) Level ground parking area CO ppm

11/12 (Wed.) Level ground parking area CO ppm

11/13 (Thu.) Level ground parking area CO ppm

11/11 (Tue.) Level ground parking area CO2 ppm

11/12 (Wed.) Level ground parking area CO2 ppm

11/13 (Thu.) Level ground parking area CO2 ppm
From the “TuBE Guidebook” (Created in March, 2006)

4. Successful Cases of Energy Conservation Measures in Office Buildings

5.Effective Tools and Techniques for Promoting Energy Conservation by Improved Operation
ECCJ provides tools and techniques for further energy conservation
useful for improving operations of large-scale buildings for business
use without charge.
The three tools and techniques are:(1)ESUM：Energy Speciﬁc Unit Management Tool
ESUM is computer software which estimates energy consumptions of a building and compares
the consumptions before and after implementing an energy conservation measure todemonstrate the energy reduction effect.

(2)TuBE：Tuning of Building Systems for Energy Conservation
TuBE is a document which defines how to select and carry out operational improvement actions
among various energy conservation measures.

(3)EAST：Energy Analysis Support Tool
EAST is computer software which compiles operation process data of air-conditioning units and heatsource equipment and make a graphic presentation of the trends to help you analyze their operation
conditions.

Combined use of the above three tools helps your making smoother energy conservation
activities throughout the necessary steps for the activities; analysis on operation status andconditions, selection of improvement method, estimation of its effectiveness, andimplementation of the measure.

How to obtain more detailed information onenergy conservation of buildings for business use
ECCJ has a website to provide various kind of information on energy
conservation of buildings.
The site includes:
inputs from actual users of tools (e.g. ESUM and EAST) useful for enhancing your energy
conservation activities for buildings;
various forums for different types of facilities (e.g. office buildings, commercial facilities, hotels,
and hospitals), which serve as an information exchange forum among members; andinvitations to seminars and lecture classes which provides information on successful cases ofimproved energy conservation of buildings for business use and examples of effective use ofvarious tools as well as materials for those seminars and lectures

Owners of buildings for business use
Persons in charge of energy conservation promotion
Persons in charge of energy facility management
Energy conservation business operators

Open spacefor energy
conservationin buildings

5. Effective Tools and Techniques for Promoting Energy Conservation by Improved Operation

The Energy Conservation Center, Japan

Head Office: 3-19-9, Hatchobori, Chuo-ku, Tokyo,
104-0032 Japan
Tel: 81-3-5543-3018 Fax: 81-3-5543-3022

This is translated from the original Japanese document.
For precise information and nuances, please refer to the original.
Copyright (C) The Energy Conservation Center, Japan 2010 All rights reserved

2010.03