CLD Energy Codes 3 — Questions and Answers
Question 1: Under ASHRAE 90.1, exterior lighting power is regulated using which primary zone classification system?
- IES illuminance categories A–F
- Lighting zones LZ0–LZ4 based on ambient brightness (Correct answer)
- LEED credit zones 1–5
- Dark-sky reserve tiers I–IV
Correct answer: Lighting zones LZ0–LZ4 based on ambient brightness
ASHRAE 90.1 assigns exterior lighting power allowances based on LZ0–LZ4 lighting zones that correspond to ambient light levels from undeveloped to high-activity urban areas.
Question 2: Which control strategy satisfies ASHRAE 90.1's requirement to reduce exterior building facade and landscape lighting during late-night hours?
- Manual dimmer set to 50%
- Astronomical time switch programmed to reduce output after midnight (Correct answer)
- Occupancy sensor mounted on the facade
- Photocontrol set to switch off at dawn
Correct answer: Astronomical time switch programmed to reduce output after midnight
ASHRAE 90.1 requires exterior ornamental and facade lighting to be reduced by at least 30% after a specified time using an astronomical time switch or similar scheduling control.
Question 3: What is the purpose of the 'additional lighting power allowance' for ornamental chandeliers in ASHRAE 90.1?
- To exempt historic buildings from LPD limits
- To provide extra wattage for decorative luminaires not serving a task function (Correct answer)
- To allow higher LPD in hotel ballrooms only
- To permit incandescent sources without energy penalty
Correct answer: To provide extra wattage for decorative luminaires not serving a task function
ASHRAE 90.1 grants a supplemental power allowance for decorative luminaires (chandeliers, sconces) that serve an ornamental rather than task or ambient function.
Question 4: A gymnasium with a high ceiling uses daylight from skylights. Under ASHRAE 90.1, what daylit zone boundary rule applies to a skylight?
- The daylit zone extends 10 ft beyond each skylight edge
- The daylit zone equals 0.7 times the ceiling height, measured from the skylight edge (Correct answer)
- The daylit zone radius equals twice the skylight width
- The daylit zone is defined only by window geometry, not skylights
Correct answer: The daylit zone equals 0.7 times the ceiling height, measured from the skylight edge
ASHRAE 90.1 defines the primary sidelit daylit zone from skylights as extending 0.7 times the ceiling height outward from the skylight edges.
Question 5: Which ASHRAE 90.1 section specifically covers interior lighting power for nonresidential facilities?
- Section 7 — HVAC
- Section 9 — Lighting (Correct answer)
- Section 5 — Building Envelope
- Section 11 — Energy Cost Budget
Correct answer: Section 9 — Lighting
ASHRAE 90.1 Section 9 contains all interior and exterior lighting requirements, including LPDs, controls, and exemptions.
Question 6: Emergency egress lighting is generally EXEMPT from energy code LPD calculations because it is governed by which primary standard?
- ASHRAE 90.1 Section 9
- NFPA 101 Life Safety Code (Correct answer)
- IECC Chapter 4
- IES RP-29
Correct answer: NFPA 101 Life Safety Code
Emergency egress lighting is mandated by life safety codes such as NFPA 101, and ASHRAE 90.1 explicitly exempts it from LPD compliance calculations.
Question 7: In the IECC, which compliance pathway allows a designer to exceed LPD in some spaces by compensating with lower-than-required LPD in others?
- Prescriptive compliance
- Simulated performance alternative
- Lighting power trade-off approach (Correct answer)
- Mandatory measure compliance
Correct answer: Lighting power trade-off approach
The IECC's lighting power trade-off approach (similar to ASHRAE 90.1's building area method) allows redistribution of lighting power across spaces as long as the total does not exceed the code limit.
CLD Energy Codes 3
Under ASHRAE 90.1, exterior lighting power is regulated using which primary zone classification system?