ith the power to implement regulation on a national scale that has the force of law, the U.S. Department of Energy has established strong and worthy goals to improve the energy efficiency for residential building through the 2012 implementation of the proposed International Code Council’s International Energy Conservation Code (IECC). DOE’s immediate goal is 30 percent incremental energy savings compared to the 2006 IECC.
The proposed changes in the IECC have some eye-popping requirements, especially for insulation and new window specs. For example, above-grade wall insulation in Zone 3 (See the map.) would increase from R-13 to R-20. Achieving that R-value will require additional costs and maybe a change in wall-framing techniques. A 2- by 4-inch stud wall with 3 1/2 inches of insulation achieves around R-15, not quite enough for the new IECC. If you didn’t step up to 2- by 6-inch framing, you’d have to beef up your 2- by 4-inch walls with extruded polystyrene rigid foam to meet the new spec, which will require training and quality control of the seam sealing around the foam. Most construction professionals likely will move to 2- by 6-inch stud walls because they can achieve R-20 fairly easily.
Basement wall insulation in Zone 3 would move from no insulation requirement to R-5. In Zones 5 through 8 insulation requirements would increase from R-13 to R-19. Floor insulation in Zones 7 and 8 would move from R-30 to R-38. Ceiling insulation requirements would move from R-30 to R-38 in Zone 3 and from R-38 to R-49 in Zone 5.
For lighting, you don’t have to use CFLs under the proposed IECC, but 50 percent of the lighting in a home would have to be as efficient as CFLs. Sealing leakage limits on ducts would be verified by required testing if the ducts pass through unconditioned space. (That has two motivators: One is to get you to seal ducts, which you should be doing anyway, and the other is to get you to run them through conditioned spaces to begin with.)
The proposed IECC also would demand aggressive window standards. In Zone 1, the U-factor would move from U-1.2 to U-0.5. In Zone 4, the U-factor would decrease from U-0.4 to 0.35. The U-factor expresses the rate of heat loss. The lower the U-factor, the better the window is at insulating. In areas where homeowners spend most of their energy dollars on heating, the U-factor is the rating that should be considered first.
Solar Heat Gain Coefficient (SHGC) measures the fraction of solar energy admitted by a window and tells you how well the product blocks heat caused by sunlight (radiant heat). The lower the SHGC, the less solar heat the window transmits into the living space. SHGC is measured on a scale of 0 to 1; values typically range from 0.25 to 0.8. In areas where homeowners spend most of their energy dollars on cooling, the SHGC is the rating that should be considered first. With the proposed IECC changes, in Zones 1, 2 and 3, the required SHGC would move from 0.4 to 0.3.
There invariably will be complaints about the added cost of compliance (time, materials, training) and inspections, as well as how these costs will be eventually passed on to the homeowner. However, even if costs are passed on to owners (who end up owning a dramatically more efficient house where the benefits last for decades), don’t we all benefit from the regulation?