# Lighting Design Fundamentals

## Light Levels (Foot-Candles)

### Residential
| Space | FC Recommended |
|-------|----------------|
| Living room | 10-20 (ambient), 30-50 (task) |
| Kitchen (general) | 30-40 |
| Kitchen (task) | 50-100 |
| Dining room | 10-20 (ambient), 30-40 (table) |
| Bedroom | 10-20 (ambient), 30-50 (reading) |
| Bathroom (general) | 20-30 |
| Bathroom (vanity) | 40-60 |
| Home office | 30-50 |
| Hallway | 5-10 |
| Stairs | 10-20 |
| Garage | 20-50 |
| Exterior entry | 5-10 |

### Commercial
| Space | FC Recommended |
|-------|----------------|
| Open office | 30-50 |
| Private office | 30-50 |
| Conference room | 30-50 |
| Reception/lobby | 20-30 |
| Corridor | 10-20 |
| Restroom | 20-30 |
| Retail (general) | 50-100 |
| Retail (feature) | 100-500 |
| Restaurant (fine) | 5-15 |
| Restaurant (fast) | 50-100 |
| Classroom | 30-50 |
| Library reading | 30-50 |
| Healthcare exam | 50-100 |
| Industrial | 30-50 |
| Warehouse | 10-30 |

---

## Fixture Types

### Ceiling Mounted
| Type | Application | Spacing Rule |
|------|-------------|--------------|
| Recessed downlight | General, accent | 1.5× mounting height |
| Surface mount | Low ceiling areas | Varies |
| Pendant | Dining, lobby | Per design |
| Chandelier | Formal spaces | Per design |
| Track | Retail, gallery | As needed |
| Linear | Office, corridor | Per layout |

### Wall Mounted
| Type | Application | Height |
|------|-------------|--------|
| Sconce | Corridor, accent | 66"-72" AFF |
| Vanity bar | Bathroom | 75"-80" AFF |
| Picture light | Art display | 6" above frame |
| Wall wash | General wash | Per fixture spec |

### Task Lighting
| Type | Application |
|------|-------------|
| Under-cabinet | Kitchen counter |
| Desk lamp | Office |
| Reading light | Bedroom |
| Pendant (low) | Kitchen island |

---

## Lamp Types

### LED (Standard Now)
| Type | Lumens/Watt | Life | Color Temp |
|------|-------------|------|------------|
| A-lamp LED | 80-100 | 25,000 hrs | 2700K-5000K |
| PAR LED | 70-90 | 25,000 hrs | 2700K-4000K |
| MR16 LED | 60-80 | 25,000 hrs | 2700K-4000K |
| Linear LED | 100-150 | 50,000 hrs | 3000K-5000K |

### Color Temperature Guide
| Kelvin | Description | Use |
|--------|-------------|-----|
| 2200K | Candlelight | Restaurants, accent |
| 2700K | Warm white | Residential, hospitality |
| 3000K | Soft white | Residential, retail |
| 3500K | Neutral | Office, healthcare |
| 4000K | Cool white | Office, retail |
| 5000K | Daylight | Industrial, task |

### CRI (Color Rendering Index)
| CRI Range | Quality | Application |
|-----------|---------|-------------|
| 90+ | Excellent | Retail, healthcare, residential |
| 80-89 | Good | Office, commercial |
| 70-79 | Acceptable | Industrial, parking |
| <70 | Poor | Avoid for occupied spaces |

---

## Lighting Calculations

### Lumen Method (Zonal Cavity)
```
Fixtures needed = (Area × FC required) / (Lumens per fixture × CU × LLF)

CU = Coefficient of Utilization (0.4-0.8 typical)
LLF = Light Loss Factor (0.7-0.9 typical)

Example:
- 400 SF office, 40 FC required
- Fixture: 4,000 lumens
- CU: 0.6, LLF: 0.8
- Fixtures = (400 × 40) / (4,000 × 0.6 × 0.8) = 8.3 → 9 fixtures
```

### Point-by-Point (Inverse Square)
```
FC = Candlepower / Distance²

For aiming angle:
FC = (CP × cos(angle)) / Distance²
```

### Watts per Square Foot (Energy Code)
```
Max Watts = Area (SF) × LPD (W/SF)

Example:
- 1,000 SF office
- LPD allowed: 0.98 W/SF
- Max watts: 980W
- If using 15W fixtures: max 65 fixtures
```

---

## Switching and Controls

### Residential Switching
| Room | Switch Location |
|------|-----------------|
| Entry | At door, 3-way to interior |
| Hall | 3-way at each end |
| Bedroom | At door, 3-way to bed |
| Kitchen | Multiple switches by zone |
| Bathroom | At door, separate for fan |
| Garage | At house door + car door |
| Exterior | At door, photocell optional |

### Commercial Controls (IECC Required)
| Control | Requirement |
|---------|-------------|
| Occupancy sensors | Required in most spaces |
| Daylight sensors | Required at skylights, sidelighting |
| Multi-level switching | 50% reduction capability |
| Automatic shut-off | Required for spaces > 5,000 SF |
| Time scheduling | Commercial buildings |

### Dimming Guidelines
| Space Type | Dimming | Notes |
|------------|---------|-------|
| Conference | Yes | 3+ preset levels |
| Dining | Yes | Full range |
| Lobby | Yes | Scenes for time of day |
| Office | Optional | Task vs ambient |
| Corridor | No | Not typically needed |
| Retail | Varies | Display vs general |

---

## Emergency Lighting

### Requirements
- 1 FC minimum along path of egress
- 90 minutes battery backup minimum
- Monthly 30-second test
- Annual 90-minute test
- Self-testing units preferred

### Exit Signs
- Visible from 100' (6" letters)
- Illuminated (internal or external)
- Green or red (varies by jurisdiction)
- Battery backup required
- At all exits and along path of egress

### Placement
- At all exit doors
- At intersections of corridors
- At changes in direction
- In stairwells (each landing)
- Spaced max 100' on paths

---

## Exterior Lighting

### Building-Mounted
| Location | Fixture Type | Height |
|----------|--------------|--------|
| Entry | Wall pack or soffit | 8'-12' |
| Loading dock | Wall pack | 12'-18' |
| Security | Wall pack with photocell | 10'-15' |
| Decorative | Sconce | 8'-10' |

### Site Lighting
| Area | Pole Height | Spacing |
|------|-------------|---------|
| Parking | 20'-30' | 3-4× height |
| Walkway | 12'-15' | 40'-60' |
| Plaza | 15'-20' | Varies |
| Street | 25'-35' | Per roadway |

### Dark Sky Compliance
- Full cutoff fixtures
- Max 3000K color temperature
- Max 0.1 FC at property line
- No uplighting (except flags, monuments)
- Shielding for all site lighting

---

## Specialty Lighting

### Under-Cabinet
- LED tape or linear: 3000K, 90+ CRI
- 12" on center max for puck lights
- Switch at counter or wall
- Consider dimmable

### Cove/Indirect
- LED tape or linear
- 6"-12" from wall/ceiling for wash
- Even spacing for uniform wash
- Consider color changing (RGBW)

### Accent Lighting
| Application | Beam Angle | Aim |
|-------------|------------|-----|
| Artwork | 10°-25° | 30° from vertical |
| Sculpture | 15°-40° | Multiple angles |
| Wall wash | 40°-60° | 12"-18" from wall |
| Grazing | 10°-25° | Near wall surface |

---

## Lighting Plans

### What to Show
- All fixture locations (scaled symbol)
- Fixture type designation
- Switching (letter or number)
- Circuits (if combined with electrical)
- Switching/dimming notes
- Emergency fixtures marked

### Fixture Schedule
| Mark | Manufacturer | Catalog # | Lamp | Watts | Voltage | Mounting | Notes |
|------|--------------|-----------|------|-------|---------|----------|-------|
| A | Lithonia | 2RT8 | LED | 32W | 120V | Recessed | 2x4 troffer |
| B | Halo | H750 | LED | 12W | 120V | Recessed | 6" downlight |

### Switching Schedule
| Switch | Controls | Notes |
|--------|----------|-------|
| S1 | A1, A2, A3 | 3-way with S2 |
| S2 | A1, A2, A3 | 3-way with S1 |
| S3/D | B1, B2 | Dimmer |

---

## Energy Code Compliance

### Lighting Power Density (IECC)
| Space Type | W/SF |
|------------|------|
| Office (open) | 0.98 |
| Office (private) | 1.11 |
| Conference | 1.23 |
| Corridor | 0.66 |
| Lobby | 1.06 |
| Restroom | 0.98 |
| Retail | 1.26 |
| Restaurant | 0.96 |
| Classroom | 1.24 |
| Warehouse | 0.60 |

### Required Controls
- Auto-off within 30 min of vacancy
- Daylight response in daylit zones
- Multi-level control (50% reduction)
- Master shut-off for large spaces
