← Survey overview · Case Study 04 · Updated June 2026

33 MW Data Center — Southwestern US

Generators beneath the chillers: ground-level generator containment sits directly under the rooftop array, and at 113°F ambient the exhaust is drawn straight up into the intakes above — with no margin. Public-source inputs. Screening-level.

What this page covers

This page presents a screening-level exterior CFD analysis of a 33 MW data center in the Southwestern United States, developed by a major regional colocation provider and engineered by a national firm with a dedicated mission-critical practice. Its heat rejection is a rooftop air-cooled chiller array in two banks; its standby generators sit at grade in containment structures — and on the north side, those structures sit directly beneath the chiller array above.

The result is the most direct recirculation geometry in the cohort. Under a northerly wind, generator exhaust has almost no path to disperse before it reaches the intakes overhead — and at a 113°F design ambient, there is no thermal headroom to absorb it.

Facility context

The facts below are derived entirely from cited public sources: published facility and provider materials, aerial and street-level imagery, and public terrain data. No proprietary drawings, specifications, or operational data are used. Identifying details are withheld; the facility is described by type and configuration only.

Region.

Southwestern United States (hot, arid design climate).

Owner-operator.

A major regional colocation provider. Not identified here.

Engineer of record.

A national engineering firm with a dedicated mission-critical practice. Not identified here.

Critical IT capacity.

33 MW, N+1 distributed redundancy.

Building.

Purpose-built; approximately 242,500 SF.

Cooling.

Rooftop air-cooled chillers — 20 units (19 active, 1 redundant) in two arrays, west and east, with vertical discharge and intakes drawn from below.

Backup power.

15 diesel generators in four ground-level containment structures with stack exhaust. The north-side structures sit directly beneath the north chiller array.

Scenario presented

Wind and ambient.

Wind from the north (0°) at 9 mph, 113°F ambient — a high-end desert summer design condition. Of the directions screened, this aligns the exhaust source with the chiller array directly above it.

Operating scenario.

All generators and all chillers running at full load — the on-generator condition that maximizes both the exhaust source and the heat-rejection demand together.

This case was isolated by a directional sweep across the full compass — not the standard four-point (N/S/E/W) check. Here, though, the governing variable is less the wind than the vertical adjacency: the generators are beneath the chillers, and that geometry is what the model makes visible.

What the model shows

The observations below are qualitative readings of the presented scenario. Quantitative outputs — per-unit intake temperatures, recirculation magnitudes — are shared with the owner's team on request.

1. Exhaust is drawn straight into the chillers above. Because the north-side generator containment sits directly beneath the north chiller array, the exhaust has almost no path to disperse — it is pulled up into the intakes overhead rather than lofting clear.
2. At 113°F, there is no margin. North-side intakes approach or exceed 155°F. On a design-ambient day this high, the re-ingested exhaust pushes the intake air well past the range where air-cooled chillers hold rated capacity.
3. Placement geometry, not wind variability, drives it. The exposure follows from where the equipment sits, not from a rare gust direction — which is exactly why it is worth catching on the layout, at design stage, rather than in commissioning.
4. A question for the design team. Site-scale massing and equipment placement govern vulnerability, and they are visible only when the exterior is modeled as a whole. The question worth putting to the engineering team: was the vertical relationship between generator exhaust and chiller intakes evaluated at the design ambient, or only assumed adequate?

Methodology

The methodology applied here is the same standardized exterior CFD approach applied to every facility in the cohort — cylindrical far-field domain, logarithmic atmospheric boundary layer inlet, polyhedral mesh in Siemens STAR-CCM+, realizable k-ε RANS baseline. The presented case uses a 113°F ambient. Full domain setup, boundary conditions, solver choices, and stated limitations are documented at the Methodology page. Key terms are defined at the Key Terms and FAQ page.