Daylight and electric lighting need separate notes
Daylight readings and electric-light readings can sit in the same project file, but they answer different questions. A daylight reading shows what was present at a point under a named sky, time and exposure condition. An electric-light reading shows what the active lighting state produced at a point or plane. A combined reading can describe the lived condition, but it should not be quietly treated as either daylight-only or electric-only evidence.
The daylight factor calculator compares paired indoor and outdoor daylight values. The lumens to lux calculator estimates electric-light illuminance from luminaire output, UF, MF and area. This guide keeps the note boundary clear before either value is compared with a measured result.
| Note type | What it notes | Required condition note |
|---|---|---|
| Daylight reading | Indoor or outdoor lux under a named daylight condition. | Time, sky, shading, direct sun and electric-light state. |
| Electric-light reading | Lux from the active electric lighting state. | Group, scene, dimming level, plane and daylight exclusion or presence. |
| Combined reading | Daylight plus electric lighting at the same point. | Both contributions named, with no hidden subtraction. |
| Daylight factor | Indoor daylight divided by outdoor reference, expressed as a percentage. | Paired readings under the same condition. |
| Measured comparison | Two or more readings compared at the same point or point set. | Matching plane, control state and exposure note. |
The first split is daylight-only, electric-only or combined
A note should say which condition was present before the number is interpreted. A desk reading taken beside a window at 10 am with lights on is not the same as a night electric-light reading. A skylit room at midday is not the same as a daylight-factor note unless the outdoor reference was also measured.
| Condition | Strong note wording | Weak note to avoid |
|---|---|---|
| Daylight-only | Desk P1, daylight only, lights off, overcast, blinds open. | Room daylight good. |
| Electric-only | Desk P1, night check, electric scene normal, no daylight. | Lights are enough. |
| Combined | Desk P1, daylight plus electric scene, sunny exposure noted. | One lux value with no state. |
| Daylight-factor pair | Indoor desk P1 and outdoor open-sky reference, same interval. | Indoor daylight divided by a guessed outside value. |
| Control comparison | Same point, two scene levels, daylight condition matched. | Dimmed value compared with unrelated daylight reading. |
The lux meter reading notes table is the compact owner for point, plane and state. The daylight factor reading notes guide covers paired daylight readings in more detail.
| Search job | Start with | Note separation |
|---|---|---|
| Daylight-only lux at a desk or bench. | Lux meter reading condition log | Daylight state, point and plane stay distinct from the electric-light case. |
| Electric-light lux after dark. | Lumens to lux calculator or lux meter reading notes table | Active group, scene, dimming level and no-daylight condition are recorded. |
| Daylight factor percentage. | Daylight factor calculator | Indoor and outdoor values are paired before the percentage is read. |
| Before and after a control change. | Before and after lux comparison notes table | Same point and plane, two named control states, daylight condition matched or named. |
| Window or skylight effect. | Window and skylight daylight notes | Opening state, blind state, shade and point depth stay with the daylight reading. |
Daylight notes need an exposure note
Daylight can move quickly in Australian rooms. Direct sun, bright overcast, heavy cloud, awnings, blinds, trees, adjacent buildings and room depth can all change the reading. The useful note is not just the lux value; it is the value plus the exposure note.
| Exposure field | What to write | Why it matters |
|---|---|---|
| Time and date | Reading time, date and sequence. | Daylight can change during a short visit. |
| Sky condition | Overcast, bright overcast, direct sun, broken cloud or deep shade. | The value belongs to that condition. |
| Shading state | Blinds, curtains, eaves, awnings or nearby obstruction. | Shading can change both level and glare. |
| Point depth | Distance or point label from the window or skylight. | Near-window and deep-room readings are different notes. |
| Electric-light state | Off, on, dimmed or daylight-linked state written plainly. | The number may be daylight-only or combined. |
The daylight lux values table explains why daylight values should be treated as condition-specific. The daylight factor examples table keeps indoor and outdoor values paired when a percentage relationship is needed.
Electric-light notes need a control state
Electric-light readings should name the active group and control state before they are compared. The same room can have general lighting, bench lighting, perimeter lighting, a dimmed scene and a full-output scene. A meter reading without that state is hard to repeat.
| Control field | Electric-light note detail | Related page |
|---|---|---|
| Active group | Room, bench, desk row, perimeter row, wall light or after-hours group. | Lighting zone glossary |
| Scene state | Normal, dimmed, full-output, cleaning or after-hours state. | Lighting control notes table |
| Dimming level | Stated level or observed dimming range where known. | Dimming range glossary |
| Daylight condition | Night, blinds closed, daylight present or daylight excluded. | Daylight factor vs daylight lux |
| Plane and point | Desk, bench, floor, shelf, vertical face or grid point. | Task-plane notes table |
When a sensor or daylight-linked state is active, note the state that was observed. The note should not imply future control behaviour from one reading.
Paired comparison rows
Before and after notes are stronger when the same point label is repeated. Change the state being tested, not the whole note shape.
| Pair | Point and plane | First state | Second state | Reading boundary |
|---|---|---|---|---|
| D1 / D1-E | Desk P1, horizontal task plane. | Daylight-only, lights off, sky and blinds named. | Electric-only after dark, scene normal. | Two different lighting sources, not one subtraction. |
| B1-O / B1-C | Bench P2, same meter position. | Blinds open, daylight only. | Blinds closed or tilted, daylight only. | Blind effect only if sky shift is noted. |
| C1-N / C1-D | Counter P3, same plane. | Night electric scene normal. | Daytime combined reading, daylight present. | Combined reading does not prove either contribution alone. |
| Z1-F / Z1-M | Desk row Z1, same points. | Full-output electric scene. | Manual dimmed scene. | Daylight condition must match or be named in both rows. |
| S1 / S1-O | Skylight point S1 and outdoor reference. | Indoor daylight point. | Outdoor open-sky reference. | Pair only for daylight factor when taken in the same short interval. |
Keep calculations in their own lanes
Calculated averages and meter readings are companion evidence. A calculated electric-light case can estimate average illuminance from lumens, area, utilisation factor and maintenance factor. A daylight factor can describe the percentage relationship between an indoor point and an outdoor reference. Neither result replaces a clear field note.
| Question | Better calculation page | Note boundary |
|---|---|---|
| How much electric light does the installed output suggest? | Lumens to lux calculator | Average estimate for a stated area and assumptions. |
| How many lumens are needed for a target plane? | Lux to lumens calculator | Target basis, area, UF and MF must be stated. |
| What daylight percentage was present? | Daylight factor calculator | Indoor and outdoor daylight readings paired. |
| What formula belongs with the note? | Lighting calculation formulas table | Formula result still needs condition notes. |
| How does daylight affect the remaining task note? | Daylight reading plus separate electric-light case. | A momentary daylight value is not an all-day reduction. |
The lighting units table keeps lux and lumen meanings separate. That matters because a daylight reading is illuminance at a point, while lumens describe light output before room losses and assumptions are applied.
Simultaneous and near-simultaneous readings
Daylight-factor notes are clearest when indoor and outdoor readings are taken in the same short interval. Electric-light comparisons are clearest when daylight is excluded, matched or explicitly named. The note should say which pattern was followed.
| Reading pattern | Better wording | Why it is stronger |
|---|---|---|
| Paired daylight factor | Indoor P1 and outdoor reference taken in the same short interval. | The ratio belongs to one sky condition. |
| Night electric check | Desk P1, electric scene normal, no daylight. | The electric-light value is not inflated by daylight. |
| Daytime combined check | Desk P1, daylight plus electric scene, overcast condition. | The lived condition is labelled as combined. |
| Before and after electric scene | Same point, same daylight state, two control states. | The control change is easier to read. |
| Daylight exposure comparison | Window-side and internal points, same interval. | The comparison is between locations, not lighting systems. |
The before and after lux comparison notes table gives a compact shape for repeated point comparisons. The lux meter grid point layouts guide helps keep point labels stable.
Measured comparison without overclaiming
A measured comparison can show that one point read higher or lower under the stated condition. It does not settle every task position, future daylight availability, comfort, glare, colour quality or formal obligations. If the comparison relates to a work area, keep the workplace lighting table and disclaimer nearby so the public note stays modest.
| Measured comparison | Note can say | Note should not say |
|---|---|---|
| Daylight-only point | This point read a stated lux value under a stated sky and exposure. | The room has adequate daylight at all times. |
| Electric-only point | This point read a stated lux value under the active scene. | Every point in the room is acceptable. |
| Combined condition | Occupied condition at that time had the stated reading. | Daylight or electric contribution was proven separately. |
| Daylight factor pair | Indoor/outdoor percentage for that paired condition. | A formal result for every season or sky. |
| Scene comparison | A changed control state changed the measured point. | Future behaviour is settled. |
The measured illuminance term is useful here because it keeps the number attached to a point, plane and condition rather than turning it into a whole-room claim.
Colour, glare and comfort stay separate
Daylight and electric-light notes can be numerically clear while still missing important visual notes. Direct sun can create glare. A cool electric scene can change white appearance. A high reading can still sit beside poor vertical visibility or reflected bright patches. Keep those notes as companion fields rather than folding them into the lux number.
| Companion field | Why it matters | Related page |
|---|---|---|
| Glare view | Bright source, reflected patch or direct sun from the observer position. | Glare check lighting notes plus the glare glossary |
| Colour appearance | Warm, neutral or cool white state in the electric scene. | Colour temperature table |
| Colour rendering | CRI/Ra note tied to the task surface where relevant. | Colour quality notes table |
| Vertical visibility | Face, board, shelf or wall plane checked separately. | Vertical illuminance notes |
| Surface finish | Dark, glossy or reflective finish beside the point note. | Surface reflectance planning table |
These notes do not replace the daylight or electric-light value. They explain why the same lux number may be read differently at two points.
Compact daylight and electric-light note
| Note field | Daylight/electric detail |
|---|---|
| Zone | Room, desk row, bench, counter, shelf, corridor edge or work area. |
| Plane | Task plane, floor plane, vertical face, window-side point or internal point. |
| Reading type | Daylight-only, electric-only, combined, daylight-factor pair or measured comparison. |
| Exposure | Time, sky, shading, direct sun, point depth and outdoor reference where needed. |
| Control state | Active group, scene, dimming range and daylight-linked state if observed. |
| Calculation | Daylight factor, lumens to lux, lux to lumens or formula table reference. |
| Measurement | Point label, lux value, meter orientation, same-interval note and repeat condition. |
| Boundary | Non-formal planning note; tariff, legal and full-position assessments remain outside this page. |