Lighting final

How can lighting impact interior spaces?

Lighting affects mood, perceived size/shape, color appearance, productivity, visual comfort, safety, and circadian rhythm.

five lighting layers

• Ambient — general overall light

• Task — focused light for a specific activity

• Accent — highlights objects or architecture

• Decorative — aesthetic/visual interest (chandeliers, sconces)

• Natural/Daylighting — sunlight from windows/skylights

How are light wavelengths measured?

In nanometers (nm). The visible light spectrum ranges from 380–700 nm.

Color Rendering Index (CRI)

A scale of 0–100 that measures how accurately a light source renders colors compared to natural light. The higher the number, the better the color accuracy. A CRI of 90+ is considered excellent.

Color temperature

How warm or cool a light source appears.

• Warm — orange/yellow glow (~2700–3000K)

• Neutral — white (~3500–4000K)

• Cool — blue/white (~5000–6500K)

How is color temperature measured?

In Kelvin (K).

Designing with daylight

Orient windows north/south, use light shelves, clerestories, and skylights to distribute light deeper into the space. Use lighter finishes to reflect daylight further.

Types of daylighting

• Sidelighting — windows on walls

• Toplighting — skylights or roof monitors

• Light tubes — tubes that channel sunlight from the roof into interior spaces

What happens when there is too much daylight?

Causes glare, overheating, and visual discomfort. Managed with shading devices, louvers, or glazing treatments.

Space planning for daylighting

• Place workstations perpendicular to windows

• Put storage and circulation areas near the perimeter

• Use lighter finishes to reflect daylight deeper into the space

Azimuth angle vs. altitude angle (see Intro to Solar Orientation reading on Canvas)

• Azimuth — the sun's horizontal compass direction (left/right), measured from north

• Altitude — the sun's vertical angle above the horizon (up/down), determines shadow length and how deep light penetrates a space

Types of lamps, pros/cons, & color temperatures

-incandescent

-halogen

-fluorescent

-HID

-LED

Lamp	Color Temp	Pros	Cons
Incandescent	~2700K	CRI ~100, cheap, warm light	Very inefficient, short lifespan, being phased out
Halogen	~3000K	CRI ~100, bright, crisp light	Gets very hot, less efficient than LED
Fluorescent	3000–6500K	Energy efficient, wide color range	Contains mercury, possible flicker, lower CRI (70–85)
HID	Varies	Very high output, long lifespan	Slow warm-up time, used mainly in large/outdoor spaces
LED	2700–6500K	Most efficient, longest lifespan, dimmable, low heat, no mercury	Higher upfront cost

Light fixture vs. Luminaire

• Luminaire — the complete lighting unit including the lamp, housing, optics, and driver/ballast

• Light fixture — an informal/colloquial term for a luminaire

Types of luminaires

• Direct — 90–100% of light aimed downward toward the work surface

• Indirect — 90–100% of light aimed upward, bounces off ceiling for soft diffuse light

• Direct/indirect — light distributed both up and down, reduces shadows and glare

• Diffuse — light emitted equally in all directions, frosted/translucent housing

• Asymmetric — light directed to one side, used for wallwashing and grazing surfaces

Photometry

• Illuminance — amount of light hitting a surface (measured in lux or footcandles)

• Luminous intensity — strength of light in a direction (measured in candela)

• Luminance — brightness of a surface as seen by the eye (measured in cd/m²)

Luminaire types

• Recessed downlights — installed in ceiling, focused downward light, clean minimal look

• Wallwashers — evenly distributes light across a wall, highlights texture or artwork

• Troffers — recessed rectangular fixtures in commercial ceilings, hold fluorescent or LED tubes

• Linear — strip/bar form, used for coves, under-cabinet, and architectural accents

• Cove — concealed source in a ledge or recess, provides indirect ambient light

• Task — localized light for a specific work area, adjustable arm or under-cabinet

• Decorative — primarily aesthetic, chandeliers, pendants, sconces

Types of lighting control & where/how they are used

• Switching — basic on/off, simplest and cheapest control

• Time control — scheduled on/off via timer, used for exterior and commercial lighting

• Occupancy sensing — detects presence, turns lights off when space is unoccupied, saves energy

• Dimming — adjusts light levels, improves comfort, saves energy, extends lamp life

• Daylighting — sensors automatically adjust electric light based on available natural light (daylight harvesting)

Lighting Control Systems

• Relay system — centralized on/off switching of lighting circuits, used in large commercial buildings

• Energy management system (EMS) — integrates lighting with HVAC and other building systems, monitors and optimizes overall energy use

• Preset dimming system — stores multiple lighting scenes that can be recalled at the push of a button

• Computer controlled lighting system — sophisticated scenes, scheduling, and remote access, used in theaters, hospitality, and large facilities

Simple Lumen Method vs. Simple Point Method

• Simple Lumen Method — calculates the average illuminance across an entire space, used for uniform general/ambient lighting

• Simple Point Method — calculates illuminance at a specific point from a specific luminaire, used for accent, task, or non-uniform lighting

When to use lumen method or point method

• Lumen Method — when designing uniform ambient lighting for a whole room (offices, classrooms, hallways)

• Point Method — when you need the exact light level at a specific location (accent lighting, task lighting, non-uniform spaces)

Light loss factor

A multiplier less than 1 applied to lighting calculations to account for:

• Lamp depreciation over time

• Dirt accumulation on fixtures

• Other real-world losses

Ensures the design still meets required light levels as the system ages.

Who is responsible for lighting calculations

The lighting designer or electrical engineer.

Who is responsible for lighting drawings & specifications

• Lighting designer — design intent and concept drawings

• Electrical engineer — construction documents and specifications

Typical lighting & electrical symbols

• Circle — general light fixture

• Circle with lines — recessed downlight

• Square/rectangle — troffer or surface fixture

• S — switch

• S with number — multi-way switch (S2, S3)

• D — dimmer switch

• Emergency light — battery backup fixture

• Exit sign — illuminated exit

• Occupancy sensor — motion/presence detector

• Dashed lines — circuit connection between fixture and switch

Drawings for lighting design

• Reflected ceiling plan (RCP) — shows fixture layout as viewed looking up from below, primary lighting drawing

• Lighting layout plan — shows fixture locations and circuit connections

• Photometric plan — shows calculated light levels across the space

• Detail drawings — close-up drawings of specific fixture mounting or installation

• Lighting schedule — table listing fixture ID, manufacturer, model, wattage, and mounting type

Role of codes in residential, healthcare, workplace, retail, hospitality, & classroom lighting

• Residential — minimum illumination levels required in key areas (kitchens, bathrooms)

• Healthcare — strict codes for exam areas, patient rooms, and emergency lighting

• Workplace — energy codes (ASHRAE/IECC) regulate maximum wattage and require occupancy sensors

• Retail — codes regulate energy use and maximum lighting power density

• Hospitality — codes require energy efficiency and emergency/exit lighting

• Classroom — codes require minimum illuminance levels and glare control for learning environments

Aesthetic considerations in residential, healthcare, workplace, retail, hospitality, & classroom lighting

• Residential — warm, inviting light; layered lighting for different moods and activities

• Healthcare — clean, calm appearance; minimize harsh glare for patient comfort

• Workplace — professional, uniform light; reduce glare on screens and work surfaces

• Retail — dramatic accent lighting; highlight merchandise; reinforce brand identity

• Hospitality — warm, flattering light; decorative fixtures as focal points; intimate and luxurious feel

• Classroom — clean, neutral light; uniform and glare-free for focus and learning

Range of lighting needs for residential, healthcare, workplace, retail, hospitality, & classroom lighting

• Residential — low ambient for relaxing to bright task lighting for cooking/reading

• Healthcare — low for patient recovery to very bright for exams and procedures

• Workplace — consistent ambient light with task lighting at workstations

• Retail — bright overall with high-contrast accent lighting on merchandise

• Hospitality — dim ambient to dramatic accent; flexible scenes for different times/events

• Classroom — uniform, consistent illuminance across all desks and the board

Role of daylighting in residential, healthcare, workplace, retail, & classroom lighting

• Residential — enhances livability, reduces energy use, connects occupants to outdoors

• Healthcare — supports circadian rhythm and patient recovery, reduces stress

• Workplace — boosts productivity and mood, reduces energy costs

• Retail — creates an inviting atmosphere, used carefully to avoid glare on merchandise

• Classroom — improves student alertness and mood, preferred on the side wall to avoid glare

Ceiling heights & materials used in residential, healthcare, workplace, & classroom lighting

• Residential — standard 8–9 ft ceilings, drywall/paint, allows for recessed and surface fixtures

• Healthcare — standard 9–10 ft, acoustic tile ceilings, requires recessed fixtures to maintain cleanability

• Workplace — 9–12 ft, acoustic tile or open ceilings, troffers or suspended fixtures common

• Classroom — 9–10 ft, acoustic tile, recessed troffers or suspended linear fixtures for uniform light

Purposes of retail lighting

• Attract customers into the store

• Showcase merchandise and make products look appealing

• Reinforce brand identity and create ambiance

• Guide circulation — lead customers through the space

• Create contrast — brighter accent light draws attention to key products

Characteristics & elements of hospitality lighting

• Warm color temperatures — flattering, inviting atmosphere

• Layered lighting — ambient, accent, and decorative combined

• Dimmable sources — flexible scenes for different times and events

• Decorative fixtures — chandeliers, pendants as focal points

• High contrast — low ambient with bright accents for drama

• Intimate scale — lighting creates cozy, personal feeling

Light pollution

Excess artificial light escaping into the environment. Types:

• Skyglow — brightening of the night sky over populated areas

• Glare — excessive brightness that impairs vision

• Light trespass — unwanted light spilling onto adjacent properties

Harms wildlife, disrupts human circadian rhythms, and wastes energy. Managed with full cutoff fixtures and warmer color temperatures.

Considerations when using outdoor lighting (glare, brightness, contrast, safety, etc.)

• Glare — shield fixtures to prevent blinding brightness

• Brightness — balance visibility with comfort, avoid overlighting

• Contrast — avoid extreme dark and light areas side by side, creates hazards

• Safety — uniform illumination of pathways, entrances, and parking areas

• Light pollution — use full cutoff fixtures to prevent upward light escape

• Energy efficiency — use LEDs and controls to minimize waste

• Dark sky compliance — follow ordinances that limit light pollution

Phases of design

• SD (Schematic Design) — preliminary concepts, basic fixture ideas

• DD (Design Development) — refined layouts, fixture selections, initial photometric studies

• CD (Construction Documents) — final drawings and specs issued for bidding and construction

• Bidding — contractors review documents and submit pricing

• CA (Construction Administration) — designer reviews submittals, site visits, ensures design intent is followed

Substitution of light fixtures

When a contractor proposes a substitute fixture, the designer must evaluate:

• Photometric equivalency — does it produce the same light output/distribution

• Aesthetic match — does it look the same

• Spec compliance — does it meet all specifications

The designer must approve or reject the substitution.

Working with consultants

Lighting designers coordinate with:

• Architects — ceiling design, window placement, overall space layout

• Interior designers — fixture aesthetics, finishes, and design intent

• Electrical engineers — circuitry, power, and construction documents

• MEP consultants — mechanical, electrical, and plumbing coordination

Clear communication and drawing coordination between all parties is essential.