Blind Solutions AcademyC19 · The Specifier · CPD Category 1
Blind Solutions Academy · The Specifier · Practical Guide

Daylighting & Glare: The Practical How-To Guide

A step-by-step working companion to C19 — run the metric method on a live project, space by space.

CourseC19
NQF Level6
FormatWorkflow + Checklists
How to use this guide

The six-stage daylighting pipeline


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

StageActivityOutput
1Brief & TargetsFour numbers: sDA target, ASE ceiling, UDI band, DGP limit (+ view tier, melanopic EDI)
2Basis of DesignLatitude, altitude, sky model, exterior design illuminance/luminance, data source
3Quantity AnalysisClimate-based sDA result per space, grid + schedule + blind logic stated
4Over-Lighting & GlareASE plan (read with sDA), UDI band profile, annual DGP from occupant eye
5Aperture, View & CircadianHead heights, light shelves/toplighting, EN 17037 view tier, melanopic EDI provision
6Dynamic Shading & ReportShading + control spec co-designed with glazing; bound report + commissioning protocol
Quick decision aid

Metric → design response


Symptom in the metricsWhat it meansDesign response
Low sDA, deep zoneLight not reaching room depthRaise window head / clerestory; add light shelf; lift surface reflectances
ASE > 10%Excessive direct-beam sunExternal shading geometry + selective glazing; dynamic ASE-driven control
High UDI-exceededFrequent over-lighting (glare/heat)Selective glazing (trim exceeded band); dynamic shading hour by hour
DGP > 0.40Visual discomfort at the eyeLower source luminance (shading/glazing); shift view direction; DGP-driven blind
View tier below targetEye-level landscape layer lostVenetian / top-down blind; higher fabric openness; protect middle view layer
Low morning melanopic EDIWeak circadian doseEast/NE glazing to early zones; high neutral-VLT glass; keep morning shade open
Specifier NoteNever read one metric alone. sDA and ASE are a pair; UDI-exceeded and DGP both flag glare; view and circadian goals constrain how far shading may deploy. The whole design is the resolution of these tensions.
Per-lecture working checklists

Run the method, lecture by lecture


Step 1

Daylight as a Design Material: Quantity, Quality and the Brief

Daylight is the only building material that arrives free, changes by the minute, and simultaneously carries heat, glare and biological signal. This opening lecture reframes daylighting from a vague aspiration into a measurable design discipline.

Working checklist

Step 2

The Physics of Daylight: Illuminance, Luminance and the Eye

You cannot control what you cannot measure correctly, and most daylighting confusion comes from mixing up two fundamentally different quantities: illuminance and luminance. This lecture builds the photometric foundation the rest of the course stands on.

Working checklist

Step 3

South African Sky Conditions and the Daylight Resource

Daylighting strategy is only as good as the sky model behind it, and South Africa's skies are not European skies. This lecture equips you to characterise the daylight resource for any SA site and to choose the right sky assumption for analysis.

Working checklist

Step 4

Daylight Factor and the Move to Climate-Based Metrics

Before you can use the modern annual metrics with confidence, you need to understand the metric they replaced and exactly why it fell short. This lecture dissects the Daylight Factor — its definition, its components, its enduring usefulness and its three fatal blind spots.

Working checklist

Step 5

Spatial Daylight Autonomy (sDA): The Quantity Benchmark

Spatial Daylight Autonomy is the metric that finally answers, across a real year and real skies, the question DF could only fumble: is enough of this space daylit enough of the time? This lecture defines sDA precisely, works through its thresholds, and shows how to read and challenge an sDA result. We unpack the LM-83 definition — sDA300/50%, the percentage of floor area receiving at least 300 lux for at least 50% of occupied hours — and the IES benchmarks of sDA at or above 75% for 'preferred' and 55% for 'nominally accepted' daylight.

Working checklist

Step 6

Annual Sun Exposure (ASE): The Over-Lighting and Glare Flag

If sDA tells you whether there is enough daylight, Annual Sun Exposure warns you when there is too much of the wrong kind — direct sun deep in the space, the precursor to glare, overheating and permanently lowered blinds. This lecture defines ASE, explains the LM-83 criterion ASE1000/250h, and shows how it acts as the essential counterweight to sDA.

Working checklist

Step 7

Useful Daylight Illuminance (UDI): Banding Too Little, Useful, Too Much

sDA and ASE each capture one edge of the daylight problem; Useful Daylight Illuminance folds both edges into a single banded picture of how often a space is actually well lit. This lecture defines UDI and its bins, and shows why a metric that explicitly counts over-lighting is so valuable for South African clear-sky conditions.

Working checklist

Step 8

Glare Metrics: DGP, DGI and Predicting Visual Discomfort

Glare is the daylighting failure occupants notice first and forgive last, and it is the reason blinds get pulled down and left down — defeating every daylight gain the analysis promised. This lecture gives you the metrics to predict and control it.

Working checklist

Step 9

View, Connection to Outside and EN 17037

Daylight is only half of what a window delivers; the other half is view — the connection to the outside world that affects wellbeing, satisfaction and the perceived quality of a space as much as illuminance does. This lecture formalises view as a designable, gradeable quality rather than a happy accident.

Working checklist

Step 10

Circadian Daylighting: Light for Human Health

The most significant shift in daylighting thinking this decade is the recognition that light does more than let us see — it sets the human body clock, and the right daylight at the right time is now a measurable design objective. This lecture introduces circadian (non-visual) daylighting and the metrics emerging to specify it.

Working checklist

Step 11

Daylighting Apertures and the Geometry of Distribution

Metrics tell you whether a daylighting design works; aperture geometry is how you make it work. This lecture turns the targets of the preceding lectures into built form — the size, shape, position and detailing of openings that deliver daylight deep and even rather than bright and shallow.

Working checklist

Step 12

Dynamic Shading: Automated Control as the Daylighting Engine

Every metric in this course points to one conclusion: a static daylighting design cannot satisfy goals that conflict and change by the hour, so the resolution is dynamic shading under intelligent control. This lecture is where the whole method converges.

Working checklist

Step 13

The Daylighting Analysis Report: Assembling and Defending the Design

A daylighting design is only as good as your ability to assemble it into a coherent, defensible whole and carry it through documentation, compliance and commissioning. This closing lecture binds the course into a deliverable.

Working 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 lecture it draws on.

Question 1
A client briefs you for 'lots of natural light' in a Cape Town open-plan office. To convert this into a measurable, defensible daylighting brief, which set of metrics best captures both the sufficiency and the comfort the client actually wants?
AAn sDA300/50% target, an ASE1000/250h ceiling, a UDI band target and a DGP ceiling
BA single Daylight Factor target of 2 percent for the whole floor
CA minimum window-to-wall ratio and a maximum glazing U-value
DA maintained illuminance of 500 lux measured once at midday
Show answer & explanation
Correct: A. As Lecture 1 establishes, a defensible brief must specify quantity (sDA), over-lighting/glare risk (ASE), the banded experience (UDI) and visual comfort (DGP ceiling). A lone Daylight Factor is orientation-blind and cannot see over-lighting; WWR/U-value are envelope inputs, not daylight outcomes; and a single midday lux reading ignores the annual, dynamic nature of the resource.
Question 2
An occupant complains of glare at a desk where a lux meter reads a healthy 450 lux on the work plane. The window behind the monitor shows a clear-sky patch at about 8,000 cd/m2 while the monitor sits near 150 cd/m2. What is the correct diagnosis and first design lever?
AIlluminance is too low; add more daylight or electric light
BThe luminance ratio (about 50:1) far exceeds the comfortable 1:10 to 1:20 range; reduce the source luminance with shading
CThe desk reflectance is too high; specify a matte work surface
DThe colour temperature is wrong; change the lamp spectrum
Show answer & explanation
Correct: B. Per Lecture 2, glare is governed by luminance contrast, not illuminance level. A 450 lux task next to an 8,000 cd/m2 sky is a ~50:1 ratio, far beyond the comfortable 1:10 to 1:20 task-to-surround guidance. Adding light cannot fix it; the cure is reducing the brightest source's luminance (shading/selective glazing) and/or raising surround luminance, not changing the desk finish or lamp spectrum.
Question 3
Why is the classical overcast-sky Daylight Factor a poor primary metric for a daylighting analysis on a Highveld site such as Johannesburg?
AIt overestimates available daylight on clear-sky sites and is therefore unsafe
BIt cannot be calculated without a full Typical Meteorological Year file
CIt assumes a permanently overcast sky and is orientation-blind, ignoring the clear-sky brilliance, direct-sun glare and orientation effects that dominate SA conditions
DIt applies only to toplit spaces, not side-lit rooms
Show answer & explanation
Correct: C. As Lectures 3 and 4 explain, DF is computed under a CIE overcast sky and is orientation-independent by construction. South African skies are predominantly clear or intermediate, so DF ignores the very conditions (clear-sky luminance, direct sun, orientation) that drive local daylighting and glare outcomes. DF needs no weather file (that is its convenience), and it applies to side-lit rooms too.
Question 4
A simulation reports sDA300/50% of 78 percent for an open-plan office. Per the IES LM-83 benchmarks, how should this quantity result be classified, and what must you check before trusting it?
ABelow the nominally-accepted threshold; the space is under-daylit
BExactly at the minimum acceptable level of 55 percent; no further checks needed
CMeaningless without first converting it to a Daylight Factor
DAt or above the 'preferred' threshold of 75 percent; verify the analysis grid, occupancy schedule and blind-control assumptions
Show answer & explanation
Correct: D. Lecture 5: LM-83 sets sDA300/50% of 75 percent or higher as 'preferred' and 55 percent or higher as 'nominally accepted', so 78 percent is in the preferred band. However, sDA is sensitive to grid spacing, the assumed occupied schedule, and especially the blind-operation logic (the most-gamed assumption), all of which must be verified before the number is trusted.
Question 5
A west-facing space returns an excellent sDA300/50% of 80 percent but an ASE1000/250h of 28 percent, and occupants keep the blinds permanently down. What does this combination tell you, and what is the design response?
AThere is ample light but excessive direct sun; the ASE far exceeds the 10 percent ceiling, so dynamic external shading and/or selective glazing are required to cut direct-sun penetration
BThe space is ideal; high sDA confirms good daylighting
CThe sDA is wrong because it cannot exceed the ASE
DThe blinds are faulty; replace them with fixed internal screens
Show answer & explanation
Correct: A. Per Lecture 6, ASE counts direct-sun over-exposure (1,000 lux for 250+ hours) with blinds open; the IES ceiling is 10 percent (7 percent preferred). An ASE of 28 percent means raw beam sun is intolerable, so occupants close the blinds, collapsing the in-use daylight the sDA promised. The fix is dynamic shading (preferably external) plus selective glazing to drive ASE down while keeping sDA high — not fixed screens that would kill the daylight permanently.
Question 6
A UDI analysis shows a north-facing space spends 30 percent of occupied hours in the UDI-exceeded band (above 3,000 lux). What does this reveal that a high sDA would have concealed, and which band edge defines this failure?
ANothing new; UDI and sDA always agree
BThat the space is under-lit and needs larger windows
CThat the space is frequently over-lit and at glare/overheating risk — a failure sDA is structurally blind to — with the failure defined by the 3,000 lux upper UDI band edge
DThat the Daylight Factor must be below 2 percent
Show answer & explanation
Correct: C. Lecture 7: UDI bands daylight into fell-short (<100 lux), supplementary (100-300), autonomous (300-3,000) and exceeded (>3,000 lux). The exceeded band captures over-lighting that sDA — a one-sided 'enough light' metric — cannot see. A 30 percent exceeded share signals frequent glare/overheating risk, exactly the clear-sky over-lighting failure, defined by the 3,000 lux upper edge.
Question 7
An HDR-based glare analysis from an occupant's eye position returns a Daylight Glare Probability of 0.46 looking toward an unshaded sky. Using the standard DGP thresholds, how is this classified and what are the two physical levers to reduce it?
APerceptible but acceptable; increase desk illuminance
BImperceptible; no action required
CDisturbing; the only fix is to reduce the room's electric lighting
DIntolerable (DGP above 0.45); reduce the glare source's luminance (shading/selective glazing) and/or shift its position relative to the line of sight
Show answer & explanation
Correct: D. Per Lecture 8, DGP thresholds run: <0.35 imperceptible, 0.35-0.40 perceptible, 0.40-0.45 disturbing, >0.45 intolerable, so 0.46 is intolerable. DGP is driven by source luminance and the source's position (Guth position index) relative to the line of sight. The levers are therefore reducing source luminance (shading, lower-transmittance/selective glazing, diffusing fabric) and changing the geometry/orientation so the bright source is away from the direct field of view — not adding desk light or dimming electric lighting.
Question 8
Under the EN 17037 view-out framework, which combination of factors determines the assessed view quality level (minimum, medium or high)?
AHorizontal sight angle of the view opening, the outside viewing distance, and the number of view layers (sky, landscape, ground) visible
BGlazing U-value, SHGC and visible transmittance
CDaylight Factor, sDA and ASE
DWindow-to-wall ratio and ceiling reflectance
Show answer & explanation
Correct: A. Lecture 9: EN 17037 grades view out on three quality levels using the horizontal sight angle (angular width of the opening), the outside distance to the nearest viewed object, and the number of view layers visible — sky (upper), landscape (middle) and ground (lower). Retaining the eye-level landscape layer is decisive. The other options describe thermal/energy properties or daylight-quantity metrics, not the EN 17037 view parameters.
Question 9
Why does melanopic Equivalent Daylight Illuminance (melanopic EDI) measured vertically at the eye, rather than horizontal lux at the desk, govern the circadian value of a daylighting design?
ABecause lux meters are inaccurate near windows
BBecause circadian metrics ignore light intensity entirely
CBecause the non-visual ipRGC response is driven by bright, blue-rich light reaching the eye (peak sensitivity ~480 nm), which photopic lux (weighted to 555 nm and measured horizontally) systematically under-counts
DBecause horizontal illuminance is only valid under an overcast sky
Show answer & explanation
Correct: C. Per Lecture 10, the circadian system relies on intrinsically photosensitive retinal ganglion cells (ipRGCs) most sensitive to ~480 nm blue light and on light reaching the eye, so the stimulus is measured as vertical melanopic EDI at eye level. Photopic lux is weighted to the 555 nm visual peak and measured horizontally at the desk, so it under-counts the circadian potency of blue-rich daylight — which is why WELL specifies melanopic EDI at the eye.
Question 10
A value-engineering review proposes deleting the planned automated (dynamic) shading and substituting fixed internal blinds to save cost. Drawing on the course method, what is the strongest technical objection?
AFixed blinds are always more expensive than automated systems
BInternal blinds cannot control glare at all
CAutomated shading is required by SANS 10400-XA in all buildings
DAny fixed shading position is wrong at some time of day, and manually-lowered-and-forgotten blinds collapse the in-use sDA; only dynamic control holds sDA, ASE, UDI, DGP and circadian dose in band as conditions change, so deletion breaks specific metric targets
Show answer & explanation
Correct: D. Lectures 12 and 13: a static position optimised for one moment is wrong at another, and the manually-lowered-and-forgotten blind is the dominant reason simulated daylight performance fails to materialise. Dynamic, metric-driven control (e.g. DGP-ceiling logic) holds the conflicting goals in band simultaneously and is bound in the report to specific sDA/ASE/UDI/DGP targets, so deleting it visibly breaks those targets — converting a cost argument into a compliance-and-comfort one. The claim that internal blinds cannot control glare is false (they can, though they admit heat through the glass), and no SANS clause mandates automation universally, so cost alone is not a valid justification for deletion.
Capstone

Daylighting analysis report template


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