LLC Landscape Lighting Energy Efficiency & Sustainability 3 — Questions and Answers
Question 1: When calculating the energy savings of replacing 20W halogen path lights with 3W LED equivalents across 15 fixtures running 8 hours/night, what is the daily wattage reduction?
- 204 Wh
- 2,040 Wh (Correct answer)
- 255 Wh
- 1,680 Wh
Correct answer: 2,040 Wh
Each fixture saves 17W; 17W × 15 fixtures × 8 hours = 2,040 Wh (2.04 kWh) saved per day.
Question 2: Which color temperature (CCT) is most commonly recommended for sustainable landscape lighting to minimize disruption to nocturnal wildlife?
- 6500K (cool daylight)
- 4000K (neutral white)
- 2700K (warm white) (Correct answer)
- 5000K (bright white)
Correct answer: 2700K (warm white)
Warm white (2700K or lower) contains less blue-spectrum light, reducing impact on insect and wildlife circadian rhythms compared to cool white sources.
Question 3: A landscape lighting system uses a photocell-enabled transformer. What is the primary sustainability benefit of this feature?
- It prevents voltage surges during thunderstorms
- It automatically turns the system off at sunrise and on at sunset without manual adjustment (Correct answer)
- It increases power factor correction for the entire circuit
- It limits fixture wattage to prevent overloading the transformer
Correct answer: It automatically turns the system off at sunrise and on at sunset without manual adjustment
Photocells eliminate user error in timer settings, ensuring lights never run during daylight hours and reducing unnecessary energy consumption.
Question 4: What is the recommended maximum load percentage for a low-voltage landscape lighting transformer to ensure long-term reliability and efficiency?
- 50%
- 75% (Correct answer)
- 90%
- 100%
Correct answer: 75%
Loading a transformer to no more than 75% of its rated capacity reduces heat buildup and extends component life, improving system reliability.
Question 5: Which wire gauge is most appropriate for a long landscape lighting run exceeding 100 feet to minimize voltage drop?
- 18 AWG
- 16 AWG
- 12 AWG (Correct answer)
- 10 AWG
Correct answer: 12 AWG
12 AWG wire has lower resistance than 16 or 18 AWG, significantly reducing voltage drop on runs exceeding 100 feet and improving fixture efficiency.
Question 6: A LEED-certified project requires landscape lighting to comply with light trespass standards. Which metric is most commonly used to evaluate this?
- Correlated Color Temperature (CCT)
- Color Rendering Index (CRI)
- Backlight-Uplight-Glare (BUG) rating (Correct answer)
- Efficacy rating in lumens per watt
Correct answer: Backlight-Uplight-Glare (BUG) rating
The BUG rating system quantifies backlight, uplight, and glare from a fixture, helping designers meet LEED and IES light trespass standards.
Question 7: What is the environmental advantage of using directional LED fixtures versus floodlights for tree uplighting in a sustainable landscape design?
- Directional LEDs operate at higher voltages that reduce transformer losses
- Directional LEDs concentrate light precisely on the target, reducing wasted lumens and energy (Correct answer)
- Directional LEDs emit UV light that promotes healthier tree growth
- Directional LEDs are waterproof and do not require conduit protection
Correct answer: Directional LEDs concentrate light precisely on the target, reducing wasted lumens and energy
Narrow-beam directional LEDs deliver lumens exactly where intended, avoiding sky spill and reducing total wattage needed to achieve the same visual effect.
LLC Landscape Lighting Energy Efficiency & Sustainability 3
When calculating the energy savings of replacing 20W halogen path lights with 3W LED equivalents across 15 fixtures running 8 hours/night, what is the daily wattage reduction?