HVAC Systems for Data Center Construction in Central and Southern Ohio

The mechanical infrastructure supporting a data center determines whether the facility meets its uptime commitments and operates within budget over a 15-year lifecycle. For contractors managing these projects in central and southern Ohio, understanding the region's climate advantages, redundancy standards, and the practical realities of commissioning mission-critical cooling systems is essential.

Chilled-Water vs. Direct-Expansion: Choosing the Right Approach

Large-scale data centers overwhelmingly favor chilled-water systems for a reason: efficiency at scale. A properly designed central plant with chillers, cooling towers, and computer room air handlers (CRAH) delivers a coefficient of performance exceeding 7, operates effectively under partial loads, and scales seamlessly as IT capacity grows. The capital investment runs 20–30% higher than direct-expansion alternatives, but operational savings become significant once the facility reaches multi-megawatt loads.

Direct-expansion systems—packaged CRAC units with integrated compressors—remain viable for modular deployments or builds under 500 kW. They're less expensive upfront and faster to install. However, their efficiency ceiling sits around a CoP of 2.5–4, and individual units typically max out near 100 kW of cooling capacity. For projects where the client plans phased expansion or needs to defer capital expenditure, DX systems make sense. For anything approaching 5 MW of IT load, chilled-water infrastructure becomes the practical choice.

The decision isn't purely technical. It's also about understanding what the client actually needs versus what they think they need based on a consultant's boilerplate spec.

Ohio's Climate Creates Real Cooling Advantages

Central and southern Ohio experience cold winters and hot, humid summers—a climate profile that significantly benefits data center operators willing to design for it. Chilled-water plants equipped with water-side economizers can leverage ambient conditions for free cooling during spring, fall, and winter months. Facilities properly configured for economizer operation reduce chiller runtime by 35–45% annually, translating directly to lower power consumption and operating costs.

The trade-off is complexity. Economizer systems require freeze protection through glycol loops, precise control sequences to manage transitions between mechanical and ambient cooling, and careful commissioning to avoid nuisance alarms during mode changes. These aren't theoretical concerns—they're the details that determine whether a system performs as designed or becomes a maintenance headache two months after substantial completion.

Humid summer conditions also matter. Central and southern Ohio's summer design conditions push cooling equipment hard, and systems need to be sized for both sensible and latent loads. Undersized dehumidification capacity leads to condensation risk and control instability, particularly in white spaces with high-density racks.

Uptime Tiers and What They Actually Require

Uptime Institute Tier classifications define redundancy expectations, and the mechanical design must align with the tier the client is paying for.

Tier II facilities operate with N+1 redundancy—one active chiller and one standby, one set of pumps with a backup. This configuration costs less but requires taking the facility offline for any major maintenance event. For clients who can tolerate planned downtime windows, it's adequate.

Tier III facilities require concurrently maintainable infrastructure, meaning dual chilled-water loops with independent pump sets, air handlers, and controls. Each loop must be capable of carrying full load while the other is down for service. This is the standard for most enterprise colocation and cloud service providers. The mechanical budget increases substantially—benchmarks place Tier III construction near $23,000 per kW—but the operational flexibility justifies the cost for clients with stringent SLAs.

Tier IV facilities implement full 2N or 2N+1 redundancy: two completely independent cooling plants, each capable of supporting the entire IT load. This is fault-tolerant design, and it's expensive. Hyperscale operators and financial services firms specify Tier IV. Most other clients don't need it, even if they think they do.

The challenge for contractors is ensuring the design actually delivers the tier it claims. A set of drawings stamped "Tier III" that shows a single chilled-water loop with a standby chiller doesn't meet the standard. Catching these discrepancies early prevents expensive redesigns during construction.

Self-Performed Scope Reduces Risk

Data center mechanical work involves tight coordination across disciplines—electrical, controls, fire suppression, and structural all intersect with HVAC systems. Delays in one trade cascade into others quickly.

We self-perform CRAC/CRAH tie-ins, glycol loops, and hot-aisle plumbing without delays. Keeping these scopes in-house eliminates the scheduling friction that occurs when multiple subcontractors are trying to work in the same mechanical room or above the same ceiling grid. It also means one point of accountability when a system needs to be rebalanced or a control sequence adjusted during startup.

Our crews handle HVAC, hydronic distribution, plumbing, controls integration, and Generac backup power systems. When a chilled-water valve actuator fails during commissioning or a VFD trips on overcurrent, we're not waiting on another contractor to respond. The same techs who installed the system troubleshoot it.