Per-Facility Analysis · Updated June 2026

Southern California Data Center — Generators Beneath the Chillers

Generators sited directly beneath the chillers — and a 113°F day. 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 Los Angeles market, designed by a national MEP engineering firm with a dedicated critical facilities practice. The facility uses conventional rooftop air-cooled chillers, with backup generators housed in ground-level containment structures.

Two things make this the most severe case in the survey cohort to date: the design ambient is 113°F, and the generator containment structures sit directly beneath the north-side chillers. When wind comes from the north — the summer prevailing direction — the two combine.

Facility Context

The facts below are derived entirely from cited public sources including the operator's published specifications, the engineer of record's portfolio attribution, and provided aerial imagery. No proprietary drawings, specifications, or operational data are used.

Location Los Angeles market.

Owner-operator: A major southern California colocation operator. Facility opened 2024.

Engineer of record: National MEP engineering firm with a dedicated critical facilities practice.

Critical IT capacity: 33 MW, N+1 distributed redundancy per vault. Building ~242,500 SF.

Cooling: 20 rooftop air-cooled chillers (Carrier 30XV-class), 19 active with one redundant. Grouped in two arrays — one on the west side, one on the east. Vertical discharge; intakes drawn from below.

Backup power: 15 generators (CAT C175-class) in four ground-level containment structures, stack exhaust. The north-side structures sit directly below the north chiller array.

Compliance: SOC 1/2 Type II, ISO 27001, PCI DSS, NIST 800-53 High.

Scenario Presented

Wind and ambient.
Wind from the north (0°) at 9 mph, 113°F ambient. The northerly direction is the summer prevailing case and the one that carries the north-side generator exhaust up into the chillers directly above it.

Operating scenario.
All generators and all rooftop chillers running at full load — the on-generator condition at design ambient, maximizing exhaust source and heat-rejection demand together.

This page presents the northerly case. Additional wind directions were examined as part of the survey's directional screening and are available to the engineer of record on request.

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 engineer of record on request.

1. Generator exhaust is drawn straight into the chillers above it. With the generator containment structures concentrated directly under the north-side chiller array, a northerly wind pushes exhaust heat up and directly into those chiller intakes — a short, direct recirculation path rather than the longer lofting trajectory seen where generators sit in a separate yard. The north-side intakes run markedly hotter than the south and east units as a result.

2. The 113°F ambient leaves no margin. Air-cooled chiller capacity is governed by intake dry-bulb temperature. Starting from a 113°F baseline, even modest recirculation drives north-side intakes toward the top of the modeled scale (>155°F) — well past the regime where a commercial air-cooled platform would begin shedding capacity or tripping. The recirculation stacks on top of an already-severe ambient.

3. This is a placement problem, not a wind problem. The vulnerability comes from siting the generators beneath the equipment they threaten. No amount of favorable wind removes the exposure; an unfavorable-but-common wind direction activates it. A study that happened not to run the northerly case would report a far healthier facility than the geometry actually supports.

4. Building and equipment geometry govern the result. Which chillers are affected, and how severely, is a function of containment-structure position, chiller-array layout, and building massing — an exterior-flow question that only a site-scale model resolves.

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 dense surrounding cityscape is included as bluff-body context. The presented case uses a 113°F ambient (site elevation ~59 m). Full domain setup, boundary conditions, solver choices, and stated limitations are documented at the Methodology page. Key terms used here are defined at the Key Terms and FAQ.

For the Engineer of Record

The full per-facility figure set, the complete wind-case matrix, and a quantitative summary are available on request. We share these directly with the named engineer of record, not with building owners, operators, or other parties. For a practice that already runs internal CFD, this exterior-dispersion screening is a complement — a fast, standardized read on generator-to-chiller recirculation risk across a portfolio. Contact stewart@resolvedanalytics.com and reference this Los Angeles market facility.

Abut the Author

Stewart Bible, Principal, Resolved Analytics. Resolved Analytics is a Computational Fluid Dynamics consulting practice and authorized Siemens STAR-CCM+ reseller, with a long-standing service line in mission-critical facility exterior analysis. Contact: stewart@resolvedanalytics.com.

Disclosure

This is independent research conducted by Resolved Analytics without engagement, sponsorship, or input from the building owner, operator, or engineer of record. All inputs are derived from cited public sources; no proprietary drawings, specifications, or operational data are used. Results represent idealized exterior conditions and do not represent the actual as-built performance of any facility. No claims are made regarding life-safety, code compliance, or operational performance. All firm and project references have been anonymized. This material is not engineering services rendered to any party.