ASHRAE-90.1-2022- - Page 010
Extracted Content
b. The secondary sidelighted area depth is the horizontal distance perpendicular to the vertical fenes-
tration, which begins at the edge of the primary sidelighted area depth and ends at the smaller of
- one vertical fenestration head height or
- the distance to any 5 ft or higher opaque vertical obstruction.
If the adjacent primary sidelighted area ends at a 5 ft or higher opaque vertical obstruction, there is no secondary sidelighted area beyond such obstruction.
dead band: the range of values within which a sensed variable can vary without initiating a change in the controlled process.
decorative lighting: see lighting, decorative .
dedicated replacement air: see makeup air .
degree-day: the difference in temperature between the outdoor mean temperature over a twenty-four-hour period and a given base temperature. The classifications are defined as follows:
cooling degree-day base 50°F (CDD50): 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. heating degree-day base 65°F (HDD65): for any one day, when the mean temperature is less than 65°F, there are as many degree-days as degrees Fahrenheit temperature difference between the mean temperature for the day and 65°F. Annual heating degree-days (HDDs) are the sum of the degree-days over a calendar year.
demand: the highest amount of power (average Btu/h over an interval) recorded for a building or facility in a selected time frame.
demand control ventilation (DCV): a ventilation system capability that provides for the automatic reduction of outdoor air intake below design rates when the actual occupancy of spaces served by the system is less than design occupancy.
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 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.
dimmer: a lighting control device that is capable of varying the light output and energy usage of light sources.
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 and then converted back to analog or binary form to control physical devices.
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 auxiliary equipment as fans, pumps, and transformers .
door: an operable opening area in the building envelope that is not fenestration . A door where more than one-half of the door area is glazed is considered fenestration, and a door where one-half or less of the door area is glazed is considered an opaque door . An access hatch is considered a door . For the purposes of determining building envelope requirements, the classifications are defined as follows:
metal coiling door: an upward-acting, nonswinging door assembly consisting of interlocking horizontal slats or sheets that, upon opening the door, roll up around a horizontal barrel above the door opening. nonswinging door: roll-up, metal coiling, sliding, and any other door that is not a swinging door . sectional garage door: an upward-acting, nonswinging door assembly made of two or more horizontal panels hinged together vertically. swinging door: a door having an operable opaque panel with hinges or pivots on one side.
door area: total area of the door measured using the rough opening and including the door slab and the frame. (See fenestration area .)
driver: a device designed to operate a solid-state (e.g., LED) light source.
8 ANSI/ASHRAE/IES Standard 90.1-2022 (I-P)