Sources and Methodology

Last updated: January 15, 2026

This page explains where our general lighting guidance comes from and exactly how the lighting planner calculates its estimates. We publish this page so that nothing on the site relies on an unstated assumption.

Public sources we draw on

Our general guidance on LED lighting, energy use, and lighting terminology is informed by publicly available consumer and technical resources from the following organizations. We link directly to the relevant pages wherever we cite them in a guide:

• U.S. Department of Energy, Energy Saver program — general consumer guidance on LED lighting, lighting choices, and daylighting.
• ENERGY STAR — consumer guidance on light bulbs and certified LED products.
• U.S. Environmental Protection Agency — LED basics and electronics donation/recycling guidance.
• U.S. Consumer Product Safety Commission — general home product safety guidance.
• Illuminating Engineering Society (IES) — the leading U.S. professional society for lighting science and design.
• UL (Underwriters Laboratories) — product safety listing and certification standards.
• National Electrical Manufacturers Association (NEMA) — standards for lighting products and fittings.
• National Fire Protection Association — National Electrical Code (NFPA 70) — the model electrical code referenced by most U.S. jurisdictions.

How we use these sources

Where a guide states a specific number — a typical lumens-per-square-foot range, a common color-temperature range for a type of room — we present it as commonly published general guidance rather than attribute an exact figure to one specific document as a direct quote. Local electrical codes, utility rates, and manufacturer specifications vary, so we deliberately keep numeric guidance in ranges rather than false-precision single values.

Lighting planner methodology

The planner estimates a starting lumens range using a lumens-per-square-foot figure for your selected room type, multiplied by your room's floor area, then adjusted by four factors you provide: the room's main activity, how much natural light it gets, whether its dominant surface colors are light or dark, and your personal brightness preference. The suggested split between ambient, task, and accent light is based on a typical layer distribution for that room type, shifted toward task lighting when you indicate a need for reading or detailed work. The suggested color-temperature range is a typical range for that room type, shifted warmer or cooler based on your stated preference.

Every number the planner produces is a range, not a single value, and is clearly labeled as an estimate. The tool does not calculate footcandles at specific points in a room, does not account for ceiling height beyond a general note, does not model fixture beam angles or light loss over distance, and cannot see your room. It is designed to give you a sensible, well-reasoned starting point for shopping and layout — not a replacement for a professional lighting design, which accounts for all of these factors precisely.

When our guidance is not enough

For anything involving new wiring, new electrical boxes, dedicated circuits, or fixtures in damp or wet locations, our guides direct you to a licensed electrician rather than attempting to cover code-level specifics that vary by jurisdiction and change over time.