The following is a compilation of building energy-code related terms and acronyms used on the Building Energy Codes website and throughout the building construction industry.

Select a letter to navigate through the glossary:


A (23) B (23) C (41) D (27) E (28) F (15) G (12) H (21) I (20) K (5) L (11) M (16) N (15) O (11) P (21) R (22) S (37) T (14) U (12) V (11) W (10)
Above-Grade Wall

A wall that is not a below-grade wall.

Above-Grade Walls

Those walls (Section 802.2.1) on the exterior of the building and completely above grade or the above-grade portion of a basement or first-story wall that is more than 15% above grade.


Alternate current.


Air changes per hour.


An extension or increase in the height, conditioned floor area, or conditioned volume of a building. The code applies to additions to existing buildings.

Adopting Authority

The agency or agent that adopts a code or standard.


Annual fuel utilization efficiency; combustion heating equipment efficiency is expressed in terms of AFUE. New equipment typically ranges from about 78% to 96% AFUE. Higher AFUE ratings indicate more efficient equipment.


Association of Home Appliance Manufacturers.


Air-Conditioning, Heating and Refrigeration Institute.

Air Economizer

A duct and damper arrangement and automatic control system that together allow a cooling system to supply outside air to reduce or eliminate the need for mechanical cooling during mild or cold weather.

Air Economizer Systems

Ducting arrangements and automatic control systems that allow a cooling supply fan system to supply outdoor (outside) air to reduce or eliminate the need for mechanical refrigeration during mild or cold weather.


Any construction, renovation, or change in a mechanical system that involves an extension, addition, or change to the arrangement, type, or purpose of the original installation.


American National Standards Institute.

Application Part-Load Value (APLV)

A single number part-load efficiency figure of merit calculated in accordance with the method described in Air Conditioning, Heating, and Refrigeration Institute (AHRI) Standard 550/590 referenced with the method rating conditions described in those standards.


Formerly referred to as the American Society of Heating, Refrigerating and Air-Conditioning Engineers.


American Society of Mechanical Engineers.


American Society for Testing and Materials.

Attic and Other Roofs

All other roofs, including roofs with insulation entirely below (inside of) the roof structure (e.g., attics, cathedral ceilings, and single-rafter ceilings), roofs with insulation both above and below the roof structure, and roofs without insulation but excluding metal building roofs.

Authority Having Jurisdiction

The agency or agent responsible for enforcing the code or standard.

Auto Operated Control Damper

A damper that automatically opens and closes.


Self-acting, operating by its own mechanism when actuated by some nonmanual influence, such as a change in current strength, pressure, temperature, or mechanical configuration.

Automatic Control Device

A device capable of automatically turning loads off and on without manual intervention.

Automatic Time-Switch Controls

Controls that automatically switch lights or equipment on and off.