Let the Sun Shine In
Energy prices continue to climb, but the good news is that the cost barrier to using green energy is dropping. People are seeking alternative energy sources that are abundant, environmentally sound and cost effective. Technology continues to evolve that helps us channel energy from the sun. The sun’s energy can provide space heating, hot water heating and electricity for lights and appliances.
Solar retrofits are solar energy applications made for an existing home. Since the sun is an endless, environmentally friendly energy source, using it lowers utility bills. When retrofitting, the first stage of the project is to make a record as to how energy is currently used in the home so that the right product may be chosen.
Next, determine how much sun is available. The amount of solar energy available to a home is largely dependent on the time of year and your home’s location. For example, homes in the northern hemisphere need a southeast to southwest orientation to maximize solar energy. You will also want to assess sun availability by looking at what obstructions there are on the south side of the home, such as trees or taller buildings. Solar energy retrofit options may include active and passive solar energy systems, photovoltaic panels, as well as the use of wind and geothermal energy.
Passive solar heating
Passive solar is the most cost-effective approach to maximizing the use of solar energy for your home. Passive solar heating of homes is simple: It occurs when sunlight passes through a window, and no additional equipment is used to harness the energy. Passive solar applications use building elements such as walls, windows, floors and roofs, in addition to exterior building elements. Landscaping can control overheating by providing shade and windbreaks for winter winds. Once heat is collected inside, a well-insulated, airtight “building envelope” helps prevent heat loss and allows the sun to provide more of the heat needed by the house.
Active solar systems
Active solar energy systems use solar collectors and a pump or a fan to distribute the sun’s energy. Active systems are often used for heating water. The collector is a dark color to absorb the sun’s energy and convert it into heat. Some collectors have a glass cover, collecting solar energy all year. Domestic hot water requirements can be met in part by active solar systems. In most cases solar energy will only provide partial water requirements during the winter, but will provide most of the summer season requirements. In most applications the solar energy system is used to preheat water going into a conventional water heater. Outdoor swimming pools can be entirely heated by solar energy systems, eliminating the need entirely for a supplemental heater.
Photovoltaics (solar electricity)
Sunlight converted directly to electricity through solar cells is called photovoltaic (PV) energy. Solar cells come in an assortment of sizes and will produce electricity as long as sunlight shines on them. Solar cells used for electrical generation are really just a more sophisticated version of the solar cells used in calculators and other small household electronic devices. PV cells generate direct current (DC), meaning that to use PV-generated electricity directly, DC appliances and lights must be used. These are most often used in recreational vehicles. In order to use standard household appliances the power must be converted to alternating current (AC), which is the form supplied by utility companies. So, a solar electric system must be designed to convert the power to AC. Although prices have dropped dramatically in recent years, and are still headed downward, a PV system can still be expensive. They are especially cost-effective in remote areas away from power grids, where you might need to generate your own electricity, or in recreational vehicles and boats. If you decide to install a PV system, an electrical load analysis must be done to determine capacity, paying careful attention to household appliances that require electricity.
Geothermal or ground source heat pumps take stored solar energy from the soil and bodies of water. They rely on electricity, but provide the equivalent of three times kilowatt heat for every kilowatt delivered. Heat pumps are reversible, supplying cooling and heating, so they can be useful in areas with significant cooling loads.
Think about conservation
While you’re deciding what the best options are in solar energy for your home, think about conservation as well. Draft-proof your home and upgrade insulation for optimum energy conservation.
Fossil fuels are of finite supply, meaning their supplies will ultimately diminish to the point of becoming too expensive or too environmentally damaging to salvage. Renewable energy resources, however, such as solar energy, are inexhaustible; so start taking steps to use them to your advantage at home today.
Gwen Biasi has been director of marketing and communications for the National Association of the Remodeling Industry (NARI) since July 2002. She has been active in NARI’s consumer education program, helping teach homeowners about the principles of remodeling. www.remodeltoday.com.