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:

Filter

A (25) 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)
Daylight Glazing

Exterior glazing over 6 feet above the finished floor.

DDC

See Direct Digital Control.

Deadband

The temperature range in which no heating or cooling is used.

Decorative Lighting

Lighting that is purely ornamental and installed for aesthetic effect. Decorative lighting shall not include general lighting.

Degree Day

See "Heating Degree Days."

Degree Day Base 50F

For any one day, when the mean temperature is more than 50°F, there are as many degree days as degrees Fahrenheit temperature difference between the mean temperature for the day and 50°F. Annual cooling degree days (CDDs) are the sum of the degree days over a calendar year.

Demand

The highest amount of power (average kilowatt over an interval) recorded for a building or facility in a selected time frame.

Design A

National Electrical Manufacturers Association (NEMA) design class designations for standard general purpose polyphase squirrel-cage induction motors.

Design B

National Electrical Manufacturers Association (NEMA) design class designations for standard general purpose polyphase squirrel-cage induction motors.

Design Capacity

Output capacity of a system or piece of equipment at design conditions.

Design Conditions

Specified environmental conditions, such as temperature and light intensity, required to be produced and maintained by a system and under which the system must operate.

Design E

National Electrical Manufacturers Association (NEMA) design class designations for standard general purpose polyphase squirrel-cage induction motors.

Design Energy Cost

The annual energy cost calculated for a proposed design.

Design Professional

An architect or engineer licensed to practice in accordance with applicable state licensing laws.

Direct Digital Control (DDC)

A type of control where controlled and monitored analog or binary data (e.g., temperature, contact closures) are converted to digital format for manipulation and calculations by a digital computer or microprocessor, then converted back to analog or binary form to control physical devices.

Disconnect

A device or group of devices or other means by which the conductors of a circuit can be disconnected from their source of supply.

Distribution System

Conveying means, such as ducts, pipes, and wires, to bring substances or energy from a source to the point of use. The distribution system includes such auxilliary equipment as fans, pumps and transformers.

DOE

U.S. Department of Energy.

Domestic Water Heating System (DWH)

Domestic Water Heating Systems may be circulating or non-circulating.

Door

Doors include all openable opaque assemblies (which are not fenestration) located in exterior walls of the building envelope. Doors with glass can be treated as a single door assembly, in which case an aggregate U-factor (a U-factor that includes both the glass and the opaque area) must be used, or the glass area of the door can be included with the other glazing, and an opaque door U-factor can be used to determine compliance of the door.

Door Area

Total area of the door measured using the rough opening and including the door slab and the frame. See "Fenestration Area."

Dry-Type Transformer

A transformer in which the core and coils are in a gaseous or dry compound.

DSM

Demand-side management.

Duct

A tube or conduit used for conveying air. The air passages of self-contained systems should not be construed as air ducts.

Duct Furnace

A furnace normally installed in distribution ducts of air conditioning systems to supply warm air for heating and that depends on a blower not furnished as part of the duct furnace for air circulation.

Duct System

A continuous passageway for the transmission of air that, in addition to ducts, includes duct fittings, dampers, plenums, fans, and accessory air-handling equipment and appliances.

Dwelling Unit

A single housekeeping unit of one or more rooms providing complete, independent living facilities, including permanent provisions for living, sleeping, eating, cooking, and sanitation.