Daylight factor needs paired readings
Daylight factor is a paired daylight note. It links an indoor daylight reading to an outdoor reference reading taken under the same sky condition, then keeps the point, plane, time, shade and electric-light state attached to the result.
When indoor and outdoor lux values are already recorded, the daylight factor calculator can turn that pair into a percentage. The daylight lux values table gives context for outdoor daylight conditions, and the daylight factor examples table shows how different note shapes read before a percentage is entered.
Window, skylight and rooflight opening states belong beside the same point note. The window and skylight daylight notes page keeps blind state, shade, sky condition, electric-light state and point distance visible before a daylight factor or daylight lux note is compared.
| Reading field | What to note | Why it matters |
|---|---|---|
| Indoor daylight point | Meter value at the named point, with the plane and meter orientation noted. | It anchors the daylight-factor numerator to a repeatable location. |
| Outdoor reference basis | Open-sky reference reading, position and any obstruction or direct-sun note. | It anchors the denominator to the actual outdoor condition. |
| Pair timing | Date, reading time and whether the indoor and outdoor values were taken in one tight sequence. | Daylight can shift quickly in Australian weather. |
| Sky and sun condition | Overcast, bright overcast, clear sun, broken cloud, glare patch or direct sun on the meter. | The result belongs to that condition, not every daytime condition. |
| Opening and shading state | Window, blind, curtain, awning, eave, tree or nearby building condition. | The same room can read differently when the daylight path changes. |
| Electric-light state | Off, dimmed, daylight-linked or accidentally on. | Daylight factor should stay distinct from electric-light contribution. |
Name the daylight question first
Daylight-factor wording can hide several different user jobs. Some users need a ratio, some need a daylight lux value at a desk, and some need to know whether the electric-light zone belongs in a separate note. The note should name that job before the percentage is read.
| User job | Better note owner | Keep separate |
|---|---|---|
| Calculate daylight factor at one point. | Paired indoor and outdoor daylight readings under one condition. | Night readings and electric-light output. |
| Log how bright a desk, bench or aisle is from daylight now. | Daylight lux at the named plane, with time, sky and shade state. | Outdoor ratio unless the reference reading is also recorded. |
| Map daylight across a room or bay. | Labelled point set or measured-light grid under the same condition. | One point standing in for the whole room. |
| Explain window, skylight or rooflight influence. | Opening geometry, shade position and direct-sun note beside the point note. | A daylight percentage without the daylight path. |
| Describe daylight-linked control behaviour. | Control zone, sensor state, dimming state and fallback electric-light note. | A daylight-factor percentage by itself. |
This split keeps Australian daylight notes practical for homes, offices, warehouses, retail interiors and small commercial rooms without turning a one-time reading into an all-day result.
Keep the indoor point precise
The indoor reading should belong to a task plane or named point. A desk point, kitchen bench point, meeting-table row and warehouse skylight bay are different notes. If several readings are taken, keep the point labels stable so the same locations can be compared later.
The lux meter reading note table and task plane note table keep the measurement point, height and condition together before the daylight factor is calculated.
| Indoor condition | Stronger note | Weak note |
|---|---|---|
| Desk point | Desk plane, centre of work area, distance from window wall noted. | Middle of room. |
| Kitchen bench | Bench working edge, overhead shelf or cabinet shadow noted. | Kitchen reading. |
| Meeting room | Table row, room side, blind position and wall-facing direction. | Meeting-room daylight. |
| Warehouse | Floor aisle, picking face or packing bench under named skylight bay. | Warehouse natural light. |
| Retail display | Display face, shelf depth and daylight from entry or glazing noted. | General retail reading. |
Separate the note types
Daylight-factor notes are only one part of a measured-light file. Daylight lux, electric-light lux, shading notes, control settings, energy notes and measured-light grids should stay visible, but they should not be blended into the daylight-factor pair.
| Note type | What belongs in it | What stays outside |
|---|---|---|
| Daylight-factor pair | Indoor daylight lux, outdoor reference lux, point, plane, time, sky and shade state. | Electric-light output and night condition. |
| Daylight lux only | Indoor daylight reading at the named surface, with time, sky and shade state. | Percentage result unless an outdoor reference was recorded. |
| Electric-light lux | Measured illuminance with the electric lighting state clearly labelled. | Daylight-factor percentage. |
| Shading or blind note | Blind angle, curtain state, awning, tree shade, eave line or glare patch. | Claim that the daylight condition applies when shade changes. |
| Controls and energy note | Sensor zone, dimming state, switching state and observed operating condition. | Energy conclusion from daylight readings alone. |
| Measured-light grid | Labelled point set, same condition across the set and any outlier notes. | A single point described as a room-wide result. |
Note the outdoor reference basis
The outdoor reference should describe where and how the meter was read. A shaded porch, window sill or sun patch is not the same as an open-sky horizontal reference. If direct sun hits the meter or the indoor point, say so.
| Outdoor note | Why it changes the note | Better wording |
|---|---|---|
| Open sky | Gives a clearer reference for the comparison. | Outdoor horizontal reading in unobstructed open-sky position. |
| Direct sun | Can make the reference or indoor point unstable. | Direct sun present on outdoor meter; result retained as condition-specific. |
| Broken cloud | Readings can move during the sequence. | Indoor and outdoor values taken within the same short interval. |
| Nearby obstruction | Building, awning or tree may lower the reference. | Reference position partly shaded by awning; note retained with result. |
| Different reference point | The outdoor reading may not represent the same sky exposure. | Reference taken at courtyard edge; obstruction and reason recorded. |
Separate daylight from electric-light notes
Daylight factor is not the same as maintained electric-light illuminance. A daylight reading can help explain how a space behaves during the day, but the room lighting calculator or workplace lighting calculator is the better owner when the question is the electric lighting result.
| Question | Better owner | Note boundary |
|---|---|---|
| What daylight factor did this point show? | Daylight factor calculator | Indoor and outdoor readings under the same condition. |
| Is the electric lighting enough at night? | Lumens to lux calculator | Installed lumens, area, UF, MF and control state. |
| How should daylight-linked controls be described? | Lighting control notes | Sensor zone, dimming state and operating condition. |
| What did the meter show in use? | Lux meter reading notes | Combined condition clearly labelled if electric lighting was on. |
| Which points belong in a measured-light grid? | Task plane note table | Point labels, plane and condition kept with the grid. |
Point, plane and condition fields
The point label should be plain enough for another person to find the same location. The plane should say what surface was measured, and the condition should describe the daylight path at the time of the reading.
| Field | Better note detail |
|---|---|
| Point label | Room, zone, row, bay, bench, desk, shelf or aisle label. |
| Plane | Horizontal work surface, vertical display face, floor point or named task surface. |
| Meter orientation | Direction and whether the sensor was level with the measured plane. |
| Condition snapshot | Sky, cloud movement, direct sun, glare patch, shade and window state. |
| Occupant setting | Blind position, curtain state, door opening or manual switch state. |
| Follow-up page | Page or table that should carry the note after the reading is logged. |
Follow-up notes after the reading
A daylight note is easier to keep clean when each related question has an owner page. Carry the essential fields across, then leave unrelated fields behind.
| Reading outcome | Handoff owner | Carry across |
|---|---|---|
| Paired indoor and outdoor readings are complete. | Daylight factor calculator | Indoor lux, outdoor lux, point, plane, sky, shade and electric-light state. |
| Indoor daylight readings exist without an outdoor reference. | Daylight lux values table and lux meter reading notes | Indoor daylight lux, point, plane, time, sky and shade state. |
| Several points form a grid or point set. | Task plane note table | Point labels, plane, condition and any outlier note. |
| Opening geometry explains the result. | Window and skylight daylight notes | Window, skylight, rooflight, shade, distance and direct-sun note. |
| Electric lighting is part of the question. | Room lighting calculator or workplace lighting calculator | Electric-light state, room area, installed lumens and control setting. |
| Controls affect the reading condition. | Lighting control notes | Sensor zone, dimming state, switch state and operating condition. |
Repeatable note format
A daylight-factor note should be short enough for a project file or homeowner note but complete enough to repeat.
| Field | Example wording |
|---|---|
| Zone | Home office desk near east window |
| Indoor point | Desktop plane, centre of desk, electric lights off |
| Outdoor reference | Open-sky horizontal outdoor reading |
| Pair timing | Indoor and outdoor readings taken in the same sequence |
| Note comparison | Compared with the daylight factor examples table |
| Readings | Indoor lux and outdoor lux kept as one pair |
| Condition | Bright overcast, blinds open, no direct sun on the desk |
| Handoff owner | Daylight-factor percentage kept apart from night electric-light note |
| Result | Daylight factor percentage from the recorded readings |
| Separate check | Night electric-light level recorded separately |
If blinds, curtains, awnings, trees, nearby buildings or shelves affect the reading, keep that note with the result. A daylight-factor value without the shading state can be misleading when the same room is checked in another season.
Window and skylight geometry belongs with the note
The same percentage can mean different things when the daylight path changes. A side window, rooflight, high clerestory or deep eave can produce different glare, shadow and room-depth patterns even when the indoor lux reading looks similar.
| Opening condition | Note beside the reading | Why it matters |
|---|---|---|
| Side window | Distance from window wall, blind state and view direction. | Window-side points may not represent the room depth. |
| Skylight or rooflight | Bay location, diffuser condition and direct-sun note. | A bright patch can move during the day. |
| Eave, awning or balcony | Shading edge and time of reading. | Shade can lower the indoor value and reduce glare. |
| Nearby obstruction | Building, tree or shelf blocking the daylight path. | The result may belong to that obstruction condition. |
Checks before filing
| Gap in the note | Better entry |
|---|---|
| Indoor and outdoor readings taken far apart in time. | Pair the readings as closely as practical and note the sequence. |
| Electric lighting left on without a note. | Note lighting state or turn it off for a daylight-only reading. |
| Only the brightest daylight point measured. | Label points and include the work area that matters. |
| Direct sun treated as a general daylight condition. | Note direct sun and keep the result condition-specific. |
| Daylight factor compared with an electric-light target without context. | Keep daylight availability distinct from maintained electric-light checks. |
| Grid readings missing point labels. | Keep each point label, plane and condition with the measured-light grid. |