Energy Efficiency & Sustainability Flashcards

In daylighting design, what is the primary purpose of a light shelf?

Answer: To reflect daylight deeper into the building interior

A light shelf is a horizontal reflective surface that bounces daylight off the ceiling to illuminate areas farther from the window.

Which metric is used to measure the potential of a building's daylit zones relative to all occupied hours with sufficient daylight?

Answer: Daylight Autonomy (DA)

Daylight Autonomy (DA) expresses the percentage of occupied hours when a point receives at least the target illuminance from daylight alone.

A LED lamp has a rated life of 50,000 hours. Operating 12 hours per day, approximately how many years will it last?

Answer: 11 years

50,000 hours ÷ (12 hrs/day × 365 days/year) ≈ 11.4 years.

What is the primary environmental benefit of reducing lighting energy consumption in a building connected to a coal-heavy electrical grid?

Answer: Reduced CO₂ emissions from power generation

Coal power plants emit significant CO₂; reducing electricity demand directly lowers greenhouse gas emissions at the generation source.

Which type of dimming control maintains constant light output over a lamp's life by increasing power as lumens depreciate?

Answer: Lumen maintenance dimming

Lumen maintenance dimming starts fixtures at reduced output and increases drive current over time to compensate for lumen depreciation, saving energy early in lamp life.

A 10,000 sq ft office has an allowable LPD of 0.82 W/ft² per ASHRAE 90.1. What is the maximum installed lighting wattage?

Answer: 8,200W

Maximum wattage = 10,000 ft² × 0.82 W/ft² = 8,200W.

Which lighting system characteristic most directly contributes to reducing cooling energy loads in a building?

Answer: High luminaire efficacy reducing heat output

More efficacious luminaires waste less energy as heat, reducing the thermal load that HVAC systems must remove.