The decisions that go into designing a new data center will stay in place for many years to come. For instance, the cooling solutions we put into a new data center often determine how the facility will consume vital resources such as water and energy. Equinix is committed to using water responsibly, which means we include a number of considerations about the local water context as we design our data centers, and we operate them efficiently.
Last year, we were designing a new data center project in an area where the public had concerns about water stress. The facility was originally intended to use evaporative cooling, which relies on evaporating water to cool the building. The benefit of this approach is that it is substantially more energy efficient than cooling systems that don’t use water.
We conducted an in-depth water stress analysis to gain a more comprehensive understanding of the local water context. This analysis included assessing physical water availability, infrastructure and local resiliency planning to understand how prepared the metro was in case of increased water stress.
While we learned that the metro was well prepared for a drought or other increases in water stress, we decided to switch the building cooling system to use air cooling. Since air cooling consumes substantially less water, this allowed us to proactively align with local concerns about water stress and reflect our commitment to minimizing our impact. However, air cooling also consumes more energy, which is why it isn’t right for every location.
When it comes to balancing the tradeoffs between water and energy consumption, getting it right during the design phase is essential, as there are only opportunities for incremental water efficiency improvements after a data center is operational.
What is water stress?
According to the Pacific Institute, a leading research institute focused on water issues, water scarcity refers only to volumetric availability: the ratio of human water consumption to available water supply in an area.[1] In contrast, water stress is a broader, more inclusive concept. Water scarcity is one aspect of water stress, but it also includes other physical factors, such as water quality and environmental flows, and economic factors such as water accessibility.
Source: Adapted for the Pacific Institute blog by Peter Schulte
At Equinix, understanding the local water context, including water stress levels, is the foundation of our approach to using water responsibly. In 2023, we codified our commitment to avoid using evaporative cooling in areas with high water stress. This is significant because using evaporative cooling is by far the largest driver of water consumption in data centers.
How does data center cooling impact water consumption?
As IT equipment runs in data centers, it creates heat, and that heat has to go somewhere. Otherwise, the equipment will overheat, and the data center will be unable to provide the reliable service that makes our digital world possible.
Choosing a cooling solution will determine how a facility consumes water and energy, which are both essential aspects of any data center operator’s sustainability strategy. What not everyone knows is that data centers need cooling systems at both the server level and the building level. As servers generate heat, the server-level cooling system moves the heat away from the servers to a heat exchanger, which transfers the heat to the building-level system. The building-level system then rejects the heat from the building.
There are different options for both server-level cooling and building-level cooling:
- At the server level, air cooling has long been the standard practice, but liquid cooling is becoming more prevalent as businesses look to support higher server density for AI and other compute-intensive workloads. One of the misconceptions about liquid cooling is that it’s the same as evaporative cooling. However, unlike evaporative cooling, liquid cooling doesn’t necessarily increase water consumption. This is because it uses a small amount of water moving continuously in a closed loop, rather than being evaporated.
- At the building level, the two primary methods for rejecting heat from a data center are air cooling, also known as dry cooling, and evaporative cooling. Evaporative cooling can reject the same amount of heat as air cooling while consuming significantly less energy. However, it also consumes significantly more water via evaporation.
Data center designers will typically choose between air cooling and evaporative cooling based on the unique climate conditions of each specific location. They’ll consider the local climate (weather), power availability, water stress and other factors when determining the most suitable cooling system. For instance, evaporative cooling can be particularly effective in managing energy usage in areas with power-constrained grids. In contrast, avoiding evaporative cooling in water-stressed areas minimizes water consumption, thus ensuring more water remains available for use in the community.
As previously mentioned, balancing this tradeoff is at the core of our responsible water strategy. As of 2023, Equinix uses evaporative cooling at only 40% of our data centers globally.
We also take advantage of alternative cooling methods where local conditions allow:
- Geothermal cooling methods such as aquifer thermal energy storage (ATES) and deep lake water cooling (DLWC) utilize natural cooling provided by the earth’s thermal mass. They draw cold water from large natural sources to circulate through the building-level cooling system, thus causing the water to absorb heat from the heat exchanger. Rather than rejecting it into the atmosphere via evaporating the water, geothermal cooling returns water to its original source. Therefore, the process doesn’t consume water. Similarly, one of our data centers in Toronto uses a DLWC system that pulls cold water from the depths of Lake Ontario. With this approach, we’ve reduced total energy needs for this data center by 50%[2], without increasing water consumption.
- Data center heat export allows a portion of the heat in a data center to be transferred to a third-party heat network rather than being rejected into the atmosphere. The heat can then be used for heating homes and businesses. This not only avoids unnecessary water consumption in other buildings’ cooling systems, but it also provides a low-carbon heat source for communities. Equinix is pursuing heat export in select locations worldwide. In Paris, heat recovered from our PA10 data center is transferred to the Plaine Saulnier urban development zone, including a swimming pool used at the recent Paris Summer Olympics.
Improving transparency around water consumption
At Equinix, we recognize that many of our stakeholders want to know more about how we use water and how we’re working to use it more responsibly. That’s why we’ve recently taken steps to increase transparency on our water use.
In 2023, we disclosed our water metrics via the CDP water security initiative for the first time.[3] It was also our first year including water metrics in our annual sustainability report. Those metrics show that we:
- Withdrew 5,970 megaliters of water in 2023. This is roughly equivalent to the annual water usage of 14,400 average U.S. homes, or a very small town.[4] About 25% of the amount that we withdrew came from non-potable sources.
- Consumed about 60% (3,580 megaliters) of the water we withdrew at our data centers, mainly via evaporative cooling.
- Discharged the remaining 40%, typically to the local municipal wastewater system.
In addition to our water optimization efforts summarized above, our operations team has been developing and implementing water efficiency best practices and improving our water metering systems at all existing data centers that use evaporative cooling.
Externally, we are collaborating with our peers and industry working groups to develop measurement frameworks and standards to support water reporting efforts. Earlier this year, we joined the California Water Action Collaborative, a network of diverse stakeholders pursuing collective action projects that improve water security in Equinix’s home state.[5]
We’re also currently co-funding our first offsite nature project in Finland with Neoen, our local renewable energy partner. Together, we’re working to restore 50 hectares of high-value peatland and streams. Since offsite projects like this one often provide both water and biodiversity benefits, we’re sponsoring the development of a framework to account for biodiversity benefits along with water benefits from these kinds of projects.[6]
To learn more about Equinix’s sustainability actions, including responsible resource consumption, access our interactive sustainability report.
[1] Peter Schulte, Defining Water Scarcity, Water Stress, and Water Risk, The Pacific Institute.
[2] Raouf Abdel, 10 Ways Equinix is Advancing Responsible Water Consumption, Equinix Interconnections blog, March 25, 2019.
[3] Water security, CDP
[4] The average U.S. household uses 300 gallons of water per day, or 109,500 gallons (.414 megaliters) per year. Source: How We Use Water, United States Environmental Protection Agency.
[5] California Water Action Collaborative
[6] Nature’s Balance Sheet: Introducing Biodiversity Benefit Accounting, CEO Water Mandate
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