Light & Materials Flashcards

This set of vocabulary flashcards covers fundamental lighting metrics, lamp technologies, efficiency standards, and core electrical concepts from the provided architecture and design lecture materials.

Magic light

A term used in renderings for idealized lighting that cannot exist in reality, which can create false impressions for the building owner.

Luminous Flux ($\phi$)

The total amount of visible light emitted by a source in all directions, measured in lumens (lm).

Luminous Intensity ($I$)

The amount of light emitted in a specific direction, measured in candela (cd).

Illuminance ($E$)

The amount of light falling onto a surface, measured in lux ($lm/m^2$) or foot-candles.

Luminance ($L$)

The brightness of a surface as perceived by the human eye, measured in candelas/$m^2$ or footlamberts.

Luminous Efficacy

A ratio describing how efficiently a source converts electrical power to light, measured in lumens per watt (LPW).

Lighting Power Density (LPD)

A metric used to evaluate lighting efficiency by dividing the total wattage of all luminaires by the floor area ($W/ft^2$).

Lamp

The actual light source, such as a bulb or tube (e.g., LED bulb, fluorescent tube).

Luminaire

The complete lighting unit, which includes the lamp, housing, reflector, and ballast/driver.

Ballast

A device that manages the power supply for discharge lamps by providing the high voltage needed to start and then limiting the current.

Color Rendering Index (CRI)

A scale from $0$ to $100$ that measures how accurately a lamp renders colors; incandescent and halogen lamps have a CRI of $100$.

Correlated Color Temperature (CCT)

The color of light expressed in Kelvins (K), where warm light is less than $3000\,K$ and cool light is greater than $4500\,K$.

Inverse Square Law

A calculation for nonuniform illuminance where the amount of light falling on a surface is equal to intensity divided by distance squared ($E = \frac{I}{d^2}$).

Daylight Harvesting

A control strategy using photo sensors to automatically dim electric lights when natural daylight is sufficient.

Daylight Factor (DF)

A metric that assesses the ratio of indoor light compared to outdoor light under overcast conditions.

Spatial Daylight Autonomy (sDA)

The percentage of floor area that receives target illuminance levels for a specific amount of time annually (e.g., sDA 300, 50%).

Voltage ($V$)

The electric pressure or potential difference between two points, measured in Volts.

Current ($I$)

The flow of electrons through a conductor, measured in Amperes (Amps).

Resistance ($R$)

The opposition to the flow of current, measured in Ohms ($\Omega$).

Power ($P$ or $W$)

The rate at which work is done, calculated in DC circuits as $W = V \times I$, and measured in Watts.

Peak Demand

The highest average power used during a short interval (e.g., $15$–$30$ minutes), which utilities use to calculate additional charges.

Ground Fault Circuit Interrupter (GFCI)

A safety device that shuts off power if it detects a leak in current to prevent electrocution, typically required in wet areas.

Arc Fault Circuit Interrupter (AFCI)

A device that protects against building fires by detecting dangerous electrical arcing between wires.

Transformer

Electrical service equipment that steps down high utility voltage to a lower, usable voltage for building equipment.

Variable Frequency Drive (VFD)

A device that adjusts motor speed to match actual demand, used to improve energy efficiency in HVAC systems.

Emergency Systems

Systems legally required for life safety, such as egress lighting, fire alarms, and elevators.

Standby Systems

Optional electrical systems used for business continuity, such as powering data servers or refrigerators during an outage.

Occupancy Sensor

A control device that turns lights ON automatically when motion is detected and OFF when the room is vacant.

Vacancy Sensor

A control device that requires manual activation to turn lights ON but automatically turns them OFF when the room is empty.

Luminous Flux (ϕϕ) Unit

The total amount of visible light emitted by a source in all directions, measured in lumens (lm).

Luminous Intensity (II)

The amount of light emitted in a specific direction, measured in candela (cd).

Zoning

allows for flexibility in lighting design and management, enabling effective daylight harvesting by optimizing natural light use throughout a space.

Scene Control

provides preset lighting configurations tailored for specific activities, such as presentations, dining, or cleaning, enhancing user experience and functionality.

Voltage (VV)

The electrical potential difference that drives current flow in a circuit, measured in volts (V).

Current (II)

The flow of electric charge in a circuit, measured in amperes (A). It is a crucial factor in determining the performance of electrical systems.

Power (PP or WW)

Power is the rate at which work is done, calculated in DC circuits as W=V×IW=V×I, and measured in Watts.

Resistance (RR)

the opposition to the flow of current, measured in Ohms (ΩΩ). It can be thought of as the load that causes resistance in a circuit.