CLD Sustainability 5 — Questions and Answers
Question 1: A healthcare facility wants to reduce its lighting energy while maintaining required illuminance levels. Which combination is most effective?
- Increase lamp wattage and add more fixtures
- Specify high-efficacy LED luminaires with tunable white and occupancy-based controls (Correct answer)
- Use warmer color temperature sources to reduce glare
- Install manual dimming only and rely on staff to adjust
Correct answer: Specify high-efficacy LED luminaires with tunable white and occupancy-based controls
Pairing high-efficacy LED sources with occupancy-based controls and tunable white capability optimizes energy use while meeting varied task illuminance and circadian needs in healthcare settings.
Question 2: Which of the following best describes 'luminaire efficacy' vs. 'lamp efficacy' in sustainable specification?
- They are identical metrics
- Luminaire efficacy accounts for optical losses within the fixture, giving a more accurate real-world performance figure (Correct answer)
- Lamp efficacy is always lower than luminaire efficacy
- Luminaire efficacy excludes driver losses while lamp efficacy includes them
Correct answer: Luminaire efficacy accounts for optical losses within the fixture, giving a more accurate real-world performance figure
Luminaire efficacy (lm/W at the fixture level) includes driver losses and optical losses, providing a more realistic measure of delivered light per watt than bare lamp efficacy.
Question 3: Which IES document provides the framework for measuring and reporting annual daylight availability metrics like sDA and ASE?
- IES TM-30
- IES LM-83 (Correct answer)
- IES RP-1
- IES TM-21
Correct answer: IES LM-83
IES LM-83 (Approved Method: IES Spatial Daylight Autonomy and Annual Sunlight Exposure) defines the simulation methodology and metrics sDA and ASE for annual climate-based daylight analysis.
Question 4: A lighting designer is asked to verify that an outdoor project meets the IDA/IES Model Lighting Ordinance (MLO) requirements. What does the MLO primarily regulate?
- Minimum illuminance levels for parking areas
- Uplight, light trespass, and maximum installed lighting power for exterior zones (Correct answer)
- Interior lighting power density limits
- Color temperature limits for streetlights
Correct answer: Uplight, light trespass, and maximum installed lighting power for exterior zones
The Model Lighting Ordinance regulates exterior lighting by defining lighting zones and setting limits on uplight (BUG ratings), light trespass, and total installed power to reduce light pollution.
Question 5: In lifecycle cost analysis (LCCA) for lighting, which factor most commonly tips the comparison in favor of LED over a conventional alternative even when first cost is higher?
- Lower initial purchase price
- Reduced energy and maintenance costs over the product life (Correct answer)
- Higher lumen output at installation
- Greater color rendering index
Correct answer: Reduced energy and maintenance costs over the product life
LED's lower annual energy cost and infrequent lamp replacement typically yield significantly lower total cost of ownership over the system life despite higher upfront prices.
Question 6: A project pursues LEED v4.1 Optimize Energy Performance credit for lighting. Which design tool is most appropriate for predicting annual lighting energy savings?
- DIALux or AGi32 energy simulation with controls modeling (Correct answer)
- Manual lux-level calculation (the lumen method)
- CRI measurement tool
- Glare calculation spreadsheet
Correct answer: DIALux or AGi32 energy simulation with controls modeling
Energy simulation tools like DIALux evo or AGi32 can model luminaire schedules, controls sequences, and daylight interaction to predict annual lighting energy consumption for LEED energy modeling.
Question 7: What does a high Annual Sunlight Exposure (ASE) value in a daylight simulation indicate regarding sustainable design?
- Excellent daylighting coverage across the floor plate
- Excessive direct sunlight causing potential glare and thermal discomfort for occupants (Correct answer)
- Low reliance on electric lighting year-round
- High daylight factor uniformity across the space
Correct answer: Excessive direct sunlight causing potential glare and thermal discomfort for occupants
ASE measures the percentage of floor area receiving more than 1,000 lux of direct sunlight for at least 250 hours/year, and a high ASE signals problematic glare and overheating risk.
CLD Sustainability 5
A healthcare facility wants to reduce its lighting energy while maintaining required illuminance levels.
Which combination is most effective?