Homes That Save Energy Like Never Before
Each year, approximately 20% of the energy consumed in America is related to the construction, manufacturing and operation of residential buildings. However, through advances in awareness, building materials and techniques, there’s a real possibility of reducing home energy usage by up to 30% for every homeowner.
Efficient By Design
Constructing an energy-efficient home begins well before a builder even lays the foundation. Energy-saving features should be considered during the design process, alongside the countless other factors that ultimately determine the final plan. For example, electrical lighting needs can be reduced by strategically placing windows and skylights that allow in enough sunlight to reduce the need for turning on lights or lamps during the day. Using extended overhangs or shutters can selectively allow natural light and warmth in during cold weather, while blocking it during the summer.
A pre-construction must is carefully analyzing the homesite and the local climate to determine which building orientation would best enhance the home’s energy performance. To take advantage of free solar energy you may want to place more glass on the south wall since the winter sun rises south of east and sets south of west. This same orientation will help minimize the summer heat. On the east and west sides you may consider locating a garage, storage room, or screened porch, because of valuable summertime shading. Preserving trees in these areas will help as well. To further cut cooling costs, plan on taking advantage of prevailing wind patterns, for cross-ventilation with your operable windows.
Another vital step in the design process is to have a comprehensive plan for efficiently heating, cooling, regulating moisture and ensuring adequate ventilation. Luckily, many architects, designers and builders are energy-minded and can assist homebuyers with these details.
Getting With The Program
The ENERGY STAR program is a joint venture of the U.S. Environmental Protection Agency and the U.S. Department of Energy, designed to promote energy efficiency in the home. Guidelines set by the U.S. Environmental Protection Agency state that, to qualify for the ENERGY STAR designation, a home must be at least 15% more energy-efficient than homes built to the 2004 International Residential Code (IRC). Additional energy-saving features and ENERGY STAR appliances may also be included, making the home up to 30% more efficient than standard homes. The Department of Energy estimates that, through the ENERGY STAR program, Americans reduced their home energy use enough in 2006 alone to save $14 billion on utility bills.
EarthCraft House™ is a residential green building program of the Greater Atlanta Home Builders Association in partnership with Southface. This program has been utilized in the Charleston area and serves as a blueprint for energy- and resource-efficient homes. EarthCraft-certified homes are not only ENERGY STAR-rated; they have additional guidelines that promote even more efficiency — sometimes as much as 30% more. (See Web addresses below for additional information.)
The “R” Factor
Preserving conditioned air is a prime component of reducing energy usage, since heating and cooling units account for 50% to 70% of the energy used in average American homes. Properly insulated attics (inadequate attic insulation is a potential source of almost half of a home’s heat loss), walls, floors and crawlspaces all create an energy-conserving blanket around your home. The higher a material’s ability to resist heat flow (R-value), the more insulating power it has. Different R-values are recommended for walls, attics, basements and crawlspaces, depending on your home’s location.
In addition to traditional fiberglass batt and blown cellulose, there are several new options for achieving a higher insulation R-value. Icynene is water-blown foam that expands to 100 times its initial size and hardens to form a complete barrier. Reflective, or radiant barrier, insulation is metallic foil (usually aluminum) intended to block radiant heat transfer across open spaces, and is often used in attics and floors.
Structural insulated panels (SIPs), often used for wall construction, are made from oriented strand board (OSB) sandwiched around an insulating core of expanded polystyrene foam (EPS). These panels are available in a variety of thicknesses and can be as large as eight feet by 24 feet. In addition to SIPs is autoclaved aerated concrete (AAC), which consists of pre-cast panels of lightweight concrete. AAC is manufactured through a process combining sand, cement, lime, water and aluminum powder. Millions of tiny air bubbles are embedded in the material, which make the panels both lightweight and highly effective insulation. Special adhesives used at the joints create a seamless, monolithic thermal barrier with constant R-values.
Windows and Doors
Windows and doors are obvious weak links in the quest to conserve energy in the home. Fortunately, due to advances in materials and construction, homeowners can still enjoy an impressive wall of glass and elegant entries without sacrificing energy efficiency.
When it comes to windows, the measure of thermal performance is known as the U-value, which rates the window’s ability to conduct heat. The lower the U-factor score, the better the window. A value of 0.4 or less is what The U.S. Department of Energy recommends. The process of double glazing forms an insulating air pocket of 1/4 to 1 inch between the glass panes. In high-efficiency windows, this space is often filled with non-conducting gases such as argon or krypton. Windows with a low-E coating, which reflects infrared light, are designed to keep the heat inside in winter and outside in the summer.
Installing steel or fiberglass-insulated exterior doors that have an insulation value of R-5.9 or greater is key. (A lower R-value door can be used in conjunction with a storm door.) Like your windows, all sidelights and glass panels should be of high-efficiency construction and materials. And don’t forget the garage doors, especially if there is living space above, or if the garage is attached to the house. There are products and materials that can address the loss of energy from this area. In fact, some of the newer garage doors, with their insulated glass and vinyl weather seals, are so energy-efficient that they qualify for a federal tax credit.
The Envelope, Please
The key to maximizing a home’s energy efficiency is sealing the building “envelope.” Between 25% and 40% of lost energy used for heating and cooling in a typical home is due to leaked air. Joints between building materials, gaps around doors and windows, and openings for plumbing, wiring and ducts are usually the culprits. There are a number of products available for air sealing, including caulks, foams, weather stripping, gaskets and door sweeps.
Leaks and poorly sealed connections in the duct system account for 20% of air lost in a typical home. Tightly sealing exposed ducts in attics, basements, crawlspaces, and garages is a must. You can save a significant amount of energy by insulating ducts that run through spaces that get hot in summer or cold in winter (like attics, garages or crawlspaces).
Every ENERGY STAR and EarthCraft home is tested for all of the above and must pass those tests in order to be deemed certified.
Finding Your Comfort Zone
Obtaining and properly installing the correct heating and air conditioning equipment is essential to getting the most from your new system. An oversized unit will operate in short run cycles that don’t allow it to reach efficient operation and remove humidity from the air. An undersized unit will work longer and harder and still may not sufficiently heat or cool the home.
Always consider ENERGY STAR HVAC systems. Properly installed, these high-efficiency units can save up to 20% on heating and cooling costs. Also, a programmable thermostat can save about $150 per year in energy costs and is ideal for people who are away from home during set periods of time throughout the week.
When selecting an appliance, remember that it actually has two price tags: what you pay for the appliance itself, and what you pay for the energy and water it uses. Qualified ENERGY STAR appliances incorporate advanced technologies that use 10% to 50% less energy and water than standard models. The amount of money you save on utility bills can more than make up for the cost of a more expensive but more efficient ENERGY STAR model.
A Bright Future
As new products are constantly being created to increase energy efficiency, homeowners are reaping the benefits, with reduced costs and healthier, more comfortable living environments, as well as helping the environment. Since today’s home buyers want to get the most house for their money, a durable, energy-efficient home can actually be more economical and affordable in the long run — even if the initial asking price is a bit higher than that of a home built using standard construction practices. As momentum builds and new technologies are developed, the possibilities are virtually limitless when it comes to energy efficiency.
For more information about increasing your home’s energy efficiency, please visit the following: