Glossary

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:

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A (24) B (22) C (41) D (27) E (27) 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) Z (1)
U-Factor

A measure (Btu/h ft2 °F) of how well a material or series of materials conducts heat. U-factors for window and door assemblies are the reciprocal of the assembly R-value. The smaller the number, the less the heat flow.

UA

U-factor X area; REScheck performs a simple UA calculation for each building assembly to determine the overall UA of your building. The UA that would result from a building conforming to the code requirements is compared against the UA for your building. If the total heat loss (represented as a UA) through the envelope of your building does not exceed the total heat loss from the same building conforming to the code, then the software declares that you pass. A high-efficiency equipment trade-off can also be performed under certain codes.

UL

Underwriters Laboratories, Inc.

UL 181A/B

A test procedure for tapes and mastics used to seal ductwork.

Unconditioned Space

An enclosed space within a building that is not a conditioned space.

Unenclosed Space

A space that is not an enclosed space.

Unit Energy Costs

Costs for units of energy or power purchased at the building site. These costs may include energy costs, as well as costs for power demand as determined by the adopting authority.

Unitary Cooling Equipment

One or more factory-made assemblies that normally include an evaporator or cooling coil and a compressor and condenser combination. Units that perform a heating function are also included.

Unitary Heat Pump

One or more factory-made assemblies that include an indoor conditioning coil, compressor(s) and outdoor coil or refrigerant-to-water heat exchanger, including means to provide both heating and cooling functions. When heat pump equipment is provided in more than one assembly, the separate assemblies shall be designed to be used together.

Unitary Heating and Cooling

One or more factory-made assemblies that include an evaporator or cooling coil, a compressor and condenser combination, and that shall be permitted to include a heating function as well. When heating and cooling equipment is provided in more than one assembly, the separate assemblies shall be designed to be used together.

Unitary Packaged

Each package is a standalone system that provides all of the heating and cooling requirements for the area of the building that it serves.

UV

Ultraviolet.