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An economical home was a must for the Nash family when they decided to build their house back in 1985. After choosing to take on the double-envelope design, they ultimately knew they would be saving a substantial amount of money with year-to-year costs. By 2006, three years after breaking ground, they completed their dream home, an energy-efficient home requiring minimal upkeep.
The double-envelope house is a passive solar energy design, taking the sun's radiant heat and circulating it throughout the house by a natural convection system. The warm air collected from the south-facing windows rises through a 1-foot air chamber between the interior and exterior walls, where it travels to a ridge along the roof. The shaded, north side of the house, cools the air, where it falls through the north air chamber to the basement. The circulating air creates a convection system regulating the temperature throughout the house, which can hold for up to 18 hours regardless of the temperature outside.
Insulation is key in a double-envelope house in order to maintain a constant temperature. You can find cellulose, made from recycled paper treated with borax, a fire retardant, packed into the walls, floors, ceiling joists and rafters in the Nash home. Although it is more costly upfront, cellulose insulation can save up to 50 percent on utility bills as opposed to fiberglass, according to the Department of Energy. Low-E glass Andersen windows are found throughout the house, which offer greater control over heating and cooling costs than regular windows. In addition, 5/8-inch wallboard was used instead of half-inch for its better fire rating and stronger insulation value.
A blower door test was performed on the house to determine its airtightness, which is one of many tests that measure a building’s energy efficiency. Most conventional houses of similar size to the Nash home have airflow measuring around 5,000 cubic feet per minute (cfm). However, the Nash home measured just below 3,000 cfm. The Nashes’ run their home off of propane, which is substantially less per gallon, and as a bonus has a lower carbon dioxide output when compared to oil. When compared to a conventional house run on propane, the Nash family is saving approximately 200-300 gallons of propane per year from airtightness alone, a huge savings in energy cost. Not to mention the positive impact that saving hundreds of gallons of propane has on the environment.
Heating the home during the winter requires little energy due to the 8-by-9-foot fireplace, open on all four sides with glass doors, that is centrally located on the main floor. When needed, radiant heat is used: Water heated by a Burnham high-efficiency boiler runs through tubing under all floors in 10 zones. Zones not in use can be turned off, saving energy and cost compared to heating the entire house.
In building the house, the Nashes planned to make it as maintenance-free as possible. In doing so, they chose to use 50-year roof shingles, Azek trim as opposed to wood trim, and Typar instead of Tyvek as house wrap, which offers greater protection from weather. HardiPlank siding, composed of fiber cement, surrounds the house, offering greater durability and longevity as well as protection from fires and hurricanes.
In addition to an energy-efficient home, the Nash family regularly uses environmentally friendly and energy-saving products. All of the appliances have an energy star rating, reducing energy bills and greenhouse gas emissions. Plunger lights are used in all closets to ensure that lights are not accidentally left on, and dimming lights can be found in most rooms with energy-saving light bulbs to reduce electricity usage. Solar-powered lights are used on the porches and gardens. Central air conditioning is used instead of window units. Low-flow toilets, garbage composter and compacter, and low-emission vehicles are a few more energy-saving products the Nash family uses regularly.
The Nash family believes that they are saving around 50 percent on propane costs and 20 to 30 percent on utility costs as compared to a conventional house. The carbon footprint of the Nash home is certainly less as well.
The upfront cost of some of these energy-saving substitutes may seem high. However, the savings over time has been well worth the investment.
To decrease your annual energy costs visit energizesomers.org for your free home energy assessment and ways that you can make your home more energy-efficient.
Shannon Nash is a member of the Somers Energy Environment Committee, a town-sanctioned committee.
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