Building an energy-efficient home is easier than one might think. Doing so requires additional planning and effort on the front end before breaking ground. That's where Doug Rye and the Electric Cooperatives of Arkansas can assist.
“Any home can be built in a more energy efficient manner,” said Doug Rye, a well-known energy efficiency expert who is a consultant for the Electric Cooperatives of Arkansas’ model home program. "If you are trying to educate people, why don't you build a house that they can see, touch, and feel?"
So the Electric Cooperatives of Arkansas teamed up with Rye in 1997 to build a series of energy-efficient homes across Arkansas. The homes incorporate proven energy efficiency measures, components and appliances. Each home is guaranteed not to exceed a predicted amount in heating and cooling costs.
How does the program work? First, the builder, contractors and homeowner sign a contract agreeing to comply with installation and construction of required components and measures. They also agree to follow program guidelines. A hold harmless form is also required. Energy efficiency experts from a local electric cooperative and statewide organization supervise and monitor each component through the entire construction process. Photography and video are utilized to document construction and installation. The homeowner also agrees to allow the sponsoring electric cooperative to host a public open house for one weekend. Also, Doug Rye will host his weekly radio show “Home Remedies” from the home and field questions from visitors.
According to model home program coordinator Bret Curry, the model home program is perfect for educating electric cooperative members about energy efficiency.
“We also teach members that anyone can build any new home to perform energy efficiently, with exceptional comfort and with very reasonable utility bills," Curry said.
Contact the Electric Cooperatives of Arkansas for a complete packet of energy efficiency construction literature at firstname.lastname@example.org.
Established components and guidelines are utilized to ensure that a model home meets the highest standards of energy efficiency. It is far more cost-effective to incorporate energy efficiency into a new home than to retrofit later.
When building a new home, remember the law of thermodynamics, which says heat moves from high temperature regions to low temperature regions. In other words, heat always moves to cold. So in Arkansas, the hot summer temperatures always attempt to gain access to an air-conditioned home. Conversely, the warmed air in a home tries to escape during the winter.
The following components and measures create obstacles and dramatically impede the law of thermodynamics. The effect equates to lower utility bills and a more comfortable home.
If the foundation is a concrete slab, insulate perimeter of slab using 1” extruded polystyrene foam board. Place it between the outer edges of the slab and foundation. It should extend vertically 4 inches and 24 inches horizontally under the edge of the slab.
If the foundation has a crawl space, insulate inside of stem wall with foam or cellulose, a heavy plastic or vinyl ground cover should be used as a moisture barrier, and close all vents. If this method is used to insulate a crawl space, it is critical that the elevation of the ground in the crawl space be higher than the ground elevation outside the crawl space. It is also critical there are no standing water or moisture problems within the crawl space. Insulating the slab keeps its temperature similar to that of the conditioned space. Insulating and sealing the crawl space stops sharp contrasts in temperature and humidity. It’s similar to an insulated basement.
Hot water lines in a concrete slab must be insulated with foam tubing or equal. A concrete slab acts as a heat-sink and will cause the heat from non-insulated hot water lines to quickly dissipate into the slab. Remember, a concrete slab is nearly the same temperature of the ground, unless of course it’s insulated. A homeowner spends money to heat water; keep it hot and ready for use by insulating properly.
Energy experts have determined standard 2” x 4” framing and proper insulation may be used in high efficiency home construction. However, conventional corner and tee framing are prohibited. Past construction methods left corners and partition walls without proper insulation, causing moisture, mold and mildew to develop. Corners and tees are areas that can affect the R-value of the exterior wall. The framing illustration shown is required to maximize insulation value in those areas. Framing energy corners and tees requires less lumber and does not diminish supporting strength.
An important measure to achieve energy efficiency is reducing air infiltration. Inexpensive caulking and foam sealants can seal air voids. Begin by using expanding foam to seal electrical and plumbing penetrations made in the top and bottom plates, and the inner and outer walls. On outside walls, caulk joints where two boards meet including top and bottom plates. IF IN DOUBT, CAULK IT. Caulking should be performed from the inside of the dwelling with a good silicon-based latex caulk. When caulking around doors and window jambs, use non-expanding foam. Expanding foam may exert pressure on the window or door frame and cause damage.
Windows should be constructed from wood or vinyl, double or triple glazed, and with low-e glass. A U-factor and solar heat gain coefficient (SHGC) of .31 or lower are recommended. Look for windows with a decal indicating they were tested by the (NFRC) National Fenestration Rating Council. Low-e windows reflect heat back into the conditioned area and are great in the winter. U-factor is the inverse of R-value. So, a lower U-factor is good and indicates the window has a low heat loss rate. SHGC is a measure for the amount of solar radiation that passes through a window. Hence a lower SHGC is better for the southern climate.
Insulation is intended to retard the flow of heat from warmer areas to colder areas. Proper insulation pays for itself by reducing the equipment size required to heat and cool the home. It also reduces overall heating and cooling costs. Cellulose or foam insulation is required. Fiberglass is prohibited. An R-45 is required for the attic. Currently, cellulose insulation is far less costly that foam insulation. Cellulose insulation made with recycled newspaper began in the 1950s and came into general use in the U.S. during the 1970s. Cellulose insulation by its very nature is an environmentally friendly green product. It’s treated with borate to provide the highest Class I fire retardant rating. Also, cellulose is insect resistant and provides noise reduction. Damp spray applied cellulose is used for applying cellulose to new wall construction. The only difference is the addition of a very small amount of water to the cellulose while spraying. In many cases the contractor also mixes in a very small percentage of adhesive or activates a dry adhesive present in the cellulose. Wet spray allows application without the need for a temporary retainer. In addition, wet spray allows for an even better seal of the insulated cavity against air infiltration and eliminates settling problems. Damp-spray installation requires that the wall be allowed to dry for a minimum of 24 hours (or until maximum of 25 percent moisture is reached) before being covered.
“House breathing” is a term that has been around for decades. The thought is a breathing house creates a better living environment. However, it’s quite the contrary. House breathing is actually uncontrolled air infiltration that can rob energy savings and comfort from your home. Furthermore, excessive air infiltration introduces dust, dirt, pollen, humidity and other allergens into your home. Not to mention the heating and cooling unit is working overtime to keep the living areas comfortable. No home can be built air-tight nor should it be. Following these building guidelines enables the proper construction with acceptable natural air changes per hour.
Metal ductwork is required. Each joint must be sealed with duct mastic or mastic tape. Flex duct is prohibited. If the ductwork is in the attic, when possible lay the ductwork on the ceiling joists and cover as much as possible with insulation. Installation in the crawlspace is acceptable. Rigid PVC ductwork is acceptable in concrete slab application. Sealing the ductwork properly keeps it from becoming disconnected and assures virtually 100 percent of the conditioned air stays inside the conditioned building envelope. The number one area your energy dollars are spent is for heating and cooling. Keep the conditioned air inside the duct and your building envelope by sealing them properly.
Radiant barrier roof decking is required. The shiny foil backing is installed facing downward or toward the attic. Face the shiny side outward for gable applications. During the hottest months in Arkansas, a felt-shingled roof can reach temperatures in excess of 160 degrees. That is why an attic is unbearable in the summertime. However, radiant barrier roof decking can reduce internal attic temperatures up to 50 degrees.
If recessed lights are used, they must be insulated contact air tight (ICAT) rated fixtures. Using ICAT fixtures does not enable air infiltration and they can be covered with insulation.
Compact fluorescent lamps (CFL) are recommended over standard incandescent bulbs. CFLs last up to 10 times longer than their counterpart. They also cost 75 percent less to operate and produces less heat. It surprises some consumers to learn that the energy required for standard incandescent bulbs produces 90 percent heat and 10 percent light. Imagine a hot summer day with a house full of incandescent bulbs turned on at the same time. This represents a “heat gain.” During the summer, heat from Mother Nature is constantly trying to get into an air-conditioned house. Then to add insult to injury, the heat gain from the incandescent bulbs, appliances, people, pets, cooking and other sources cause the air-conditioner to work overtime. Installing CFLs can dramatically reduce additional heat gain into a home.
Ridge vents with continuous soffit venting are required where applicable. Ventilating the attic space creates natural convective air flow and allows moist air to escape. A properly ventilated attic will not enable the formation of mold or moisture. Plus the attic stays cooler during the summer months.
The high energy-efficient Marathon water heater manufactured by Rheem is required. The Marathon has a lifetime warranted tank and is guaranteed to never leak or rust as long as a person owns their home. Units have an energy factor of .91 or higher. Contact your local electric cooperative to purchase a unit. For additional details, visit www.marathonheaters.com.
The home must be heated and cooled with an air-source heat pump or geothermal system. The minimum SEER rating for the heat pump is 13 SEER. A Manual-J load calculation must be conducted to determine the amount of heating and cooling required for the home.
To learn more about geothermal heating and cooling and the installation process, click here.
Ductwork sizing is important to obtain the proper cubic feet of supply air for each room. Construction software parameters for air infiltration must be set to “Best” to assure proper sizing. The return air must have two square feet for each ton of heating and cooling. For instance, a three-ton unit must have six square feet of return air. If there is not enough area available for properly sized return air, two return air systems may be utilized. A heating and cooling system can only supply the same amount of air that can be obtained from the return.
Supply air registers should be located toward the outside walls, and air should wash the outside walls when the unit is running.
Programmable or set-back thermostats are not required. Homeowners should tell the heating and cooling contractor what temperature they are most comfortable during the winter and summer. Doing so enables the correct design temperature during the Manual-J load calculation. Also, when using air or ground-source heat pumps, set the thermostat and refrain from making adjustments. Simply set it to the desired temperature. Do not locate the thermostat on outer walls, near doors and windows, and away from major appliances. Consult a heating and air contractor for additional information.
The garage walls and ceiling must be insulated. The garage door must also be insulated.
Cook-tops must be vented to the exterior of the home and not into the attic or living space. Doing so vents latent heat/moisture outside the conditioned air space. Venting into the living space causes the cooling unit to work harder in order to remove the humidity. Venting into the attic can cause moisture, mildew or mold issues if the home has inadequate ventilation.
Humidity-Sensing exhaust fans must be installed in bathrooms to remove excess moisture. Venting to the outside is the preferred method. Excess moisture inside the conditioned air space can lead to the formation of mildew and mold.
The sponsoring electric cooperative may meter electric consumption of the Marathon water heater and heating and cooling system separately. Doing so enables the utility to monitor consumption and the guaranteed performance.