Component reference · Pub 5653 + Rev. Proc. 87-56

Data center cooling system depreciation

CRAH/CRAC precision cooling, chilled-water plant, hot/cold aisle containment, economizers, raised flooring — engineering-method classification under Rev. Proc. 87-56 and IRS Pub 5653. 5-year MACRS personal property vs. 15-year land improvements vs. 39-year building shell.

Why cooling classification matters at data center density

Cooling infrastructure is among the highest-density reclassifiable components in any data center. A typical small-to-mid data center has 8–15% of basis in CRAH/CRAC precision cooling units (5-year MACRS personal property) plus 3–7% in external chilled-water plant components (15-year MACRS land improvements). Combined, cooling-only components often represent 11–22% of basis sitting in accelerated MACRS that default 39-year straight-line treatment would miss entirely.

With 100% bonus depreciation restored permanently under OBBBA (PIS after January 19, 2025) and 100% available in many prior years (2017–2022), the cooling carveout alone often surfaces seven-figure first-year deductions on a $20M+ facility — even before adding UPS, PDU, racks, and other personal-property components.

The classification framework: cooling components dedicated to IT-load process cooling (not human-comfort HVAC) are 5-year MACRS personal property when removable / equipment-specific. External chilled-water plants and cooling towers physically located outside the building shell are 15-year MACRS land improvements. Base-building HVAC serving human-comfort areas (offices, common spaces) remains 39-year building shell.

Cooling component classification

Per Rev. Proc. 87-56 asset class table and IRS Pub 5653 component analysis. Engineering analysis per facility refines allocation; ranges below are illustrative.

5-year MACRS personal property

Equipment-specific / facility-process-specific cooling components. Eligible for 100% bonus depreciation under §168(k) per OBBBA (PIS after 1/19/2025).

Component Basis share
CRAH / CRAC precision cooling units
Process cooling for IT load, not human-comfort HVAC
 8–15%
Hot/cold aisle containment
Modular, removable architectural element
 1–3%
Raised flooring (modular, pedestal-mounted)
Under-floor cable plenum + cool-air supply path; functionally facility-process
1–3%
In-row / in-rack cooling, liquid cooling distribution
Direct-to-chip, rear-door heat exchangers; AI/GPU-dense facilities
2–6%
Air-side / water-side economizers (when IT-load dedicated)
Outside-air dampers, plate heat exchangers, control sequences
1–3%

15-year MACRS land improvements

Cooling plant components physically located outside the building shell.

External chilled-water plant, cooling towers
 3–7%
Underground chilled-water distribution piping
Between external plant and building entry point
0.5–2%

39-year MACRS building shell

Cooling components NOT eligible for accelerated MACRS. Base-building HVAC serving human-comfort areas stays here.

Base-building HVAC (human-comfort areas)
Separate from IT-load process cooling
 3–6%

Per IRS Cost Segregation Audit Techniques Guide (Pub 5653, Chapter 7) and Rev. Proc. 87-56 asset class table. Engineering analysis per facility documents whether each cooling component is dedicated to IT-load process cooling (5-year personal property) or base-building HVAC (39-year shell).

Worked example: $20M colocation cooling carveout

Illustrative; $20M regional colocation engagement, ~3MW IT load, partnership-held, placed in service 2025 (100% OBBBA bonus). Cooling-only component carveout — full-facility cost-seg engagement surfaces additional deductions on UPS, PDU, racks, security, fire suppression beyond what's shown here.

Facility
Regional colocation operator (partnership-held), ~3MW IT load
Depreciable basis
$20,000,000
CRAH/CRAC + in-row cooling (5-yr)
~12% = $2,400,000
Aisle containment + raised flooring (5-yr)
~3% = $600,000
External chilled-water plant (15-yr)
~5% = $1,000,000
Year-1 deduction (cooling only)
~$3,200,000 (100% OBBBA bonus on 5-year + first-year 15-year MACRS)
Estimated federal tax savings (cooling)
~$1,180,000 at 37% blended partnership rate

Assumes 37% blended federal rate for partnership-held real estate flowing through to investor K-1s. Actual depends on each investor's bracket, at-risk basis, passive-activity status under §469, and state conformity to §168(k). Cooling-only carveout shown for illustration; the full-facility cost-seg engagement adds UPS, PDU, racks, security, fire suppression and typically reaches 45–55% total reclassification.

Cooling depreciation questions

Are CRAH (computer room air handler) units 5-year MACRS personal property or 15-year land improvements?
CRAH and CRAC (computer room air conditioner) units installed inside the building, dedicated to IT-load process cooling, are typically 5-year MACRS personal property under Rev. Proc. 87-56 asset class 57.0 — the equipment is removable, equipment-specific, and serves the facility process (IT load), not human comfort. The IRS Cost Segregation Audit Techniques Guide (Pub 5653, Chapter 7) addresses precision cooling explicitly: process cooling for IT load qualifies as personal property when documented separately from base-building HVAC for human-comfort areas. External chilled-water plants and rooftop cooling towers are typically 15-year land improvements (asset class 00.3); only the chiller plant components physically external to the building shell.
What about hot/cold aisle containment systems — building improvement or removable equipment?
Hot/cold aisle containment (transparent panel curtains, end-of-row doors, ceiling baffles, modular containment kits) is 5-year MACRS personal property when modular and removable. The containment system is facility-process-specific (engineered to optimize cooling efficiency for IT load), not part of the building shell. Reclassification holds when the containment can be physically removed without damaging building structure — the modular kits from Vertiv, Schneider, CommScope, Subzero, and similar vendors meet this test. Built-out cold-aisle containment that's been drywalled in or structurally integrated may classify differently; engineering analysis per facility.
How is an external chilled-water plant classified — and can the underground chilled-water piping be reclassified?
External chilled-water plants (chillers, cooling towers, pump skids physically located outside the building shell) are typically 15-year MACRS land improvements per Rev. Proc. 87-56 asset class 00.3. Underground chilled-water distribution piping between the plant and the building can also classify as 15-year when documented as a site improvement serving the facility process. Internal chilled-water piping inside the building shell distributing to in-row coolers is typically 5-year personal property when serving IT-load process cooling. The 15-year vs. 5-year distinction often turns on whether the component is inside the building envelope or outside it — engineering analysis per facility, documented against building site plans.
What about free cooling / economizer systems (air-side or water-side)?
Free cooling and economizer systems (air-side: outside-air dampers, mixed-air plenum, control sequences; water-side: heat exchangers between chilled-water and condenser-water loops) are typically 5-year MACRS personal property when dedicated to IT-load process cooling — the equipment is engineered for the facility process, not human-comfort HVAC. Air-side economizers built into the base-building HVAC system serving the entire facility (not just the DC space) may classify as 39-year. Engineering analysis per facility based on whether the economizer is dedicated to IT-load cooling or integrated with building-wide HVAC.
Is raised flooring 5-year personal property or 39-year building shell?
Raised flooring (pedestal-mounted floor tiles forming the under-floor cable plenum and cool-air supply path) is typically 5-year MACRS personal property when modular and removable. Per IRS Pub 5653 framework, raised flooring engineered to support facility process (under-floor cooling supply, structured cabling pathways, equipment power distribution) qualifies as personal property — the flooring is functionally part of the facility process, not the building shell. Structural slab beneath the raised floor stays 39-year. Reclassification holds for standard pedestal-mounted modular raised floor systems (Tate, ASM, similar vendors); engineering analysis per facility.
Can we do Form 3115 §481(a) catch-up on missed cooling reclassification from a 2019 PIS facility?
Yes. Form 3115 (Application for Change in Accounting Method) under automatic-consent procedures in Rev. Proc. 2015-13 may allow a §481(a) cumulative catch-up of previously-missed accelerated depreciation in the current tax year — without amending prior returns. For a 2019-PIS data center with standard 39-year straight-line treatment on all cooling infrastructure, the §481(a) catch-up surfaces the difference between actual claimed depreciation and what an engineered cost-seg study would have allowed. Cooling-only engagements are possible (engineering-method analysis carving out only the cooling components), but most enterprise customers do the full-facility cost-seg engagement because the marginal cost of expanding scope is small. Engineering workpapers + §481(a) computation included. Verify treatment with your CPA before filing.

See pricing on the full data center cost-seg engagement.

Cooling carveouts work, but the full-facility engagement (UPS + PDU + racks + cooling + fire + security) is where the real reclassification % lands. Published pricing for sub-$25M facilities + hyperscale floor at $49,995.

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