Bowdoinham Area Sustainable Energy Group
in
Contact:
Peter Feeney
Phone / Fax:
666-8907
Hours:
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Solar Power for Your Home
Brought to you by the Bowdoinham Area Sustainable Energy Group
Solar energy is our most abundant and readily available renewable energy resource. Harvesting the solar energy directly can take a variety of forms. Passive solar design of your home is a cheap and easy way to capture this energy. Active solar energy systems are the next step in this energy capture process. Active solar systems are typically solar domestic hot water, solar space heating, and solar photovoltaic systems. The Bowdoinham Area Sustainable Energy (BASE) group hosted a talk with John Capron from Revision Energy in February and learned more about these systems. Revision Energy, formally operating under the name of “EnergyWorks,” is the largest installer of solar energy systems in Maine, with offices in Liberty and Portland.
A solar domestic hot water system (solar DHW) installed here in Maine is typically an indirect system, in which an anti-freeze is actually the fluid that is being heated in a solar array as opposed to water. The typical solar DHW system in Maine has a series of collectors that heat the anti-freeze fluid. The fluid is heated through a series of collectors, then pumped through insulated piping to a lower coil inside an insulated reservoir tank in the basement. The coil releases its heat to the domestic hot water within the tank. An upper heating coil in the reservoir tank is typically connected to a supplemental heating source such as a zone from your furnace or an electric coil. When there is insufficient heat for the anti-freeze, as would occur on a very cold, cloudy day, the supplemental heat will cut in and heat the domestic hot water if it is required.
Solar domestic hot water systems offer a homeowner the most “bang for the buck." Apparently, our state and federal governments agree because there is a combination of incentive and tax credit programs available to make these systems more affordable. The state offers a thirty percent rebate on the cost of systems installed up to $2,500 for residential homeowners. The financial limit amount increases to $3,000 if your home is energy star rated. Commercial installations get a thirty-five percent rebate up $10,500. The federal government offers a thirty percent tax credit, capped at $2,000 for residential systems, uncapped for commercial systems. These two programs combined will reduce the end-cost to a residential homeowner by approximately forty percent. The initial cost of a typical solar domestic hot water system is approximately $9,000. After state rebates and federal tax incentives, that cost is reduced to approximately $5,500. This is still a lot of money, but the system should pay for itself in only four to six years.
A solar thermal space heating system is similar to a domestic hot water system in that the heat is absorbed from the sun through the same process of circulating an anti-freeze solution through a collector array. Solar thermal space heating systems are best used with radiant floor heating rather than baseboard heating because the temperature of the fluid is in ninety to one hundred twenty degree Fahrenheit range rather than the one hundred sixty to one hundred eighty degree range required for baseboard heat.
Solar photovoltaic systems are silicon-based electric cells that generate a direct current like a battery, only without the chemicals found in a battery. Though the cost of a solar PV system is quite high, efficiencies in manufacturing are beginning to bring down the price. Solar PV is a viable alternative for electrical energy production, but solar thermal systems are more cost effective.
Considering the cost of actively collecting energy from the sun, we should all remember that reducing consumption through conservation and new technologies is the least expensive step toward sustainable energy. After all conservation measures have been taken, the solar systems presented by Revision Energy are exciting options, with solar domestic hot water at the top of the list because of its relatively short amount of time that the installation cost is recouped. For more information on the Bowdoinham Area Sustainable Energy (BASE) group, or to be included on the group's e-mail list, contact Pete Feeney at 666-8907 (peterfeeney@suscom-maine.net) or Ben Long at 666-8859 (benhlong@suscom-maine.net).
STAYING WARM - AND SAVING MONEY WHILE YOU DO IT
SOME BASIC INFORMATION ON SEALING AND INSULATING YOUR HOME
The following information is provided by the Bowdoinham Area Sustainable Energy Group. This information was gathered from one of our regular meetings in which a contractor, Charlie Huntington from I&S Insulation of Newcastle, gave a brief presentation on residential building science. For more information about the group, or to be included on the group's e-mail list, contact Pete Feeney at 666-8907 (peterfeeney@suscom-maine.net) or Ben Long at 666-8859 (benhlong@suscom-maine.net).
For insulating your home, there are three basic alternatives and they are listed in order of cost: 1) fiberglass insulation, 2) cellulose insulation, and 3) spray foam insulation. Within these three areas, there is some variation in how these products can be applied. For fiberglass insulation, it can beinstalled in the conventional batt method or it can also be sprayed into the framing. Cellulose insulation is typically applied with a blower. It can be applied loosely in attic spaces, but its use in walls is accomplished by a dense packing method (more on this in a moment). For spray foam insulation, as the name implies, it is applied by spraying. It is the best way to seal a new home, but it also the most expensive method.
DENSE-PACKED CELLULOSE INSULATION
I&S Insulation recommends the cellulose dense-packed method and states that it gives you the most "bang for your buck" for insulating your home. Cellulose insulation is a green product in that over eighty percent of it comes from recycled newspaper. The newspaper is treated with boric acid (a mild additive - borax soap basically) which makes it highly fire resistant, mold resistant, and insect/rodent repellant. The dense packing of cellulose is accomplished by securing a membrane on the inside of the framing and then blowing the insulation between the membrane and the outer wall using a blower until a density of at least 3 pounds per cubic foot is achieved. This high density application contributes to a very tight building envelope with a high R-value. This dense packing method can also be applied to existing homes by blowing it into the walls.
SEALING YOUR HOME
An important distinction was made between insulation and building envelope tightness. You may have a tremendous amount of insulation in your home, but if your home is not sealed properly to prevent both cold air infiltration and warm air exfiltration, you are wasting energy to heat your home. This is most evident with fiberglass insulation because fiberglass allows air to pass through it. The warmer the air, the more moisture it can hold. Warm moist air from your home will rise. Properly sealing your attic space is critical in minimizing the loss of this warm air. If the attic space is not sealed, the warm air will pass up through the insulation and out of your home. So even if you choose not to add insulation, one of the best things you can do is head to your attic and seal gaps around your toilet vents, chimneys, recessed lighting, etc. Once you have done that, then you may want to consider adding more insulation. Otherwise, adding more insulation in your attic without properly sealing it could lead to condensation and damage due to rot. The more insulation you have in your attic, the colder it will be, and the more likely thatthe moisture in the escaping air will condense out within the attic space.
THE BUILDING ENVELOPE - HOW TIGHT TO MAKE YOUR HOUSE
Another misconception that was discussed was how "tight" to make your home as far as sealing the building envelope. Charlie coined the phrase, "Build it tight and then ventilate right." In short, make your building envelope as tight as you or your contractor can possibly make it to minimize the energy consumption to heat your home. Once you have the building envelope sealed, have a blower door test performed on your home by an energy auditing company. The blower door test basically applies a negative pressure to your home with the use of a specialized fan and measuring equipment. Your home should be designed to allow a minimum amount of air changes per hour. If the building is too tight based on blower door test results, the correct amount of ventilation can be added to your home to give the home the correct amount of air changes per hour without any additional loss. This ventilation can be achieved in a variety of ways. The use of an air exchanger is popular in that it is a ventilator that will heat the incoming air with the warm air leaving. This reduces the energy required to heat the cold air being sucked into your home.
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