DesigningWith Light 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 CFL100 W Inc. Running cost over 10,000 hrs* $20$100 Avg life10,000 hrs1,000 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 ting/index.cfm/mytopic=11980http:// ting/index.cfm/mytopic= nergy_secondary.htmlhttp:// nergy_secondary.html Jacobson, M., Silverstein, M., Winslow, B. (October/November 2002). Fine Homebuilding. Designing a House for the Sun: 4 Strategies.