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Solar, Technology

Nano Crystals

Nanocrystal solar cells or quantum dot solar cells, are solar cells based on a silicon substrate with a coating of nanocrystals.

While previous methods of quantum dot creation relied on expensive molecular beam epitaxy processes, fabrication using colloidal synthesis allows for a more cost-effective manufacture. A thin film of nanocrystals is obtained by a process known as “spin-coating”. This involves placing an amount of the quantum dot solution onto a flat substrate, which is then rotated very quickly. The solution spreads out uniformly, and the substrate is spun until the required thickness is achieved.
Quantum dot based photovoltaic cells based around dye-sensitised colloidal TiO2 films were investigated in 1991 [1] and were found to exhibit promising efficiency of converting incident light energy to electrical energy, and were found to be incredibly encouraging due to the low cost of materials in the search for more commercially viable/affordable renewable energy sources. A single-nanocrystal (channel) architecture in which an array of single particles between the electrodes, each separated by ~1 exciton diffusion length, was proposed to improve the device efficiency (figure below) [2]and research on this type of solar cell is being conducted by groups at Stanford, Berkeley and the University of Tokyo.
Although research is still in its infancy and is ongoing, in the future quantum dot based photovoltaics may offer advantages such as mechanical flexibility (quantum dot-polymer composite photovoltaics [3]) as well as low cost, clean power generation [4] and an efficiency of 65%.[5].
Recent research in experimenting with lead selenide (PbSe) semiconductor, as well as with cadmium telluride (CdTe), which has already been well established in the production of “classic” solar cells. Other materials are being researched as well. These materials are unlikely to have an impact in generating clean energy on a widespread basis, however, due to the toxicity of lead and cadmium.
Polymer solar cell
Polymer solar cells are a type of organic solar cell: they produce electricity from sunlight. A relatively novel technology, they are being researched by universities, national laboratories and several companies around the world.
Currently, many solar cells in the world are made from a refined, highly purified silicon crystal, similar to those used in the manufacture of integrated circuits and computer chips. The high cost of these silicon solar cells and their complex production process has generated interest in developing alternative photovoltaic technologies.
Compared to silicon-based devices, polymer solar cells are lightweight (which is important for small autonomous sensors), disposable, inexpensive to fabricate, flexible, customizable on the molecular level, and have lower potential for negative environmental impact. An example device is shown in Fig. 1.
The following discussion is based primarily on Mayer et al.’s review, cited below. Organic photovoltaics are comprised of electron donor and electron acceptor materials rather than semiconductor p-n junctions. The molecules forming the electron donor region of organic PV cells, where exciton electron-hole pairs are generated, are generally conjugated polymers possessing delocalized π electrons that result from carbon p orbital hybridization. These π electrons can be excited by light in or near the visible part of the spectrum from the molecule’s highest occupied molecular orbital (HOMO) to the lowest unoccupied molecular orbital (LUMO), denoted by a π -π* transition. The energy gap between these orbitals determines which wavelengths of light can be absorbed.
Unlike in an inorganic crystalline PV material, with its band structure and delocalized electrons, excitons in organic photovoltaics are strongly bound with an energy between 0.1 and 1.4eV. This strong binding occurs because electronic wave functions in organic molecules are more localized, and electrostatic attraction can thus keep the electron and hole together as an exciton. The electron and hole can be dissociated by providing an interface across which the chemical potential of electrons decreases. The material that absorbed the photon is the donor, and the material acquiring the electron is called the acceptor. In Fig. 2, the polymer chain is the donor and the fullerene is the acceptor. After dissociation has taken place, the electron and hole may still be joined as a geminate pair and an electric field is then required to separate them.
After exciton dissociation, the electron and hole must be collected at contacts. However, charge carrier mobility now begins to play a major role: if mobility is not sufficiently high, the carriers will not reach the contacts, and will instead recombine at trap sites or remain in the device as undesirable space charges that oppose the drift of new carriers. The latter problem can occur if electron and hole mobilities are highly imbalanced, such that one species is much more mobile than the other. In that case, space-charge limited photocurrent (SCLP) hampers device performance.
As an example of the processes involved in device operation, organic photovoltaics can be fabricated with an active polymer and a fullerene-based electron acceptor. The illumination of this system by visible light leads to electron transfer from the polymer chain to a fullerene molecule. As a result, the formation of a photo-induced quasiparticle, or polaron (P+), occurs on the polymer chain and the fullerene becomes an ion-radical C60– Polarons are highly mobile along the length of the polymer chain and can diffuse away. Both the polaron and ion-radical possess spin S= ½, so the charge photoinduction and separation processes can be controlled by the Electron Paramagnetic Resonance method.
Architectures
This section is derived largely from Mayer’s review, referenced below. The simplest architecture that may be used for an organic PV device is a planar heterojunction, shown in Fig. 1. A film of active polymer (donor) and a film of electron acceptor are sandwiched between contacts in a planar configuration. Excitons created in the donor region may diffuse to the junction and separate, with the hole remaining behind and the electron passing into the acceptor. However, planar heterojunctions are inherently inefficient; because charge carriers have diffusion lengths of just 3-10nm in typical organic semiconductors, planar cells must be thin to enable successful diffusion to contacts, but the thinner the cell, the less light it can absorb.
Bulk heterojunctions (BHJs) address this shortcoming. In a BHJ, the electron donor and acceptor materials are blended together and cast as a mixture that then phase-separates. Regions of each material in the device are separated by only several nanometers, a distance optimized for carrier diffusion. Although devices based on BHJs are a significant improvement over planar designs, BHJs require sensitive control over materials morphology on the nanoscale. A great number of variables, including choice of materials, solvents, and the donor-acceptor weight ratio can dramatically affect the BHJ structure that results. These factors can make rationally optimizing BHJs difficult.
The next logical step beyond BHJs are ordered nanomaterials for solar cells, or ordered heterojunctions (OHJs). This paradigm eliminates much of the variability associated with BHJs. OHJs are generally hybrids of ordered inorganic materials and organic active regions. For example, a photovoltaic polymer can be deposited into pores in a ceramic such as TiO2. Holes still must diffuse along the length of the pore through the polymer to a contact, so OHJs do have thickness limitations. Mitigating the hole mobility bottleneck will thus be key to further enhancing OHJ device performance, but controlling morphology inside the confines of the pores is challenging.
 Engineers at the University of California, San Diego (UCSD) have employed “nanowires” to boost the efficiency of organic solar cells [1].
Conclusion
At the moment, an open question is to what degree polymer solar cells can commercially compete with silicon solar cells. The silicon solar cell industry has the important industrial advantage of being able to leverage the infrastructure developed for the computer industry. Besides, the present efficiency of polymer solar cells lies near 5 percent, much below the value for silicon cells. Polymer solar cells also suffer from environmental degradation. Good protective coatings are still to be developed.
Still, organic PV devices show great promise for decreasing the cost of solar energy to the point where it may become widespread in the decades ahead. While great progress has been made in the last ten years with respect to understanding the chemistry, physics, and materials science of organic photovoltaics, work remains to be done to further improve their performance. Specifically, novel nanostructures must be optimized to promote charge carrier diffusion; transport must be enhanced through control of order and morphology; and interface engineering must be applied to the problem of charge transfer across interfaces. Novel molecular chemistries and materials offer hope for revolutionary, as opposed to evolutionary, breakthroughs in device efficiencies in the future.
Hybrid photovoltaic cells are a mix of two solar cell technologies[1].
They comprise dye-sensitized titanium dioxide coated and sintered on a transparent semi-conducting oxide, and a p-type, polymeric conductor, such as PEDOT or PEDOT-TMA,[2][3] which carries electrons from the counter electrode to the oxidized dye. Since the one polymer replaces the multi-component electrolyte the cells are expected to be far simpler to make reproducibly and should afford the same or similar form factors as the polymer solar cells. This technology, like that of the polymer cell, has not yet advanced to the performance level of that of the dye-sensitized solar cell technology. The efficiency values are in the single digits range. One of the causes of low performance is incomplete filling of the small cavities in the titanium dioxide nanoparticles.
Organic photovoltaic cells are solar cells made mostly of organic molecules. Specifically, the active layer of the device is made of organic material.
Many scientists and engineers believe organic solar cells will provide a cheaper alternative to traditional inorganic cells, since it is thought that economies of scale due to large-scale production of organic polymers will turn out to be less expensive than the current costs for fabrication of silicon or other inorganic materials. However, organic solar cells have much lower efficiencies than traditional technologies. Organic solar cells are considered to be a third generation technology.
There are three main types of organic photovoltaic technologies: 1) Molecular OPV, 2) Polymer OPV, and 3) Hybrid OPV. The main differences between these three technologies are the fabrication methods employed and the types of materials that are used. [1]
Molecular OPV
Molecular photovoltaic devices are typically fabricated by sublimating successive layers of electron and hole transporting materials under vacuum. Common materials include PTCBI, PTCDA, Me-PTCDI, Pe-PTCDI, H2Pc, MPc where M stands for (Zn, Cu), TPyP, TPD, CBP, C60, and PCBM.
Polymer OPV
Polymer photovoltaic devices are typically made by solution processing blends of two conjugated polymers or a conjugated polymer with a molecular sensitizer. The most common materials are PPV – Poly(p-phenylene vinylene), polyfluorenes, or polythiophenes. Polymer solar cells are the most heavily researched of all OPV technologies because they are the most promising when it comes to low cost. In general, it is thought that solution processing will be the most cost effective way to fabricate solar cells.
Hybrid OPV
Hybrid photovoltaic devices make use of both organic and inorganic materials. For example, research has been done on polymer-nanocrystal blended active layers, including the use of quantum dots. Research has also been done on the use of metals such as TiO2. These technologies have not yet surpassed the best polymer OPV technology, but they are promising.
References
Sun, Sam-Shajing & Sariciftci, Niyazi Serdar, (2005). Organic Photovoltaics: Mechanisms, Materials, and Devices. Boca Raton, Fl: CRC Press.
Going Green, Solar, Technology

Solar Power Sources

Any time we start to believe that fossil fuels are running out or we see their costs going way up, renewable sources of power, such as solar, come to the forefront of people’s minds—including mine. So I started thinking about the feasibility of the sun providing the primary source of power for companies.
How It Works
There are different types of solar-powered systems. Two such systems, solar thermal and solar photovoltaic, use solar panels to convert the sun’s energy. Solar thermal uses the sun’s energy to heat water, which then is converted to electricity. Solar photovoltaic uses the sun’s energy to “knock loose” electrons and then convert the created energy into electricity.
Solar-generated electricity can be used directly, stored in a battery for later use, or put back into the public power/utility grid and drawn back out when insufficient electricity is being produced to meet the user’s needs. (When solar energy is put into a public-utility grid, the user/producer’s utility meter will actually spin backward.) Power companies in 40 states have programs that will buy the electricity that you produce through solar.
Weighing Our Options
My colleagues and I tried to figure out if enough energy could be produced by the sun to power our collocation facility, which serves about 200 corporate customers and houses all of our Internet equipment—mail servers, Web servers and other customers’ servers. A lengthy research effort revealed that there is not a lot of information available about the viability of converting offices to solar power.
As an alternative, our VP of finance used a proven residential-based model and estimated the cost of installing solar photovoltaic panels that will provide 24/7 power would be around $600,000. We also got a quote from a roofing company that installs solar photovoltaic panels. Its estimated price is $375,000 for a system that produces only enough power for the facility during the day. We would have to tap into commercial power at night.
Another concern was whether we would have enough roof-top space to accommodate all the solar panels we would need. This was not an issue, since it was determined that we would only need to use 50 percent of our 5,000-square-foot rooftop.
The good news: It appears that a large facility like ours can be powered with solar. The bad news (at least for my company): The current 20- to 30-year payback makes installing panels to power our collocation facility cost-prohibitive.
Looking Ahead
Solar technology is improving, and the cost of creating solar panels continues to decline. It’s already dropped 90 percent over the past 20 years, according to a representative of the Solar Energy Industries Association (www.seia.org). One exciting development comes from SUNRGI, a company that recently announced its proprietary technology could reduce the wholesale cost of producing solar energy to five cents per kilowatt hour. That’s competitive with the wholesale cost of producing energy from fossil fuels.
Going Green

5 Easy Steps to Greening Your Kitchen

While going green in the kitchen will save you money on energy costs, eco-friendly products have a reputation for being expensive, frumpy and difficult to find.
The good news:  Earth-friendly products are available in a wider range of styles and costs than ever before, letting you go any shade of green you desire.
According to Good Green Kitchens author Jennifer Roberts, when you’re contemplating how to make your kitchen eco-friendly, don’t assume you need to spend big bucks. Ask yourself, “‘What environmental problem am I trying to solve, and what are some easy steps to take for maximum impact?'” Roberts says. Here are her recommendations:
1. EAT SUSTAINABLY
“This is easily the most important step,” Roberts says. “If you grow some of your own food or buy as much locally grown produce as you can, you’re more than halfway there in terms of having a green kitchen.” When you eat from your own garden, you eliminate the need to use fossil fuels to transport vegetables from a faraway farmer’s field to your plate. Even growing your own herbs on the windowsill helps; when you buy fresh herbs at the grocery store, you usually end up wasting leftovers and throwing away the plastic package.
2. WORK WITH WHAT YOU ALREADY HAVE
“People think making a kitchen ‘green’ means you have to go out and buy new stuff and throw out what you’ve got,” Roberts says, “but the greenest approach is actually to try to work as much as possible with what you already have.” Think “refresh,” not “remodel.” New paint and updated hardware for cabinets can give you a new look without producing the landfill waste that a remodeling project generates.
Most major paint manufacturers now make zero- or low-VOC paint, which means they emit fewer volatile organic compounds. VOCs are linked to health problems and are considered greenhouse gases; the fewer in your home, the better.
3. REMODEL WITH RECYCLED MATERIALS
Buy lightly used cabinetry at a building salvage shop, find countertops and backsplashes made of recycled aluminum or glass and purchase locally made new materials. Purchasing local products reaps great environmental savings in fuel and other transportation costs.
4. CHOOSE ENERGY-SAVING APPLIANCES
“At the top of this list is the refrigerator,” Roberts says. “If it’s more than 10 or 12 years old, it’s time to replace it with an energy efficient model. These days you can get a really great refrigerator that will consume less than 400 kilowatt-hours per year, which is low.” (Older fridges consume as much as 1200 kilowatt-hours per year.)
Dishwashers can also be a great place to save energy. If you’re purchasing a new one, compare labels to find those that use the least energy and water (even appliances that meet government Energy Star requirements vary in energy savings), and if you already have one with water-miser and heat-free dryer settings, use them. Small households that don’t use many dishes can cut energy use with drawer-sized dishwashers, Roberts says, “but if you create a lot of dirty dishes, one big model is best. I’ve seen some luxury homes that have two or three of the drawer-sized models, and that’s not saving energy.”
5. WHEN COOKING, THINK SMALL
“Use smaller appliances whenever possible,” Roberts says. “If you can cook in the microwave rather than the full-size oven, it saves energy. You’re also producing less heat in the kitchen, which is great in the summer because your air conditioner doesn’t have to work as hard.” Even small things make a difference, such as using lids on pots to bring them to a boil faster and using as few burners as possible.
Going Green

Eco Unclogging

BB90365C-EB20-4C24-9731-083F58012EA3
Ditch the Harsh Chemicals
 Earth Enzymes
$8.39, ecos.com
Mix the sand-like granules from the bottle with warm water and pour it down the problem pipe. After 24 hours, flush with water and voila—a cleared drain. It’s biodegradable, non-toxic, and works pretty well to unclog that pesky plug.
Bio-Flow
$19.50 (1 gallon), greenchem.com
Total Solutions’ Bio-Flow contains enzymes and bacteria that help break down grease and food in your drain. It works well on clogged sinks while deodorizing the area with a minty scent. The ingredients can irritate your eyes and skin, though, so make sure to avoid splashing it as you pour.
CLR
$9.99, jelmar.com
This liquid is the result of a partnership between CLR and the EPA’s Design for the Environment program, meaning it’s an eco-friendlier option than most commercial products. It seems to be the best bet for more serious clogs, plus it comes with a money-back guarantee.
Liquid-Plumr: Power Jet
$6.29, liquid-plumr.com
This drain cleaner is also free of harsh chemicals because it uses a jet of liquid and air to blast out clogs It works surprisingly well for minor clogs that cause slow drainage. Take note: The container can be difficult to recycle, depending on local regulations.
Drainbo Natural Drain Cleaner
$7.99, drainbo.com
We love the pun-y name of this non-toxic liquid, which contains only natural ingredients. Its eco appeal makes it worth a shot for slow drains, but, unfortunately, it doesn’t work very well for serious blockages.
Going Green

Eco Friendly Kitchen Ideas

Environmentally-friendly options for your kitchen are everywhere. Here are some good places to start looking:
  • Bamboo. According to housewares expert Gus Dallas, the latest in environmentally-friendly kitchens includes fast-growing bamboo. The material makes great cutting boards and it can also be used for backsplashes and flooring.
  • Scrap wood. IKEA kitchen designer Martha Saldumbide says, “Where we can spare the environment, we do. We use a lot of scrap wood in cabinets. It’s the wood that nobody else wants but it’s still really good hard wood.”
  • Lighting. To cut down on lighting costs, try using fluorescents. They cut energy use by 50 percent. Whenever possible use natural light to brighten up your kitchen and bring down your electrical bill.
  • Cork. This renewable resource is made from the bark off a tree. It’s also sound-absorbing, hypoallergenic and resistant to mold and mildew, making it an excellent choice for kitchens.
  • Recycled stone-chipped composite countertops. These countertops resemble granite and are just as durable.
  • Top and bottom freezer/refrigerator units. These are more energy-efficient than side-by-side models because not as much cold air escapes. Not sure if your fridge can pass the eco-friendly test? Shut the door on a dollar bill — if it slides out easily then it’s a sign the seal needs to be replaced.
  • Recycling stations. Handy recycling stations pull out for easy access. Other recycling cabinets are set on wheels so they can be moved wherever needed.
  • Convection ovens. This type of oven uses a fan to drive heat rapidly from source to food so it cooks it 25 percent faster than a conventional oven.
  • Natural fabrics. Choose cotton or wool for your dining chairs and window dressings since man-made fabrics are made with chemicals that harm the environment.
Technology

10x Technology uses cutting edge technology to build products such as pain-free hypodermic needle alternatives

10x Technology specializes in replicating precision microstructures into polymeric and metallic substrates.
They are currently supporting several companies in the development of microneedle arrays for transdermal drug delivery. The platform will enable a pain free and convenient alternative to hypodermic syringes for a wide range of drugs.Their capabilities include product design, prototype production on pilot plant and full scale manufacturing.
Food

EGG RECALL: Salmonella Poisoning

EGG RECALL: Salmonella Poisoning

The eggs have been sold in various stores, including Food Lion and Walmart.

Rose Acre Farms, of Seymour, Indiana, issued a voluntary recall for 206,749,248 eggs distributed to restaurants and retail stores in the following states: Colorado, Florida, New Jersey, New York, North Carolina, Pennsylvania, South Carolina, Virginia and West Virginia.

According to the FDA, the eggs were distributed from the farm in Hyde County, North Carolina, and reached consumers in the following states: Colorado, Florida, New Jersey, New York, North Carolina, Pennsylvania, South Carolina, Virginia, and West Virginia through retail stores and restaurants via direct delivery.

The eggs that are part of the recall can be identified by the plant number, P-1065, with the Julian date range of 011 through 102 printed on either the side portion or the principal side of the carton or package. The FDA, urges you to stop using the recalled eggs right away and return them to the store you bought them from for a full refund.

Going Green

A Green Gaggle

Simple Steps to Decreasing Your Environmental Footprint

1)  Packaging a Punch:
Cut Online purchasing.  I know, I know with one click of the mouse  your item(s) seem to show up nearly the next day.  It’s soooo convenient, I get it!   Well here’s the but, there is plenty of entropy (packaging material) that’s walloped in that box – and the box too, not to mention the delivery truck fuel/manpower.  The eco-cost is high,  if you plan your trip to get an item with other necessities you’ll drop your footprint, and you won’t have to wrap up all that cardboard for recycling day.   

2)  Chopping the Logs: 
Cancel the Catalogs :   Still getting catalogs from a store that you no longer have an interest in?  Surf the net instead  to find the store your cute pair of shoes are at, and cancel the catalogs.  Recycle the ones you do have, American’s throw out up to 1,300 lbs of catalogs (each) every year. 

3)  Trash the Bags
Paper or Plastic – how about fabric?  Most plastic and paper bags from the grocery store have a sprinter pace life of 54 seconds or less.  Get one of those nifty canvas bags for your shopping trips, and clean out the corner cabinet where you stash your trash bags.

4 )  This hot coffee is HOT !
Burning cardboard, or paper produces particulate matter in the air that we breathe.  Wood is a better choice, or now there are JAVA logs.  Which are made out of wood particles and you guessed it COFFEE.  This reduces the particulate matter in the air too. 

5)  Hang Out 
Use a multi-tiered system to cool your house.  Have a 2 foot roof overhang so there’s more shade.  Install a Radiant Barrier under the plywood for your roof (looks like aluminum foil) this can deflect up to 30% of the heat sun during the day, and doesn’t cost much more than the foil in your kitchen already.  This will send the heat from the sun back out through the roof instead of being absorbed into you attic air space.  Install whole house fans that pull the hot air out through the attic 

6)  Run Hot and Cold
Hydronic Air Handler – Heat Recovery Ventilation – purifies the air then pumps it heated through the house.  Can allow you to create a true hybrid system utilizing a boiler as the central heat source.  In many retrofit or new building construction applications, various types of heating are desired, such as radiant, baseboard, or warm air along with the need to provide cooling to the structure.  Utilizing separate equipment for each application is costly and requires more space than allotted for the various mechanical equipment.  In an integrated hybrid system a boiler is utilized as the heat source for all heating requirements, including radiant for hard surfaces such as tile, driveway snow melt, a loop of hot water baseboard or a ducted system for warm air via the air handler. Versatility is unlimited.

Since the boiler is being used as the heat source, various supporting equipment, including an indirect water heater, pool or spa heater can easily be integrated with this type of system.

Another use for air handlers is to provide supplemental heat to a radiant system. There are several reasons why the contractor may want to provide supplemental heat. If a system is designed as an on/off system then it takes time to drive up the temperature in the slab. Using a two stage thermostat, the air handler will provide heat to make the space comfortable until the radiant has ramped up and can then take over.

7)  It’s Soy Good!
Soy Based Foam Insulation  – Saves on energy bills and has no VOC’s (Volatile Organic Compounds).  Until recently, most polyurethane products utilized only petroleum or petroleum derivatives; now you have a choice … an environmentally friendly alternative.  The foam is manufactured from renewable soy beans. Among its best features is that it expands to 100 times its volume to completely fill every space and void creating a barrier and thermal seal. The thermal seal keeps your heating and cooling costs low. The barrier keeps pollutants out of your home and greatly reduces noise pollution. As an inert substance Soy-Based Spray Foam Insulation retains its structural integrity for the life of your home. It is not effected by moisture, mold, insects or rodents.

8)  I got an E?
Install Efficient Windows :  Low-E and solar control low-E (also called spectrally selective) coatings can be used to boost the energy efficiency of windows. Low-E double pane windows, most common in cold and moderate climates, are more energy efficient than clear windows because the low-E coating reduces heat loss through the window.
Solar control glass, also called Low E2, is a good glass for hot climates because, in addition to improving the insulating ability of windows, it also limits solar heat gain by blocking passage of infrared and some ultraviolet rays. Solar control glass allows a higher level of visible light to pass through a window with less solar heat gain reduction than tinted window coatings.
An NFRC label on the window will contain the information regarding the glazing features of a window – U-value, Solar Heat Gain Coefficient (SHGC), and Visible Light Transmittance (VT). Generally, the lower the U-value, the better the window performs at preventing heat loss (or gain in hot climates). U-value is equal to the inverse of R-value. SHGC is the fraction of sunlight which is admitted through a window and released as heat indoors. It is expressed as a number between 0 and 1– the higher the number, the more solar heat the window transmits. VT is the portion (between 0 and 1) of the sun’s visible light that is transmitted through a window. 

9)  Beating the Heater…
Install an On-demand Water Heater  –  Tank less hot water heaters reduce energy use while making hot water available whenever you turn on the tap.  Most water heaters heat 30 to 70 gallons of water and keep it hot until it’s needed. When you open the tap, hot water flows through the pipes and cold water enters the tank to be heated. But when you’re not using hot water, it’s being maintained at 120 degrees Fahrenheit (or more) — all day and all night, increasing your energy bills but not contributing to your comfort. Wouldn’t it be great if you didn’t have to keep a tank of hot water available to use the next time you open the hot water tap? A tank less or on-demand water heater makes it possible.

10)  It’s not just shiny it’s Radiant!
Radiant barriers are materials that are installed in homes/ buildings to reduce summer heat gain and winter heat loss, and hence to reduce building heating and cooling energy usage. The potential benefit of attic radiant barriers is primarily in reducing air-conditioning cooling loads in warm or hot climates. Radiant barriers usually consist of a thin sheet or coating of a highly reflective material, usually aluminum  (actually it looks like thick aluminum foil) , applied to one or both sides of a number of substrate materials. These substrates include kraft paper, plastic films, cardboard, plywood sheathing, and air infiltration barrier material. Some products are fiber reinforced to increase the durability and ease of handling.  

11)  Raindrops keep falling in my barrel
 Harvest Rainwater – Collect the rainwater from your down spout.  The water can easily be put to use watering your lawn or garden.  One 55 gallon barrel can save up to 2,500 gallons a year for “regular” rainfall.  There are simple systems out there that are already assembled.  Or if you’re handy, save a even more money, buy a barrel and the parts and assemble yourself.  There are dozens of websites on how to assemble your own barrel.  Make sure you get a barrel from a local vendor so you can be even more green.  Worried about the overflow?  There are diverters, and inchworms to the rescue so you won’t be soaking your foundation. 

 12)  I see the LED at the end of the tunnel
 Use LED lights  – they cost more initially but some are guaranteed to last for up to 24 years.   CFL’s cut down on carbon emissions too, but the light from LED’s is more natural looking.