HVAC and Climate-Control Systems
Central heating and air conditioning that condition a building are listed structural components. Separate machinery whose sole justification is process temperature or humidity can be personal property. Publication 5653 restaurant matrices say allocating a mixed HVAC unit is not appropriate. Educational information, not tax advice.
Educational information, not tax advice.
Updated 2026-10-14
Key takeaways
- Treas. Reg. §1.48-1(e)(2) lists all components of a central air-conditioning or heating system, including motors, compressors, pipes, and ducts, as structural components.
- The sole-justification exception is written for machinery required to meet temperature or humidity needs essential to other machinery or to processing materials or foodstuffs.
- Restaurant matrices treat central HVAC as building and say allocation of HVAC is not appropriate.
- Scott Paper functional allocation is an electrical method; the audit guide does not accept it as an HVAC allocation method.
- Courts have split on HVAC claims: Boddie-Noell denied listed structural components, and AmeriSouth kept most special HVAC with apartments.
Most rooftop units, air handlers, and duct mains exist so people can occupy the building. Treas. Reg. §1.48-1(e)(2) lists all components, whether in, on, or adjacent to the building, of a central air-conditioning or heating system, including motors, compressors, pipes, and ducts, as structural components. Tangible personal property excludes those items. A building is a structure enclosing space, usually roofed, used for shelter, housing, or working, office, parking, display, or sales space. Local law does not control whether the unit is a fixture.
The same paragraph of the regulation contains a narrow exception. Structural components do not include machinery whose sole justification for installation is that it is required to meet temperature or humidity requirements essential for the operation of other machinery or the processing of materials or foodstuffs. The machinery may still qualify if it incidentally provides employee comfort or serves non-critical areas to an insubstantial degree. The regulation’s example is textile-plant humidification. Hospital Corp. of America held that these tests still apply under MACRS. The IRS acquiesced in the legal test, not in every hospital item.
Publication 5653 industry matrices apply that framework as examiner guidance. Restaurant central HVAC is treated as building property. Separate kitchen HVAC units that meet the sole-justification test are treated as section 1245 property in class 57.0, and the matrix states that allocation of HVAC is not appropriate. Pharmaceutical process air handlers can be personal property; clean-room enclosing walls remain building. Auto-manufacturing process chilled water is treated as activity-class personal property, while building chilled water is building. Those rows are general fact patterns for those industries.
Whiteco’s six permanence factors are a court test for inherently permanent structures, not a substitute for the central-HVAC list. A rooftop unit is designed to remain for the life of the system and is a listed component of a central system even if a crane can lift it off. Scott Paper, Morrison, and A.C. Monk are electrical-distribution cases. Publication 5653 Chapter 8.A limits examiner acceptance of functional allocation to primary and secondary electrical distribution. Do not spread a kitchen’s cooling load across a mixed rooftop unit and describe that spread as an IRS-accepted HVAC method.
Boddie-Noell held that items expressly listed as structural components were not investment-credit property and separately rejected unreliable after-the-fact HVAC percentages. AmeriSouth kept most special-HVAC claims with 27.5-year apartments. Courts have therefore split not because the regulation is ambiguous about central systems, but because taxpayers sometimes claim process HVAC without a separate unit or without records. Comfort cooling that also helps a kitchen does not meet a “sole” test.
Central system versus a process machine
A packaged rooftop unit that serves dining, offices, and a kitchen is a central system on ordinary facts. A dedicated computer-room air conditioner, a process chiller piped only to equipment, or a kitchen makeup-air unit sized solely to an exhaust hood is the process side in the matrices — if the unit is separate and the justification is process, not occupancy. The regulation requires sole justification, not primary justification.
How Publication 5653 discusses HVAC
Every Chapter 7 matrix that addresses HVAC keeps building comfort systems with the building. The restaurant no-allocation sentence is the clearest examiner instruction against splitting a mixed unit. Data centers have no matrix; sole-justification cooling for equipment is a regulation argument that still needs engineering support. Generators and HVAC are different assets: life-safety generators are building in the casino and residential matrices.
Building-system capitalization is a different question
Treas. Reg. §1.263(a)-3 lists HVAC — motors, compressors, boilers, furnaces, chillers, pipes, ducts, radiators — as a building system for improvement testing. Replacing a system can be a restoration of that unit of property. A partial disposition election may apply to the retired unit under the MACRS disposition regulations. Those rules do not turn a new rooftop unit into five-year property.
Documentation for a sole-justification claim
Mechanical schedules, sequences of operation, and load calculations should show that the unit is required for machinery, process, or foodstuffs and that occupancy comfort is incidental or insubstantial. Photographs of a separate kitchen or process unit help. A single mixed AHU with a kitchen percentage is the fact pattern the restaurant matrix tells examiners not to allocate.
Cost-estimating approaches in Publication 5653 Chapter 3, including detailed engineering and residual estimation, are methods examiners observe. Super Intelligence extraction is a proposed product description, not an operational claim. This page is educational information, not tax advice.
Related specialized ventilation
Kitchen exhaust hoods and makeup air solely for that exhaust are discussed on the specialized-ventilation page and in the restaurant hook-up row. They are not a license to reclass the dining-room rooftop unit. Residential built-in stove hoods are building in the residential matrix. Read the property-type row before analogizing a restaurant kitchen to an apartment.
Sources
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- 3IRS Publication 5653 — Cost Segregation Audit Techniques Guide (rev. 2-2025)(opens in a new tab)
Written for IRS examiners. The guide states it is not an official pronouncement of law and cannot be cited as authority. It predates the July 2025 law.
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