LIGHTING AND ACOUSTICS AP 215 Aditi Padhi MBS School of Planning and Architecture

LIGHTING CONCEPTS In this unit: Day lighting Integrating day lighting with artificial lighting Electric light sources and their efficiency Artificial lighting: Lumens; lux; M.F; R.I.R. lighting level requirement for various functions

DAY LIGHTING Day lighting is the controlled admission of Natural light – direct sunlight and diffuse skylight.

DAYLIGHTING Place most used rooms in the daytime on the south side Provide light from two or more sides of the room Open curtains and shades in the heating season Light-colored surfaces reflect light better (walls and ceilings) Bonus: Solution for SAD (Seasonal Affective Disorder) image 4

DAYLIGHTING HISTORY Oculus: Pantheon Rome, Italy 126 A.D. “Natural light is the only light that makes architecture” Louis Kahn

MAXIMIZE DAYLIGHT PENETRATION Clerestory Windows Consider Surface’s reflectance for Daylight Penetration Day Light Penetration- As a thumb, daylight generally penetrates into a building a distance of 1.5 x the height of the top of the windows

BOUNCE DAYLIGHT Bounce daylight off surrounding surfaces Bring daylight in high and wash it down the space MET NY

ADVANCED WINDOW STRATEGY Light colored pavement or gravel can reflect Wide windowsills can be used as light reflectors Light shelves are usually placed above eye level to prevent glare from the top shelf. They also act as overhangs for the view windows underneath

TOPLIGHTING STRATEGY When applicable, horizontal openings (skylights) offer two important advantages. They offer fairly uniform illumination over very large interior areas. Horizontal openings also receive much more light than vertical openings.

SKYLIGHTS Veiling reflections are avoided when skylights A system of baffles can control direct glare and to some extent veiling reflections.

Assignment

Assignment Riola Parish Church, Riola Italy Alvar Aalto 1978

Visibility, which is the state of being perceivable by the eye, is often thought to depend principally upon the amount of light on the object or task to be seen, and that more light on the object or task will make it more visible. To some degree this is true, but visibility also depends upon visual acuity (the ability to distinguish fine details), and contrast sensitivity (the ability to detect the presence of luminous, or brightness, differences). Both visual acuity and contrast sensitivity vary with task luminance (brightness), which is determined by the amount of incident light, where the incident light comes from, and the reflectivity of the task. Daylight in Architecture, Benjamin Evans

TERMINOLOGY Illumination: luminous flux at any point on a surface exposed to incident light (direct or indirect) Lighting: Method to provide artificial illumination Shading: produce gradations of light or color

TERMINOLOGY Ambient Lighting: > scattered > no detectable direction > backlighting in a room > can use to give a feel for the main color in a room > not dependent on viewpoint Diffused Lighting: > directional > scatters equally in all directions once hits object > closest to the color of light > not dependent on eye position Specular light : > comes from a detectable direction > bounces off object in preferred direction > plays a role in shininess > dependent on viewpoint

TERMINOLOGY point source vs spotlight : > point source: light emitted in all directions > spotlight: cone-shaped positional vs directional Lighting: > positional: like a desk lamp > directional: like the sun all rays parallel when reach object

MATERIAL PROPERTIES 1. reflectance of light b. diffuse a. ambient > amount of ambient light > most visible where no direct light hits b. diffuse > degree of scattering of light on surface > matte vs flat paint finish Color of object == ambient and diffuse (typically set the same)

Light & Material Properties Examples increasing diffuse increasing ambient increasing specular

Fluorescent Fixtures Fluorescent fixtures are especially important in places where the lights are used extensively, like kitchens, playrooms, and living rooms. CFL’s, T8 and T5 bulbs are the most efficient. 20

Valence Lighting image Provides efficient background and task lighting for the room Total of 70 watts using T-8 fluorescent bulbs Design recommended 21

Compact Fluorescent Bulbs CF bulbs are 4x as efficient as incandescent lights. Many are equivalent in size to standard incandescent bulbs. This shows a ceiling light with 2 compact fluorescent bulbs. 22

Other Fluorescent Lighting Fixtures are available in a variety of styles to fit a home’s décor Fluorescent fixtures should always be installed in places that will use lighting extensively, but they are not needed in closets 23

Carefully Choose Your CF bulbs Energy Star rated CF’s must meet higher standards and will last longer Choose the right size (follow recommendations) Choose the right color (daylight, cool white, warm white) for your application (try one and see if you like it) Make sure it has a flicker-free, electronic instant -start ballast 24

Types of Fluorescent Lights Ballast – activates the low pressure gas inside the bulb by varying the current (used in all fluorescent bulbs) Always choose electronic ballasts and instant-start flicker-free bulbs. Integral compact fluorescent – single unit (most common) Modular compact fluorescent – separate ballast and tube Ballasts can last 50,000 hours while bulbs may last 10,000 to 20,000 hours 25

Energy and Environmental Savings A single 18 watt CF bulb replacing a standard 75 watt incandescent bulb saves over its lifetime of 20,000 hours1 570 kw-hr of electricity 500 lbs of coal 1300 lbs of carbon dioxide 20 lbs of sulfur dioxide 26

Task Lighting In many cases, it is more efficient to use task lighting for desks, workbenches, etc. than to illuminate the entire room at a high intensity. 27

Incandescent Lighting There are appropriate places to use incandescent bulbs, especially in low use areas like Closets Storage rooms Utility closets Any minimal light use area 28

Measure of Lighting Efficiency Efficacy - measure of bulb efficiency ratio of the light output power (visible region, measured in lumens) to the electrical input power (measured in watts). Standard incandescent bulbs range from 8 to 20, halogen incandescent range from 12 to 24, while fluorescent bulbs range from 32 to 104.2 29

Other Lighting Outdoor HID (high intensity discharge) bulbs include mercury vapor, high-pressure sodium, and metal halide. The latter two are more efficient. Mercury vapor have efficacies of 20-60 compared to a range of 50 to 180 for sodium and metal halide.2 There are also cold-start CF bulbs for outdoors. Indoor halogen lights for high quality or precise focusing. Better than incandescent but not as efficient as fluorescent. Solar-powered walkway and patio lights. Easy to install. 30

Lighting Controls Simplest and cheapest strategy – turn off the lights manually when not in use Heat sensors (occupancy) Motion sensors (occupancy) Light sensors (for outdoors) Dimmers 31

Late Comers Assignment 10 Lighting Terminology