We are empty nesters and have decided to build our dream home. What are some of the most energy efficient home construction methods that also offer strength? Severe weather is always a concern in our area.
There are several relatively new home construction methods that are much stronger and more efficient than typical insulated, wood framing built to code. Some of these methods use more than double the insulation value of typical framed walls and can even withstand hurricane- and tornado-force winds.
If you decide on a wood-framed house, use staggered, double-stud walls. This construction method not only provides double the insulation value, but by staggering the wall studs, it minimizes thermal bridges (direct non-insulated heat flow paths from indoors to outdoors through the wood studs).
For a wood-framed home, install rigid foam wall sheathing on the exterior so that all of the lumber’s thermal mass is inside of the insulation envelope. This can be covered with any type of exterior finish, such as siding, brick or stucco. Use a relatively square or circular shape to minimize the exterior wall and roof area. With similar insulation levels, a wall that is twice as big as another will lose about twice as much heat. Generally, square and circular shaped homes resist the forces of storm winds best. This is why animals typically build round nests and dens, which can withstand major storms.
The “stay-in-place” home construction method uses concrete and rigid foam insulation, known as “insulated concrete forms” or ICF; this method is efficient and strengthens the home. The insulation forms, which hold the wet concrete, are not removed, and they provide the insulation and substrate surface for installing the interior and exterior wall coverings.
A similar method uses hollow foam blocks made to fit your home’s plans. The blocks are designed so there is an open cavity throughout the inside. Concrete is pumped into the openings at the top of the walls and flows throughout the blocks, which creates a strong, efficient structure.
Structural insulated panel systems, or SIP, are a subset of standard foam insulated panels, which have a thick foam core sandwiched between two rigid sheets of various materials. The standard panels are often used for the exterior walls to enclose post and beam-framed and steel-framed homes for some of the highest insulation levels possible.
The rigid SIP sheets are unique because they are made of oriented strand board, which creates a strong, highly insulated panel. The panel is self-supporting and does not require additional basic wall framing. Once the panels are attached to the foundation and are connected, the panels support themselves, the floors, ceiling and roof.
Steel-framed construction is an excellent construction method if strength is the goal. Steel is strong. It does not burn or change shape over time as lumber does, and each steel piece is nearly identical. Also, much of the steel used today in home construction is recycled from scrap materials.
From an efficiency standpoint, steel is superior to most other framing materials. Although steel is not a good insulator, its strength allows for thinner studs and wider spacing. This leaves much more room for additional insulation inside the walls and fewer thermal bridges.
Although they may look unusual, a geodesic dome design makes for an efficient and strong home. The most efficient models are constructed with thick foam panels. Concrete is sprayed over the exterior, completely covering the panels and filling the gaps between panels for strength. Another plus – the spherical exterior allows high storm winds to flow smoothly over it without damage.
James Dulley is a nationally syndicated engineering consultant based in Cincinnati. If you have a question about energy use or energy-efficient products, send it to: James Dulley, Electric Consumer, 6906 Royalgreen Drive, Cincinnati, OH 45244; or visit www.dulley.com.