# Architectural Lighting Design Architectural lighting design integrates artificial illumination with the spatial, aesthetic, and functional requirements of buildings. Good lighting design supports visual tasks, enhances spatial perception, promotes occupant wellbeing, and reduces energy consumption. The architect must coordinate lighting with daylighting strategy, interior design, electrical systems, and building performance targets. --- ## Table of Contents - [Lighting Design Principles](#lighting-design-principles) - [Light Source Metrics](#light-source-metrics) - [Luminaire Types](#luminaire-types) - [Lighting Layers](#lighting-layers) - [Lighting Calculations](#lighting-calculations) - [Integration with Daylighting](#integration-with-daylighting) - [Lighting Controls](#lighting-controls) - [Space-Specific Requirements](#space-specific-requirements) - [Energy Efficiency](#energy-efficiency) - [See Also](#see-also) --- ## Lighting Design Principles | Principle | Description | |-----------|-------------| | **Task Illuminance** | Provide adequate light levels for visual tasks | | **Uniformity** | Even distribution avoiding dark spots and excessive contrast | | **Glare Control** | Limit direct and reflected glare (UGR ratings) | | **Colour Rendering** | Accurate colour appearance of surfaces and objects | | **Visual Hierarchy** | Use light to emphasise and structure spatial perception | | **Ambiance** | Light quality supports intended mood and atmosphere | | **Circadian Support** | Spectral content appropriate for time of day and occupant health | | **Energy Efficiency** | Minimise power consumption while meeting design objectives | --- ## Light Source Metrics | Metric | Unit | Description | |--------|------|-------------| | **Luminous Flux** | Lumens (lm) | Total light output from a source | | **Illuminance** | Lux (lm/m²) | Light arriving at a surface | | **Luminance** | cd/m² | Brightness of a surface as seen by the eye | | **Colour Temperature (CCT)** | Kelvin (K) | Warm (2700K) to cool (6500K) appearance | | **Colour Rendering Index (CRI)** | Ra (0–100) | Accuracy of colour reproduction; Ra > 80 minimum, > 90 excellent | | **Efficacy** | lm/W | Lumens produced per watt of electrical power | | **UGR** | Unified Glare Rating | Discomfort glare metric; lower is better | | **Lifetime** | Hours (L70/L80) | Time to 70%/80% of initial lumen output | ### LED Colour Temperature Guide | CCT | Character | Application | |-----|-----------|-------------| | 2200–2700 K | Warm, intimate | Restaurants, hotel lobbies, residential | | 3000 K | Warm neutral | Offices, retail, healthcare corridors | | 3500–4000 K | Neutral | Task areas, laboratories, kitchens | | 5000–6500 K | Cool daylight | Art studios, operating theatres, industrial | --- ## Luminaire Types | Type | Mounting | Application | |------|----------|-------------| | **Recessed Downlight** | Ceiling | General illumination, corridors, offices | | **Surface Mounted** | Ceiling/wall | Where recessing is not possible | | **Pendant** | Suspended | Feature lighting, dining, reception | | **Linear** | Recessed/surface/suspended | Offices, retail, corridors | | **Track** | Ceiling track | Galleries, retail, flexible spaces | | **Uplighter** | Floor/wall | Indirect lighting, lobbies | | **Wall Washer** | Ceiling/wall | Uniform vertical illumination | | **Spotlight** | Various | Accent/display lighting | | **Cove Lighting** | Concealed in architectural detail | Indirect ambient, feature | | **In-Ground** | Floor/ground | Landscape, facade uplighting | | **Bollard** | Ground | Pathway lighting | --- ## Lighting Layers Effective architectural lighting uses multiple layers: | Layer | Purpose | Example | |-------|---------|---------| | **Ambient** | General background illumination | Indirect cove lighting, recessed downlights | | **Task** | Focused light for specific activities | Desk lamps, under-cabinet, operating lights | | **Accent** | Highlight features and create visual interest | Spotlights on art, wall washers, facade lighting | | **Decorative** | Light source as visual element | Chandeliers, pendants, neon | | **Orientation** | Wayfinding and safety | Step lights, exit signs, emergency lighting | --- ## Lighting Calculations ### Lumen Method (Average Illuminance) E = (n × Φ × UF × MF) / A Where: - E = average illuminance (lux) - n = number of luminaires - Φ = luminous flux per luminaire (lumens) - UF = utilisation factor (depends on room geometry and reflectances) - MF = maintenance factor (accounts for lamp ageing and dirt) - A = area of working plane (m²) ### Room Index (RI) RI = (L × W) / (Hm × (L + W)) Where L, W = room dimensions, Hm = mounting height above working plane. Higher RI values indicate more efficient light distribution. ### Lighting Power Density (LPD) LPD = Total installed lighting power (W) / Floor area (m²) Compliance metric for energy codes such as [[ASHRAE 90.1 Energy Standard]]. --- ## Integration with Daylighting | Strategy | Description | |----------|-------------| | **Daylight-linked dimming** | Photosensors reduce artificial light when daylight is sufficient | | **Daylight zoning** | Separate lighting circuits for perimeter and core zones | | **Supplementary lighting** | Task lights complement daylight in deep-plan spaces | | **Glare management** | Coordinate blinds/shading with artificial light response | | **Spectral blending** | Match artificial light CCT to varying daylight colour | See [[Daylighting Fundamentals]] for daylighting metrics and strategies. --- ## Lighting Controls | Control Type | Function | |-------------|----------| | **Manual switching** | Simple on/off by occupant | | **Dimming** | Variable light output (0–10V, DALI, DMX) | | **Occupancy/vacancy sensing** | Automatic on/off based on presence | | **Daylight harvesting** | Dimming based on photosensor input | | **Time scheduling** | Automated on/off by time-of-day | | **Scene setting** | Pre-programmed lighting configurations | | **Tunable white** | Variable CCT for circadian/mood control | | **DALI-2** | Digital Addressable Lighting Interface — individual luminaire control | --- ## Space-Specific Requirements | Space | Illuminance (lux) | UGR Limit | CRI Minimum | Notes | |-------|-------------------|-----------|-------------|-------| | Office (desk) | 500 | ≤19 | 80 | EN 12464-1 | | Corridor | 100 | ≤25 | 80 | | | Classroom | 300–500 | ≤19 | 80 | Whiteboard 500 lux vertical | | Hospital ward | 100 (general), 300 (examination) | ≤19 | 90 | Circadian considerations | | Retail (general) | 300–500 | ≤22 | 80–90 | Higher for displays | | Gallery/museum | 50–200 (light-sensitive) | — | 90+ | UV and IR filtration | | Industrial | 200–500 | ≤25 | 60–80 | Depends on task | | Residential | 100–300 | — | 80+ | Warm CCT preferred | --- ## Energy Efficiency | Strategy | Saving Potential | |----------|-----------------| | LED replacement of fluorescent | 30–50% | | Daylight-linked dimming | 20–40% | | Occupancy sensing | 15–30% | | Task-ambient approach | 20–40% | | High-efficiency luminaires | 10–20% | | Optimised controls (DALI) | 30–50% combined | Lighting typically accounts for 15–30% of total building energy consumption. It is the first system to address in [[Net Zero Energy Buildings]] strategies. --- ## See Also - [[Daylighting Fundamentals]] - [[Electric Lighting Systems]] - [[Circadian Lighting Design]] - [[Emergency Lighting Design]] - [[WELL Building Standard]] - [[ASHRAE 90.1 Energy Standard]] - [[Building Management Systems]] --- #lighting-design #illuminance #luminaire #led #energy-efficiency #building-performance