3. Focused Research (2)In Pursuit of Carbon Neutrality in the Data Center

3.1 Introduction

are effectively impacting climate change rather than simply

Over 120 countries have declared their intention to achievemechanically disclosing data, and these developments alsocarbon neutrality—achieve zero greenhouse gas (CO2,no doubt create an incentive for carbon neutrality.

methane, N2O, chlorofluorocarbons [CFCs]) emissions—by 2050, a goal of the international climate change treaty

Data center carbon neutrality will be achieved via two

known as the Paris Agreement. The Japanese government

avenues: saving energy by using it more efficiently and using

also declared its 2050 carbon neutrality goal in Octoberrenewable energy not tied to CO2 emissions. Matsue Data

2020. And in the Green Growth Strategy it unveiled inCenter Park (Matsue DCP) and Shiroi Data Center Campus

December 2020, it set goals for a wide range of industries,(Shiroi DCC), which IIJ built and operates, feature highlywith the following goals being laid out for data centers.

energy-efficient equipment and outside-air cooling systems
the technology for which was developed and tested with

• By 2030, all newly constructed data centers should
consumer 30% less energy and be partly powered byhigh energy-saving goals in mind, and the resulting energy
savings are reducing IIJ’s greenhouse gas emissions.

renewable energy• Aim for carbon-neutral data centers by 2040

In addition to such energy savings, we also plan to makeincreasing use of renewable energy ahead by setting up

Data center carbon neutrality is to be achieved primarily bycarbon-neutral data centers so that renewable energy

reducing CO2 emissions from power consumption to zero.

generation systems and the data center can work in concert

This will entail costs including for the purchase of renewablewith each other.

electricity, technology development, and capital investment,24

but achieving carbon neutrality early will help companies

Below, we go over our energy-saving initiatives at Matsue

differentiate from peers and enhance service value. Carbon

DCP and Shiroi DCC, where we have achieved strong

neutrality is also starting to appear among procurement

energy-saving performance, and we round out the discussion

criteria for products and services, and equity markets areby presenting a reference model for carbon neutrality in thecalling on companies to disclose information on how they

data center.

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3. Focused Research (2)3.2 Outcomes at Matsue Data Center Parkand introduce new systems that consume less power.

On April 26, 2011, we opened Japan’s first commercial

Based on past demonstration testing, IIJ determined thatmodular data center with outside-air cooling systems,

outside-air cooling systems that use outside air to reduce

Matsue Data Center Park in Matsue-shi, Shimane Prefecture.

power consumption and do not require cooling towers andMatsue DCP features IZmo units, IT modules developed by

the like would be suited to its next-generation data centers.

IIJ and imbued with its extensive data center operational

Outside-air cooling, however, involves the exchange ofknowhow. To expand into more enterprises in Japana large volume of air, so the intakes and outlets need toand abroad and tap into new markets, we also operate

be installed directly on the server rooms. This raises a

co-IZmo/I modular data centers, which use indirect

number of difficult problems to do with building structure

outside-air cooling systems. Matsue DCP has been in stable

when seeking to install such systems on existing buildings.

operation since being opened as the core facility for IIJ’s

So we developed the IZmo IT module, in which the air

GIO cloud services, and with 90% of the server-hous-

ducts are integrated with the server room.

ing containers now installed, the total number of servers
running is in the tens of thousands. Site 2, added next

PUE (Power Usage Effectiveness), a metric developed by theto Site 1 in 2013, introduced co-IZmo/I units in addition

Green Grid, is often used as a measure of how effectively ato IZmo and uses a three-phase four-wire configuration

data center uses power. Figure 2 shows the PUE equation.

to power its servers and other IT equipment, reducing
power distribution losses and thus saving energy (Figure

Theoretically, the smallest (best) PUE score is 1.0, which

1). Data centers generally house large-capacity electricaloccurs when zero power is consumed by air conditioning

equipment and air conditioning systems to create anequipment etc. Figure 3 shows five years of measurements

environment in which large numbers of servers and otherfor the IT-module-only metric pPUE (partial PUE, ignores

IT equipment can be installed efficiently. IT equipment

energy losses from shared resources etc.).

is the biggest consumer of data center power, but air
conditioning systems are right behind it. So we needed to

The summer pPUE readings are higher than for otherrethink the use of conventional air conditioning systems

seasons because the air conditioning modules run in a

Total facility energy (energy used by IT equipment + energy used by air conditioners etc.)

PUE =Energy used by IT equipment

Figure 2: The PUE Equation

Site 1
1.5
1.4
1.3■Average
■2020
■2019
■2018
■2017
■2016

1.2

Site 2

1.1
1.0

Figure 1: Matsue Data Center Park Site 1 and Site 2(Photo of Matsue Data Center Park taken around 2019)

Apr.

May

Jun.

Jul.

Aug.

Sep.

Oct.

Nov. Dec.

Jan.

Feb.

Mar.

Figure 3: Annual pPUE Scores for the Past Five Years© Internet Initiative Japan Inc.

25

high-power-consumption mode that does not use outside air.

centers, the servers had to be unpacked one by one,

In comparison, spring and autumn pPUE readings are aroundinstalled in a rack, and wired up. But with containerized

1.1 because the modules run in a low-power mode that uses

data centers, the servers are installed into IT modules at

outside air. In winter, the modules mix IT equipment exhaustthe server factory, and the IT modules are transported byand outside air to achieve the right temperature, and sincetruck for installation at the site. This eliminates box andthis mode also consumes less power, pPUE is around 1.1.

packaging waste, makes better use of resources and is

The average over the past five years is 1.18.

better for the environment, and helps reduce CO2 emissions
from equipment transportation. Recently, when replacing■ IZmo and co-IZmo/I

IT equipment, instead of removing the entire container,

The IZmo IT module is a non-building container conforming

operators can opt to remove all of the server racks

to technical advice issued by Japan’s Ministry of Land,

from the container and take them to the server factory,

Infrastructure, Transport and Tourism in March 2011.

where the new equipment is installed in the racks so

The modules are easy to set up because there is no need

they can then be reinstalled in the containers.

to apply for building permission. With conventional data

PUE score
2.2
Conventional data center PUE

2.0
1.8
1.6

1.483

1.4

PUE of data centerwith high-efficiency equipment

1.426

1.2

1.240

1.209

1.210

1.237

2017

2018

2019

2020

1.0
0.8
0.6
0.4
0.2
0
2015

2016

Figure 4: Annual Average PUE for Matsue DCP as a Whole

Figure 5: IZmo and co-IZmo/I

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3. Focused Research (2)IZmo uses direct outside-air cooling and automatically

voltage (low current). It is widely used in Japanese factories.

switches between three modes depending on outside air

One of the three 400V wires from the UPS can be isolated

temperature and humidity. It controls the temperature atalong with the neutral wire to pull out a 230V supply

the intake port within the IT module to meet thewithout a transformer. This is common in data centers

recommended temperature and humidity conditions set byoverseas where 100V is not required, but the common

Ashrae (American Society of Heating, Refrigerating andneed for 100V in Japan means that, until now, transformers

Air Conditioning Engineers) in 2008.

have commonly been installed in three-phase three-wire
UPSs to transform power from 400V to 100V. Since servers

co-IZmo/I uses indirect outside-air cooling. In contrast

can operate at any voltage from 100V to 230V, andwith direct outside-air cooling, outside air is not channeledbecause IIJ uses a lot of servers for its cloud infrastructure,

directly into the container, and instead, internal heat is

we chose a three-phase four-wire system, eliminating theexpelled indirectly via a heat exchanger, so this method

need for transformers.

can be used even when outside air conditions are poor.
We have also exported some of these modules internationally.

Given that power (W) = current (A) x voltage (V), a

See Figure 5.

reduction in wire size means that, for any given load
capacity (W), the higher the voltage (V), the more you canTheoretically, IZmo, which uses direct outside-air cooling,

reduce the current (A). Specified currents for electricalis more efficient (lower pPUE) than co-IZmo/I with its indirect

wire (the maximum current it can carry) are set according

outside-air cooling (pPUE value is low), but as Figure 6

to the type of insulating sheath and the size of the wireshows, the fine-tuning of control mechanisms and the like(mm2). So at lower specified currents, wires with a lower

make it possible to run co-IZmo/I modules at pPUE scorespermissible current can be used, and the lower a wire’s

similar to those of IZmo.

permissible current, the smaller its diameter, which canhelp reduce the investment cost. Further, voltage drop

■ Three-Phase Four-Wire System

can be reduced because three-phase four-wire systems

At Site 2, we introduced a three-phase four-wire unin-are even less susceptible to voltage drop than three-phaseterruptible power supply (UPS) system, a first among

three-wire systems, in which the voltage drop decreases

Japanese data centers (Figure 7). Three-phase four-wireas the current decreases. At Matsue DCP, this allows for

power transmission involves three wires for three-phasea lower transmission current between the UPS output

AC plus a grounded neutral wire. It is more efficient thanand the server input, and it reduces losses because no

single-phase AC, uses a lower current, and conductortransformers are used. This results in a theoretical(wire) size can be reduced by transmitting power at highreduction in losses of around 25%.

*Assuming a Y configuration is used
1.3

400V

400V÷√3 230V

400V

230V

1.195

1.2
1.163

1.161

1.159

1.168 1.161

1.179

230V

1.168

1.1

UPS
■co-IZmo/I
■IZmo

1.0
2016

2017

2018

2019

2020

(year)

Figure 6: Comparison of IZmo and co-IZmo/I pPUE Scores

400V equipment(UPS etc.)

Ground230V equipment(Servers etc.)

Figure 7: Y-connection Overview of Three-phase Four-wire System© Internet Initiative Japan Inc.

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■ Environmental Initiatives

Factory. We have appointed an Energy Manager and formu-

In terms of environmental initiatives, we have ISO 14001

lated a medium-term plan, and we implement and evaluate(EMS, Environmental Management Systems) certificationenergy-reducing initiatives based on the facility’s energy

and work to comply with energy conservation laws andusage every year. As the facility has many air conditioning

regulations.

systems, we also comply with Japan’s CFC emissions law
by measuring the amount of CFC gas leaked and identifying

Matsue DCP operates in accord with its ISO 14001

leaks and their causes through inspections and such.

certification, acquired in 2013. We set annual targets forenvironmental initiatives. Our past efforts have included

As Matsue DCP’s electricity usage increases by the year,

going paperless, reviewing the air conditioner temperature

efforts to save more energy and further reduce CO2

settings within buildings and operations rooms, and reducing

emissions are becoming increasingly important. We will

pPUE by 0.01 per year. Using power more efficiently is

continue to focus on environmental initiatives including

one thing, but the EMS certification also requires us tothose to reduce energy consumption, use renewableaddress the risk of the environmental impact on lives andenergy, and install renewable-energy equipment.

ecosystems from atmospheric pollution caused by fires
and the impact of soil pollution caused by the leakage of

3.3 Initiatives at Shiroi Data Center Campus

fuel from emergency power generation facilities. We have

We opened Shiroi Data Center Campus on May 1, 2019

therefore prepared response manuals for emergencies

in Shiroi-shi, Chiba Prefecture (Figure 8). Shiroi DCC issuch as fires, earthquakes, and equipment accidents, anda large-scale data center designed to cope with the explosive

we regularly conduct response training sessions, environ-

growth in data center demand for 5G, IoT, AI, cloud

mental management education and training sessions, andservices, and the like. It brings together the data center

environmental compliance assessments. Matsue DCP is intechnologies and knowhow that IIJ has developed or

an area that experiences relatively few natural disasters

evaluated to address issues with data center operations

and earthquakes, but we strive to raise environmental

in the past. It is also a system module-type data center

awareness through regular education and training.

where we can actively roll out new technologies.

On the topic of environment, energy, and CO2 emissions,

Shiroi DCC draws on the successes of Matsue DCP and

we have compiled data on our energy usage into periodic

is designed to overcome the obstacles and challenges

reports in accord with energy conservation laws andencountered. On the energy front, it inherits the concept of

regulations since Site 1 was opened in 2011. Because

modular server rooms, direct outside-air cooling systems,

Matsue DCP’s energy usage exceeded 1,500kL (crude oil

three-phase four-wire UPS and bus duct power transmission

equivalent) in fiscal 2013, we have also been working

technology. The entire Shiroi DCC facility runs at an annual

on energy saving measures in accord with the facility’s

average PUE of under 1.2, and we are endeavoring to expandclassification as a Type 2 Designated Energy Management

the usage scenarios for its power systems.

Administrationbuilding

Site area~40,000m2

Modular structureServerbuilding

Maximum power input capacity

Equipment capacity

50MW

6,000 racks

Figure 8: Artist’s Impression of
Shiroi Data Center Campus Once Completed

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3. Focused Research (2)■ Direct Outside-Air Cooling Systems and System Modules■ Chimney Effect

As a new modular data center, Shiroi DCC takes advantage

The direct outdoor-air air conditioning systems in use atof operational experience from Matsue DCP and knowhow

Matsue DCP and on IZmo containerized data center units

gleaned from containerized data center development,

have greatly reduced the annual power consumption attrib-

applying this on a floor scale (several hundred racks or

utable to outdoor units, resulting in an annual average PUEso) and using system modules capable of serving needsof 1.237 for Matsue DCP and annual average pPUE of 1.18

on a larger scale. The buildings follow a systematizedfor containers. The systems need ventilation fans to blow

construction scheme based on standard shapes and ar-cool air into the cold areas year round, however, and therangements for the steel building frames and outer walls,

power used by these fans was the next energy-saving issue

facilitating rapid construction at low cost and high quality

we faced with the air conditioning systems. To tackle this(Shiroi DCC phase-1 building: from start of construction,issue, in 2012 we conducted tests (Figure 9) to see if we

it took four months to have the roof frame in place, eight

could take advantage of the chimney effect (phenomenon

months to fully complete). All of the internal elements

whereby the difference in temperature on the inside andof the system modules—electrical system, air conditioning

outside of a chimney causes an upward current) to cool thesystem, and server racks—are modularized, making it

servers. If this was possible, we thought, it could greatly

possible to add or replace (upgrade) equipment for eachreduce the power consumed by the ventilation fans and takeserver room individually.

us closer to a PUE of 1.0, and if it also made it possible toreduce IT equipment internal fans, this could also help to

These system modules are also integral to the reduced energy

further reduce overall data center power consumption.

usage of the air conditioning systems at Shiroi DCC,
which has a huge number of racks. Using the system

Although the conditions under which the chimneys were in-modules’ characteristically large space, large apertures,stalled (weather, air temperature and humidity, wind speed,

and wide span, we created a side-flow direct outside-airetc.) did affect the results, our tests showed that airflow

cooling system that utilizes the chimney effect.

volume increased roughly proportionally with increases in
the height and load capacity of the chimneys (Figure 10). As
a result, we determined that we could assist the air conditioner ventilation fans by grouping several racks into a single
module and positioning several modules at the center of theroom so that outside air could be drawn in from the sides of
the room, and exhaust air from the modules could be expelled from the top of the building. Shiroi DCC is designedwith these test results in mind in terms of the system

Load capacity (kWh)

Airflow volume (m3/h)

module layout and the direct outside-air cooling systems.

Chimney height (m)Figure 9: Test of the Chimney Effect (2012)*Patent no.: 6153772 (granted June 9, 2017)

Figure 10: Chimney Effect Test Results(excerpt: change in airflow volume according to chimney height)© Internet Initiative Japan Inc.

29

■ Side-Flow Air Conditioning

and the heat generated by the servers can be dissipated by

Shiroi DCC uses a side-flow system (IDC-SFLOW, a trademark

blowing air via the inlets into the server room at a slow

of Takasago Thermal Engineering Co., Ltd.) that supplies

airflow rate of 2m/s. This made it possible to greatly reduce

cool air directly into the server room via the partition wall

(to around a third) the amount of power consumed by the

between the server room and the air conditioner room

air conditioning system’s ventilation fans. The low airflow(Figure 11).

rate also makes for a better working environment in theserver rooms and greatly reduces the stress on workers.

Data centers housed in buildings often employ floor ventilation
with air supplied via the space under a raised, free-access■ Direct Outside-Air Coolingfloor. Space is tight, however, and the speed of airflow

Shiroi DCC uses direct outside-air cooling systems that arethrough the server room inlet (free-access grille) is high.

integrated with the system modules. Air is drawn into the air

This sort of design also has communications and power

conditioner room via intake ports on the eaves on the side ofcables routed through the same space, which increases air

the system module, passing through a medium-performance

supply resistance and results in a greater loss of pressure.

filter, and then mixed with server exhaust heat and supplied

A large pressure loss means more energy is required forinto the server room at a set temperature and humidity. And

air conditioning, so the ventilation fans use more power.

server exhaust heat, in the same amount as the outside air

Shiroi DCC’s wall-based side-flow air conditioning uses thedrawn in via the eaves, is expelled via exhaust ports at thesystem modules’ characteristically large space, large aper-

top of the building.

tures, and wide span as the air supply air route. The inlet
openings are designed to be as large as possible so that

Figure 12 shows the basic plan for a large-scale data center

when air is blown through the server room, air supply re-created in 2012. At the time, there was skepticism within IIJ

sistance is lower and the pressure loss is thus minimized.

about whether we could actually build something like this.

Shiroi DCC is designed to use an average of 6kW/rack,

But the direct outside-air cooling systems designed on top

Wall-mounted side-flow outlets

Figure 11: Side-flow Air Conditioner Outlets

ExhaustHot area A/C

Chimney

Exhaust port

Outside air

Inlet port

Hot aisle capping

Above ceiling(hot area)

Outside air

Cold area A/C

Below ceiling(cold area)

Server racks

Server room

Figure 12: Modular Data Center Design Proposal
at Time of Chimney Effect Testing (2012)30

A/C plant
room

Cross-section of A-A’

Figure 13: Cross-sectional View of Shiroi DCC System Module (2019)© Internet Initiative Japan Inc.

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3. Focused Research (2)of knowhow gleaned from Matsue DCP and technical tests

etc. When Matsue Site 2 went into service in 2013, we de-on the chimney effect and the like culminated, after almost

veloped co-IZmo/D, a new type of containerized data center

10 years of effort, in Shiroi DCC as depicted in Figure 13.

module that uses year-round outside-air cooling, and started
conducting a whole series of tests (Figure 14). co-IZmo/D■ Using AI to Optimize Air Conditioning Systems

integrates air conditioning features and IT equipment modules

At Shiroi DCC, we use AI to find the optimal combination

into an ISO-standard 20-foot container without the use ofof parameters for not only the air conditioners but the IT

external air conditioners or humidifiers. In one of our tests,

equipment as well. We endeavor to optimize air conditioning

dubbed the 2013 IT Equipment Adaptation Test, we worked

system operating conditions based on metrics of energy

with major IT equipment vendors to evaluate the character-savings, cost savings, and CO2 reductions.

istics of IT equipment in summer and winter in a completely
outside-air air conditioned environment and assessed the■ 2012 Chillerless Tests and 2013 IT Equipment Adaption

health of IT equipment under year-round outside-air cooling.

Tests
The air conditioning systems on the IZmo units in use at

We ran the tests on IT equipment supplied with a maximum

Matsue act as direct outside-air systems during autumn,

air temperature of 35°C/40°C, and the IT equipment

winter, and spring, but during summer, the outside air isfunctioned normally in a high-temperature environment of

shut off and indoor units are used to cool and dehumidify

45°C without any drop in CPU processing performance etc.

(circulation mode), so the energy savings in summer are

In a high-humidity environment, however, we did observe aworse than in the other seasons (autumn/winter/spring

noticeable deterioration in the IT equipment boards. FrompPUE = 1.095, summer pPUE = 1.331). In an effort tothese tests, we concluded that high humidity would reduce

resolve these issues, we did an assessment of data center

IT equipment operating life and increase fault rates. The

health under a scenario of using outside-air cooling year

tests also revealed that the rotation speed characteristics

round and not running the external air conditioners, chillers,of IT equipment internal fans vary a bit depending on the

Figure 14: co-IZmo/D© Internet Initiative Japan Inc.

31

IT equipment manufacturer’s design (Figure 15). From atemperature, actual IT equipment current draw, amount offacilities perspective, letting server room temperature riseheat processed, and so forth are taken and analyzed while

by 1°C will save on air conditioner power consumption.

the facility is in operation to provide (rule-based) estimates

But with tens of thousands of IT equipment units all runningof the characteristics of each individual rack. Similarly, air

in a unique way as the temperature rises, the power

conditioning system characteristics are estimated based

consumption of those units also changes. To maintain dataon certain operating conditions, parameters, and so forth,center quality and achieve true energy savings, therefore,

and a rule engine infers the operational settings that will

we determined that, instead of simply raising server room

minimize the combined power consumption of the IT equip-

temperature, we should understand the individual

ment and air conditioning systems, with the result being

characteristics of the IT equipment and control operations

to optimize air conditioning system operating conditions.

to be jointly optimal for both the IT equipment and thefacility itself.

So we have deployed the direct outside-air cooling systems
developed at Matsue on system modules that minimize■ AI Control

pressure loss by virtue of a large space, large apertures,

Shirai DCC uses AI-based air conditioning control thatand wide span, and combined this with AI control, and we

minimizes the combined power consumption of the IT

intend to proactively adopt new technologies going forward,

equipment and air conditioning systems, the main data

our ultimate goal being to achieve an annual average PUE

center elements, based on what we learned from ourof under 1.2.

testing efforts, including chillerless operation tests and IT
We have chased energy savings at Matsue DCP throughtures (as measured in Shiroi DCC’s test environment) are

the use of outside-air cooling and air conditioning units

recorded in a database, and measurements of server roomwith high COP scores, and by selecting high-efficiency IT

RPM■ Lithium-ion Batteries

such as rated current and current draw at different tempera-

RPM

equipment adaptation tests. IT equipment characteristics

Cold area temperature (°C)

RPM

RPM

Cold area temperature (°C)

Cold area temperature (°C)

Cold area temperature (°C)

Figure 15: IT Equipment Internal Fan Rotation Speed Characteristics by Manufacturer (Chillerless Tests, 2012)32© Internet Initiative Japan Inc.

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3. Focused Research (2)equipment. Air conditioning systems and IT equipment are

peak shaving at a similar cost level to the lead-acid battery

always the main factor in data center energy savings. The

UPS. Powerpack enables peak shaving and load shifting

key element in a data center, however, is the power system.

with respect to the power received by the data center,

We see the power system as the next key avenue for saving

which peaks during summer daytimes. It makes it possibleenergy. Accordingly, we adopted a three-phase four-wire

to reduce basic charges by reducing the demanded power

UPS and bus ducts at Matsue DCP Site 2, and we also con-and to reduce electricity charges by using power at off-tinue to evaluate software for predicting electricity usage

peak times and thus purchasing electricity at lower prices

and for peak-shaving control, and continue to devise and(Figure 17).

evaluate mechanisms for the selective supply of power fromfuel cells, PV systems, and DC UPS systems.

In the past, UPS systems, emergency generators, and othersuch power systems played a behind-the-scenes role in

Before designing Shiroi DCC, we also conducted a tech-ensuring high quality. At Shiroi DCC, we are working tonology survey, mainly looking at lithium-ion batteries, with

develop a new business model by actively looking for morea focus on two particular themes: (i) highly economicallyways to use such systems as data center energy resources.

viable power generation systems based on summer usage,
peak usage, etc. and (ii) electricity/power systems capable

3.4 Carbon Neutral Data Center Modelof delivering high efficiency in view of future technology■ IIJ’s Carbon Status and Road to Carbon Neutrality

trends. Based on this, we selected Powerpack, a lithium-ion

Manufacturing industries are being called on to reduce

battery storage solution from Tesla that offers operating

the CO2 emissions that result from making products incontrol features, installing it in November 2019 (Figure

factories, and the transport industry to reduce the CO216). Powerpack replaced the lead-acid battery UPS that weemissions from trucks. Given that over 90% of IIJ’s CO2

initially intended to install as a backup power supply for thecan be traced back to the power consumed by its data

air conditioning systems, and it offers the added feature ofcenters, the use of energy-saving equipment and renewables

Electricity (kW)Load shifting means electricity
can be bought at cheaper
off-peak prices
Load

Fluctuation
in A/C power
through day/night

Large

Discharging
Charging

Fluctuationin IT load
through day/night

Air conditioning power

Charging

Power for lighting etc.

Small

IT power

00:00

Figure 16: Powerpack installed at Shiroi DCC

Cutting peak usage
reduces demand rates

12:00

24:00

Figure 17: Data Center Power Demand and Peak Shaving/ Peak Load Shifting© Internet Initiative Japan Inc.

33

directly impacts on the carbon neutrality status of IIJ as

Although renewable generation costs are falling, power

a whole.

generated from non-solar sources including wind andbiomass remains more expensive than ordinary power

We plan to continuously improve the energy-saving tech-purchased from electric utilities. And building a power

nologies implemented at Matsue DCP and Shiroi DCC

plant will take time, including the time needed to obtainas described above to make the facilities even morea suitable site, so it is more realistic as a medium- toenergy efficient. Meanwhile, we have only just started

long-term proposition. Near term, we need to implement

working on the use of renewable energy, and one of themechanisms for the supply of power with a focus onearly possibilities for tackling this will be to switch tosolar, or photovoltaic (PV), generation.

an electricity retailer supply contract for the supply of
renewable energy certified as non-fossil fuel electricity.

■ Carbon Neutral Data Center Model

There are disadvantages, however. Renewable energy is

In light of all this, with a view to achieving carbon

more expensive than ordinary electricity, and there is noneutrality, we have defined a carbon-neutral data center

guarantee that it will be supplied at a stable price overreference model with the features listed in Table 1, andthe long term. So with the cost of generating renewable

we plan to continue modifying our data centers andenergy falling year by year, possible next steps may be tobuilding new ones in this light.

buy electricity directly from renewable energy plants or tohave our own generation plants.

No.

Feature1

Use of energy-saving technologies, such as outside-air cooling systems that substantially reduce air conditioning power consumption and an efficient three-phase four-wire
UPS, to reduce absolute power consumption levels.

2

Absence of other equipment and fixtures on building roofs to make large roof areas available for the installation of on-site PV systems.

3

In the short term, procure power from a combination of extra-high-voltage, high-voltage, and low-voltage off-site PV systems. Long term, allow for the possibility of procuring
power from other sources such as wind and hydrogen.

4

When daytime power supply exceeds consumption, store the excess in batteries for use at night.

5

Use of network measurement and control functions between generation equipment and the data center to balance the amount of power generated and the amount consumed.

6

Use of IT load control to channel loads toward times of surplus power.

Table 1: Features of a Carbon-Neutral Data Center

Type of facility

Office building

Warehouse

Conventional data center

Carbon-neutral data
centerPower consumption

Low

Low

Medium to highMedium to highPower density

Low

Low

High

High

On-site PV installation space

Small
Typically, external A/C units etc.
are installed on rooftops

MediumLarge-scale rooftop installations
possible

Small to medium
Similar to office buildings, but
dedicated equipment can be used
to create space

MediumRoof structure allows forlarge-scale rooftop installations

Generated
Consumed

Electric power

Typical daily power profile

Morning

Noon

Night

Morning

Noon

Night

Morning

Noon

Table 2: Differences in Electric Power by Type of Facility

34© Internet Initiative Japan Inc.

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Morning

Noon

Night

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3. Focused Research (2)The first feature is the use of energy-saving technology

3 shows, off-site PV is more expensive than on-site PV,

to the greatest possible extent to reduce absolute power

but increasing off-site PV capacity is a viable option for

consumption.

securing the required amount of power.

The second feature is the installation of as much on-site PV

Off-site PV systems can be classified into three types according

generation capacity as possible, as the cost of generating

to the voltage at which they connect to the power grid,electricity this way is now lower than ordinary electricity

as shown in Table 4. To adequately supply a several-doz-charges. As Table 2 shows, data centers bring together

en-MW-scale data center, a large, extra-high-voltage PV

vast amounts of IT equipment and thus consume several

system is efficient, but these tend to take a long time todozen times more power per unit floor area than officebuild because you have to find a suitably large site, nego-buildings and the like (said to be around 50–100W/m ). As

tiate connection terms and conditions with the electric

they consume so much in absolute terms, PV generation

utility, and so forth. The high-voltage and low-voltage

alone cannot keep up with demand for power across theoptions are quicker to build, but if you want to generate

entire data center. But by adopting a warehouse-like build-the same amount of power as a 50MW extra-high-volt-ing structure and making the roof, where PV systems are

age PV installation, for example, you will need 1,000

installed, as large as possible, you can increase low-cost

50KW low-voltage generation plants. Given the amounton-site PV generation capacity.

of power required and time required, we think off-site

2

PV power needs to be sourced from a combination
The third feature is the installation of off-site powerof extra-high-voltage, high-voltage, and low-voltage

generation equipment (off-site equipment that supplies

systems.

power to your site via the power utility grid). As Table

System typeOn-site PV

Off-site PV

Characteristics

・No need for a dedicated site if installed on your building rooftops etc.

・Initial costs, including those for the land, are higher than for on-site if you take・In contrast with off-site PV, involves no wheeling charges or renewableenergy levies, and use of subsidies can make it even more cost effective.

on the capital investment yourself.
・Need to enter into long-term contracts if having power supplied from another

・But scale is small (can only supply a few percent of total data center usage).

company’s equipment.
・Involves wheeling costs as power is supplied via the power utility grid.
・Systems/procedures can change.
・Can adjust the amount of power generated by increasing scale or adding
plants.

Table 3: Differences Between On-site and Off-site PV

Power grid connection

Extra-high-voltage

High-voltage

Low-voltage

voltage

2,000kW or more

500–2,000kW

up to 50kW

Required site area (at 10m2/KW)

20,000m2 (2ha) or more

500m2 – 20,000m2 (2ha)up to 500m2

Initial investment

22.2 yen/kW

22.2–25.5 yen/kW

25.5 yen/kW

440mn yen or more

13–440mn yen

up to 13mn yen

Construction period

1 year or more

up to 1 year

up to 6 months

No. plants needed for 50MW output

5MW/plant

500kW/plant

50kW/plant

10 plants

100 plants

1,000 plants

Table 4: PV System Categories© Internet Initiative Japan Inc.

35

Storage is the fourth feature required for carbon-neutral data

The sixth feature is the use of IT load control, which involves,centers. As Figure 18 illustrates, as off-site PV increases,

for example, halting servers on nights when there is not

the power supplied by PV capacity in the daytime canenough power and only running them in the day, so thatovershoot data center power consumption, in which casethe load is channeled toward times when there is surplus

it is stored and used at night. This makes it possible topower. Information systems generally cannot be stopped

use renewable energy at night as well, but the fact thatfor 24 hours at a time, but we can expect more and more

the cost of storage batteries is still high is an obstacle to

new use cases amenable to load control to appear—data

the full-fledged rollout of such systems.

analysis tasks that can be given a manageable timeframe tocomplete or mining tasks that require low-cost processing.

The fifth feature is the use of network functions thatenable measurement and control of what happens between

Figure 19 illustrates how a carbon-neutral data center withthe power generation equipment and the data center. This

these features could be set up. To realize carbon neutrality

makes it possible to balance supply and demand and ensure

while maintaining the reliability and other quality attributes

the stable operation of the grid.

required of a data center, we need to create a new model

Electric
power
Load balancing
using storage batteries

50MW
Data center
power consumption

Non-PV
renewable energy

Powerfrom PV plants

Night

Day

Night

Figure 18: Data Center Power Supply/Demand Overview

Extra-high-voltage (2000kW or more)
5MW × 10 = 50MW

High-voltage (up to 2000kW)
500kW × 100 = 50MW

Low-voltage (up to 50kW)
50kW × 1000 = 50MW

Off-site PV plants

Measurement/control network
Power gridWind, hydrogen, biomass power, etc.

Load balancing battery(includes imbalance correction)

On-site PV

Figure 19: Carbon-Neutral Data Center Model

36© Internet Initiative Japan Inc.

Feb.2022

Vol.

53

3. Focused Research (2)that organically combines the generation equipment that

JCM (Joint Crediting Mechanism) to reduce greenhousesupplies the power and the data center that consumes thatgas emissions, as part of which IIJ provided support for

power. While we only have a conceptual model to illuminate

the construction and operation of a highly energy-efficient

the way forward at this stage, we will be conducting technicalcontainerized data center in the Laotian capital of Vientiane.

tests and working with external partners going forward, onboth the business and technological fronts, to sort out the

The road to carbon neutrality will no doubt be long anddetails and apply what we have learned when modifying ourchallenging, but we will continue to take advantage ofown data centers or building new ones.

Internet technologies, including IoT and mobile, and test
and implement systems, and we will seek to apply the

3.5 Conclusion

knowledge and insight we gain not just internally at IIJ

IIJ has also been involved in external initiatives using the

but also in the world at large, our aim being to contributetechnologies it has developed in-house, one example being a

toward carbon neutrality in the data center and, ultimately,

NEDO (New Energy and Industrial Technology Development

across society as a whole.

Organization) demonstration project aimed at using the

Isao Kubo
General Manager, Infrastructure Services Department, Infrastructure Engineering Division, IIJ.
Mr. Kubo joined IIJ in 2008. He oversees the data center business and the construction of Matsue DCP and Shiroi DCC. His aim is toachieve carbon neutrality as soon as possible.

3.2 Outcomes at Matsue Data Center Park
Yoshimasa Kano
Manager, Matsue Data Center Park, Infrastructure Services Department, Infrastructure Engineering Division, IIJ.
Mr. Kano joined IIJ in 2016. He is engaged in the operation of containerized data centers and the testing of next-generation modular data centers.

3.3 Initiatives at Shiroi Data Center Campus
Akio Hashimoto
Deputy General Manager, Infrastructure Services Department, Infrastructure Engineering Division, IIJ.
Director, Shiroi Data Center Campus, Infrastructure Services Department, Infrastructure Engineering Division, IIJ.
Mr. Hashimoto joined IIJ in 2009. He works on the study and design, construction, and operation of next-generation data centers andactively pursues data center automation and efficiency gains.

© Internet Initiative Japan Inc.

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