CLD Daylighting Design 3 — Questions and Answers
Question 1: A designer specifies electrochromic glazing in a daylighting system. What is the primary performance advantage over static tinted glass?
- Lower installed cost per square foot
- Dynamically variable visible transmittance that adapts to changing sky conditions (Correct answer)
- Higher thermal resistance (U-value) in all tint states
- Elimination of the need for any interior shading devices
Correct answer: Dynamically variable visible transmittance that adapts to changing sky conditions
Electrochromic glazing can electrically switch its visible transmittance across a range of states, optimizing daylight admission and glare control dynamically rather than using a fixed tint.
Question 2: Which LEED v4 credit requires spatial Daylight Autonomy (sDA) and Annual Sunlight Exposure (ASE) as the primary simulation metrics?
- IEQ Credit: Daylight (Correct answer)
- IEQ Credit: Quality Views
- EA Credit: Optimize Energy Performance
- IEQ Prerequisite: Minimum Indoor Air Quality Performance
Correct answer: IEQ Credit: Daylight
LEED v4's IEQ Credit: Daylight uses sDA300/50% and ASE1000,250h as the primary metrics for Option 1 (simulation) compliance.
Question 3: What does an Annual Sunlight Exposure (ASE) value of ASE1000,250h indicate?
- The percentage of floor area receiving at least 1,000 lux for at least 250 occupied hours per year (Correct answer)
- The annual average illuminance across all occupied hours
- The percentage of hours when daylight exceeds 1,000 lux anywhere in the space
- The peak instantaneous solar irradiance measured at the work plane
Correct answer: The percentage of floor area receiving at least 1,000 lux for at least 250 occupied hours per year
ASE1000,250h is the percentage of the regularly occupied floor area that receives direct sunlight of 1,000 lux or more for at least 250 occupied hours per year, indicating a glare/discomfort risk.
Question 4: In daylighting design, what is 'veiling reflections' and how does daylighting position affect it?
- Reflections from luminaires that reduce task contrast; daylighting from the side minimizes them on horizontal tasks (Correct answer)
- Glare from sky visible through windows; avoided by positioning windows behind occupants
- Reflections from exterior surfaces that increase interior illuminance
- A measurement artifact in photometric testing; irrelevant to daylighting
Correct answer: Reflections from luminaires that reduce task contrast; daylighting from the side minimizes them on horizontal tasks
Veiling reflections are specular reflections of bright sources (including windows) on task surfaces that reduce contrast; sidelighting rather than overhead lighting reduces them on horizontal work surfaces.
Question 5: Which window orientation typically provides the most uniform and controllable daylight with the least direct solar gain in the Northern Hemisphere?
- South-facing
- East-facing
- North-facing (Correct answer)
- West-facing
Correct answer: North-facing
North-facing windows in the Northern Hemisphere receive only diffuse skylight throughout the year with no direct solar penetration, providing consistent and controllable illuminance.
Question 6: A sawtooth roof monitor with glazing facing north is commonly used in industrial buildings primarily to achieve:
- Maximum solar heat gain for passive heating
- Uniform, glare-free diffuse daylight distributed across a large floor plate (Correct answer)
- Dramatic shadow patterns that indicate time of day
- High visible transmittance with maximum solar spectrum transmission
Correct answer: Uniform, glare-free diffuse daylight distributed across a large floor plate
North-facing sawtooth monitors deliver consistent diffuse skylight uniformly across large industrial floor plates while eliminating direct sun penetration and associated glare.
Question 7: In Radiance-based daylighting simulation, the parameter that most directly controls the accuracy of inter-reflected light calculations is:
- -ab (ambient bounces) (Correct answer)
- -ar (ambient resolution)
- -av (ambient value)
- -af (ambient file)
Correct answer: -ab (ambient bounces)
The -ab (ambient bounces) parameter in Radiance controls how many times diffusely reflected rays are traced, directly determining the accuracy of inter-reflected daylight calculations.
CLD Daylighting Design 3
A designer specifies electrochromic glazing in a daylighting system.
What is the primary performance advantage over static tinted glass?