The fundamentals of energy efficiency; Jim Hackler explores the latest bright ideas for saving money and the Earth's resources.
The bigger picture is energy inefficient homes contribute to pollution. The electricity, fossil fuels and other energy sources our homes consume contribute to global warming, acid rain, smog, and other serious environmental problems. Wasted energy needlessly pollutes the environment. The Southface Energy Institute in Atlanta, Georgia was formed in 1978 to address this problem through education and research in energy, building science, and environmental technologies. One of the non-profit organization's most successful new programs is EarthCraft House, one of the fastest growing green home building programs in America. EarthCraft House is a partnership with the Greater Atlanta Home Builders association that trains builders to construct energy efficient, environmentally friendly, and more healthful homes.
Energy efficiency means quality and affordability
At the core of the EarthCraft House program is energy efficiency. Making a home more energy efficient offers benefits such as increased comfort, reduced noise and greater fire safety. Energy efficient homes also experience less condensation, which protects framing, windows and finish materials. Better control of moisture and temperature means less movement of materials that reduces floor squeaks and drywall cracks. While some energy features add to construction costs, others can reduce costs. For example, increasing insulation and sealing air leaks reduce heating and cooling needs, allowing the use of smaller equipment and ductwork. The savings on the mechanical systems can pay for the increased cost of insulation and air sealing. Energy efficient framing techniques can reduce lumber costs over fifteen percent and prevent mold growth in outside walls and ceilings.
What makes a home energy efficient? Increasing energy efficiency does not have to add greatly to construction costs, nor require special materials or construction skills. However, cutting energy waste; ensuring occupant health, safety, and comfort; and improving building durability does require careful planning, training, and quality control during construction.
Poor design and installation of heating, ventilation, and air conditioning (HVAC) equipment commonly increases energy costs ten to thirty percent. This wastes money and can endanger the health of families. Proper design and installation of HVAC equipment is usually the top priority for cutting energy bills.
Equipment that is too big (excess capacity) costs more to buy and operate, and leads to poor comfort, excess noise, and greater pollution. Do not allow rules of thumb, such as so much heating or cooling per square foot of living area, to be used to determine equipment size. To size equipment, require exact calculations that consider insulation levels, window type and orientation, and air sealing measures. Calculating equipment size should take less than an hour for most home designs, and will prevent the purchase of costly, oversized equipment and provide significant savings to homeowners for years to come.
Equipment efficiency and energy source
The professional that calculates the size of the HVAC equipment should also be able to determine estimated operating costs for various equipment efficiencies and energy sources. Smaller, high efficiency models may not cost considerably more than standard equipment. While future prices can vary, it is important to consider the cost of energy sources when selecting equipment. Saving a few dollars on equipment is no bargain if families will pay hundreds more because the equipment uses an expensive energy source.
Today's homes need controlled ventilation. Relying on cracks in the building envelope to provide proper ventilation endangers health and safety. For most home designs, simple, controlled ventilation systems can be economical to install and operate. In temperate climates, many affordable housing providers rely on upgraded bath fans and kitchen range hoods ducted to the outside. In more severe climates, heat recovery ventilation and other techniques may be practical.
Improving the efficiency of ductwork is the single most important energy measure for homes. Poor ductwork can area, not in attics or crawl spaces. Do not use building cavities, such as closet returns, as part of the duct system. Make sure all joints in the ductwork are sealed permanently with mastic, a thick paste that provides a durable seal for all types of duct. Duct tape does not provide an effective seal for ductwork. After ducts are sealed, ensure they have adequate insulation.
Excess air leakage in homes can increase heating and cooling bills by 30 percent and reduce fire safety. Although windows, doors and outside walls contribute to air leakage, the biggest holes are usually hidden from view and connect the house to the attic, crawl space, or basement. Reducing air leakage
[Text incomplete in original source.] costs less than $200 for all average home and is required by the Model Energy Code.
Houses will not get the full benefits of their insulation if it is installed poorly. Gaps and compressed areas in the insulation can cut savings over twenty-five percent. Poor installation also leads to condensation and comfort problems. The Model Energy Code sets minimum requirements for insulation levels, but it is often cost-effective to exceed these levels.
A family of four can spend more for hot water than heating or cooling. Consider the cost of various fuels for heating water as well as the efficiency of the water heater. Simple conservation measures, such as low-flow showerheads, tank insulation jackets, and convection traps in hot and cold water lines pay back quickly. Replacing inefficient plumbing fixtures in older homes can save families hundreds of dollars.
While energy efficient windows cost more than standard models, they can cut energy bills significantly and lower other construction costs. High performance windows can reduce heating and cooling needs enough to permit smaller, and cheaper, HVAC equipment and ductwork. The use of energy efficient windows greatly improves comfort by increasing surface temperatures and cutting drafts. They also reduce condensation that protects building materials and reduces mold growth.
Energy efficient lighting saves on electric bills, helps keep the home cooler by reducing waste heat, and lasts longer. Specify. compact or tubular fluorescents for interior fixtures that will be on for 4 hours or more each day, usually kitchens, hallways, and some living areas. Energy efficient fluorescents provide excellent light quality, and are long lasting. Their extra cost is repaid in energy savings. Exterior security lighting can cost hundreds of dollars a year to operate if it is not energy efficient. Install only compact fluorescent or high pressure sodium fixtures for security lighting and consider motion sensors or photocells to operate lights automatically.
Appliance energy use is usually greatest for refrigerators, clothes washers and dryers, and dishwashers. Remember, the true cost of an appliance is the purchase price plus the cost for energy and water for operation. Providing a cheap, inefficient appliance will waste the money of low-income families for years to come. Federal law requires that most appliances have Energy Guide tags that compare estimated operating costs between energy efficient and standard models.
Jim Hackler is the EarthCraft House director at the Southface Energy Institute. For more detailed information on Southface and its EarthCraft House program, go to www.southface.org and www.earthcrafthouse.com.
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|Publication:||New Life Journal|
|Date:||Apr 1, 2002|
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