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Daylighting
Daylighting is the practice of placing windows, skylights or other transparent media, and reflective surfaces so that, during the day, natural light provides effective internal lighting.
Within the overall architectural design of a building, particular attention is given to daylighting when the aim is to maximize visual comfort, productivity, or to reduce energy use. Energy savings from daylighting are achieved in two ways:
- reduced use of electric lighting or
- from passive solar heating or cooling
Electric lighting energy savings can accrue because occupants choose not to switch their lights on, or because an automatic lighting control system ("photocontrol system") switches the lights off or dims them to a lower level.
Demand Limiting
Demand Limiting (or Load Shedding or Demand Response) predicts potential energy peaks by monitoring the building’s utility meters, then employing a flexible control strategy to defer energy-consuming loads to times of the day when energy usage is billed at lower rates. Load Rolling reduces total energy usage by temporarily turning off or resetting noncritical equipment.
Demand Response
See Demand Limiting
Digital Addressable Lighting Interface (DALI)
A digital protocol for the controlling of lighting in buildings that addresses electrical ballasts.
DALI was established as an open standard rival to Digital Signal Interface (DSI), on which it is based. DALI is standardized in accordance with International Electrotechnical Commission IEC 60929, standard for fluorescent lamp ballasts.
Each piece of operating equipment with a DALI interface can be communicated with over DALI individually. Using a bi-directional data exchange, a DALI controller can query and set the status of each light. As a standalone system, DALI can be operated with a maximum of 64 devices. Alternatively, DALI can be used as a subsystem via DALI gateways.
Damp Location
UL listing for fixtures used in a moist unexposed area, such as a bathroom or porch area.
Design Energy Cost
(as relates to ASHREA/IESNA standard 90.1 and LEED) The Design Energy Cost is calcualted by a simulation program based on the proposed design of the building in its final form, that is, the design submitted for the building permit approval. Compare this to Energy Cost Budget. Design Energy Cost refers to the design case of the project. Energy Cost Budget refers to the baseline case of the project as defined by a standard such as ASHRAE 90.1 (reference: ASHRAE Std. 90.1 Users Manual)
Dichroic Coating
Film that reflects visible light and transmits infrared light. Reflector lamps with dichroic coatings, such as most MR16s provide a cooler beam because most of the heat goes out the back. Dichroic PAR lamps are often called “cool beam.”Diffuser
Light control device that spreads light by scattering it. Opal glass and plastic, etched glass, fabric and paper shades act as diffusers.Dimmer
Control that varies the output of the light source by reducing the voltage or current to the lamp.Direct Digital Control (DDC)
A control system in which a digital computer or microprocessor is directly connected to the valves, dampers, and other actuators which control the system, as opposed to indirectly controlling a system by resetting setpoints on an analog pneumatic or electronic controller.Direct Lighting
Lighting that casts all, or at least 90%, of its light downward. The term can also refer to the distribution of light or the fixtures that produce this type of lighting. With intense beams, direct lighting is very dramatic, rendering forms and textures well. Typical fixtures include recessed lights, track lights, some pendant lights and task lights.Direct-Indirect Lighting
Light comes from up and down. This light is well balanced and pleasing. Light that is predominately direct is also called”semi-direct.” Typical fixtures include most pendant lights, wall brackets and wall valances. Uses include task/ambient lighting over tables and in hallways.
DOE - U.S. Department of Energy
United States Department of Energy (DOE) is Cabinet-level department of the United States government responsible for US energy policy and nuclear safety.
U.S. Department of Energy
c/o Superintendent of Documents
U.S. Government Printing Office
Washington, DC 20402-9325
Downlights
Downlights usually refer to recessed downlights. However, some designers use the term to describe any fixture aiming straight down.
Headlines
Jul 1, , 2009
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Feb 05, 2009
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The Sustainable Integration Solution
Lumisys advocates specifying integrated lighting controls in the way that moves the expertise and accountability to those who are best positioned to be successful.
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