Articles

Submitted by John Hall (jdhall@mac.com)

Using LED technology lighting, you will never have to change another light bulb and you may save on your house heating bill.

We have essentially unlimited energy from the sunlight.  Only 7 billionths of the Sun’s energy strikes the earth but that energy striking the earth is 3 billion billion watts or about 1 kW per sq. meter. Today’s PV solar panels can convert at maximum about 15% of the energy to electricity.  On my house I have 76 sq. meters of PV panels that are rated at 10.3kW/hr of electrical power. Over the year this is 100% of my electrical needs and my house is now 99.9% electric based.

Challenge:

Looking at ways to reduce the impact of my lifestyle on the environment, I could have changed the way I live and live with less or I could have chosen to use technology to transform that impact.  I chose technology.   I believe with the right choice of technology we can solve all the current environmental problems and at the same time raise our standard of living. I am out to show that that is possible as well be a pioneer for that cause.

Currently, my house has the maximum area possible covered with solar panels and therefore I am now limited in my electrical generation capacity until PV efficiency improves.  Though all my current electrical need are being met there are new things that I would like to convert to be more energy efficient.  I drive a Toyota Prius and get sufficient mileage compared to other cars today but we will be able to do better with the plug-in technology and electric car technology that is coming.  With that in mind, I decided to reduce my current electricity use to make room for my future car(s).

Currently, the easiest way to do this is to reduce the power consumption of the house lights but I will not sacrifice lighting comfort and environmental damage by using fluorescents, which contain a small amount of mercury (a hazardous material).  Fortunately technology again provides for reduced energy, little environmental impact and personal comfort.  The answer is in LED (light emitting diode) technology.  Manufacturing is essentially the same as computer chip fabrication technology, which we have mastered and improves yearly.

Solution Details

Knowing that LED lighting was becoming feasible and cost effective in the home, I looked into commercial LED availability.  What I found was beyond what I expected.  LEDs now come in many colors, brightness levels, are dimmable, and  are now packaged in a way that they can replace any current light bulb in appearance or shape.  They have lifetimes in the 50,000 hour range which is about 35 years at 4 hours per day, though they probably will last even longer.  Their price now makes them cheaper than incandescence in the long run where their dollar crossover point is about 7,000 hours or 3 bulbs and 16,000 hours or 3 bulbs for CFL (Compact Fluorescent Lights).  However CFLs contain mercury and therefore are bad for the human environment when disposed and are slow to light to full brightness.  Economically the LEDs begin to win as you change to the 4th bulb.

My house has 6 inch recessed in-ceiling lights to light all rooms of the house except the kitchen and dining room.  When installed they were installed with Phillips 65 watt indoor flood incandescent lights and they had just the right amount of light and color for my taste.  Jim Wright of “Geo-Solar” helped me realize that recessed lights with incandescent lights generate a large amount of heat and because the recessed cans are open to the attic and because heat rises, they were sucking heat from the house and leaking that into the attic area.  Not only were they using a large amount of electricity but they were drawing cold air from the outside of the house and dumping house heat into the attic.

I decided to replace all 35 recessed lights with LEDs and when searching I found the perfect replacement that solved both the light and heat problem.  There is now a 6” LED recessed light made by CREE (model CR6) that is intended to replace all parts of a 6” recessed light.   The light itself uses only 10.5 watts, is slightly brighter than the incandescent, comes in “soft white” (which is identical to the incandescent), is dimmable down to 5% using standard dimmable switches, and is supposed to last 50,000 hours of roughly 35 years!!  Each bulb costs $49.97 (online) but by my calculations, the extra cost pays for itself in less than 3 years due to energy and bulb replacement savings.  See calculations below…

The LED light fixtures replaced Phillips R30, 65 watt incandescent floods that are dimmable, warm white, last 3,000 hours and cost $9.97.  I also compared them to the EcoSmart R30 600 lumens, 23 watt, dimmable, soft white, CFL indoor flood, 8,000 hours that cost $8.97.  All are available at home Depot.

The CREE CR6 is built in such a way that you remove all parts of the recessed light interior and exterior hardware except the socket, screw in the new light into the socket and slip the new light into the recessed light can.  The new light even comes with a cover ring in white or beige to finish the look of the light fixture.  The new light comes with metal fingers to hold the light in place and it is mechanically build in such a way that removing the light is just a twist in a counter clock-wise direction.  The new light is all one integrated part and is sealed to completely block air access to the attic.  This same fixture can even be used in a shower or bath area since it is completely sealed and will not allow condensation near any electrical connections.

Benefits & Payback

My house then went from 35 bulbs and can parts at 65 watts per bulb or 2.2Kw per hour to 35 LED replacement fixtures at 10.5 watts or .7 Kw per hour.  I am now saving electricity for other uses directly and indirectly reducing the house heat loss.  The one additional benefit to the long life of these LEDs is that I never have to buy or replace another light bulb.

Cost of Ownership Comparison:

Some calculations assuming 1 light at 4 hours per day, $0.125 per Kw/hr and 50,00 hours or 35 years (LED life):

The power savings for the LED lighting vs incandescent is 78.48 Kw/yr or 7 to 10 hours of full sunlight generation.

The savings for the CFL is the mercury not added to landfills and the heat loss that would still occur thru the recessed fixtures.

The savings to me is not having to change another light bulb!

PG&E rates

Informational Links:

Home Depot – All About LED Bulbs

Home Depot – CREE Model CR6

Moraga Hardware – carries an LED flood light

James Phillip Wright, AIA, “Geo-Solar”, CrawlSpaceEnergy.com