How to plan lighting in layers and control glare
General, task, accent and night light, the fixtures that deliver them, the lumen method for how much light a layer needs, and how to keep bare bulbs out of view.
- Start here: the essentials
- 1. Layers: what each light is for
- 2. Fixtures: what they do and where they go
- 3. Keeping glare out of view
- 4. The lumen method: how much light a layer needs
- 5. Layers without wiring: lamps and plug-in lights
- 6. See it: Marisol's living room and Tunde and Sam's downlights
- 7. Practice: a layer plan for one room
- 8. Your rooms
- 9. Check your work
- 10. Knowledge check and scenario
Start here Essentials
At minimum, write your first room's lighting as layers, get a starting lumen range for the general layer, and add one light you can plug in. Everything marked Go deeper can wait.
- Write the room's layers in the plan sheet. What each one lights and when you use it (layers).
- Run the lumen calculator for the general layer. Note the range from each target beside the row (the lumen method).
- Choose one task or accent light you can add with a lamp or plug-in fixture. Name it in its row (layers without wiring).
- Look for a bare bulb from the main seat. Note each one you can see and how you would shield it (glare).
- Mark every row "me", "landlord" or "electrician". Anything that adds or moves a ceiling or wall fixture is electrician work (fixtures).
Minimum time: about 40 minutes. Done when: the layers sheet has a row per layer for your first room with a lumen range and a lamp or fixture named, and every row says who does it.
1. Layers: what each light is for Understand
A room lit by one ceiling fixture asks that fixture to do everything: light the floor so you can cross the room, light the page so you can read, make the walls visible so the room does not feel like a cave, and stay comfortable to look at. One source is rarely in all the right places at once. Planning in layers splits those jobs among several lights, each placed for its own job and switched on its own. Every course we compared names the same layers, and the research and government sources below supply the reasons.
| Layer | What it lights | When it is on | Common sources |
|---|---|---|---|
| General (ambient) | The room as a whole: floor, walls, ceiling, the way across | Whenever the room is in use after dark | Ceiling fixtures, wall sconces aimed up, floor lamps aimed at the ceiling, several table lamps |
| Task | The surface where something is done: page, counter, desk, mirror | During the task | Reading lamps, desk lamps, under-cabinet lights, lights beside a mirror |
| Accent | One thing on purpose: a picture, a plant, a shelf, a textured wall | When you want the room to look a certain way | Picture lights, small spotlights, track heads, a lamp placed beside an object |
| Night | The floor of a path, at a low level, without waking anyone fully | From bedtime to morning | Plug-in nightlights, sensor lights, lit switches |
General light (also called ambient light) is the base layer. Task light is light aimed at a work surface, usually closer and brighter than the general layer. Accent light picks out one object or surface. A night light layer is the dimmest of the four, there only to show the path; Living rooms, bedrooms and stairs covers the night path.
Three principles that decide placement
Light on walls and ceiling makes a room read brighter. The Lighting Research Center's living-room guidance says lights aimed at the walls and ceiling make the room appear brighter than light aimed only at the floor (archived copy of a page the Lighting Research Center no longer hosts). The Defense Department's housing criteria describe living-room accent lights the same way, as providing wall brightness. A room with a lit floor and dark walls and ceiling is the cavern effect from How light works in a room. So the general layer is often better served by a lamp that throws light up or a sconce that washes a wall than by a brighter downward fixture. Convention
Task light goes in front of and to the side of the person. The Lighting Research Center's kitchen guidance puts luminaires slightly to the side of and in front of where the person stands, and warns against a single fixture in the middle of the ceiling, which casts the person's shadow onto the counter or sink (archived copy of a page the Lighting Research Center no longer hosts). For reading, its living-room guidance places a floor lamp behind and slightly to the side of the reader, with the bottom of the shade at seated eye level. The shadow check in Survey and test your rooms finds the cases where this goes wrong. Convention
Each layer gets its own control. The Defense Department's criteria call for separate switching for ambient and task light in kitchens, bedrooms and living rooms, and a separate switch for task light over the sink or work surfaces. A layer that only comes on with the others tends not to be used the way it was planned. Switches, dimmers and evening light covers controls for each layer. Convention
Not every room needs all four layers. A hallway may have a general layer and a night layer. A kitchen's general and task layers matter most. The layers sheet starts each room with the rows that usually apply, and you add or delete from there.
2. Fixtures: what they do and where they go
Fixture names describe how a light is mounted. What matters for a plan is what each one does with its light, and any type can serve more than one layer depending on where it is and how it is aimed.
| Type | What it does with light | Usual layers | Wiring |
|---|---|---|---|
| Flush-mount or semi-flush ceiling fixture | Spreads light down and sideways; a semi-flush also throws some onto the ceiling | General | Hard-wired |
| Pendant | Hangs on a cord or rod; a shaded pendant aims down, a glass one spreads light | Task over an island or table, general | Hard-wired (plug-in versions exist) |
| Chandelier | Several sources at one point; often in direct view | General over a table, decorative | Hard-wired |
| Recessed downlight | Aims light down from inside the ceiling; little reaches the walls unless placed near them | General, task, accent | Hard-wired, through a hole in the ceiling |
| Wall sconce | Up, down or both, from the wall | General (aimed up), task (beside a mirror), accent | Hard-wired or plug-in |
| Track | Several adjustable heads on one rail | Accent, task | Hard-wired (some plug-in) |
| Under-cabinet light | Lights the counter from just above and in front | Task | Hard-wired, plug-in or battery |
| Floor and table lamps | Shaded light near where people sit; torchieres aim at the ceiling | General, task, accent | Plug-in |
| Plug-in and battery lights | Small sources placed where needed | Task, night, accent | None |
Distribution: direct, indirect, diffuse
A fixture's distribution is where its light goes. Direct light goes straight from the fixture to the surface, as from a downlight or a shaded reading lamp; it is efficient on the task and makes sharper shadows. Indirect light goes to the ceiling or a wall first and reaches the room by reflection, as from a torchiere or an uplight sconce; it is softer and depends on how light the surfaces are. Diffuse light leaves a frosted glass or fabric shade in many directions at once. Most rooms need some of each: direct on the tasks, indirect or diffuse for the general layer. Physical principle
A fixture also keeps some of its own light. DOE's LED primer notes that with many fixture types, including recessed downlights and under-cabinet fixtures, it is not uncommon for only 50 to 60 percent of the light produced to leave the fixture (DOE, LED Basics). This is why a fixture's specification sheet may list "delivered" lumens below the bulb's, and why the lumen method below discounts what bulbs emit. Product-specific
Downlights: spacing comes from the fixture, not a rule of thumb
Recessed downlights are often laid out by a rule of thumb, such as spacing them at half the ceiling height. We found no standards source for that rule, and we do not use it. The spacing that gives even light depends on the fixture's beam. Photometric reports give a spacing criterion: a ratio, derived from the fixture's light distribution, of the spacing to the mounting height that gives uniform light on the work surface from an even grid. Lighting Analysts' documentation for its photometric software lists three values (along each axis and diagonally) and says to use the lowest (AGi32, IES Indoor Report Summary). The height in the ratio is the fixture's height above the work surface, not above the floor: Cornell's worked example divides the spacing by the height above the work plane (Cornell DEA 3500, Zonal Cavity notes). Product-specific The electrician or lighting supplier reads the criterion from the maker's sheet for the downlight you choose and lays out the grid from it.
Spacing criterion, worked. Suppose a downlight's sheet gave spacing criteria of 1.3, 1.3 and 1.2 (an illustrative example, not a real product). Use the lowest, 1.2. In a kitchen with an 8 ft ceiling and 3 ft counters, the fixtures sit about 5 ft above the counter. The maximum spacing for even light on the counter is about 1.2 × 5 = 6 ft. A downlight with a narrower beam has a lower criterion and needs closer spacing. Over the floor instead of the counter, the mounting height is 8 ft and the same fixture could spread farther, which is why the work plane has to be named first.
Recessed lights in an insulated ceiling
A recessed light sits in a hole in the ceiling. When there is insulation above, two separate ratings matter. IC-rated means the fixture is rated for contact with insulation; PNNL's recessed-lighting brief for DOE's Building America program says codes require fixtures in direct contact with insulation to be IC-rated, and that insulation is not to be placed above a non-IC fixture or within 3 inches of its parts. Airtight means the fixture is labeled for low air leakage; the model energy code the brief describes calls for recessed fixtures in the building's thermal envelope to be IC-rated and labeled at no more than 2.0 cubic feet per minute of leakage, and sealed to the ceiling (PNNL, Recessed Lighting Code Compliance Brief). The brief cites 2015 code editions; your area may have adopted a different one. One rating does not imply the other. Whether a fixture meets the code your area has adopted is for your electrician and inspector; Working with an electrician puts it in the brief. Ask the authority
Size and hanging height are conventions
Fixture size and hanging height are matters of convention, with designers on both sides. The most repeated figure is for a fixture over a dining table: Hunker, a home-design publication, gives the bottom of the fixture 30 to 34 inches above the tabletop for an 8 ft ceiling, and says designers differ for taller ceilings, some keeping the same range and others adding 3 inches per extra foot (Hunker, The Height of a Light Over a Dining Table). It also suggests a fixture at least 12 inches narrower than the table. Convention We give these as a range to try, not a rule. The same article gives 1.5 watts per square foot as a way to size the light for a room; that is an incandescent-era figure, and we show it only as an example of a rule not to use with LEDs. The lumen method below replaces it.
The test that settles size and height is a mock-up: a cardboard circle or box the size of the fixture, hung or held at the planned height, looked at from each seat and from standing. For a lamp, hold the lamp where you plan to put it and switch it on. Ten minutes with cardboard catches a fixture that blocks a view across the table or glares into a seated eye. Kitchens, bathrooms and desks uses the same method for pendants over an island. Test it
Anything that adds or moves a ceiling or wall fixture, adds a switch, or puts a recessed light in a ceiling, insulated or not, is electrician work. NFPA's consumer guidance says electrical work should be done only by a licensed electrician and that some communities require a license and permits. Write the row as "electrician" and take it to Working with an electrician. If you rent, the landlord decides any change to fixtures, and the request goes in writing. Ask the authority
3. Keeping glare out of view
Glare is light in the field of view that makes seeing harder or less comfortable. The International Commission on Illumination (CIE) separates two kinds. Discomfort glare causes discomfort without necessarily impairing vision (CIE e-ILV 17-22-102). Disability glare impairs vision without necessarily causing discomfort (CIE e-ILV 17-22-103). How light works in a room covers how age changes both. A bare bulb in view from the sofa is usually discomfort glare; a bright window behind someone's face, which hides their expression, is disability glare.
Shielding
The simplest control is to keep the bright part of a fixture out of view. The CIE defines the shielding angle as the angle, measured from the horizontal, down to which the light source is screened by the fixture (CIE e-ILV 17-30-036). Physical principle A deep lampshade, a downlight with the source set well back, or a louver gives a larger shielding angle: you have to be closer to underneath before you see the bulb. The Lighting Research Center's living-room guidance says to hide bare lamps behind shades, architectural features or the opaque parts of fixtures, and its dining-room guidance says no one seated should see the bare lamp. Convention
The check is the one from Survey and test your rooms: sit in the main seat, lie in the bed, stand at the counter, and look for any bulb you can see directly. For each one, note in the plan sheet how it will be shielded: a deeper or opaque shade, a frosted bulb, a different position, a lower lamp, or a fixture the electrician installs.
Reflections, surfaces and aim
- Matte surfaces. The German electrical industry association's position paper on glare lists bright, matte room surfaces among the means of glare control, along with shielding and controlled distribution (ZVEI, UGR method: application and limits). A glossy counter or table under a downlight returns a reflection of the source; the mirror test in Survey and test your rooms finds it.
- Accent light aimed away from faces. The Lighting Research Center's dining guidance says to aim accent light at the object and away from people's faces.
- Balance. A very bright source against dark surroundings glares more than the same source in a lit room. Light on the walls (the general layer from section 1) reduces glare as well as the cavern effect.
- Dimming. A fixture that is comfortable at half output may glare at full. Switches, dimmers and evening light covers dimming.
UGR, for anyone reading a commercial spec sheet. Some fixture sheets print a UGR (Unified Glare Rating), a number from a CIE method that rates discomfort glare from all the fixtures in a room, using each source's brightness, size and position and the brightness of the background. The ZVEI paper explains the scale: limits run 16, 19, 22, 25, 28, and each step is a noticeable change. Office reading and computer work typically get 19 or less. The same paper explains why the number rarely applies at home: the tabular method covers rooms from 2 to 12 times the fixture's height above the eye, and in rooms smaller than that, discomfort glare from the overhead fixtures is unlikely by the method's own terms. It does not apply to wall washers, fully indirect fixtures or adjustable spotlights, and it ignores the observer's age, though glare sensitivity rises with age. The Defense Department's criteria take a different route for occupied rooms in housing: they limit fixture brightness between 45 and 90 degrees from straight down, unless the occupant has continuous dimming. For a home, the seat test and the shielding angle tell you more than a UGR.
4. The lumen method: how much light a layer needs
The lumen method works backward from a target light level on a surface to the lumens the bulbs need to produce. An-Najah National University's lighting-design lecture gives it in its usual form: the light on the work surface equals the lumens produced, times two discount factors, divided by the area (An-Najah National University, Electrical lighting design). Turned around, that gives the arithmetic the lumen calculator uses:
lumens needed = target (footcandles) × area (square feet) ÷ (CU × LLF) Physical principle
A footcandle is one lumen per square foot, so target times area is the lumens that would have to land on the surface. The two factors account for light that does not land there.
- The coefficient of utilization (CU) is the share of the bulbs' lumens that reaches the work plane. The Defense Department's criteria define it as the ratio of lumens received on the work plane to the lumens emitted by the light sources, and as the product of the room's utilization and the fixture's efficiency. It is lower when walls are dark (they absorb more), when the room is small for its height (more light hits walls), and when fixtures keep some of their own light.
- The light loss factor (LLF) allows for bulbs dimming with age and dirt on fixtures and room surfaces. Cornell's worked example multiplies four such factors to get 0.78.
Why the CU here is an assumption
Designers read a CU from the fixture maker's table for the specific room. Those tables are for specific commercial fixtures, and we found no free source giving a CU for a typical home room. So the calculator uses three bands as our assumptions, not table values, chosen to bracket the one worked example we could read: Cornell's office of 30 by 20 ft with light surfaces, where the CU came to 0.48. Home rooms are smaller, and lose more light to the walls, so the bands sit at and below that figure.
| Walls and ceiling | CU band (our assumption) | Light loss factor |
|---|---|---|
| Mostly light | 0.40 to 0.50 | 0.8 |
| Medium | 0.30 to 0.40 | 0.8 |
| Mostly dark | 0.20 to 0.30 | 0.8 |
The light loss factor of 0.8 is close to Cornell's 0.78. The calculator works out each target twice: the low end uses the lower target and the higher CU, the high end the higher target and the lower CU. So the range carries both the uncertainty in the target and the uncertainty in the room.
Two targets, two answers
The calculator runs each room against the targets from the target table in Survey and test your rooms: the Defense Department's housing criteria and the commonly cited ranges attributed to older IES guidance, plus the Lighting Research Center's floors when you say someone 65 or older lives with you. It shows them side by side, because they disagree. For a living room the two main targets are 30 lux (2.8 fc) and 10 to 20 fc, a gap of about four to seven times once the CU band is applied. Across all the published sources, the Defense Department's 30 lux and the Lighting Research Center's 300-lux floor for older adults differ by ten times. We do not pick one. The range is where to start a trial; your reading after the change, in the same spot with the same device, settles it.
A worked line, for a 12 by 14 ft living room with medium surfaces against the Defense Department's 30 lux:
- Convert the target. 30 lux ÷ 10.764 = 2.79 fc.
- Multiply by the area. 2.79 × 168 sq ft = 468 lumens on the floor.
- Divide by CU × LLF at each end of the band. 468 ÷ (0.40 × 0.8) = about 1,460; 468 ÷ (0.30 × 0.8) = about 1,950.
- Divide by lumens per bulb and round up. At 800 lumens a bulb, 2 to 3 bulbs.
The lumen method assumes an empty room and perfectly diffuse surfaces, and its reflectances and maintenance factors are estimates; the An-Najah lecture lists those assumptions itself. With a CU that is our assumption rather than a table value, the answer is a starting range for a trial, not a purchase list and not a verdict on your room. It gives an average for the general layer across the room; it does not say how much light reaches a page, a counter or a face. Your own before-and-after readings in the tests sheet overrule it. Test it
Two things follow for task light. First, bringing a whole room up to a task level is expensive in lumens; a lamp or under-cabinet light aimed at the work reaches the task level with far fewer. Second, a lamp's light on a page follows the inverse-square law from How light works in a room for a small source: halving the distance gives about four times the light. The move-the-lamp calculator estimates it, and the meter or phone confirms it.
Room cavity ratio: why small rooms lose light. Designers describe a room's shape with the room cavity ratio (RCR): 5 × h × (length + width) ÷ (length × width), where h is the height from the work plane to the fixtures. A high RCR means a lot of wall for the floor area, so more light strikes the walls before reaching the work plane, and the CU falls. Cornell's 30 by 20 ft office with fixtures 7 ft above the work plane has an RCR of about 3 (5 × 7 × 50 ÷ 600 = 2.9). A 12 by 14 ft living room with an 8 ft ceiling, measured to a 2.5 ft seat height, has h = 5.5 and an RCR of about 4.3 (5 × 5.5 × 26 ÷ 168). That is why this manual's bands sit below Cornell's 0.48. The An-Najah lecture shows the formula as an image; this is its standard form.
What goes into the light loss factor. The An-Najah lecture lists the factors: lamp lumen depreciation, dirt on the fixture, dirt on room surfaces, burned-out lamps, and others for temperature and voltage. Cornell's example uses lamp depreciation 0.88, fixture dirt 0.90, room-surface dirt 0.98 and burnouts 1.0, which multiply to 0.78. In a home with LED bulbs replaced when they fail, 0.8 is a reasonable middle; an enclosed fixture that runs hot, or a dusty glass dish, would lower it.
Accent light on art. Accent light is judged by eye, not by the lumen method. Aim it at the object from an angle that does not reflect into a seated viewer's eyes, which the mirror test from Survey and test your rooms checks on a framed picture's glass.
5. Layers without wiring: lamps and plug-in lights
Every layer can be built without touching the wiring. That is the renter's whole toolkit, and for owners it is the way to try a plan before paying an electrician to make it permanent.
- General: a torchiere or floor lamp aimed at the ceiling, two or three table lamps around the room, a plug-in wall sconce aimed up.
- Task: a floor lamp beside the reading chair, a desk lamp on the side opposite your writing hand (so your hand does not shade the page), plug-in or battery under-cabinet lights, a lamp beside a mirror.
- Accent: a small uplight behind a plant, a battery picture light, a lamp beside a shelf.
- Night: plug-in nightlights, battery motion lights along a path.
Cords are the main hazard. NFPA's consumer messages say to avoid putting cords under rugs or carpets, across doorways, or where furniture can pinch or damage them; to use extension cords only temporarily; and to keep lamps and bulbs away from anything that can burn, including furniture, bedding and curtains. Run a lamp's cord along the wall behind furniture. Where a lamp would need an extension cord in permanent use, CPSC's checklist says to have new outlets installed where needed or move the lamp closer to an outlet. A new outlet is electrician work, so that row becomes an electrician row. Buy plug-in lights with a recognized testing-laboratory mark (Survey and test your rooms covers the marks). Convention
Adhesive or screwed-on lights, even plug-in ones, may touch a lease. Ask the landlord in writing before mounting anything, and keep the answer; Working with an electrician covers what renters ask and how. Ask the authority
A switched outlet, where one wall switch controls an outlet, can put a lamp layer on the wall switch by the door. Switches, dimmers and evening light shows how to find a switched outlet without opening anything.
6. See it: Marisol's living room and Tunde and Sam's downlights See it
Marisol's living room. All readings and measurements in this example are invented for this manual. Marisol rents. Her living room is 12 by 14 ft (168 sq ft, 15.6 m²) with an 8 ft ceiling, medium gray walls and a white ceiling. She has a ceiling flush-mount with two 800-lumen bulbs (one 2700 K, one 5000 K) and a floor lamp behind the sofa with a 450-lumen bulb: 2,050 lumens. The tests in Survey and test your rooms found direct glare from the ceiling dish at the sofa and a heavy shadow at the desk, with phone readings of 38 lux at the sofa arm, 52 at the coffee table and 61 at the desk.
The calculator, under its assumptions. Living room, medium surfaces (CU 0.30 to 0.40), light loss factor 0.8. Against the Defense Department's 30 lux (2.8 fc) at the floor: 1,460 to 1,950 lumens, two to three 800-lumen bulbs. Against the commonly cited 10 to 20 fc: 5,250 to 14,000 lumens, 7 to 18 bulbs. Her 2,050 lumens sit just above the first range and far below the second. The calculator does not say which is right for her; her readings after a change do.
Her layer rows. General: the ceiling fixture, with the two bulbs matched to 2700 K (the color check in Bulbs, labels and color), on the switch by the door. Task, reading: the floor lamp moved from behind the sofa to beside the sofa arm. Halving its distance to her book gives about four times the light on the page under the inverse-square law for a small source; the phone, not the estimate, will confirm it. Task, desk: a desk lamp on the side opposite her writing hand, for the shadow. Accent: none for now. Glare: from the sofa she can see the ceiling dish, so her plan leans on the lamps in the evening; changing the fixture itself would be the landlord's decision. Every row says "me".
Open. Whether the lamps bring the sofa arm up enough for her: settled by her retest with the same phone in the same spots (Your lighting plan).
Tunde and Sam's kitchen. Tunde Adeyemi and Sam Clarke own a 1958 ranch house with an insulated attic above the kitchen. The kitchen is 12 by 13 ft (156 sq ft) with an 8 ft ceiling, light maple cabinets and white counters. Their general contractor's drawing shows eight 6-inch recessed downlights in a grid on one switch. Each is rated 700 lumens on its spec sheet: 5,600 lumens in all. They also want under-cabinet lights, two pendants over the island and a dimmer at the dining end.
The calculator, under its assumptions. Kitchen general light, light surfaces (CU 0.40 to 0.50). Against the Defense Department's 50 lux (4.6 fc) at the floor: 1,810 to 2,260 lumens. Against the commonly cited 30 to 40 fc: 11,700 to 19,500 lumens. The two targets differ by about six to nine times here. Under the first, eight downlights are potentially more than the general layer needs; under the second, they are less. The counter is lit by the under-cabinet task layer, not by the general layer, so the downlights do not have to bring the counters to a task level.
Who settles it. Whether eight is the right number: the electrician's layout from the downlight maker's spacing criterion, and their own readings after the work. Whether the downlights are IC-rated and airtight for the insulated ceiling: the electrician's quote and the fixture sheets (Working with an electrician). Which dimmer works with the chosen downlights: the maker's compatibility list, checked by the electrician (Switches, dimmers and evening light). Pendant height: their cardboard mock-up within the convention range (Kitchens, bathrooms and desks). Every row except the plug-in trials says "electrician".
Free sources behind this chapter's method:
- Lighting Research Center, living room (archived copy of a page the Lighting Research Center no longer hosts): a layered living room with the reasons for each light. Its bulb types are dated; the placement is not.
- Cornell, Zonal Cavity notes: a full lumen-method calculation with a real CU and light loss factor, for an office.
- AGi32, IES Indoor Report Summary: what the spacing criterion on a photometric report means.
- PNNL, Recessed Lighting Code Compliance Brief: IC and airtight ratings, for the conversation with your electrician.
7. Practice: a layer plan for one room Practice
Minimum: one row per layer for your first room in the layers sheet, a lumen range for the general layer from the calculator, one plug-in task or accent light named, a bare-bulb check from the main seat, and every row marked with who does it. Time: about 40 minutes. Materials: your sheets from Survey and test your rooms, a tape measure or a phone's measuring app, cardboard and tape for a mock-up (optional).
- Measure the room. Length and width in feet, wall to wall at the floor. Add them to setup so the calculator fills them in.
- Open the layers sheet and list the layers. For each: what it lights, when it is on. Delete layers the room does not need.
- Run the lumen calculator for the general layer. Use the surfaces you recorded in Survey and test your rooms; medium if unsure. Copy both ranges into the lumens column, with the target each came from.
- Compare with what is there. Add up the lumens in the fixtures that make up the general layer now. Write the comparison as "within", "below" or "above" each range, not as a verdict.
- Name a lamp or fixture for each row. For task and accent rows, prefer something you can plug in and try. Write its lumens and kelvin.
- Do the bare-bulb check. From the main seat, the bed or the work spot, note each bulb you can see and how it will be shielded.
- Mark who does it. Me for bulbs, lamps and plug-in lights; landlord for anything a renter does not control; electrician for anything that adds or moves a fixture or switch, or a recessed light.
- Mock up one fixture. Cut cardboard to the fixture's size, hang or hold it at the planned height, and look from every seat and from standing.
- Estimate a lamp move. Use the move-the-lamp calculator with a reading from Survey and test your rooms, then move the lamp and read again.
- Read a downlight's sheet. If your plan has downlights, find the spacing criterion on the maker's sheet and note it for the electrician.
8. Your rooms Your rooms
9. Check your work Check your work
Criteria
- Does each layer row say what it lights and when it is on?
- Does the general row carry a lumen range from the calculator, with the target it came from?
- Is there at least one task or accent light you can try without wiring?
- Is every bare bulb visible from the main seat noted with how it will be shielded?
- Does every row say me, landlord or electrician, with recessed lights and any added or moved fixture marked electrician?
- Does the plan read as a trial to be tested, not a shopping list?
Worked example
Marisol's rows (fictional) meet each criterion: general, reading and desk rows, each with what it lights; the general row carries 1,460 to 1,950 and 5,250 to 14,000 lumens with their sources; the floor lamp move and a desk lamp are plug-in trials; the ceiling dish is noted as visible from the sofa; every row says "me". Tunde and Sam's (fictional) carry their kitchen's own ranges, 1,810 to 2,260 and 11,700 to 19,500 lumens, each with its source, mark the downlights, pendants and dimmer "electrician", and leave the number of downlights to the electrician's layout.
Common mistakes
- Sizing the whole room to a task target. A task lamp reaches the page level with a fraction of the lumens.
- Spacing downlights by a rule of thumb instead of the maker's spacing criterion.
- Using watts per square foot. It dates from incandescent bulbs.
- Treating the calculator's range as what to buy, instead of where to start a trial.
- Choosing a pendant height from a number without a mock-up.
- Planning a recessed light in an insulated ceiling without asking about IC and airtight ratings.
What is still unresolved
The plan does not say whether it works. That is settled by trying the plug-in parts and retesting in the same spots (Your lighting plan), and for wired parts by the electrician's layout and the readings after the work (Working with an electrician). Controls for each layer come next, in Switches, dimmers and evening light.