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With the current situation the world finds itself in one thing has become abundantly clear, data centers have provided people a safe haven in their own homes whilst lockdowns have been enforced across the globe, at one point half of the human race was in lockdown in one form or another.

There have been both positives and negatives that have arisen from this though, from the ‘key worker’ status held by data center employees and their primary suppliers highlighting how governments across the world perceive the industry and its need, through to a sterner examination from the wider world on energy consumption and water usage.

Uptime and reliability have always driven the major data center design philosophy, trade-offs have been made, understandably, in order for comfort to be achieved for the operators and owners to be safe in the knowledge that design and variability across sites maintains consistency and brings down the risk of misalignment or calculation.

Whilst data centers are more efficient than they have ever been on a whole, there is still a vast amount of improvement that can be made, in particular on both energy consumption for cooling and the consumption of water in the requirement for adiabatic cooling.

China

One of the major active equipment manufacturers has openly said that a realistic figure for water use per mW can be 68,000 litres of water a day.  Unfortunately information is scarce and so a conservative figure of 1000mW can be used across the country, this would potentially give a usage of around 68 million litres of water per day.

India

One of the major active equipment manufacturers has openly said that a realistic figure for water use per mW can be 68,000 litres of water a day.  Whilst public information is scarce a very conservative figure for water usage is around 34 million litres of water a day in the Indian market,   utilised for cooling based on 500mW cooling capacity across the country.

The Nordics

One of the major active equipment manufacturers has openly said that a realistic figure for water use per mW can be 68,000 litres of water a day.  Whilst public information is scarce a very conservative figure for water usage is around 20 million litres of water a day in the Nordics, utilised for cooling. However importantly a large proportion of data centre owners have utilised the areas climate to reduce the mechanical power requirement, which whilst increasing water usage will provide greater overall efficiency for traditional systems.

London

One of the major active equipment manufacturers has openly said that a realistic figure for water use per mW can be 68,000 litres of water a day.  Even if you only take the 13 largest data centre operations in the UK then this would equate to 58,412,000 litres of water that are wasted each day.

San Francisco bay area

In 2014 Lawrence Berkeley National Laboratory in California issued a report that 639 billion liters of water were used in the USA alone on data center cooling, in 2020 the forecasted usage figure was predicted to be a startling 674 billion liters of water. 

What is adiabatic cooling?

The reason that water is used in these data center cooling solutions is traditionally to obtain the lowest possible air temperature entering the external plant and therefore extracting as much of the heat from the data center using the natural environment before the mechanical chiller needs to be implemented.

In any air content there are two temperature points, Dry Bulb (DB) and Wet Bulb (WB), the dry bulb is what you would feel if you were dry, the best way to describe wet bulb is when you walk out of the shower before you manage to get to the towel! The water on your body enables the air to reach the temperature of the relative humidity as you move through it, this is always equal to or lower than the DB temperature.

For example if the DB temperature in a room is 20°C/70°F and the WB temperature is 14°C/57°F then, if a wet object or air is pushed through a wet area or membrane the temperature would potentially reach the WB temperature, that is until the object is heated or dried.

Why is this usage so high?

The usage of water is inversely proportional to the water temperature flow to the data centre internal cooling equipment. The lower the temperature of the water flow into the data centre the higher the water usage by the external plant. Traditional plant has a normal water flow temperature of 7°C/45°F which means the highest temperature that you could potentially utilise naturally to get to the desired flow temperature is 5°C/41°F.

How can you improve this usage?

The best possible way to reduce the usage is to elevate the water temperature that the data centre requires in order to cool the equipment efficiently and effectively, the rear door cooler is a great example of this because, unlike traditional CRAC systems, instead of using colder air to mix with warm air to provide an ambient you are instead neutralising the air itself and therefore you can use a higher water temperature to obtain the same result. The graphs below show the average high temperature for DB and WB over a thirty year period.

China
China 1 WUE Graph
China 2 WUE Graph

As you can see above China provides a challenging environment for any cooling requirement, particularly in summer, with high DB temperatures and relatively high WB temperatures to suit.

The important factor here is that anything above the blue line can utilise the DB and therefore not require any additional water usage. Anything between the blue line and the orange line can be cooled using an adiabatic system and this is where the water usage would come into being. Anything beneath the orange line would require additional mechanical cooling such as a traditional chiller system, this would then be using maximum water and additional power for the mechanical equipment.

India
India 1 WUE Graph
India 2 WUE Graph

As you can see above India provides a challenging environment for any cooling requirement, with high DB temperatures and relatively high WB temperatures to suit.

The important factor here is that anything above the blue line can utilise the DB and therefore not require any additional water usage. Anything between the blue line and the orange line can be cooled using an adiabatic system and this is where the water usage would come into being. Anything beneath the orange line would require additional mechanical cooling such as a traditional chiller system, this would then be using maximum water and additional power for the mechanical equipment.

The Nordics
Nordics 1 WUE Graph
Nordics 2 WUE Graph

As you can see above the Nordic region provides a very low dry and wet bulb for a large proportion of the year, this helps with efficiency on a whole.

The important factor here is that anything above the blue line can utilise the DB and therefore not require any additional water usage. Anything between the blue line and the orange line can be cooled using an adiabatic system and this is where the water usage would come into being. Anything beneath the orange line would require additional mechanical cooling such as a traditional chiller system, this would then be using maximum water and additional power for the mechanical equipment.

London
London 1 WUE Graph
London 2 WUE Graph

As someone that lives in the UK I can safely say that our weather isn’t always the best, however this gives a wonderful opportunity for eliminating excess water use.

The important factor here is that anything above the blue line can utilise the DB and therefore not require any additional water usage. Anything between the blue line and the orange line can be cooled using an adiabatic system and this is where the water usage would come into being. Anything beneath the orange line would require additional mechanical cooling such as a traditional chiller system, this would then be using maximum water and additional power for the mechanical equipment.

San Francisco bay area
SanFrancisco 1 WUE Graph
SanFrancisco 2 WUE Graph

San Francisco and California in general are blessed for most of the year with the weather but you can above see there is a large variation in DB and WB temperature.

The important factor here is that anything above the blue line can utilise the DB and therefore not require any additional water usage. Anything between the blue line and the orange line can be cooled using an adiabatic system and this is where the water usage would come into being. Anything beneath the orange line would require additional mechanical cooling such as a traditional chiller system, this would then be using maximum water and additional power for the mechanical equipment.

What happens when you implement a ColdLogik rear door?

China
China 3 WUE Graph
China 4 WUE Graph

In the graphs above you can see the marked difference between using a traditional cooling system, which is marked in yellow, and the ColdLogik cooling requirement, marked in Grey.

In China its clear to see that by utilising the traditional approach you would, on average, have a need for the adiabatic system for almost the whole year and you would also require mechanical for half the year in varying load. However, as most chillers have a minimum run of 25% less of the free cooling may be available.

By utilizing the ColdLogik door, on average, you would not need to use any additional water for 6 months of the year to provide adiabatic cooling, you would only require mechanical cooling assistance for around 1-2 months. Chillers would normally remain on site to provide redundancy on the rare occasions that a heat wave outside of the average occurs, however the chillers may not need to be run for 10 months of the year, causing an additional operational saving.

India
India 3 WUE Graph
India 4 WUE Graph

In the graphs above you can see the marked difference between using a traditional cooling system, which is marked in yellow, and the ColdLogik cooling requirement, marked in Grey.

In India its clear to see that by utilising the traditional approach you would, on average, have a need for the adiabatic system for the whole year and you would also require mechanical for the whole year in varying load. However, as most chillers have a minimum run of 25% less free cooling may be used.

By utilizing the ColdLogik door, on average, you would not require any additional mechanical cooling on site for standard operation. This is in the form of chillers with refrigeration circuits, whilst normally these systems would remain on site in order to maintain redundancy in case of exceptional need they would not be required on a regular basis. The water usage would be less for 6 months of the year on the ColdLogik system, this would most likely account for a drop in water usage across this period of around 20%.

The Nordics
Nordics 3 WUE Graph
Nordics 4 WUE Graph

In the graphs above you can see the marked difference between using a traditional cooling system, which is marked in yellow, and the ColdLogik cooling requirement, marked in Grey.

In the case of the Nordic region its clear to see that by utilising the traditional approach you would, on average, have a need for the adiabatic system for two thirds of the year and you would also require mechanical for just under half of the year in varying load. However, as most chillers have a minimum run of 25% less free cooling could be available.

By utilizing the ColdLogik door, on average, you would not need to use any additional water for 9 months of the year to provide adiabatic cooling, you would not require any mechanical assistance through the remaining 3 months either. Chillers would normally remain on site to provide redundancy on the rare occasions that a heat wave outside of the average occurs, however the chillers may not ever need to be run, causing an additional operational saving.

London
London 3 WUE Graph
London 4 WUE Graph

In the graphs above you can see the marked difference between using a traditional cooling system, which is marked in yellow, and the ColdLogik cooling requirement, marked in Grey.

In the case of the United Kingdom and in particular the London area its clear to see that by utilising the traditional approach you would, on average, have a need for the adiabatic system all year round and you would also require mechanical for over half of the year in varying load. However, as most chillers have a minimum run of 25% making less of the free cooling available.

By utilizing the ColdLogik door, on average, you would not need to use any additional water for 8 months of the year to provide adiabatic cooling, you would not require any mechanical assistance through the remaining 4 months either. Chillers would normally remain on site to provide redundancy on the rare occasions that a heat wave outside of the average occurs, however the chillers may not ever need to be run, causing an additional operational saving.

San Francisco bay area
SanFrancisco 3 WUE Graph
SanFrancisco 4 WUE Graph

In the graphs above you can see the marked difference between using a traditional cooling system, which is marked in yellow, and the ColdLogik cooling requirement, marked in Grey.

In the case of San Francisco and the Bay area its clear to see that by utilising the traditional approach you would, on average, have a need for the adiabatic system all year round and you would also require mechanical assistance all year round in varying load. However, as most chillers have a minimum run of 25%, less free cooling could be available.

By utilizing the ColdLogik door, on average, you would not need to use any additional water for 7 months of the year to provide adiabatic cooling, you would not require any mechanical assistance through the remaining 5 months either. Chillers would normally remain on site in order to provide redundancy on the rare occasions that a heat wave outside of the average occurs, however the chillers may not ever need to actually be run, causing an energy saving too.

Conclusion

China

In conclusion, without considering the lower water usage across the remaining 4 months which could be substantial, the ColdLogik door would likely be able to save a minimum of 25% additional water that would otherwise be consumed by the traditional cooling methods.

Translating into physical water usage over the year, and based on the conservative 1tW figure, this could drop the current projected usage figure of 24.82 billion litres of water down to 18.6 billion litres of water which is a 6.2 billion litre drop. This is the equivalent of filling the Birds nest stadium in Beijing with water twice over which was the pinnacle of the 2008 Olympic games.

India

In conclusion, considering the lower water usage across the 6 months, the ColdLogik door would likely be able to save a minimum of 10% additional water that would otherwise be consumed by the traditional cooling methods.

Translating into physical water usage over the year, and based on the publicly available information for India, this could drop the current projected usage figure of 12.37 billion litres of water down to 11.13 billion litres of water which is a 10% drop. In the future, as the Ashrae guidelines are pushed more into the allowable limits, the amount of water that could be saved is limitless.

The Nordics

In conclusion, without considering the lower water usage across the remaining 3 months which could be substantial, the ColdLogik door would likely be able to save a minimum of 50% additional water that would otherwise be consumed by the traditional cooling methods.

Translating into physical water usage over the year, and based on the publicly available information in the Nordic region, this could drop the current projected usage figure of 4.86 billion litres of water down to 2.43 billion litres of water which is a massive 50% drop. This is the equivalent of filling the infamous Blue Lagoon in Iceland a whopping 270 times, which really does give it perspective.

London

In conclusion, without considering the lower water usage across the remaining 4 months which could be substantial, the ColdLogik door would likely be able to save a minimum of 66% additional water that would otherwise be consumed by the traditional cooling methods.

Translating into physical water usage over the year, and based on the 13 largest publicly available data centres in the UK, this could drop the current projected usage figure of 21.32 billion litres of water down to 7.11 billion litres of water which is a 14.21 billion litre drop. This is the equivalent of filling 5550 Olympic swimming pools which would take up an area more than 130 x that which Windsor castle and it’s grounds currently occupies.

San Francisco bay area

In conclusion, without considering the lower water usage across the remaining 5 month which could be substantial, the ColdLogik door would likely be able to save a minimum of 58% additional water that would otherwise be consumed by the traditional cooling methods.

Translating into physical water usage over the year this could drop the current projected figure of 674 billion liters of water down to 283 billion liters of water which is a 391 billion liter drop. This is the equivalent of filling 156,400 Olympic swimming pools which would take up an area 1.5 times that of San Francisco city.

If you are looking to improve your water usage with a product that is tried and tested and deployed into the market worldwide then get in touch with USystems today.

Conventional air cooling traditionally consumes significant energy when using mechanical chillers, one way to reduce and potentially eliminate the additional energy wastage is by utilising adiabatic cooling. Whilst significantly improving efficiencies on one hand this exponentially increases water usage in order to equip evaporative cooling. The major down side however is the growing scarcity of water in certain geographical locations. A typical large scale Data Center consumes an equivalent of 2,500 peoples water which is putting pressure on local governments in order to drop water usage.

By utilising liquid cooling you can effectively increase the water temperature to the point where adiabatic cooling is no longer needed, giving the best of both worlds, no excess water wasted and better energy efficiency with a simpler site set up and requirement. It really is a WIN-WIN-WIN.

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