Principles of Building Planning MCQ with answer and solution

Concept

Standard angle of light plane

Formula

NONE

Step-by-step solution

1. The light plane determines the unobstructed angle through which natural daylight reaches a building facade. 2. An angle of 45° measured from the horizontal plane is standardly adopted in building design for adequate natural illumination. 3. Therefore, the angle of light plane commonly adopted is 45°. Answer: B

Explanation

The angle of light plane determines the maximum allowable building height relative to surrounding spaces so that adjacent properties receive adequate natural daylight. An angle of 45 degrees is standardly adopted in building planning as it ensures a balanced obstruction line between neighboring structures. Therefore, 45 degrees is the commonly used angle for light planes.

Why the other options are wrong

A) 30° is too shallow and requires excessively large open spaces in front of buildings. C) 63.50° is used for sky factor calculations rather than defining standard light planes. D) 55° is steeper than the standard 45° angle prescribed for street daylighting regulations.

Shortcut

The standard angle of the light plane for building daylighting is 63.50° (or 45°).

Common mistake

Confusing the standard 45° angle of light plane with the 63.5° angle used for specific street height restrictions.