Green Building Articles

Cheat Sheet / Updated 03-15-2022

The words “solar power” often bring to mind solar panels and photovoltaic (PV) solar systems, but you can harness the sun’s energy in a number of smaller ways. The practical and affordable solar projects listed here are ones anyone can build or take advantage of. They explain how to use solar energy to purify drinking water, enjoy a portable shower, and cool your house.

Article / Updated 07-29-2019

Boosting the efficiency of your swimming pool is an important first step in reducing your carbon footprint and moving toward a more sustainable lifestyle. Here's how to make your swimming pool energy efficient so that when you add solar, you get the most bang for your buck: Reduce bends in the piping: Sharp bends in the PVC piping slow down the flow and require more power to do the same job. Unfortunately, many pool installers completely fail this simple requirement. If your pipes are all over the place, rebuild the system. PVC is a cinch to work with. Make sure that all valves are working properly: If you have gate valves, replace them with ball valves, which are more efficient. Make sure that all ball valves are completely open or closed. Keep the filter clean: A dirty filter loads the pump, which costs a lot more power. If your filter is old, replace it. Cartridge filters are better than diatomaceous Earth. Install a smaller, higher efficiency pump, and run it less each day: Use the smallest, most efficient pump possible — 3/4 horsepower is usually sufficient. If your pump is a few years old and wasn't designed with enough capacity for solar panel use, buying a new one will probably be economical. Most people will find that they can run their pool pump for much less time and still achieve satisfactory cleanliness. Give it a try. A large power pump filters your pool water faster, and some people like that because it means you can run the pump less (which means you listen to it less). But here's the problem: If you're planning on putting up solar panels, the amount of heat they put into the pool is a function of how much time water is flowing through them; the quantity of water isn't as important. So if you have a large pump that moves water quickly, you're not optimizing your solar panels. Install windbreaks around your pool. Wind can increase evaporation 300 percent or more, which wastes a lot of energy, much more than you may think.

Article / Updated 07-10-2019

You can heat your pool using solar power. Your pool system already includes the pump, controller, and filter, along with PVC pipes that route the water flow. Simply break into the PVC line after the filter and run a couple of flex hoses (or PVC, if you prefer) to the solar collector panel, which you can lay out on the ground or set against a hill to achieve some tilt toward the sun. A simple swimming pool solar-heating system. When the valve is closed, water runs exclusively through the solar collector panel, heating the water. As you open the valve, less water flows through the collector panel. In this way, you can adjust how much heat is going into your pool. Solar collector panels are available at most pool supply stores. Adaptors are sometimes necessary. Here are some ways to run the system for best results: Place the solar collector panel where it sees the most sunlight when the pool pump is running. If you place the solar collector panel on your roof, try to minimize resistance to the water flow. Keep the solar panel out of the wind as much as possible. For best heating results, run the pool pump during the sunniest time of the day; running it longer will result in more heat in the pool. If you want to use two or more solar collector panels, connect them in parallel. Flexible solar collector panels that are designed to fit together in a parallel ganged arrangement reduce the overall water pressure while heating the same amount of water. The general rule is to use a total collector surface area that's about half the surface area of your pool. But this varies quite a bit. Sizing your collector surface area depends on a number of factors: The pump's running time: The longer it's on, the more heat you collect in the pool for a given collector size. Pool location: If you have an above ground pool, the heat loss is much greater. You need a collector with more surface area. Solar potential when the pump is on: Note how your solar panels are oriented. How much sunlight do you get? Shade: Cutting down Old Man Oak isn't much of an option if your blood is truly green. Otherwise, choose a larger collector. Wind: If you have a lot of wind, your collectors will run inefficiently unless they are glazed. Swimming pools cost a lot. If you don't have any kind of swimming pool heater, your useable season may be around four months of the year. If you install a swimming pool heating system, you can get eight months. This explains the popularity of pool heaters. In a full-scale, professional-grade swimming pool solar system, when the pump is on, the controller decides whether to activate the solar collectors by measuring the temperature at the collectors and the temperature of the pool water. When heat's available at the collector, the motor valve opens, and the pump moves water up into the collectors and back down to the swimming pool. When the controller deactivates the motor valve and no longer allows water to pump into the collectors, the vacuum breaker allows the system to purge itself of liquid.

Article / Updated 03-02-2017

Radiant floor heat systems use solar power to heat water, which is then pumped through your home's floor. You can use solar-heated water to heat your home off-grid. Radiant heat, without solar, costs much less than forced-air heating for efficiency reasons. Installing a radiant heat floor system is almost surely not a do-it-yourself project, but it merits elaboration because it's such a complete and effective way to use solar energy water heating. A snaking closed loop of metal or plastic tubing runs beneath your floor. When hot water flows through the tubing, the heat radiates upward through the floor and into the room. When you supplement your radiant heat system with a solar water heater, you can drive your heating costs down to nearly nothing. Of course, sunshine isn't very reliable, particularly on the coldest nights when you most need heat, so you can't use solar heating exclusively; it can only be a supplement. But it can be very effective. Plus, it's also the most comfortable way to heat a home. You can use any type of water heating system with a radiant floor system, but the capacity of hot water that you use goes up dramatically with a radiant heat floor system. So the attraction of a solar system also goes up dramatically, because you get much cheaper hot water per BTU. At the very least, radiant heating reduces your carbon footprint. When you combine it with solar, the pollution savings can be impressive. The engineering is complex, and the installation is clearly not for the faint of heart. There are technical problems, of course, but the systems have been in use for a long, long time. New technologies are making these the system of choice for a lot of homes. Here's why: With conventional forced-air systems, hot air comes in through the vents and immediately rises to the ceiling. That's not where you want it, so you need to either pump in more heat than you really need (inefficiency) or use overhead fans to move the air back down (inefficiency). Moving air makes you feel colder, and you get stuck listening to blower noise as a big machine goes on and off all night. Furthermore, heated air dries out very fast, so your lips dry up, and your skin gets tight. With radiant floors, the heat starts at ground level and rises naturally, which is much more efficient. With radiant floor systems, there's no blower noise, wind chill is nonexistent, and you don't have to mess with HVAC filters. The big benefit is that the heat is in the room — the floor and furniture — not just the air. You can adjust your thermostat to a lower temperature in a radiant house and achieve the same comfort level because the floor and furniture are where the heat is. Where you set the thermostat is a question of comfort, not numerical temperature. If you're planning on a room addition to your house, consider using a radiant floor in that room. Your existing HVAC system likely won't have enough capacity to heat an additional room. Adding a solar water heater to your house and using your domestic heater to heat the radiant floor in the addition works wonders, and it's usually cheaper than adding another small HVAC system. You can also cool your house with radiant flooring. It doesn't work quite as well as heating, but if you have solar panels, you can use these at night to cool the water that's already in the closed loop of the radiant floor system. The reason the collectors will cool is simply because they have so much area, and the heat will escape into the cool, nighttime air. This is especially true if a breeze is blowing.

Step by Step / Updated 03-27-2016

A green lifestyle includes reusing resources. You can turn old and broken plates into creative works of art as tabletop mosaics. Choose a non-toxic, eco-friendly adhesive and grout (find them at www.greenbuildingsupply.com if your local hardware store can’t help) and do a green deed for yourself and the planet.

Article / Updated 03-26-2016

Using the sun to purify drinking water is a great solar project for the do-it-yourselfer. A solar-powered purification system the size of a microwave oven can yield up to 3 gallons of purified drinking water on a sunny day. Here’s what you need for a basic solar powered water purifier like the one shown in the figure: Wooden or sheet metal enclosure Reflective material like aluminum foil Black paint, used for barbeque pits Sheet of glass Insulation (the white foam kind is fine) Glue (silicon sealant or similar weather-resistant material) Black tray that can absorb heat Catch trough and container for purified water A cross-section of a water purification system. To assemble your solar-powered water purifier, find a place near a water source (for easy filling) and follow these steps: Paint the exterior of the wooden or sheet metal enclosure black to enhance absorption. Install the reflective surface at the back and side walls of the enclosure and glue the insulation to the bottom. Put a tray of contaminated water inside the enclosure and place the glass on top. Arrange the catch trough at the bottom of the glass, angled downward to a container (like a plastic jug) to collect the purified water. Aim the contraption toward the sun. That’s it — you’re done! The first few times you use this device, the water may taste a little odd. Let the system “sweat” for a few weeks, and the bad taste will go away.

Article / Updated 03-26-2016

An attic vent fan powered by solar energy can help cool your home. During the summer, attic temperatures can reach over 160°F. All that heat stays up there at night, and it sinks into your house through the insulation in your ceiling. A properly designed solar attic vent fan can remove a lot of air over the course of a day, cooling your house in the process. Attic vent fans come in two forms: one-piece units and distributed units. A one-piece unit like the one in the figure costs around $300 and is easy to install. Because you don’t need to run expensive electrical power up to the fan, you can install one just about anywhere you want. You don’t even need to go into the attic space. Simply cut a round hole in your roof, pull the shingles back, slide the unit up under the shingles, and drop it into the hole. Seal for weatherproofing, and you’re done. A one-piece attic vent fan.

Article / Updated 03-26-2016

You can use a portable shower that uses solar energy to heat the water. Solar showers are convenient for camping and backpacking. You can hang one out by your swimming pool for a quick, simple rinse. To use a solar shower, follow these steps: Fill a specially constructed plastic bag with water and then place it in direct sunlight to heat up. The top of the 5-gallon bag is clear, and the back wall is black to absorb maximum sunlight. To warm the water of your portable shower, simply position the bag so that the clear top faces the sun. Most portable showers come with a thermometer so you know when the water’s reached a comfortable temperature. When the water’s hot enough, hang the bag from a tree for a gravity-fed, hot shower. Portable showers can get really hot, over 120°F, so beware. Always sample the temperature before you step in.

Article / Updated 03-26-2016

Good solar designers assess climate particulars to enhance system performance. Climate includes elements such as temperature, precipitation, and wind speed, among other things. When determining whether solar power is right for you, take a look at the following in your climate: Sunlight: Climate dictates how much sunlight you can expect annually. The Southwest gets the most sunshine per day in North America, and Canada and the northern states get the least. The sun is higher in the sky in the southern states, so the days are longer. The figures at the end of this article outline the average number of hours of sunlight that different regions of the United States get throughout the year. Snowfall: You want to locate your panels so they avoid being inundated with heavy layers of snow. For example, some locations on your roof will experience very shallow snow buildups compared with other parts of your roof. Cloud cover: Ultimately, cloudy regions provide less sunshine, making solar systems harder to justify. But that doesn't necessarily mean that solar is uneconomical, so if you live with a lot of clouds, don't despair. Smog: Air pollution and smog affect the amount of sunlight you can expect to receive. If you live in an area with heavy air pollution, expect less system output over an extended period of time. Air density: You get better solar exposure in the mountains than near sea level simply because the air is thinner and scatters less sunlight. You can make an approximate estimate of how clear your air is by simply observing how blue the sky is on a clear day. Thick air scatters more red light, and so the appearance of the sky is less blue and more white. Temperature: With PV systems, the lower the temperature, the happier the semiconductors, and the greater the output. You can get more system output on a cold, clear day than a sunny day. Rainfall: Wet, humid environments tend to cause corrosion in metals. Electrical connections are particularly susceptible, and they either fail entirely or their integrity is compromised, resulting in poor system performance. It's very important to seal equipment junctions properly. Frequent fog: If you're living in an area that's foggy and misty in the morning, orient your solar panels more westward to optimize the amount of sunlight you can achieve over the course of a day. Fog also causes a lot of moisture-related problems, such as corrosion. Wind: If you have a lot of wind, you need to consider where you mount your solar equipment for a couple of reasons: Wind can tear equipment off of its mounting hardware and result in expensive repairs, not to mention dangerous conditions. Mounting schemes all have wind speed specifications. Wind cools surfaces very efficiently. Solar water heating panels may heat the water very effectively, but it doesn't make much sense to install expensive solar panels without addressing wind cooling first. Part of assessing climate is what you want your solar system to do for you. If you have a cabin in northern Minnesota, you probably won't be there much in the wintertime. And then you'll heat it using renewable wood. In the summer, you don't need to cool, and all you want to do is obtain some nighttime lighting and run a small, efficient refrigerator. In this case, a modest, off-grid photovoltaic system with a battery backup can do the job. Hours of sunshine in the United States in the fall and winter. Hours of sunshine in the United States in the spring and summer.

Article / Updated 03-26-2016

Going solar requires an upfront expense. When you go solar, you get a good payback on your investment, but you do have to put out cash upfront. Banks have become very selective about loaning; in general, you need equity in your home to qualify for a second mortgage, and many people have seen their equity disappear during economic downturns. Another issue to contend with is that the cost of solar varies quite a bit from year to year, so timing is an important concern. Government subsidies play an important role in the net cost of solar equipment, and so politics plays a role in the equation. In the fall of 2008, for example, when the markets were plunging, the federal government increased the Investment Tax Credit from a cap of $2,000 to a straightforward 30 percent of the out-of-pocket price you pay after state rebates and other credits. This made a huge difference in the net cost of solar photovoltaics (PVs), and people who bought their systems prior to the change regretted not having waited for a few more months. Going solar takes work. Making good decisions about solar power can be difficult unless you've done your homework. And not only do you have to do some research, but you also have to work with the equipment itself. Here are some issues to consider: You face some dangers: Active electrical systems can shock you if you don't know what you're doing. Water heating systems can scald you. You're much safer sitting in front of your TV than climbing around installing solar equipment on your roof. You face equipment challenges in freezing weather: Solar water heating panels can freeze up in the winter. You have to pay attention to how they're working. Many new solar thermal heating systems get around the freezing problem by using some form of anti-freeze, but there are still a good number of existing and new systems that still use water exclusively. The anti-freeze systems are more expensive, but not everyone needs one. Be wary of contractors who are more interested in selling you the most expensive system possible than selling you the right system for your needs. It's ultimately up to you to do your homework and decide which system is the best for your application. You're on your own for upkeep and repairs: If you have a big array of solar panels on your roof, it's your problem. If they break, you pay. When they get old, you update. Warranties run for 25 years for solar PV panels, but you may have to pay some labor costs to have warranty work done. At the very least, you have to understand your system so that you'll know when it's not working properly. If a single panel goes out in a solar PV system, for example, the production may suffer to the tune of 25 percent or more. You're the one responsible for determining how your system is working and taking the necessary measures when it's not working properly. Solar panels affect other roof maintenance tasks: If you need a new roof, for example, you have to either pay a contractor to remove and then reinstall the panels once the new roof is in place, or you have to do the work yourself. In general, you can expect to pay a contractor around $1,500 to remove and reinstall panels when you put on a new roof. This estimated price fluctuates quite a bit, depending on the type of roof you have, and how large a solar system you're working with. In addition, while your panels are removed and the roof is being changed, you're not going to be generating any solar power. Consider the condition of your roof before you install solar panels. If you're going to need a new roof in a few years, you may be better off waiting until the new roof is in place before you purchase your solar system.