Lighting Flashcards
What is the Daylight Factor (DF)?
The Daylight Factor (DF) is the ratio of the light level inside a structure to the light level outside the structure. It is a measure of daylighting potential that describes the amount of natural light that enters a building through windows. It is expressed as a percentage and calculated as the ratio of the illuminance at a reference point inside the building to the illuminance of unobstructed sky outside the building.
What are the three components of the Daylight Factor (DF)?
The three components of the Daylight Factor (DF) are:
Sky component (SC) - the direct sunlight that enters the building through the windows
Externally reflected component (ERC) - the light reflected from external surfaces such as clouds, buildings, and trees
Internally reflected component (IRC) - the light reflected from internal surfaces such as walls and furniture.
What is illuminance?
Illuminance is the amount of light that falls on a surface. It is measured in lux (lm/m2) and describes the amount of light that reaches a surface per unit area. It is a key metric in lighting design and is used to determine the required amount of artificial light needed to adequately illuminate a space.
What is luminance?
Luminance is the amount of light that is reflected by a surface. It is measured in candelas/m2 (cd/m2) and describes the brightness of a surface. It is an important consideration in lighting design as it affects the visual perception of a space.
What is the difference between direct and diffuse light?
Direct light is light that travels in a straight line from the source to the surface, while diffuse light is light that has been scattered or reflected before it reaches the surface. Direct light creates sharp shadows and highlights, while diffuse light creates a softer, more even lighting effect.
What is the significance of measuring lighting in building design?
Measuring lighting in building design is important for assessing the lighting conditions of a space and guiding design decision-making. It helps to determine the required amount of artificial lighting needed to adequately illuminate a space and assesses the potential for natural lighting through the use of metrics such as the Daylight Factor. It also affects the visual perception of a space, which can have an impact on the atmosphere and experience of the space.
