4. Super-Insulate the Building Envelope
- Use advanced framing techniques to save wood and allow space for insulation.
- Use double 2×4″ walls, with off-set studs on 24″ centers, spaced 5″ apart, to form a foot thick wall cavity in northern climates. In more moderate climates, double walls with an 8″ or 9″ cavity may suffice, depending on the R-value that needs to be met. View the Double Wall Construction and Blown –in Insulation video.
- Use raised-heel trusses to provide ample space for ceiling insulation. View the Raised-Heel Truss video.
- In colder, northern climates, fill walls and floor with dense-pack fiberglass or cellulose to get to R-50, and blow in loose-pack ceiling insulation to R-60. Lower R-values may suffice in warmer climates.
- Always ask for bids for R-value rather than thickness of insulation.
- Utilize energy modeling to adjust the above R-values higher or lower for local climate and weather conditions.
Twelve Steps to Affordable Zero Energy Home Construction