Environmental Science in Building - Lighting Flashcards
What does the sign (i) stand for in relation to reflection?
The angle of incidence (i)
What does the sign (r) stand for in relation to reflection?
The angle of reflection (r)
What are the two methods in changing the direction of light by the reflection process?
Specular Reflection & Diffuse Reflection
Describe a diffuse reflection?
A reflection in which the light is scattered in various
What is a specular reflection?
A direct reflection in one direction only.
What is the amount of reflection at a surface measured by?
The reflection factor
Describe the utilisation factor
The utilisation factor is the ratio of the total flux reaching the working plane compared to the total flux output of the lamps
What is the light loss factor
The light loss factor is the ratio of the illuminance provided at some given time compared to the initial illuminance
What does the British zonal system or BZ system classify [in relation to artificial lighting]
The British Zonal System classifies luminaries into 10 standard light distributions with numbers from 1 to 10 BZ1
Describe a direct ratio
A direct ratio is the proportion of the total downward flux from the luminaries which falls directly on the working plane
Describe the meaning of room index
A number which takes account of the proportions of the room using the room index formula
Describe the meaning of room index
A number which takes account of the proportions of the room using the room index formula
What is the meaning of service illuminance
Service illuminance is the mean illuminance achieved during the maintenance cycle of a lighting system, and average of the area considered
