The increasing use of data centers, which serve as digital infrastructure, helps society as a whole
to save energy, but as the market expands in size, the energy use of the infrastructure itself is
becoming an issue that must be dealt with. The Japanese government's Green Growth Strategy sets
targets for a wide range of industries, including the following targets for data centers:
・ By
2030, all new data centers should achieve 30% energy savings, and data centers should use renewable
energy for a portion of their energy requirements.
・ Achieve carbon-neutral data centers by
2040.
At IIJ, we see efforts to reduce greenhouse gas emissions through the use of renewable energy
and improvements in energy efficiency at data centers, which account for over 70% of our greenhouse
gas emissions (Scope 1 and 2), as a priority, and as such, we have set goals for our efforts as shown
below. We have also acquired the ISO 14001 certification of our data centers. It is the international standard for environmental management systems. We are also working to improve environmental performance, including in terms of carbon neutrality.
| Measure | Goals |
|---|---|
| Use of renewable energy | We aim to raise our data centers' (Scope 1 and 2) renewable energy usage rate to 85% by FY2030. |
| Improve energy efficiency | Through ongoing technological innovation out to FY2030, we aim to have the PUE*1 readings of our data centers below the industry ceiling*2. |
*1. PUE (power usage effectiveness): Total data center facility energy consumption / IT equipment energy consumption
*2. Industry PUE ceiling: PUE of 1.4 or lower (as of April 2022, the Agency for Natural Resources and Energy has set the benchmark index and target level for the data center industry to be a PUE of 1.4 or lower; businesses that achieve this are regarded as energy-saving leaders).
Reference: https://www.iij.ad.jp/en/ir/integrated-report/tcfd/
Energy-saving initiatives
Outside air cooling
Here, we will examine energy-saving technologies that we are using at IIJ data centers to achieve carbon neutrality. Actively using outside air is one potential method of reducing the energy used in the cooling of IT equipment, which is the most power-hungry aspect of data center facilities. Using air from outside the facility to cool IT equipment helps minimize the amount of time the air-conditioning equipment (compressors and chillers*) is running, and this is the main energy-consuming equipment in the data center facilities.
*Compressors: Devices used in cooling systems that cool air by compressing refrigerant gases.
Chillers: Devices used in cooling systems that cool by circulating cold water and exchanging heat.
Cooling systems that use outside air can use either direct outside-air cooling or indirect
outside-air cooling. True to its name, direct outside-air cooling uses outside air to directly cool IT equipment. This uses less energy than indirect methods that uses the cold of outside air to condition indoor air via a heat exchanger. However, because outside air comes into direct contact with the IT equipment, air quality and other aspects of the environment in which the system is installed must be considered. IIJ uses direct outside-air cooling systems at its Shiroi Data Center Campus and in the air-conditioning modules of the IT modules (IZmo) at
its Matsue Data Center Park.
Here, we use the air-conditioning modules as an example to explain
the way in which the direct outside-air cooling systems are controlled in order to cool the IT
equipment. Although the temperature and humidity of outside air fluctuate and are thus not constant,
we need to use that outside air to continuously maintain the required temperature and humidity in
the environment in which the IT equipment is installed. The air-conditioning modules have three
operation modes for creating the required temperature and humidity.
1. Outside air mode
Used when outside air conditions are suitable for cooling IT equipment. The outside air is supplied to the IT equipment intake as is, and the IT equipment waste heat is simply expelled. Only the fans consume power in this mode, so energy-saving performance is high.
2. Mixing mode
It is used mainly in the winter when it is too cold to supply outside air directly to IT equipment. IT equipment constantly emits warm exhaust air, so a damper is opened/closed to achieve the right mix of outside air and warm IT equipment exhaust, making the temperature suitable for IT equipment air intake. The only power consumed is that used to run the fans plus a negligible amount for actuating the damper, so this mode has excellent energy-saving performance.
3. Circulation mode
It is used mainly in the summer when the outside air is too hot to be used to cool IT equipment. The air-conditioning module actuates a damper to close the outside air intake and exhaust ports, and it runs a compressor. Its energy-saving performance is inferior to the outside air and mixed modes.
With our co-IZmo/D modules, which integrate air-conditioning and IT equipment into a single unit, our goal was to save even more energy by using a year-round direct outside-air cooling system that manages humidity and temperature using only outside air and without the use of chillers and humidifiers. Our demonstration tests showed that we could reduce air-conditioning power consumption, but the IT equipment consumed more power because of increased fan speed, so while pPUE* did improve, our work has also revealed that we need to optimize IT equipment and air-conditioning control if we are to reduce total power consumption.
*pPUE (partial Power Usage Effectiveness): While PUE is an indicator of the energy efficiency of the data center as a whole, pPUE is an indicator of the energy efficiency of specific parts of the data center, such as modules and rooms.
Indirect outside-air cooling is less efficient than the direct method, but it has the advantage of being able to use outside air for cooling even in environments where outside air quality is poor. IIJ uses indirect outside-air cooling on its co-IZmo/I modules integrating IT equipment and air conditioning, and this contributes to the high degree of flexibility co-IZmo/I offers in terms of installation location.
Here, we use the air-conditioning control on co-IZmo/I as an example to explain the way in which the indirect outside-air cooling systems are controlled in order to cool the IT equipment. The basic concept is the same as for the air-conditioning modules that use direct outside-air cooling, with the difference being that a heat exchanger is used to prevent outside air from being drawn directly into the IT equipment.
1. Indirect outside-air mode
Used when the IT equipment can be cooled using outside-air heat exchange only (mainly in winter). Fans are the main power consumers, so energy-saving performance is high.
2. indirect outside-air + refrigeration hybrid mode
It is used when IT equipment cannot be cooled using outside-air heat exchangers alone (mainly in in-between periods such as autumn and spring). The system runs a compressor but also uses outside air, so power consumption is lower than when cooling using a compressor alone.
3. Circulation mode
Used mainly in summer when outside air is too hot for IT equipment intake.
It is used mainly in the summer when the outside air is too hot to be used to cool IT equipment.
When it comes to cooling IT equipment at IIJ, we endeavor to save energy not only on the hardware
front but also via software. One way we are doing this is by using AI for air-conditioning control,
which we are testing at Shiroi Data Center Campus. The status of data centers is monitored, including the status of equipment operations, and AI is used to determine the optimal air-conditioning settings for the environment to ensure that energy savings are realized. We plan to connect systems more closely to IT equipment in the future and increase the amount of feedback air-conditioning control systems receive in the future, so that control schemes include the IT equipment side of operations as well.
Three-phase four-wire power distribution
As an energy-saving measure, we use a three-phase four-wire power distribution system for electrical equipment. Conventionally, data centers in Japan have used a 100V AC power supply, as this
is the most versatile system available in Japan. Amid the rise of cloud computing, cloud providers
have themselves begun to build data center facilities suitable for cloud infrastructure, and it is now
possible within such cloud infrastructure facilities to use 200V AC, instead of 100V AC, as standard.
To increase efficiency, IIJ has revised its power distribution systems and adopted 200V AC systems
throughout Matsue Data Center Park and Shiroi Data Center Campus. This has made it possible to reduce the current flowing through the power delivery paths, enabling us to suppress the voltage drop, increase power supply efficiency, and reduced the size of power cables.
In data centers, uninterruptible power supplies are used to provide IT equipment with a high-quality power supply with a constant voltage and frequency. Typical UPS outputs include three-phase three-wire 400V AC and three-phase four-wire 400V AC. Typically, a UPS outputs three-phase three-wire 400 V AC and three-phase four-wire 400 V AC. Both systems output at 400 V, but three-phase three-wire systems use a transformer to step down to 100 V and 200 V AC, the operating voltages of IT equipment. Three-phase four-wire systems are capable of directly providing a 230 V AC power supply. Stepping down
using a transformer involves power loss, so three-phase four-wire systems offer better power supply
efficiency. Three-phase four-wire systems are widely used in data centers overseas and are now
increasingly being adopted in data centers in Japan. IIJ was a first-mover in Japan with the use of
three-phase four-wire systems on IZmo ver. 2 (November 2013) modules at Matuse Data Center Park, and
it has adopted such systems at Shiroi Data Center Campus as well.
One metric for measuring how efficiently a data center uses power is PUE*, with a PUE reading closer to 1.0 indicating better efficiency. Matsue Data Center Park has a PUE in the 1.3 range and Shiroi Data Center Campus is designed for a PUE in the 1.2 range. Japan's Act on the Rational Use of Energy (the “Energy Saving Act”) was revised in 2022 to add data centers to the list of industries subject to its benchmark system, with a benchmark target of a PUE of 1.4 or lower being set, so both data centers can be considered highly energy efficient in this sense.
*PUE is calculated by dividing a data center's total power consumption by the power consumption of its IT equipment (servers, etc.). The greater the power consumed by the data center's equipment other than its IT equipment, including its air-conditioning systems, the higher the PUE.
