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Orientation and Solar Groups

Classify elevations into the orientation groups used for solar heat gain checks.

9 minFenestration Fundamentals
Diagram for Orientation and Solar Groups
Fenestration Fundamentals Orientation and Solar Groups
How to use the diagram Read the visual first, then connect each label to the lesson text and your calculator inputs. The aim is to make every assumption visible before you calculate.

Learning Objective

By the end of this lesson you should be able to group each elevation before applying SHGC checks.

Orientation is assessed from the outside face

For each facade, use the direction perpendicular to the external surface and pointing outward. This matters because a room may feel like it faces a direction, while the compliance check follows the envelope element orientation.

Separate sun-exposed and southern groups

SANS 10400-XA:2021 treats solar-exposed orientations differently from south-side orientations for vertical fenestration SHGC checks. Keep these groups independent so their weighted averages are not mixed.

Handle angled facades consistently

Where a facade sits between compass points, assign it to the correct sector before calculating. Document the basis for the decision, especially on complex plans with chamfered walls or curved facades.

Practice Task

  • Take a plan and draw an outward arrow on each glazed elevation.
  • Label each arrow with its sector.
  • Group the items into solar-exposed and southern sets before entering them.

Calculator Tip

Use the orientation field as a classification tool, not just a label. The calculator uses it to decide which SHGC rule family applies.

Worked Example: First-Pass Fenestration Check

Scenario

A single storey has 52 m2 nett floor area and three glazed elements: 1.8 m2 at U 2.8 / SHGC 0.32, 5.0 m2 at U 2.2 / SHGC 0.25, and 1.1 m2 at U 3.0 / SHGC 0.35.

Calculator Entry

Enter each glazed element with its area, orientation, U-value and SHGC. Use the result cards to check glazing percentage and weighted performance.

Step-by-step method
  1. 1Add the three glazed areas to get total fenestration area.
  2. 2Divide total fenestration area by nett floor area to get glazing percentage.
  3. 3Calculate weighted U-value and SHGC using area x value products.
  4. 4Compare the results to the applicable SANS 10400-XA:2021 route and document supplier evidence.
Expected conclusion

The important decision is not only whether the numbers pass, but whether every value can be traced to drawings and supplier data.

Common Mistakes

  • Using glass-only U-values or SHGC values instead of whole-window values.
  • Mixing solar and non-solar orientation groups in one weighted average.
  • Calculating glazing percentage across the whole building instead of per storey.

Quick Knowledge Check

1. What should you confirm before applying this lesson to a project?

Did every glazed external wall element get an orientation?

2. Which piece of evidence should support the main input in this lesson?

Take a plan and draw an outward arrow on each glazed elevation.

3. What is the safest action if the information is incomplete?

Flag the missing evidence, use a conservative assumption where appropriate, and avoid claiming compliance until the information is confirmed.

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