Building An Addition To Your Home
Home additions offer an opportunity to increase the energy efficiency of your home. A properly sealed, well-insulated addition will increase the comfort of your home while costing less in the long run. Extensive information is available on the building envelope-windows, insulation, foundation, structure, and roofing-to help you plan your addition. The Insulation section discusses recommended insulation levels and types of insulation. The Sealing Air And Moisture Leaks section discusses vapor and moisture barriers.
An important option to consider for new additions is to use structural insulated panels (SIPs, also called foam-core panels), which are thick slabs of foam insulation sandwiched between two layers of a structural material such as plywood. They can be used for both walls and ceilings. Although SIPs cost more than traditional building materials, they require less labor to install, so the total cost is roughly the same as stud-framed walls. These structural insulated panels are easy to install and provide high R-value insulation. For more information about SIPs see the Insulation section.
Building an addition also gives you the opportunity to size and place your windows to provide the best light and ventilation. Windows can also be located to provide solar heating in cold climates or avoid solar heating in hot climates. In cold climates, where solar heating is desirable, you should also consider ways to add thermal mass, such as tiles, masonry, or even water-filled walls to the floors and walls near south-facing windows. See section Using Solar In Your Home.
A common approach is to add on a sunspace. Sunspaces can provide useful solar heat to your home, but must be vented in the summer to prevent overheating. For more about sunspaces - See section Sunspace Basics.
Windows also offer an opportunity to add daylighting to your home. If practical, clerestory windows are an effective way to add both light and ventilation to a home. In a clerestory design, one part of the roof is positioned higher than the other, with vertical windows bridging the gap between the two. Clerestory windows can add both light and ventilation to your home.
Figure 7: Home construction incorporating energy efficient design, including design of the framing.
Another obvious approach is to add skylights, but they often cause overheating in the summer and heat loss in the winter. Triangular "roof monitors," with vertical glazing, are a more energy efficient approach. If you are considering installing skylights, see the Skylights For Residences section.
In climates where natural ventilation makes sense, windows need to be located on both the windward and leeward sides of the house. Roughly equivalent-sized openings on both sides of the house will maximize the airflow through the house. The windows should be offset so that the air will circulate through the house rather than blowing directly through it.
Windows can now be designed for a number of purposes. Some windows are designed to let the sun's heat in while insulating against the cold, and are ideal for south-facing windows in cold climates. Others are designed to reject the sun's heat while providing insulation, and are ideal for all windows in hot climates and east- and west-facing windows in moderate climates. See section Buying Windows For Energy Efficiency on for information about which windows you should buy for your location.