CLC Daylighting Integration 3 — Questions and Answers
Question 1: Which fenestration strategy is most effective at controlling direct beam sunlight on east- and west-facing facades?
- Horizontal overhangs
- Vertical fins or louvers (Correct answer)
- Light shelves
- Diffuse glazing with low VT
Correct answer: Vertical fins or louvers
Vertical fins are most effective on east and west facades because the sun's low lateral angles require vertical shading elements to intercept direct beam radiation.
Question 2: Annual Sunlight Exposure (ASE) is used in daylighting to measure:
- The total daylight hours available at the building site
- The percentage of floor area receiving more than 1,000 lux of direct sunlight for more than 250 occupied hours per year (Correct answer)
- The annual energy savings from daylighting controls
- The fraction of sky visible from a sensor point
Correct answer: The percentage of floor area receiving more than 1,000 lux of direct sunlight for more than 250 occupied hours per year
ASE quantifies the risk of glare and overheating by measuring how much of the floor area is exposed to high direct-sun illuminances for extended periods annually.
Question 3: A toplighting system using a sawtooth roof with north-facing glazing (in the Northern Hemisphere) provides:
- Maximum solar heat gain in winter
- Uniform diffuse daylight with minimal direct sun penetration (Correct answer)
- Concentrated beam daylight for task lighting
- Primarily reflected ground light
Correct answer: Uniform diffuse daylight with minimal direct sun penetration
North-facing sawtooth glazing admits uniform diffuse sky light while avoiding direct sun, making it ideal for spaces requiring consistent, glare-free illumination.
Question 4: What is the recommended minimum Daylight Factor for a typical office environment according to daylighting guidelines?
- 0.5%
- 2% (Correct answer)
- 5%
- 10%
Correct answer: 2%
A Daylight Factor of approximately 2% is commonly cited as the minimum for office spaces to be considered adequately daylit under overcast sky conditions.
Question 5: Dynamic glazing (electrochromic glass) in a daylighting system primarily benefits occupants by:
- Eliminating the need for any electric lighting
- Allowing real-time adjustment of tint to control glare and solar heat gain (Correct answer)
- Permanently blocking all direct sunlight
- Increasing the center-of-glass U-value
Correct answer: Allowing real-time adjustment of tint to control glare and solar heat gain
Electrochromic glazing can be tinted on demand, letting occupants or automated controls balance view, glare control, and solar heat gain dynamically throughout the day.
Question 6: In a photosensor-based daylight harvesting system, 'open-loop' control means the sensor:
- Measures total illuminance including both daylight and electric light
- Measures only daylight contribution without detecting the electric light output (Correct answer)
- Turns off all lights when daylight exceeds the setpoint
- Requires manual calibration by occupants each morning
Correct answer: Measures only daylight contribution without detecting the electric light output
An open-loop photosensor measures incoming daylight only (typically pointed toward the window or sky) rather than the combined ambient illuminance, avoiding feedback interference.
Question 7: Which building orientation strategy maximizes winter solar gain while minimizing summer overheating in a temperate US climate?
- Large glazing areas on the north facade
- Elongating the building on the east-west axis with large south-facing glazing and horizontal overhangs (Correct answer)
- Equal glazing distribution on all four facades
- Concentrating glazing on east and west facades for morning and afternoon light
Correct answer: Elongating the building on the east-west axis with large south-facing glazing and horizontal overhangs
Elongating on the east-west axis maximizes south exposure; horizontal overhangs block the high summer sun while admitting the lower winter sun, optimizing solar access.
CLC Daylighting Integration 3
Which fenestration strategy is most effective at controlling direct beam sunlight on east- and west-facing facades?