ARE 5.0 PPD · Complete public sample

Screen solar access together with site constraints

Use a defined sun condition to test a design option rather than relying on orientation alone.

Understand the governing concept.

Orientation influences solar exposure, but an adjacent obstruction can erase the benefit of an otherwise favorable facade. Establish the climate objective and the particular sun condition the project asks you to protect. At the defined condition, a simple shadow calculation can screen whether an obstruction reaches the target glazing.

A solar-access result is only one constraint. Preserve protected landscape, respect boundaries and consider glare, overheating and views alongside that result. Select an alternative that meets every supplied mandatory condition before ranking its optional benefits.

By the end of this refresher

Explain the basis or assumption controlling this decision.
Apply the method within its stated limits.
Check the result and choose a related study task.

L_s=\frac{H_o}{\tan \alpha}

For the supplied level-ground, aligned-sun model, calculate the horizontal shadow length cast by a vertical obstruction.

Define the basis before substituting a value
Symbol	Meaning	Unit or basis
$L_s$	Horizontal shadow length	ft
$H_o$	Obstruction height above the target's ground plane	ft
$\alpha$	Solar altitude above the horizon	degrees; calculator in degree mode

When the method applies

The simple shadow model assumes level ground, a vertical obstruction and a target at ground level, with the solar azimuth aligned with the obstruction-to-target line. Real facade analysis needs actual three-dimensional sun and site geometry.
Solar access is not a universal design goal. Climate, occupancy, cooling demand and glare may favor different facade and shading strategies.

A20-ft obstruction casts a34.64-ft shadow on level ground for a30-degree aligned solar altitude. A target40ft away is outside that shadow; the protected grove must still be preserved. — Evaluate the supplied sun position and site constraints. Use the worked-case givens and limits below. Open the diagram for a full-size view; scroll horizontally on a narrow screen.

Original teaching case

Work the decision, then cross-check it.

A hypothetical winter-access study requires a ground-level point at south glazing to remain unshaded at a supplied solar altitude of 30°. A 20 ft tall obstruction lies due south, aligned with the sunlight direction. Level ground separates it from the point by 40 ft. The proposed layout also preserves the site's protected grove.

Calculate shadow length: 20/tan(30°) = approximately 34.64 ft.
Compare the 40 ft clearance with that length; the ground-level point lies approximately 5.36 ft beyond the shadow.
Confirm that the layout also preserves the mandatory grove; then retain it for further glare, shading and annual-performance study.

L_s=\frac{20}{\tan 30^{\circ}}=34.64\ \mathrm{ft},\qquad 40-34.64=5.36\ \mathrm{ft}

Decision

The option passes the two supplied screening conditions at this single sun position.

Independent check

At a 45° sun altitude the same obstruction would cast a 20 ft shadow; a lower 30° altitude should create a longer one.

A fresh application

Use the concept under changed conditions.

Choose a response before inspecting the reasoning. This is a learning check, separate from scored diagnostic and mock attempts.

Connect this refresher to your program.

Open related lesson PPD-L02 in owner review →
Connect this prerequisite to the complete program explanation and its conditions.
Move to related program practice →
Use new questions after focused repair; keep learning checks separate from diagnostic and mock results.

NCARB provides examination formulas, structural resources and case-study material. Refresh site response, system selection and tradeoffs before comparing design alternatives. The full PPD program is in invited development review; paid enrollment remains closed. This topic is classified as understanding and application; no individual reference omission has been verified.

Original ReasonSpan^™ teaching material. AI-assisted checks are complete; independent specialist review remains pending.