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Turning old data centres green

Image: Adobe Stock / Gorodenkoff

Jamie Cameron, Associate Director, Critical Systems at Cundall, explores why refurbishing beats rebuilding when it comes to making efficiency, cost, and environmental gains in data centres.

Amid the advancements in AI and liquid cooling technologies, a significant trend demands attention: the refurbishment of ageing data centres. These facilities, foundational to the digital age, were built during the mid-2000s internet boom. The explosive growth of cloud-hosted business software, social media, and streaming services has elevated data to a critical asset. However, the infrastructure supporting this growth is reaching, and in many cases exceeding, two to three decades of service. Consequently, the need for comprehensive upgrades has become imperative. Addressing the refurbishment of these data centres is not merely a routine concern but a strategic priority for organisations committed to sustaining and managing the industry’s exponential growth.

Factors driving data centre refurbishment

Refurbishing older data centres rather than constructing new ones offers many advantages, particularly for colocation providers – organisations that lease out data space to others. Existing colocation sites often operate at low utilisation levels, with actual kilowatt (kW) consumption significantly lower than the kW capacity sold, often by as much as 50%. By upgrading these facilities, operators can unlock trapped capacity within the mechanical, electrical, and plumbing (MEP) infrastructure or utilise secured yet unused utility power, a critical resource in developed markets. This approach not only enhances operational efficiency but also provides a cost-effective solution.

Operational enhancements are not the only benefits of refurbishing existing data centres. Significant financial gains can also be made. Refurbishing existing data centres often requires lower Capital Expenditure (CapEx) than building new facilities. This approach also contributes to sustainability by reducing embodied carbon – carbon emissions of materials and construction processes throughout the whole lifecycle of a building. Retrofits, as opposed to demolition and reconstruction, mitigate upfront carbon emissions, making it a more sustainable alternative. These financial benefits and environmental advantages make data centre refurbishment a smart and cost-effective choice.

Sustainability is a key pillar of data centre refurbishment. Equipment lifecycle upgrades allow data centre operators to implement more efficient MEP systems. These upgrades lower Power Usage Effectiveness (PUE) and reduce overall energy waste. For instance, replacing traditional cooling systems and legacy Uninterruptible Power Supplies (UPS) with modern free cooling chillers and transformer-less UPS units significantly enhances energy efficiency. This reduces operational costs and contributes to a greener, more environmentally friendly future, a cause that we all should feel deeply about.

Another critical advantage of refurbishment is the improvement in power density. Modernising data centres from outdated designs to contemporary configurations can achieve higher power densities, thereby boosting performance. For example, Cundall collaborated with a client to refurbish existing 2MW data halls with 2N mechanical and electrical infrastructure in the UK. Transitioning to an N+1 (3+1) system increased IT capacity from 4 MW to 6 MW while retaining most of the existing infrastructure. The infrastructure, such as a reserve generator, enhances performance and resilience, safeguarding against unexpected issues.

Navigating complexities in data centre refurbishment

Data centre operators face significant challenges when undertaking large-scale upgrades that integrate with existing systems. To design effective upgrades, operators must understand the site’s operations under all scenarios. This includes normal day-to-day usage, system adjustments during planned maintenance, and responses to the emergence of failures. This task is particularly complex for older sites where records and construction specifications are often incomplete or outdated. Consequently, substantial time must be invested in on-site investigations and consultations with technical operations teams. These reviews typically involve examining extensive hard-copy Operation and Maintenance Manuals and As-Constructed Drawings, which can span thousands of pages, adding to the complexity.

Another significant challenge is maintaining operational continuity during upgrades. Careful planning and sequencing are required to ensure that power and cooling systems remain fully functional throughout refurbishment. Since such projects often last several months, temporary power and cooling solutions are essential. For high-end tenants and operators, the risk of relying on a single N infrastructure (where N denotes the number of generators representing the level of redundancy) over an extended period is unacceptable, as it can limit opportunities for planned preventative maintenance.

Power density is another critical issue, especially in older sites where the standard was 2-5 kW per rack, compared to the current industry standard of 8-12.5 kW for air-cooled data halls. The emergence of liquid cooling technologies, which can significantly increase rack density, exacerbates this discrepancy. Operators must significantly enhance power and cooling capacity within existing spatial constraints to justify the business case for such upgrades.

Rising global temperatures further complicate data centre refurbishment. Many older data centres were designed with a maximum external temperature of around 35°C. However, with London temperatures reaching as high as 40°C in 2023, the increased heat stress impacts cooling systems, necessitating upgrades to prevent failures and ensure reliability in higher temperature conditions.

The case for refurbishment over rebuilding

Despite the challenges, retrofits and refurbishments are becoming essential to the data centre industry. Establishing new data centres on greenfield sites involves significant financial, sustainability, and time constraints. Therefore, while upgrades are not a new concept, the increasing commercial value of data and the intense competition for space in key locations make them increasingly necessary.

The industry’s chronic shortage of skilled professionals further underscores the need for refurbishments. Recycling existing infrastructure is increasingly seen as the most pragmatic approach. Organisations can expand their footprint in terms of sustainability and economics through meticulous planning and leveraging insights from industry experts. This strategic shift aligns with the industry’s evolving needs, balancing growth with resource efficiency.

Picture of Jamie Cameron
Jamie Cameron
Associate Director, Critical Systems at Cundall

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