Sunday, November 15, 2009

How many years to change a lightbulb?

For 130 years, inefficient incandescent light bulbs have been the world’s dominant source of lighting. They pass current into a fragile filament that can break at the slightest shock – just the surprise of being switched on can be enough.

Worse, its chief output is heat. Its luminous efficiency (ratio of light output to power input) is at best 2.6 per cent.

Competing technologies have emerged: compact fluorescent (CFL) bulbs, for example, which can offer luminous efficiency of up to 8.8 per cent. But they are relatively expensive, bulkier and slow to turn on fully.

Another is the white Light Emitting Diode. Current LEDs can achieve a luminous efficiency of up to 10 per cent; next generation models offer up to 22 per cent. LED bulbs also boast superior longevity of up to 50,000 hours (equivalent to 17 years with an average eight hours light a day).

For years, LEDs were not bright enough, did not emit the right colors and cost too much, limiting them to traffic lights, a few high-end vehicles, and a range of consumer devices.

But white LEDs are becoming commercially viable. Problems over intensity and color appear resolved and, while they are costly, long life makes them competitive. Long life also allows lighting to be used in awkward places – because with a 17 year life span, there is little need to worry about changing a light bulb.

Tuesday, November 10, 2009

Green: Play food

If you have a little one on your list, or even someone young at heart, consider feeding the dolls (and bears, and squirrels, and tigers) this Christmas.

Rather than spending money on factory-made plastic play food, why not support the handmade movement? Many creative Etsy artisans have designed original toys with your child's heart and imagination in mind. They encourage hours of unplugged, unscripted fun.

I remember spending time at my Granny's house playing with a hand-crocheted set of Snow White and the Seven Dwarfs, and although I had plastic dolls too, these never failed to inspire my play time.

Handmade items are made with love, and never come over-packaged. They are not made with toxic materials, there's no assembly required, and they won't break right out of the box. Many can be designed by you, come in a variety of colors and materials, and can even be personalized, usually at no additional cost.

Monday, November 9, 2009

Green Clean Your Dish wash

I have an older dishwasher and I am fighting a battle to keep it running in good condition until I can go buy a nice, eco-friendly, energy efficient model. If you are on a quest for sparkling dishes too, some of these tips might be helpful.

First, we considered having a repair man in for a check up on the dishwasher. We were getting lots of little food particles sprayed everywhere. Then, before we called the repair man we put boiling hot water and baking soda down the kitchen drain adjacent to the dishwasher and cleaned out the bottle of the dishwasher really well. There was much improvement.

Other options to consider would be getting and old toothbrush and some white vinegar and scrubbing areas like the door seal and all the little nooks and crannies at the bottom. You can also wipe down the inside with white vinegar to combat staining and gunky build-up.

You can also run a high heat cycle with a cup or bowl of white vinegar in the top rack (no dishes, just the vinegar) to help get rid of any more gunk you couldn't get with the toothbrush.

If you're trying to make your dishwasher last longer until you can afford a sparkling high efficiency model, a good green cleaning might drastically improve your performance. Try it and see!

Friday, November 6, 2009

Why GE and Philips do not focus on LED

It seems that General Electric and Philips have enough inventory of regular incandescent and fluorescent (with mercury) bulbs to last for the next few they appear not ready to be offering their retailers a product that can change the world.
Solid State Lighting will replace all lighting within the next 15 years and certain light bulbs can be replaced immediately with LED lamps.
All spot light and flood lights...all decorative interior and exterior lights.

Easy way to decrease your bills dramatically

Switch to light emitting diodes

Light emitting diodes (Led) can be a huge energy saver. Replace some (or all) of you incandescent bulbs with Led and enjoy reduction in heat production, energy use, and electric bills! Savings: changing five of the most frequently used light bulbs in your home can save you $100 per year on electric bills!

Wednesday, November 4, 2009

Lumen versus candela

The lumen (symbol: lm) is the SI unit of luminous flux, a measure of the perceived power of light. Luminous flux differs from radiant flux, the measure of the total power of light emitted, in that luminous flux is adjusted to reflect the varying sensitivity of the human eye to different wavelengths of light. The lumen is defined in relation to the candela by 1 lm = 1 cd·sr = 1 lx·m2
That is, a light source that uniformly radiates one candela in all directions radiates a total of 4π lumens. If the source were partially covered by an ideal absorbing hemisphere, that system would radiate half as much luminous flux—only 2π lumens. The luminous intensity would still be one candela in those directions that are not obscured.

The candela (IPA: /kænˈdɛlə/, /-ˈdiːlə/, symbol: cd) is the SI base unit of luminous intensity; that is, power emitted by a light source in a particular direction, weighted by the luminosity function (a standardized model of the sensitivity of the human eye to different wavelengths, also known as the luminous efficiency function. A common candle emits light with a luminous intensity of roughly one candela. If emission in some directions is blocked by an opaque barrier, the emission would still be approximately one candela in the directions that are not obscured.
The candela is the luminous intensity, in a given direction, of a source that emits monochromatic radiation of frequency 540 × 1012 hertz and that has a radiant intensity in that direction of 1/683 watt per steradian.

The definition describes how to produce a light source that (by definition) emits one candela. Such a source could then be used to calibrate instruments designed to measure luminous intensity, for example.

The candela is sometimes still called by the old name candle, such as in foot-candle and the modern definition of candlepower.

Relationship between luminous intensity and luminous flux
If a source emits a known intensity (in candelas) in a well-defined cone, the total luminous flux in lumens can be calculated by taking the number of candelas, and dividing it by the number in the table below that corresponds to the "radiation angle" of the lamp (the full vertex angle of the emission cone). Example: A lamp that emits 590 cd with a radiation angle of 40°: 590/2.64 = approximately 223 lumens.

The lux (symbol: lx) is the SI unit of illuminance and luminous emittance. It is used in photometry as a measure of the apparent intensity of light hitting or passing through a surface. It is analogous to the radiometric unit watts per square metre, but with the power at each wavelength weighted according to the luminosity function, a standardized model of human brightness perception. In English, "lux" is used in both singular and plural.

Lux versus lumen
The difference between the lux and the lumen is that the lux takes into account the area over which the luminous flux is spread. A flux of 1,000 lumens, concentrated into an area of one square metre, lights up that square metre with an illuminance of 1,000 lux. However, the same 1,000 lumens, spread out over ten square metres, produces a dimmer illuminance of only 100 lux.
Achieving an illuminance of 500 lux might be possible in a home kitchen with a single fluorescent light fixture with an output of 12,000 lumens. To light a factory floor with dozens of times the area of the kitchen would require dozens of such fixtures. Thus, lighting a larger area to the same level of lux requires a greater number of lumens.

Lux versus footcandle
One footcandle ≈ 10.764 lux. The footcandle (or lumen per square foot) is a non-SI unit of illuminance. Like the BTU, it is mainly only in common use in the United States, particularly in construction-related engineering and in building codes. Because lux and footcandles are different units of the same quantity, it is perfectly valid to convert footcandles to lux and vice versa.

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