DesigningDesigningWithWith

LightLight

http://www.keithv.com/scans/brugge_sunset.jpg

Erin Farrell

Sep 25, 2006

LIGHT FACTS

• Most efficient light is natural light

• Artificial light is almost 15% of a household's electricity use

• New lighting technologies can reduce lighting energy use in homes by 50%–75%

• If you replace 25 percent of your light bulbs in high-use areas with fluorescents, you can save ~50% on your lighting bill

DAYLIGHTING

• Orientation– In northern hemisphere, greatest solar gain is on

the south elevation– Siting building diagonally to the south takes

maximum advantage of available sunlight

• Interior Design– What rooms serve what purpose? How can design

take advantage of natural sunlight?– Kitchen on east side – light in morning– Living/dining room on west side – light in evening

when sun setting

DAYLIGHTING

• Maximize light availability to rooms

– Design so light can enter every room from at least two sides

– If second side isn’t possible, consider gathering light from above

• Skylight; ridge skylight; light monitors, dormers, clerestory windows; light shelf

• Light pipes

ENERGY EFFICIENT LIGHTING

Incandescent

• Most commonly used

• Heat electric element to white hot

• Inexpensive to buy; running costs high

• Least energy efficient – only 10% energy consumed produces light; rest is heat

• Do not last long, so suitable for areas of infrequent or short period use

Fluorescent

• Most efficient

• Cause phosphor coat inside of glass tube to glow

• Produce less heat

• More expensive to buy; running costs lower

• Suitable to areas requiring long period use

Fluorescent: two types

• Compact– Usually designed to fit into conventional light

sockets– Four times more efficient and last up to 10 times

longer than incandescents– Use 50-80% less energy than incandescents

• Tubular– Straight or circular style– Cheaper than compact; but require special fittings

Fluorescent: ballasts

• Used to start fluorescent lamps

• Can be magnetic or electronic

• Magnetic – Older type; less expensive; cannot be dimmed

• Electronic – Newer type; more expensive but more energy efficient; start lamp quicker; some units can be dimmed

EFFICIENCY AND COST

• Cost directly related to wattage plus any associated ballast

• Higher the wattage, the higher the running cost

COST

* Based on 10 cents per unit of electricity

20 W CFL 100 W Inc.

Running cost over 10,000 hrs*

$20 $100

Avg life 10,000 hrs 1,000 hrs

Purchase cost $25 for 1 lamp $5 for 10 bulbs

Total Cost $45 $105

FINAL FACTS

• In a typical home, one compact fluorescent bulb can reduce carbon dioxide emissions by 260 pounds per year

• If every American household replaced one of its incandescent light bulbs with a CFL, it would save the same amount of energy as a large nuclear power plant produces in a year

• Saving electricity reduces CO2 emissions, sulfur oxide and high-level nuclear waste

Works Cited• http://oikos.com/library/eem/skylights/lightpipes.html

• http://www.greenhouse.gov.au/yourhome/technical/fs10.htm

• http://www.eartheasy.com/live_energyeff_lighting.htm

• http://www.eere.energy.gov/consumer/your_home/lighting_daylighting/index.cfm/mytopic=11980

• http://www.eia.doe.gov/kids/energyfacts/saving/efficiency/savingenergy_secondary.html

• Jacobson, M., Silverstein, M., Winslow, B. (October/November 2002). Fine Homebuilding. Designing a House for the Sun: 4 Strategies.