BLDG7021 Chap.7 Facade Orientation and Sun Control
Facade Orientation and Sun Control
Fixed shading must respond to orientation and the critical solar period. This chapter uses plan and section geometry to distinguish high-angle and low-angle exposure, then coordinates shade depth with structure, drainage, maintenance, views and facade modules.
Performance evidence and construction details must describe the same device.
Add a comparison at a facade corner, where two orientations and their devices meet. Draw the plan, elevation and a small junction sketch using the same dimensions as the tested sections. Check support, drainage, movement, view and cleaning access, then note whether the environmental logic survives the transition.
If the corner requires a different device, name it as a controlled exception and state how its performance would be verified. This prevents a strong typical bay from masking unresolved edge conditions.
What this chapter covers
- 01
Identify critical solar periods
- 02
Draw plan and section rays
- 03
Choose horizontal or vertical control
- 04
Size an indicative projection
- 05
Detail support and drainage
Worked example · free
Size a horizontal shade
- 1Use depth equals protected height divided by tangent of altitude.
- 1Calculate 1.8 divided by tangent 55 degrees.
- 1Obtain about 1.26 metres, then test lateral sun and buildability.
Key terms
- Solar altitude
- The vertical angle of the sun above the horizon.
- Solar azimuth
- The horizontal direction of the sun relative to the facade orientation.
- Fixed shading
- A permanent external device designed to block selected solar angles.
Facade Orientation and Sun Control FAQ
When is horizontal shading most useful?
Horizontal projections are a strong starting response to high-angle sun because their depth intercepts steep rays before they reach the glazing, occupied zone and critical reference point.
Why do low-angle facades need another approach?
Sun arriving from the side can pass beneath a horizontal projection, so vertical fins or a combined device may be needed after plan and section testing.
What makes a solar diagram credible?
It names orientation, date, time and reference point, derives rays from geometry, and connects the tested shade dimensions to the final coordinated section and construction detail.
Why test the corner condition separately?
Different orientations meet there, while support, drainage, movement and cleaning routes also change; a resolved typical bay does not prove that the complete transition works.
Assessment move
Study sun control by linking orientation, solar geometry, occupied comfort and construction. Begin with an orientation plan and nominate the facade segment under review. State the critical period and the reason for testing it. High-angle exposure and low-angle morning or afternoon sun require different responses, so avoid copying one device around the building.
Where solar angles or performance outputs are used, identify their source and assumptions. Treat any simplified AskSia geometry as a learning method rather than a substitute for verified project analysis. Draw a no-shade baseline and at least two alternatives using identical conditions. In section, mark the glazing plane, occupied reference point, shade projection, vertical separation and critical ray.
In plan, test oblique or low-angle exposure and corner conditions. Label dimensions so another person can reproduce the comparison. Do not shift the reference point or solar period between options, because that would make the graphic persuasive but analytically invalid. Record what each device protects and what trade-off it creates for view, daylight, facade depth or maintenance.
Translate the preferred environmental geometry into a buildable assembly. Show how the shade connects to slab edge, secondary framing or facade mullions; allow for drainage, movement, waterproofing and tolerances; and identify how it can be cleaned, inspected or replaced. Check whether the device conflicts with sprinklers, signage, operable elements or facade access.
At corners and changes of orientation, draw the transition explicitly. The dimensions tested in the performance study should remain traceable in elevations, schedules and details. Compare orientation-specific strategies in a small matrix. Useful criteria include critical solar protection, daylight effect, glare risk, outward view, material quantity, structural support, weathering and access.
Explain the ranking with evidence rather than using unexplained scores. A deeper device is not automatically better if it reduces useful winter sun, obstructs view or demands heavy support. Likewise, a visually light screen may perform poorly for low-angle exposure. The matrix should make the selected balance legible. Run a consistency audit after facade development.
Select one representative bay and trace its geometry from environmental diagram to elevation, section, schedule and enlarged detail. Search for changed projections, spacing or glass zones. If consultant modelling alters the performance target, update the construction documents or explain why a different response is retained. Keep unverified numerical claims labelled and direct project decisions to current specialist analysis.
Visual coherence should not conceal a broken evidence chain. For revision, prepare a one-page case study with orientation, baseline, two tested sections, the selection matrix and one junction detail. Ask a peer to identify the critical period, occupied point, tested dimension and maintenance route. If they cannot, improve the captions and hierarchy.
Conclude with two statements: what the study demonstrates about the proposed device, and what remains dependent on project climate data, facade engineering or environmental modelling. This distinction produces a credible architectural argument without overstating certainty.