What does the "three times the head height" measure mean?

The head height is the height of the window glazing. If you have a 10' high window, area within 30' of the window can be claimed as having a view (assuming no obstructions). 

Hi Marine,   The “three times the head height” refers to the 3x height of vision glazing from the floor finish level.  Please refer to the LEED BD+C v4 guide, page 751. There is a case example with an illustration of the figure.    Best regards – Afogreen Build Team       

The requirement you're referring to—"unobstructed views for regularly occupied floor area within three times the head height"—is often seen in building and sustainability standards like LEED or WELL. Here's how it generally works: Head height refers to the average height of a person’s eye level when standing (around 5 to 6 feet, or 1.5 to 1.8 meters). To meet the requirement, you calculate three times this height (so about 15 to 18 feet, or 4.5 to 5.4 meters), and any regularly occupied floor area within this distance from a window should have an unobstructed view to the outside. For example:

• If the head height is 5 feet, any regularly occupied space within 15 feet from the window should have a clear, unobstructed view to the outside (no walls, columns, or other obstacles blocking the sightline).

To measure:

1. Identify the regularly occupied areas.
2. Measure the distance from eye level to three times that distance towards the window.
3. Ensure the view is clear (without partitions, furniture, or other barriers).

This guideline ensures natural light and views, which can improve well-being and productivity. If you're still unsure, you might want to check specific building codes or reach out to a LEED/WELL consultant for precise guidelines tailored to your project.

It seems that we have two different responses to the question. For LEED's purposes, the first response is correct. "Head height" refers to the distance from the floor to the top of the vision glazing. The metric in the second response is typically referred to as "eye level" (which is a term also mentioned in that response).