Energy Efficient New Homes Save Like Never Before. Understanding How and Why

The term “energy efficiency” has been a homebuilding industry buzzword for quite a while.  Buyers expect new construction to be energy efficient however it is not always quantified and when it is, the “rating” system is not typically common knowledge or fully defined.  In addition to hearing about the energy efficient products, building materials and methods your homebuilder uses in the construction of your home, you might also hear about a HERS rating that your particular home received.

RESNET (The Residential Energy Services Network), the organization behind the  HERS index, is a non-profit founded in 1995 with the purpose of assisting homeowners improve the energy efficiency and performance of their homes.  Nationally recognized HERS is an industry-standard rating that evaluates the energy-efficiency of a home. In the case of a HERS score, the lower the score the better it is. A standard new-construction home will have a HERS rating of 100 so anything lower than 100 is above average.  The certified rater will compare your home to a “reference home” of comparable size and shape.  According to RESNET, factors such as mechanical systems (thermostat, water heating, HVAC); all exterior walls, ceilings, and roofs; floors over unconditioned spaces, attics foundations and crawlspaces; windows, doors, vents and ductwork are taken into account when applying this rating system.

One of the biggest considerations for today’s home buyers is how much and what kind of energy their new homes will use … and at what price. Approximately 20% of the energy consumed in America each year is related to the construction, manufacturing, and operation of residential buildings. However, with awareness and technological advances in building materials and techniques, there is 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 be 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.

 

 

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 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

Doors and windows are obvious weak links in the pursuit to reduce and conserve energy in the home. Homeowners can still enjoy an impressive wall of glass and elegant entries without sacrificing energy efficiency fortunately, due to advances in materials and construction.

Installing steel or fiberglass-insulated exterior doors with 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. Be sure not 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. Today’s newer energy efficient garage doors typically include insulated glass and vinyl weather seals.
When it comes to windows, the measure of thermal performance is known as the U-Factor, which measures the rate of heat transfer and tells you the window’s ability to conduct heat and how well it insulates. The lower the U-factor score, the better the window. A value of 0.2 – 1.20 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. Windows with a low-E coating, which reflects infrared light, are designed to keep the heat inside in winter and outside in the summer.

 

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 numerous 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).

 

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 do not allow it time 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.

Today the minimum SEER rating is 13, with a rating above 16 considered high efficiency. The high efficiency systems (16 SEER or greater) use less energy, which translates to less money spent on energy bills however you need to determine the value difference. For example, a 16 SEER verses a 14 SEER system saves approximately 13% in energy usage.  So, for every $100 spent you would $13 with a 16 SEER system.
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. 

 

Other Considerations

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. Energy efficient appliances incorporate advanced technologies that use up 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 model.

 

A Bright Future

As new products are constantly being created to increase energy efficiency, convenience and safety measures homeowners are reaping the benefits, with reduced costs and healthier and more comfortable living environments. 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 an older home built using older or standard construction practices. Keep that in mind when visiting Charleston area homebuilders, new home neighborhoods and available new construction homes. Because as momentum builds and new technologies are developed, the possibilities are virtually limitless when it comes to energy efficiency.

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