Energy Efficiency

As the "about me" section indicates we are trying to do some things with the design of the house around energy efficiency and generally being "green." The neighborhood restrictions keep us from doing a modular home (not a trailer...modular...two entirely different things) so we have to site build. However, there is more than one way to site build. The most popular way is technically called "balloon framing" and is the standard 2x4 construction we are all used to seeing.

It turns out that there is more than one way to do balloon framing however. Most builders use 2x4 construction as I mentioned before and fill in between the framing members with fiberglass insulation. For extra insulation you can go up to a 2x6 wall and get a thicker fiberglass bat. However, now matter how well you place that fiberglass in there will always be voids and gaps. Additionally, every framing member functions as a thermal bridge. This means your framing is working against your insulation! Another technique is to use a 2x6 sill plate and alternate 2x4 framing members one against the inside edge and the next against the outside edge. Then when placing insulation you weave it in between your studs and have fewer gaps.

In the end we decided that traditional stick framing simply wasn't very efficient. We are using structural insulated panels (SIPS). These panels are made by taking two sheets of OSB (oriented strand board) plywood and layering EPS (expanded polystyrene) insulation in between. Most manufacturers use a high pressure glueing system to join the EPS to the OSB. A 2x4 SIPS wall is actually more thermally efficient than a 2x6 stick framed wall with fiberglass bats. The panels are generally four feet wide and the EPS is recessed to recieve a spline that is glued into the recess. The panel is then nailed to the sill plate and the spline. The spline is simply a 2x4 or 2x6 depending on the thickness of panel you choose.

These panels help create a very tight housing envelope. Because it also performs very close to its "R" rating (a rating for insulation level) generally you can use a smaller HVAC system than a traditional stick frame house. So you hold in your heat and cold better and you use less energy getting the temperature where you want it to begin with!