Written by Eamonn Ryan

Rack densities may be the hottest thing in a data centre. Literally. The Pan-African Data Centre Exhibition & Conference boasted a high proportion of HVAC&R companies. It also hosted a panel discussion on the subject of Key Considerations in Future Cooling Applications for Data Centres. The latter was moderated by Jonker Bester, director: Spoormaker & Partners, with the following industry expert panellists:

• Vincent Laidet, managing director: Systemair

• David Bourke, director of sales: data centre technologies EMEA, Munters

• Matteo Faccia, product management director and tech dep operation coordinator, HiRef

The following is a summary of their discussion. Efficient cooling is a critical aspect of data centre operations, directly impacting equipment performance, energy consumption, and overall reliability. The panellists shared insights on cooling strategies, common mistakes, and best practices to achieve optimal airflow management. By examining design considerations, temperature control, and infrastructure maintenance, data centre operators can enhance cooling efficiency and reduce energy costs.

Understanding airflow management: To ensure effective cooling, it is essential to focus on airflow management within data centres. The panel emphasises the importance of correct positioning and sizing of equipment to maintain optimal conditions. Simply increasing airflow speed may not yield the desired results. Instead, the goal should be to provide the right amount of airflow consistently, optimising energy usage and equipment performance. The discussion highlights the need to align with basic principles and avoid common mistakes that hinder proper airflow management.

Avoiding common mistakes: The panel points out two common mistakes frequently encountered in data centres:

• The first involves placing server cabinets too close together, causing short cycling and inadequate airflow circulation. This error limits cooling efficiency and may lead to equipment performance issues.

• The second mistake pertains to incorrect installation of the cooling unit. Sometimes, the cooling unit is mounted upside down or obstructed by design elements, impeding its functionality, and forcing the system to work harder to achieve desired results. Such errors can be avoided with attention to detail and adherence to best practices.

Temperature control and humidity considerations: Proper temperature and humidity control play a crucial role in data centre cooling. The panel emphasises that achieving the right temperature range is essential for optimal performance and energy efficiency. Even minor deviations in temperature can lead to higher energy consumption and equipment strain. Maintaining a balanced airflow that efficiently removes heat from the server cabinets and controls humidity levels ensures a conducive environment for equipment operation. The panel stresses the importance of maintaining the right balance in airflow and temperature for maximum efficiency.

Best practices and infrastructure maintenance: Implementing best practices is vital to achieving efficient cooling in data centres. Properly sizing the data centre and adopting conservative expenditure graphs help align infrastructure with operational needs, reducing unnecessary energy consumption. Regular maintenance and infrastructure audits allow operators to identify potential issues and implement corrective measures promptly. The panel emphasises the significance of maintaining a pre-emptive approach to infrastructure maintenance to ensure optimum cooling performance.

The volume of equipment in large data centre server rooms creates considerable heat and require extensive cooling facilities leading to high levels of energy demand. Image supplied by Trafo

The volume of equipment in large data centre server rooms creates considerable heat and require extensive cooling facilities leading to high levels of energy demand. Image supplied by Trafo

Choosing the right cooling technology: The panel emphasises the importance of choosing the appropriate cooling technology for each specific case. They acknowledge that there is no onesize-fits-all solution and stress the need to analyse requirements and goals before making a decision. Factors such as system efficiency, cost, and ease of implementation are taken into account when considering options like water cooling or air cooling. While water cooling may offer greater cooling capacity, it also requires a larger volume of cooler air. On the other hand, air cooling is more cost-effective but may result in quicker temperature increases within the data centre. Ultimately, the choice depends on the specific needs and circumstances of the data centre.

The growth of data centres has created special opportunities for the application of dry-type transformers. Image supplied by Trafo

The growth of data centres has created special opportunities for the application of dry-type transformers. Image supplied by Trafo

Maintenance and efficiency: The significant role of regular maintenance in ensuring optimal cooling system performance is emphasised. Proper maintenance not only contributes to the longevity of the system but also helps maintain efficiency. Neglecting maintenance can result in decreased efficiency, increased energy consumption, and potential system failures. Regular inspections, cleaning, and filter replacements are essential to avoid additional strain on the system and unnecessary energy wastage. The discussion underscores the need for competent individuals to carry out maintenance tasks to maximise efficiency and minimise operational issues.

Configuring cooling units: The panel addresses the importance of appropriately sizing and configuring cooling units within the data centre. Factors such as the position of the cooling unit, duct sizing and configuration, and external static pressure influence the energy consumption and efficiency of the system. Placing the cooling unit closer to the centre reduces energy consumption, while the sizing and configuration of ducts affect the external static pressure required for optimal performance. Regular maintenance of filters and ensuring proper airflow also play a role in maintaining efficiency and minimising energy waste.

Left to right: Jonker Bester, director: Spoormaker & Partners; Matteo Faccia, product management director & tech dep operation coordinator, HiRef; David Bourke, director of sales: data centre technologies EMEA, Munters; Vincent Laidet, managing director: Systemair Image supplied by © Eamonn Ryan/RACA Journal

Left to right: Jonker Bester, director: Spoormaker & Partners; Matteo Faccia, product management director & tech dep operation coordinator, HiRef; David Bourke, director of sales: data centre technologies EMEA, Munters; Vincent Laidet, managing director: Systemair Image supplied by © Eamonn Ryan/RACA Journal

Sensitivity ratio and energy optimisation: The significance of the sensitivity ratio in energy optimisation efforts was highlighted. Aiming to achieve a sensitivity ratio close to 1 helps reduce wasted electricity and improve overall energy efficiency. This involves maintaining the right temperature and airflow conditions within the data centre. By considering factors like row design and temperature control, data centre operators can minimise energy wastage and achieve optimal cooling efficiency.

Understanding the factors that influence cooling solutions, such as system configuration, maintenance, and sensitivity ratio, allows data centre operators to make informed decisions and optimise energy consumption. By prioritising these considerations and adopting best practices, data centre operators can enhance cooling efficiency, improve equipment reliability, and reduce overall energy costs.

Local impact and modularity: The discussion begins by highlighting the importance of considering local factors when designing data centres. Factors such as load shedding, power usage, and temperature variations across different markets and regions need to be taken into account. The panel emphasises the need for data centre designs to be adaptable and modular, enabling them to be deployed worldwide. By adopting modular solutions and considering commonality within each market, data centre operators can achieve consistency and efficiency across various locations. The panel discusses the benefits of modular solutions, which allow for flexible expansion and efficient use of resources. Modular data centres can be easily integrated into existing infrastructure, supporting scalability and adaptability to changing demands.

Efficiency in system design and management: The panel emphasises the need for efficient system design that goes beyond considering worst-case scenarios. Instead, the focus is on developing systems that can adapt and perform optimally during regular operations. The discussion explores the concept of managing systems efficiently by switching on and off cooling elements based on real-time requirements. The use of variable speed compressors and fans is highlighted as a way to enhance cooling efficiency, especially for large machine units. By optimising cooling distribution and considering customer needs, data centre operators can achieve greater flexibility and energy efficiency.

Addressing rattling issues and scalability: Another crucial aspect discussed is the increasing challenges posed by rattling in data centre environments. The panel acknowledges the rise in rattling incidents and emphasises the need to design data centres that can handle higher heat loads per rack, ranging from six to eight kilowatts and even up to 20 to 24 kilowatts in certain instances. Data centre operators need to devise consistent solutions that can effectively handle higher heat loads while considering future scalability. Exploring alternative cooling methods, such as immersion cooling, is also mentioned as a consideration for future infrastructure planning.

Future-proofing infrastructure: The panel emphasises the importance of building data centre infrastructure with an eye toward the future. While air cooling remains prevalent, the discussion suggests the potential for alternative cooling solutions, such as immersion cooling. Data centre operators are advised to consider long-term infrastructure planning, keeping in mind emerging technologies and trends that may require different cooling approaches. By implementing infrastructure that is adaptable and forward-looking, data centres can remain efficient and relevant in the face of evolving demands. By addressing local impact, adopting modular solutions, optimising system design, and planning for future scalability, data centre operators can navigate the challenges of cooling and achieve greater efficiency in their operations.

Embracing sustainability: The panel highlights the need for the data centre industry to prioritise sustainability. As the sector continues to grow, there is a concern that current practices may not align with sustainable principles. The panel agrees on the importance of learning from past experiences and implementing lessons to drive positive change. This includes a focus on sustainability from a global perspective, with specific attention to regions like Africa.

Harnessing heat recovery: One of the key strategies discussed is the significant potential of heat recovery in data centres. The panel emphasises the importance of exploring heat recovery applications, particularly in regions such as the colder Nordic countries and other parts of Europe. While the market demand for heat recovery may vary, there is a consensus on its value in reducing energy waste. By capturing and utilising excess heat, data centres can achieve both energy efficiency and sustainability goals.

Addressing water and power scarcity: Water and power scarcity emerge as critical considerations in data centre design. The panel recognises the need to account for these challenges when developing cooling systems. To mitigate water scarcity, alternatives to traditional cooling methods, such as refrigerant usage reduction, are explored. Additionally, the discussion touches on the importance of considering power scarcity and the potential for data centres to integrate with local energy grids, benefiting both the centres and surrounding communities.

Exploring efficient cooling technologies: The panel acknowledges the importance of adopting efficient cooling technologies to minimise energy consumption. The panellists highlight the need to reduce reliance on refrigerants and explore alternative cooling approaches. Examples include direct and indirect air cooling, liquid cooling, and the integration of renewable energy sources. By leveraging advanced cooling technologies, data centres can optimise energy usage, reduce carbon emissions, and enhance overall sustainability.

The vital importance of air conditioning and cooling in data centre construction

One delegate to the Pan-African Data Centre Exhibition & Conference estimated the growth trajectory for the Africawide data centre market at 600% over the next four years, based on scheduled projects and orders.

With the increasing demand for data storage and processing, ensuring the proper management of heat, temperature, humidity, and air quality is essential. Implementing efficient and reliable cooling systems not only protects valuable equipment but also optimises energy consumption, reduces downtime, and contributes to the overall success and longevity of data centres in the digital era. Schneider Electric has an area of specialisation in data centre building management systems (BMS) solutions and has a strong presence in Africa.

Describing the need for BMS in data centres, Mark Freeman, offer manager Digital Buildings, Anglophone Africa at Schneider Electric, says: “BMS is particularly well-suited for buildings with complex requirements such as data centres, hospitals, hotels, and commercial office parks.

These facilities often consume more energy than typical buildings and require precise monitoring and control. Additionally, BMS can optimise energy usage and space allocation, allowing for efficient segregation of offices and dynamic adjustments to HVAC systems. Any building that benefits from intelligent control, improved energy management, and cost savings can greatly benefit from a BMS implementation.

“Data centres require meticulous control and monitoring due to their constant energy demand and the need for temperature and humidity regulation. BMS offers advanced capabilities for managing HVAC systems, particularly the intricate cooling requirements common to data centres. By integrating with various sensors and equipment, BMS provides real-time monitoring and control of temperature, humidity, and airflow. This ensures that servers operate within optimal conditions, mitigating the risk of overheating and potential system failures.

“Unlike traditional buildings, data centres have specific challenges that need to be addressed. The constant load on HVAC systems and the sensitivity of equipment necessitates precise temperature management. BMS helps detect and visualise potential hotspots within the data centre, allowing operators to distribute cooling more effectively and prevent equipment failures. Additionally, data centres require robust backup power solutions, and BMS plays a vital role in monitoring and controlling generators, ensuring uninterrupted power supply during utility outages,” says Freeman.

How humidifiers are used in data centres

Supplied by Humidair

Humidity control in data centre environments has come a long way over the years. From the early computers which used punched cards that needed humidification to maintain the physical properties of the card to magnetic tape data storage that needed a level of humidity to prevent dust and debris adhering to the reels.

As technology has evolved so has the need for data centre humidification. The main reason to humidify data halls has been to combat electrostatic discharge (ESD) that can damage sensitive electronics. However, servers have now evolved to minimise the risk of damage from ESD, reducing the need for humidification of data halls.

This led ASHRAE (American Society of Heating, Refrigerating and Air-Conditioning Engineers) to change its recommended guidelines on the acceptable lower level of humidity in data centres in 2008. Previously the recommended humidity level included a minimum of 40% RH (relative humidity) but was reduced and is now measured in dew point rather than RH as studies suggested absolute humidity has a greater impact on ESD. The new recommended lower limit is a line from 18°C dry bulb temperature and 5.5°C dew-point temperature to 27°C dry-bulb temperature and a 5.5°C dew-point temperature. Over this range of dry-bulb temperatures and a 5.5°C dew point, the recommended RH varies from approximately 25to 45%.

The reduction in the minimum recommended humidity level has resulted in a fewer number of hours per year when humidification (and its associated energy use) to combat ESD is necessary. However, humidification is still be needed in winter months when cold outside temperatures result a very low internal humidity and increase the potential risks from ESD. Traditionally, electrode boiler steam humidifiers incorporated in the CRAC (Computer Room Air Conditioning) units have been used to combat ESD in data centres. However, this type of humidifier has a high energy consumption and maintenance requirement, giving it a high overall operating cost. More recently, low energy cold water humidifiers have been used in innovative energy saving strategies.

For instance, in 2008 the Fujitsu data centre in North London employed spray humidifiers to prevent ESD by preheating the cold, saturated, fresh air to 30°C with heat recovered from the data halls. Heating the incoming air allowed it to absorb more moisture and after humidification with the low energy JetSpray humidifier, it was returned to a room supply temperature of 17°C at an optimum 50% ±10% RH. The energy cost saving of using a JetSpray humidifier combined with heat recovery, compared to a steam humidifier was around UK£35 000 a year.

The change in the ASHRAE guidelines for environmental control included an expansion of the recommended temperature window, from 20-25°C to 18-27°C and an increase in the maximum humidity level from 55%RH to 69% RH and 15°C dew point. This loosening of the guidelines made the use of low energy ‘free air cooling’ systems more practical in data centre environments. Fresh air brought in from outside is used to provide cooling rather than compressor driven CRAC units. In a UK climate this type of cooling can maintain a data hall environment to the recommended levels for around 70% of the year.

Alongside the use of free air-cooling systems, humidification took on a different role within the data centre environment. A cold-water humidifier will provide around 680W of cooling for every 1kg of moisture it evaporates and can operate on as little as 550W while providing up to 840kg per hour. By supplementing free air-cooling systems with evaporative cooling from cold water humidifiers, the use of free air-cooling systems can be extended from 70% of the year to 95%, reducing the reliance on compressor driven cooling to just 5% of the year – the hottest days.

There are two types of evaporative cooling using cold water humidifiers – direct and indirect. Direct evaporative cooling sees the humidifier providing moisture to the incoming air, increasing its humidity while decreasing its temperature. Indirect evaporative cooling is when the humidifier operates on the exhaust air. Before being expelled, the air is humidified and cooled, then passed through a heat recovery unit to transfer the cool thermal energy to the incoming air. This cools the incoming air without adding any additional moisture.

Packaged heat recovery AHUs are starting to be manufactured with this type of innovative indirect evaporative cooling technology incorporated. The AHU passes the return air through a HumEvap MC3 evaporative humidifier, humidifying the air and cooling it by several degrees. The AHU’s heat recovery unit then transfers a percentage of this temperature drop to the incoming fresh air reducing the load on energy-hungry chillers. Other packaged AHUs using evaporative humidifiers in a direct evaporative cooling capacity have been able to achieve up to 12°C cooling from the humidifier when used in data centre environments in hot climates.

The efficiency of a data centre is measured in what is called the Power Usage Effectiveness (PUE), which is a ratio of the energy consumed by the servers compared to the energy consumption of other services such as the lights or cooling equipment, for instance. If a data centre has a PUE of 2.0, then for every kW used by the servers another kW is being used by the other services within the data centre. Ideally the PUE should be as close to 1.0 as possible. The revised ASHRAE guidelines and the resulting adoption of free air cooling have resulted in many modern data centres being built with a greatly reduced PUE.

Although the revised guidelines have reduced the need to humidify to combat ESD, the use of humidifiers in data centres has actually increased as a result. Low energy cold water humidifiers are not only delivering energy efficient humidification in cold winter months but are helping reduce PUE in warmer months when free air cooling alone doesn’t deliver enough cooling to satisfy the demand.

Huawei’s Zhou on data centre trends, challenges, and development direction

While the remainder of this feature deals with the cooling aspect of data centres, RACA Journal had the opportunity at the Pan African DataCentres Exhibition & Conference, to talk to Huawei director of IT Consulting & System Integration Department, Zhou Yilin, about the data centre landscape and future trends in 2023.

“Digital technologies have ushered in a new wave of technological revolution and industry transformation. Increasing requirements for data storage and processing the rapid development of data centres. At the same time, this brings new challenges to data centres, including different policy environments in regional customer requirements, and low-carbon sustainable development requirements. Globally, data centres are facing more complex and changing situations,” says Zhou.

“In the future, data centres in Africa will focus more on environmental protection, data security, and privacy protection. In addition, data centres in Africa will face more opportunities and challenges from the following aspects:

  • Development of cloud computing and edge computing: With the increasing popularity of cloud computing and edge computing, data centres in Africa will face more challenges and opportunities. Data centres and service capabilities need to evolve and enrich to meet users’ requirements for intelligent, efficient, and secure services;
  • Construction of green data centres: African governments have started to promote the construction of green data centres to reduce their impact on the environment. In the future, Africa’s data centres will focus more on environmental protection and sustainable development, and adopt more energy-saving and environmentally friendly technologies and equipment;
  • Data security and privacy protection: With the increasing number of data breaches and cyber-attacks, data centres in Africa will pay more attention to data security and privacy protection. They need to adopt more secure and reliable technologies and solutions to enhance data encryption and access control to protect user data security and privacy.
Huawei VP of Global Technical Service and Director of IT Consulting & System Integration Department, Zhou Yilin. Image supplied by Eamonn Ryan | Raca Journal

Huawei VP of Global Technical Service and Director of IT Consulting & System Integration Department, Zhou Yilin. Image supplied by Eamonn Ryan | Raca Journal

In the context of global digital transformation, Zhou describes the direction of Huawei’s core competitiveness in the future:

“As the key foundation for carrying digital economy services, data centres are the cornerstone of digital transformation in various industries. In the digital era, customer service scenarios in various industries are changing from single product integration to full-stack data centre integration. Huawei’s full-stack data centre integration service solution provides full-stack service solutions, including data centre facility integration, IT integration and auxiliary operation, migration and disaster recovery, scenario-based intelligence, and campus digital platform integration. It covers the entire process of planning, construction, and operation, meeting the requirements of comprehensive, efficient, and intelligent construction in the architecture design, service rollout, and system operation of the data centre.

“Huawei data centre integration service uses low carbon, energy saving, and prefabricated assembly to build green and simplified scenario-based typical configuration solutions,” says Zhou. “For example, for integrated DC scenarios, L1 + L2 are integrated to build a full-stack liquid cooling solution. We also build an efficient air-cooled and water-cooled system to support scenario-based energysaving solutions for hub clusters, helping customers reduce the PUE from more than two to less than 1.5. PUE is the ratio of the total amount of power used by a computer data centre facility to the power delivered to computing equipment.

However, frequent natural disasters may cause power failures, device damage, and network interruptions in data centres, undermining the running and data security of data centres. Zhou explains that Huawei improves data centre resilience and ensures service continuity by providing automatic disaster warnings, automatic recovery solutions, one-click service switchovers, and unified ransomware detection and recovery management, helping customers improve service continuity and reduce disaster recovery (DR) management costs.

“To meet the high reliability requirements of industry systems, Huawei provides industry-leading DR consulting, DR integration, DR drill services, and intelligent DR management platforms for industries such as finance, government, healthcare, electric power, and energy. It provides service solutions such as intra-city active-active, remote DR, two-site three-centre, and multi-centre, helping customers improve service continuity,” says Zhou.

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