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Lighting Efficiency Tips

Reduce Light Levels

You can often reduce light levels without reducing light quality by the following procedure:

  • Redesign visual tasks. For example, begin using a better printer with darker lettering, or install light filtering shades to reduce glare.
  • Reduce light levels where there are no visual tasks. Provide minimum light necessary for safety, security, and aesthetics.
  • Reduce light levels for visual tasks where those levels are currently excessive.

If you want to cut lighting energy consumption, while enhancing light quality, consider the following:

  • Paint and decorate using light colors.
  • Establish ambient illumination at minimum acceptable levels.
  • Provide task lighting at optimal level, depending on the difficulty of visual tasks-for example, sewing requires more light than cooking.
  • Replace lamps, ballasts, and fixtures with more efficient models.
  • Buy and use CFLs.
  • Improve light quality by reducing glare and brightness contrast.
  • Use daylight.

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Posted by Fay B. Castro - January 11, 2012 at 3:10 pm

Categories: Ecology, Global Warming Effects, Save Energy   Tags:

Lighting Efficiency

Energy Efficiency Lighting

Lighting accounts for 20% to 25% of all American energy consumption. An average household dedicates 5% to 10% of its energy budget for lighting, or commercial establishments consume 20% to 30% of their total energy use for lighting.

Electricity is usually converted into light (in residential buildings) in incandescent or fluorescent lamps.



A lumen measures light output from a lamp. All lamps are rated in lumens. For example, 100-Watt  incandescent lamp produces about 1750 lumens. Dividing a lamp’s number of lumens by its watts gives efficacy-a measurement of lighting efficiency.

The distribution of light on a horizontal surface is called its illumination. Illumination is measured in footcandles. A footcandle of illumination is a lumen of light distributed over one square foot of area.

The amount of light required, measured in footcandles, varies according to the difficulty of a visual task. Ideal illumination is the minimum footcandles necessary to comfortably perform a task at the maximum practical rate of speed without eyestrain.

In the past, illumination of 100 footcandles was thought to be minimum for visual tasks in the workplace. Now, the Illuminating Engineering Society says that 30 to 50 footcandles is adequate for most home and office work. Difficult and lengthy visual task, like sewing for extended periods of time, requires 200 to 500 Footcandles. When no seeing task are performed, the lighting system needs to provide only security, safety, of visual pleasure – from 5 to 20 footcandles.

Lighting uses

Three categories of lighting by faction are ambient lighting, task lighting and accent lighting.

Ambient lighting provide security and safety, as well as lighting the tasks that occur throughout the lighted space.

Task lighting provides light at the work area. Illumination levels should be high enough for accurate task execution in task areas – not throughout the entire lighted space.

Accent lighting illuminates walls so that their brightness contrasts less with brighter areas, like ceilings and windows. Accent lighting is also used to make the space more visually comfortable.

Lighting Color

Lamps are assigned a color temperature depending on their “Coolness” or “warmness.” people perceive color of the blue-green end of the color spectrum is cool and those of the spectrum’s red end as warm. Morning light from the North is a more bluish then Southwest evening light.

Cool light sources are preferred for visual task, since they produce better contrast at the printed page, workbench, or other tasks. Warm light sources are preferred for living space, because they are more flattering to people’s skin and clothing.

Incandescent Lamps

Incandescent lamps are the oldest, most common, and most inexpensive lamps. Incandescent lights is produced by a white-hot coil of tungsten wire that glows when heated by electrical current. The type of glass enclosures surrounding this tungsten filament determines its light beam’s characteristics. Only 10% of the electricity is converted into light, the other 90% becoming heat.

Incandescent lamps have the shortest service life of the common lighting types. All incandescents are relatively inefficient compared to other lighting types. However, significant savings are possible – if you select the right incandescent lamp for his purpose.

Referred to by lighting experts as the A-type light bulb, these lamps are the most common and the most inefficient light source available. Larger wattage bulbs are more efficient than smaller wattage bulbs. Long-life bulbs, with thicker filaments and lower efficacy, are a common variant.

Fluorescent Lamps

Fluorescent lamps produce light by passing electric current through a metallic gas. The flow of electricity through the gas excites special chemicals called phosphors, causing them to glow or “fluoresce.” Fluorescent lighting is used mainly for indoor lighting. Fluorescent lighting needs controlling devices, called ballasts, the starting the circuit protection. Ballasts also consume energy.

Fluorescent lights for approximately three to four times as efficient as incandescents, and their lamp life is about ten times greater. Fluorescent lamps convert 80% of the electricity they use into light.

Compact fluorescent (CFLs) the most significant recent lighting advance for homes. They combined their efficacy of fluorescent lighting with the convenience and universality of incandescent fixtures. Recent advances in CFL designs also provide more natural color rendition and less flicker than older designs.

Recessed Fixture Issues 

Recessed light fixtures, especially cylindrical ones called “cans,”are often direct leak through the air barrier. These fixtures, when they contain incandescent bulbs, must be ventilated by holes in their shell to purge heat to from the fixture.

Installed in soffits, cathedral ceiling, and suspended ceiling, recessed light fixtures connect the conditioned space to attics or roof cavities. Not only do they exchange air between conditioned spaces and building cavities, recessed light fixtures also allow warm, moist indoor air to reach cold roof decking, causing condensation.

One remedy is to replace the fixture with a similar fluorescent fixture, which produces only a quarter of the heat and doesn’t need venting.


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Posted by Fay B. Castro - January 11, 2012 at 12:18 pm

Categories: Ecology, Global Warming Effects, Save Energy   Tags:

House Insulation

Insulation Types

Insulation slows heat transmission to the buildings floors, walls and ceiling or roof. Heat transmission is the average homes leading cause of winter heat loss. Both single-family homes lost three to six times as much heat through transmission as through air leakage.

Why insulate?

When you say that insulation and resists heat transmission, we mean it resists conduction, convection, and radiation heat flow through a buildings component. In the case of a uninstall wall cavity, convection and radiation dominate heat transmission through the wall’s empty cavity. Insulation, installed in the wall cavity, forces the heat conduct from fiber to fiber and through the insulation’s tiny air pockets- a slower heat- transmission process than convection and radiation.

Insulation performs the following thermal functions:

  • Conserves energy by slowing heat transmission.
  • Enhances comfort by reducing temperature variations within the conditioned space.
  • Reduces the size of heating and cooling equipment needed by a building in direct proportion to R value.
  • Prevents wintertime condensation by improving low interior surface temperatures.

Insulation may also offer the following non-thermal benefits:

  • Adds structural strength.
  • Reduces noise and vibration.
  • Impedes air leakage and water vapor transmission.
  • Improves the building’s fire resistance.

Conductivity of Building Materials

Aluminum is the most conductive common building material. It’s thermal conductivity is more than five times greater than steel, 1000 times greater than wood, and 10,000 times greater than air. One square foot of steel, the next most conductive building material, conducts as much heat and 50 ft.² of concrete, 200 ft.² of wood, or 1000 ft.² of glass wool, assuming all are of the same thickness.

Insulation characteristics

Insulation is installed in building cavities, attached to a building’s structural frame, or attached to the building shell’s exterior surfaces.

Insulation slows heat transmission in two important ways:

1. By forcing the heat to conduct through air or some other gas. Gases are generally poor heat conductors.

2. By reducing heat radiation and air convection within cavities where it is installed.

Insulating materials are not as continuous or dense as other building materials which are heat conductors- they harbor millions of tiny air pockets within their fibers of bubbles ( in plastic foam insulation). Heat transmission proceeds slowly through insulation, having to cross this myriad of slow conducting their pockets.

If air from inside or outside the building leaks into a insulated cavity, the effectiveness of the insulation is further reduced. This reduction typically varies from 15 to 50%. Air can even flow-through fibrous insulating materials such as loosely install fiberglass. Installation’s installed density an important issue, especially in cold climates.

Wind also affects insulation performance. Wind convects heat away from the surfaces of a building. If voids and edge gaps exist, wind can push outdoor air through building cavities around the insulation or push air through insulation. These effects increase heat transmission.

Moisture Condensation:

Absorbed water decreases the R-value of insulation. Water fills the insulation’s air spaces, and conducts heat far better than air. Water and ice also can damage insulation. Wet insulation can help corrode metals and supply water to insects and microorganisms that rot organic building materials.

Air leakage is the most potent moisture carrying mechanism affecting condensation in building cavities. Vapor diffusion is water vapor traveling through permeable materials like drywall and masonry. Low-R building materials combined with water-absorbent building materials create the largest potential moisture problems.

Types of insulation:

Insulation materials are made of mineral organic materials that trap air. Plastic foams also use other gases that conduct heat more slowly than air. Mineral insulation include: mineral and glass fibers, vermiculite, and perlite. Organic insulating materials include plastic foams and cellulose.

Insulation comes in various product types: flexible materials, such as batts and blankets; rigid materials, such as foam-board; and fiberboard; sprayed on materials, such as polyurethane; and loose fill insulation, such as cellulose. Batts are narrow blankets sized to fit between wall studs, floor joists, and ceiling joists.

Fiberglass is the most popular insulation material; it is manufactured in batts, blankets, loose fill and rigid boards. Cellulose insulation is also popular for residential buildings it is manufactured as a loose- fill insulation from wood fiber on recycled paper. Plastic foam insulation is manufactured in 4-by-8 foot sheets in thicknesses from 1/4 inch to 4 inches.

Cellulose and fiberglass loose-fill insulation are good air sealers for inaccessible building cavities providing air-leakage pathways. Cellulose is superior to fiberglass because it packs tighter and has smaller fibers that are driven into small gaps during installation. However, cellulose can absorb water from leaks and high humidity. Technicians can seal areas where they can’t crawl or reach by using fill tubes to blow tightly packed insulation into the cavities.

Loose-fill insulation has particular importance to energy retrofits because of its ability to fill spaces inside closed cavities, such as walls. Sprayed insulations are often used to retrofit masonry walls, especially those with irregular surfaces.

It’s important to know each insulation materials temperature, toxicity, fire and moisture characteristics. Foam insulation can be damaged by high temperature and sunlight. Fiberglass irritates skin and lungs. Cellulose absorbs water in humid conditions. Kraft paper batt facing is flammable. And foam insulation produces toxic smoke when burned.

Fiberglass batts and blankets

Fiberglass batts and blankets are the most common and widely available, American insulation products. Mineral wool have a small market in the U.S. but it is common in Canada and popular in Europe.

Batts are most commonly installed into building cavities during construction. Batts a commonly sized to fit between framing members that are spaced on 16 inch or 24 inch centers. As a retrofit, batts are applied most often to ceilings with an attic and below the floor when there is a crawlspace.

Blown Cellulose

Blown cellulose is usually ground-up newspaper or wood wastes, treated with fire retardants. Cellulose for plowing is packed in compressed 24-to-40 pound bales.

It blows quickly and easily, achieving a high density in wall. Cellulose usually contains a lot of small fibers that tend to pack into cracks and crevices of closed building cavities, retarding airflow through these cavities. This characteristic is of cellulose is used extensively for air sealing older homes. Cellulose has better resistance to air convection than fiberglass act is commonly installed density.

Blown Fiberglass

Blown fiberglass is manufactured in two types: chopped-up batt waste and virgin short fibers. The batt waste type as long fibers and binder, so its R-value per inch is slightly lower than the virgin fibers, which are thinner and shorter. The shorter thinner fibers create smaller and more numerous air spaces.

Fiberglass for blowing is packed in compressed 24-to-40 pound bales. The compressed fiberglass requires a blowing machine with an agitator that tears it up into small pieces that travel fluidly through the blower hose.

It is easy to over-fluff fiberglass in attics, leading to low-densities and excessive air permeability. Cellulose insulation is superior to fiberglass at resisting convection as attic insulation because it blows at higher density.


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Posted by Fay B. Castro - January 10, 2012 at 1:33 pm

Categories: Energy Conservation, Green Solutions, Save Energy   Tags: