Sustainable & Energy-Efficient Lighting Solutions Flashcards

Which of the following best describes the 'whole building' method versus the 'space-by-space' method in ASHRAE 90.1 lighting compliance?

Answer: Whole building averages LPD across the entire building; space-by-space applies individual limits per room type

The whole-building method applies a single averaged W/ft² budget to the total floor area, while space-by-space assigns specific LPD limits to each space type, allowing design flexibility.

A CLD is designing a parking garage with a target of reducing energy use by 60% versus a conventional HID system. Which combination of strategies is most likely to achieve this?

Answer: LED fixtures + occupancy-based bi-level control + daylight harvesting at perimeter

Combining LED efficacy gains (~50% savings vs. HID), bi-level occupancy dimming, and perimeter daylight harvesting compounds savings to reach 60% or more in parking structures.

What is 'circadian-effective' lighting design primarily concerned with in sustainable buildings?

Answer: Aligning the spectrum and intensity of light with occupants' natural biological rhythms to support health

Circadian-effective lighting uses spectrally tunable or well-designed fixed-spectrum sources to support alertness during the day and promote relaxation and melatonin production in the evening.

In an energy audit of an existing office building, which existing condition most strongly indicates an opportunity for lighting energy savings?

Answer: Illuminance levels consistently 3× the IES recommended target with no dimming controls

Chronic overlighting (illuminance far exceeding IES targets) with no dimming controls represents direct wasted energy that can be recovered by reducing wattage or adding controls.

What role does a 'lighting energy dashboard' or submetering system play in a sustainable building's post-occupancy phase?

Answer: It provides real-time and historical energy data to verify savings and identify control system failures

Submetering and dashboards enable ongoing measurement and verification (M&V), confirming that projected savings are achieved and flagging malfunctioning sensors or drivers.

Which IES document establishes recommended illuminance levels used as the basis for energy-code LPD allowances?

Answer: IES RP-1 (Recommended Practice for Office Lighting) and other application RPs

IES Recommended Practices (RP series) define illuminance targets per application type, which inform ASHRAE 90.1's space-by-space LPD allowances.

When a lighting designer applies 'right-sizing' to a sustainable retrofit, the primary goal is to:

Answer: Match the installed lumen output and distribution precisely to the actual task requirements, avoiding over- or under-lighting

Right-sizing delivers exactly the illuminance recommended by IES for each task, avoiding the energy waste of overlighting while ensuring visual adequacy.