How to read daylight in a floor plan: windows, depth and obstructions

Mark windows, balconies, main rooms and nearby buildings on the plan, and note whether it matches the site. If orientation comes from an old or third-party drawing, mark it for verification.

Nearby buildings, trees or deep balconies can flag areas for a site check, but they are not daylight measurements by themselves.

Observe rooms when residents normally use them. Record weather, curtains, electric lighting and where daylight falls. Photos help comparison, but note the time and conditions.

One observation period cannot establish all-day performance. Separate what was seen from what remains a hypothesis.

• Location: room, window and activity area
• Conditions: date, time, weather, obstructions and curtains
• Use: activity taking place and visual needs

More openness may affect privacy, glare, noise or cooling demand; heavy screening may also affect use. Compare daylight needs with each room’s function.

Layout or finish changes are options to compare—not guarantees of a particular illuminance or daylight rating.

Mark daylight direction, obstructions and activity areas on the plan, then revisit under comparable conditions. For performance conclusions, use project-appropriate measurement or analysis.

• Observed: a site condition recorded with time, place and context
• Clue: a possible issue suggested by drawings, photos or recollection
• To verify: a question needing measurement, documents or professional analysis

This is a preliminary observation method. Final assessment depends on site, season and use. Structural changes, regulations and performance targets need project-specific verification.