The purpose of building codes are to guide government agencies in meeting their minimum obligations to protect the general welfare of the population they serve. Codes are designed to prevent damage to property, as well as injury or death to persons, and these objectives are accomplished by applying accumulated knowledge to the avoidance, reduction, or elimination of definable hazards.

Codes generally apply to the built environment and, when adopted by the pertinent authority, become lawful requirements that mandate compliance. An authority may write its own code document or may adopt other code documents. Different states and/or municipalities are free to adopt different codes.

Standards are usually regarded only as recommendations that do not have the force of law, unless the standard is adopted by the authority having jurisdiction. It is common for sections of a local code to refer to nationally recognized standards. In many instances, entire sections of the standards are adopted into the code by reference, and then become legally enforceable.

There are three main organizations in the United States who write codes that impact HVACR: IAPMO, ICC and NFPA.

The following national codes make reference to specific ACCA procedures in order to comply. Jurisdictions that adopt these codes require the use of ACCA procedures as outlined in our technical manuals.

The IAPMO's Uniform Mechanical Code requires the use of Manual J (Residential Load Calculation), Manual N (Commercial Load Calculation), Manual D (Residential Duct Systems), and Manual Q (Commercial Duct Systems).

The ICC's International Mechanical Code requires the use of Manual D (Residential Duct Systems).

The ICC's International Residential Code requires the use of Manual J (Residential Load Calculation) and Manual D (Residential Duct Systems).

The ICC's International Energy Conservation Code includes Manual J as one of the approved methods of sizing.

» Codes Brochures
ACCA has developed a number of brochures to help codes inspectors understand quality HVAC (and contractors understand codes).

» Codes Links
Links to the major codes organizations.

» Codes Changes
Learn how you can get involved in the code development process.

» Code References
Find code references and guidebooks at the ACCA online store.

» Residential HVAC System Design Review Form
ACCA has crafted an easy-to-use evaluation of HVAC system design elements in the pertinent building codes.