# Fan System Bhp: Building Code Definition > How the IECC 2009 define fan system bhp, where the wording differs, and which chapters depend on the term. - Canonical: https://harth.build/resources/glossary/fan-system-bhp/ - Last updated: 2026-09-07 - Data source: Definitions quoted from the 2009 International Codes as transcribed in this site's building-codes collection, with the source chapter linked for each quotation. Usage counts are computed over the chapters hosted here, one copy per code. The [ICC code library](https://codes.iccsafe.org/codes) publishes the current model text and the [ICC adoption maps](https://www.iccsafe.org/advocacy/code-adoption-maps/) show which edition a jurisdiction has adopted; those sources control. ## Key facts | Fact | Value | | --- | --- | | Defined in | IECC 2009 (2009 editions transcribed in this corpus) | | Primary source | IECC 2009 Definitions (model text, not a jurisdiction's adopted text) | | Chapters using the term | 2 (counted across the codes hosted here) | | Wording identical across codes | Single code (compare before citing one code's wording under another) | ## Direct answer Fan system bhp is a defined term in the International Energy Conservation Code (IECC) 2009, in Definitions. The code's own words are: “The sum of the fan brake horsepower of all fans that are required to operate at fan system design conditions to supply air from the heating or cooling source to the conditioned spacers) and return it to the source or exhaust it to the outdoors.” No other I-Code in this corpus defines it, so the IECC 2009 definition is the one to work from. The term is used in 2 chapters of this corpus, most often in Commercial Energy Efficiency (IECC 2009), Definitions (IECC 2009). These pages transcribe the 2009 model text; verify the definition against the edition and amendments your authority having jurisdiction has adopted. *Content and cited inputs reviewed by [Scott Barrington](https://nz.linkedin.com/in/barrington), Harth founder and architectural technology specialist · Published 2026-09-07 · Updated 2026-09-07.* ## What does this term mean? **Fan System Bhp** — IECC 2009, Definitions: > The sum of the fan brake horsepower of all fans that are required to operate at fan system design conditions to supply air from the heating or cooling source to the conditioned spacers) and return it to the source or exhaust it to the outdoors. ![Labeled code-term definition diagram: Fan System Bhp: Building Code Definition](https://efwwel0vyt9vy5so.public.blob.vercel-storage.com/images/glossary/fan-system-bhp/diagram-1344.webp) *How the IECC 2009 define fan system bhp, where the wording differs, and which chapters depend on the term.* ## What must be verified before using this guidance? **Fan System Bhp** is defined once in this corpus, in the [Definitions](https://harth.build/resources/building-codes/us-states/maryland/iecc-2009/definitions.md) chapter of the International Energy Conservation Code (IECC) 2009: > The sum of the fan brake horsepower of all fans that are required to operate at fan system design conditions to supply air from the heating or cooling source to the conditioned spacers) and return it to the source or exhaust it to the outdoors. ## Where fan system bhp is used in the code The term appears in 2 chapters of the 2009 I-Codes hosted here. The chapters that lean on it hardest are the ones to read next. | Chapter | Code | Mentions | | --- | --- | --- | | [Commercial Energy Efficiency](https://harth.build/resources/building-codes/us-states/maryland/iecc-2009/commercial-energy-efficiency.md) | IECC 2009 | 3 | | [Definitions](https://harth.build/resources/building-codes/us-states/maryland/iecc-2009/definitions.md) | IECC 2009 | 1 | ### The term in use How the code actually writes about fan system bhp, quoted from the 2009 text hosted here: > Each HVAC system at fan system design conditions shall not exceed the allowable fan system motor nameplate hp (Option 1) or fan system bhp (Option 2) as shown in Table 503.2.10.1 (1). — [IECC 2009 §503.2.10.1](https://harth.build/resources/building-codes/us-states/maryland/iecc-2009/commercial-energy-efficiency.md) ## The terms fan system bhp is built out of The definition above leans on 2 other defined terms. Each carries its own code definition, and a local amendment to any of them changes what fan system bhp covers: - **[Supply Air](https://harth.build/resources/glossary/supply-air.md)** — IRC 2009: Air delivered to a conditioned space through ducts or plenums from the heat exchanger of a heating, cooling or ventilating system. - **[System](https://harth.build/resources/glossary/system.md)** — IFC 2009: An assembly of equipment consisting of a tank, container or containers, appurtenances, pumps, compressors and connecting piping. ## Fan System Bhp: what to open, and in what order Every row is a document this term depends on. The [ICC code library](https://codes.iccsafe.org/codes) and the [ICC adoption maps](https://www.iccsafe.org/advocacy/code-adoption-maps/) cover the middle rows. | Check | Where | Confirmed | | --- | --- | --- | | Read the definition in the adopted IECC | Definitions | | | Re-check the requirement that uses it | Commercial Energy Efficiency (IECC 2009) | | | Re-check the requirement that uses it | Definitions (IECC 2009) | | | Confirm the dependent definition | Supply Air | | | Confirm the dependent definition | System | | | Local amendment to any of the above | Jurisdiction's amendment list | | **A research aid, not a code determination.** The authority having jurisdiction decides which edition and which amendments apply. ## Where can you explore related guidance? - [Explore all glossary guidance](https://harth.build/resources/glossary.md) - [Supply Air: Building Code Definition](https://harth.build/resources/glossary/supply-air.md) - [System: Building Code Definition](https://harth.build/resources/glossary/system.md) ## Sources and method Definitions quoted from the 2009 International Codes as transcribed in this site's building-codes collection, with the source chapter linked for each quotation. Usage counts are computed over the chapters hosted here, one copy per code. The [ICC code library](https://codes.iccsafe.org/codes) publishes the current model text and the [ICC adoption maps](https://www.iccsafe.org/advocacy/code-adoption-maps/) show which edition a jurisdiction has adopted; those sources control. ### Source links - [codes.iccsafe.org](https://codes.iccsafe.org/codes) - [iccsafe.org](https://www.iccsafe.org/advocacy/code-adoption-maps/) ## Frequently asked questions ### What is the code definition of fan system bhp? The International Energy Conservation Code (IECC) 2009 defines it in Definitions as: “The sum of the fan brake horsepower of all fans that are required to operate at fan system design conditions to supply air from the heating or cooling source to the conditioned spacers) and return it to the source or exhaust it to the outdoors.” The 2009 model text is reproduced here; the definition that binds your project is the one in the edition your jurisdiction has adopted, as amended locally. ### Which parts of the code depend on fan system bhp? In this corpus the term is used across 2 chapters, led by Commercial Energy Efficiency in the IECC 2009. Those are the sections whose scope moves if the definition is amended locally, so read them together with Chapter 2 rather than on their own. --- - Continue in Harth (open this topic in the Harth agent): https://app.harth.build/agent?context=%2Fresources%2Fglossary%2Ffan-system-bhp%2F - View this page in a browser: https://harth.build/resources/glossary/fan-system-bhp/ - All resources for agents: https://harth.build/llms.txt