Blind Solutions AcademyC18 · The Specifier · CPD Category 1
Blind Solutions Academy · The Specifier · Practical Guide

Facade Analysis: The Practical How-To Guide

A step-by-step working companion to C18 — run the method on a live project, one facade at a time.

CourseC18
NQF Level7
FormatWorkflow + Checklists
How to use this guide

The five-stage pipeline


This guide turns the masterclass into a working method. Run the five stages in order for every project, and the per-lecture checklists below for every facade. Each checklist item is a deliverable; collected, they become your facade analysis report.

StageActivityOutput
1Climate & SiteClimate basis of design: zone, latitude, altitude, design dry-bulb, peak DNI
2Orientation AuditOrientation decision matrix: device family per face
3Solar GeometrySite sun-path chart with design sun positions + obstruction mask
4Glazing & LoadGlazing/device pairing table; quantified per-facade gain (kW, W/m²)
5Device EngineeringShading specification + compliance map
Quick decision aid

Orientation → device family


FacadeSolar geometry (SA / S. hemisphere)Primary deviceFallback
NorthHigh altitude near noon, small wall-solar azimuthShallow horizontal overhang / louvresOperable horizontal louvres
SouthMostly diffuse; brief low summer flanking sunLight-diffusing / glare control; edge return finsOperable internal screen
EastLow-altitude morning sun, wide azimuthVertical fins / operable external venetianSolar-control glazing + internal screen
WestLow-altitude afternoon sun + ambient peak (worst case)Deep vertical fins / egg-crate / motorised venetianSHGC ≤ 0.25 glazing + high-reflectance screen
Specifier NoteThe west facade is the hardest problem in any SA building because peak solar coincides with peak ambient temperature and accumulated daily heat. Never treat it with a north-facade overhang.
Per-lecture working checklists

Run the method, lecture by lecture


Step 1

The Facade as a Thermal Filter: Framing the Analysis

Before any blind, louvre or fin is specified, the facade must be understood as a dynamic thermal filter that mediates between the South African sky and the occupied space behind it. This opening lecture establishes the mental model the entire masterclass depends on: every square metre of glass is a two-way valve admitting daylight and solar heat while leaking conditioned air, and the specifier's job is to tune that valve orientation by orientation.

Analysis checklist

Step 2

South African Climate Data & Solar Resource by Region

Shading design is only as good as the climate data feeding it. This lecture equips you to source, read and apply the right meteorological inputs for South African sites, moving past generic 'sunny country' assumptions to the genuinely different design conditions of the six SANS climatic zones.

Analysis checklist

Step 3

Sun-Path Geometry: Altitude, Azimuth and the Stereographic Chart

This is the geometric heart of the course. You will learn to read and construct a sun-path diagram for any South African latitude and to extract, for any date and hour, the two angles that govern shading: solar altitude and solar azimuth.

Analysis checklist

Step 4

Shadow Angles: Horizontal and Vertical Shadow Angle Method

Sun angles describe where the sun is; shadow angles describe what a device must do. This lecture introduces the two angles that translate solar geometry directly into device geometry: the Horizontal Shadow Angle (HSA) and the Vertical Shadow Angle (VSA).

Analysis checklist

Step 5

Orientation Audit: North, South, East and West Strategies

With sun-path and shadow-angle tools in hand, this lecture systematises the per-orientation strategy that defines competent SA facade design. We walk each cardinal face — and the awkward intermediates — and prescribe the device family that suits its solar geometry: horizontal overhangs and louvres for the north, light management rather than heat rejection for the south, and the genuinely difficult east/west problem that demands vertical, operable or high-performance-glazing solutions.

Analysis checklist

Step 6

Glazing Performance: SHGC, U-Value, VLT and the Spectral Trade-off

Shading devices and glazing are two halves of one system, and this lecture gives you fluency in the glazing half. We define the three numbers on every glazing datasheet that matter for facade analysis — Solar Heat Gain Coefficient (SHGC/g-value), U-value, and Visible Light Transmittance (VLT) — and the Light-to-Solar-Gain ratio (LSG) that captures the spectral selectivity you want.

Analysis checklist

Step 7

Solar Gain & Cooling Load: Quantifying the Facade

Analysis must end in numbers a mechanical engineer can use. This lecture shows you how to convert your orientation, sun-path, shadow-angle and glazing work into a quantified solar gain and its contribution to peak cooling load.

Analysis checklist

Step 8

Overheating, Comfort and Glare: The Occupant Criteria

Cooling load is the engineer's metric; overheating, comfort and glare are the occupant's — and they are what generate complaints and disputes. This lecture connects facade performance to human criteria: adaptive thermal comfort, overheating risk metrics, mean radiant temperature near glazing, and glare indices.

Analysis checklist

Step 9

SANS 10400-XA, SANS 204 and Green-Building Compliance

Every SA facade decision sits inside a regulatory and rating framework, and a specifier who cannot map shading to clauses cannot get a project approved or credited. This lecture decodes the compliance landscape: SANS 10400-XA as the mandatory energy-usage regulation, SANS 204 as the energy-efficiency design standard it references, and the voluntary rating tools — Green Star SA and EDGE — that reward good shading.

Analysis checklist

Step 10

Device Engineering: Fixed, Operable and Motorised Systems

Geometry tells you what shape a device must be; engineering tells you how to build it, operate it and keep it working. This lecture surveys the device families and their selection logic: fixed overhangs, fins, louvres and egg-crates; operable external venetians, roller screens and folding shutters; and motorised, sensor-driven systems integrated with the building management system.

Analysis checklist

Step 11

Dynamic Simulation: From Hand Calculation to Verified Model

Hand calculations size the problem and sanity-check the answer; dynamic simulation proves it across the whole year and underpins compliance and rating submissions. This lecture demystifies thermal and daylight simulation: what an hourly energy model does, the inputs it consumes from your facade analysis, and how to read and trust its outputs.

Analysis checklist

Step 12

The Facade Analysis Report & Specification Hand-off

Analysis only creates value when it is communicated in a form the design team can build from. This closing methodology lecture assembles everything into the two deliverables that carry your work into construction: the facade analysis report and the shading specification.

Analysis checklist

Self-assessment

Assessment Question Bank (10 MCQs)


Application-based questions. Minimum pass mark 70% (7 of 10). Reveal each answer to check your reasoning and the section it draws on.

Question 1
On a north-facing facade in Pretoria (latitude ~26 S), the summer-solstice midday sun reaches an altitude near 87 degrees while the winter-solstice midday sun is far lower. Which device family most efficiently exploits this geometry to shade summer sun yet admit winter sun?
AA shallow fixed horizontal overhang or horizontal louvres
BDeep fixed vertical fins
CAn internal roller blind with 10% openness fabric
DA reflective body-tinted single glazing with no device
Show answer & explanation
Correct: A. High summer-sun altitude on the north facade produces a high Vertical Shadow Angle, so a shallow horizontal overhang fully shades summer sun (P = h/tan(VSA) is small) while the much lower winter sun passes underneath — the seasonal selectivity described in Lectures 4 and 5. Vertical fins suit low-altitude east/west sun, and an internal blind or tint does not give seasonal selectivity.
Question 2
A west window 1.8m tall must be fully shaded at a design afternoon instant when the Vertical Shadow Angle is just 30 degrees. What horizontal overhang projection would full beam cut-off require, and what does this imply?
AAbout 0.32m, so a horizontal overhang is the correct, economical choice
BAbout 3.1m, an impractical projection, so a vertical/operable device should be used instead
CAbout 1.8m, equal to the window height, which is acceptable
DZero, because west facades receive no direct beam
Show answer & explanation
Correct: B. P = h / tan(VSA) = 1.8 / tan(30 deg) = 1.8 / 0.577 = 3.12m. The shallow VSA of low-altitude west sun forces an absurd overhang depth, which is exactly why Lecture 5 prescribes vertical fins, egg-crates or operable systems for east/west rather than horizontal overhangs.
Question 3
A glazing datasheet lists SHGC 0.28, VLT 0.62 and U-value 1.6 W/m2K. What is the Light-to-Solar-Gain ratio, and how should a specifier interpret it?
A0.45 — poor selectivity; the glass rejects more light than heat
B1.90 — moderate; typical of clear single glazing
C2.21 — high selectivity; admits useful daylight while rejecting near-infrared heat
DIt cannot be calculated from these figures
Show answer & explanation
Correct: C. LSG = VLT / SHGC = 0.62 / 0.28 = 2.21. An LSG well above ~1.25 indicates a spectrally selective product that admits daylight while rejecting near-infrared solar heat (Lecture 6), which preserves the SANS 204 daylighting benefit while controlling cooling load.
Question 4
An unshaded west facade has 120 m2 of clear DGU (SHGC 0.70). At the design instant the vertical-plane irradiance is 800 W/m2 (620 beam + 180 diffuse). What is the approximate instantaneous solar gain, and what is its main design consequence?
AAbout 6.7 kW — negligible, no shading needed
BAbout 67 kW — a major load that can drive significant chiller oversizing
CAbout 134 kW — but only relevant in winter
DAbout 20 kW — fully offset by the U-value term
Show answer & explanation
Correct: B. Q = A x SHGC x I = 120 x 0.70 x 800 = 67.2 kW (Lecture 7). A single facade contributing ~67 kW at the design instant is exactly the kind of load that oversizes chillers when uncontrolled — the business case for engineered shading.
Question 5
Why does an external shading device control occupant thermal comfort near glazing more effectively than an internal blind of identical fabric?
AInternal blinds increase air velocity, which always feels colder
BExternal devices stop beam radiation before it reaches the glass, keeping the inner glass surface cool and lowering mean radiant temperature; an internal blind absorbs transmitted radiation and itself becomes a hot radiating surface
CInternal blinds have no effect on glare or heat at all
DExternal devices raise the U-value, reducing conduction
Show answer & explanation
Correct: B. Comfort near glazing is dominated by mean radiant temperature and radiant asymmetry (Lecture 8). An external device prevents the beam reaching the glass so the inner surface stays cool; an internal blind sits inside the envelope, absorbs the already-transmitted beam and re-radiates heat at the occupant, improving glare but not radiant comfort.
Question 6
Under SANS 10400-XA, a west facade at 55% window-to-wall ratio fails the SANS 204 fenestration energy limit on glazing performance alone. How can compliant external shading most directly resolve this?
ABy increasing the glazing U-value to trap more heat
BBy reducing the effective combined SHGC credited in the fenestration calculation, bringing the calculated fenestration energy within the limit via the rational route
CBy exempting the facade from SANS 204 entirely
DBy raising the VLT so more daylight enters
Show answer & explanation
Correct: B. SANS 204's fenestration provisions combine area, orientation and SHGC; documented external shading lowers the effective combined SHGC used in the calculation, which is how shading makes an otherwise non-compliant facade pass via the rational-design route (Lecture 9). Increasing U-value or VLT does not fix the solar-gain failure.
Question 7
Two vertical fins on a west facade must achieve full beam cut-off at a design hour when the Horizontal Shadow Angle is about 53 degrees, with fins spaced 600mm apart. What fin projection depth is required?
AAbout 200mm
BAbout 320mm
CAbout 450mm
DAbout 800mm
Show answer & explanation
Correct: C. For vertical fins, full cut-off requires d = s / tan(HSA) = 600 / tan(53 deg) = 600 / 1.327 = 452mm, i.e. about 450mm (Lectures 4 and 5). This is the geometry that replaced the failed 150mm fins in the Durban case study.
Question 8
A specifier is choosing a roller-screen fabric openness factor for a west facade where glare control is the priority but a residual view is desired. Which choice and rationale is most appropriate?
A10% openness, because lower openness blocks all view
B0% (blackout), because any openness causes glare
CAbout 3% openness, giving strong glare and solar-gain control while retaining a usable view
DOpenness factor is irrelevant to glare and gain
Show answer & explanation
Correct: C. Openness factor trades view/daylight against heat and glare rejection (Lecture 10). A ~3% fabric gives strong glare control with a residual view and feeds a low device-transmission F into the gain calculation, whereas 10% admits more glare/heat and blackout kills the view and daylight.
Question 9
When reconciling a hand-calculated design-instant west peak gain against a dynamic annual simulation, the two differ by a modest margin. What is the most professionally sound interpretation?
AThe hand calculation must be discarded; only the model is ever correct
BA modest, explicable difference is expected because the model includes thermal mass lag and exact transposed irradiance; a large divergence signals an input error to resolve
CAny difference means the simulation software is faulty
DThe two methods measure unrelated quantities and should never be compared
Show answer & explanation
Correct: B. Hand calculation and simulation should agree within a sensible tolerance; differences arise from thermal mass, exact irradiance transposition and ground reflectance the hand calc simplifies (Lecture 11). Reconciliation is a deliberate error-catching discipline — a wild divergence means a wrong input, not that one method is invalid.
Question 10
A quantity surveyor proposes deleting the external west fins to cut cost. Which specification approach best protects the shading from value engineering?
ADescribe the fins only by size and material, leaving cost the deciding factor
BMark the fins as architectural and therefore optional
CRemove all performance numbers so the specification reads more cleanly
DBind each device to a quantified outcome, a compliance dependency and an occupant consequence — e.g. peak gain rising ~18 kW, the SANS 204 fenestration limit being breached, and operative temperature reaching ~30 C with glare
Show answer & explanation
Correct: D. A spec survives value engineering when deletion visibly threatens approval, plant sizing and comfort (Lecture 12). Tying every device to a quantified performance outcome, a SANS compliance dependency and an occupant consequence makes the consequences of removal explicit, so cost pressure redirects rather than deletes.
Capstone

Project deliverable template


Assemble the outputs from every checklist above into a single report with this spine: