Below is a brief review of the major types of insulation, from simplest to more complex and from least cost to most. Remember: As we improve our thermal enclosure, we also can reduce the complexity and size of our heating and cooling systems. This reduces first cost and saves on long-term operating cost. In a Life Cycle Assessment of this approach, higher-performing insulation will result in the best choice.
BATTS: If you are considering using batt insulation, select high-density batts with a higher insulating value. Remember that careful installation is vital; too often, poor installation techniques, design complexities, framing challenges, and other factors can cause gaps and voids between and around batts, seriously deteriorating their performance over time.
LOOSE-FILL SPRAY: Fibrous spray insulations are an innovative use of some traditional blown insulation products or recycled materials all using low-toxicity binders. These loose-fill solutions can be sprayed when mixed with moisture or binding agents. Some are intended for filling cavities while others are designed to adhere to exposed surfaces such as joists and floor pans. Correct installation requires careful management of moisture content and carefully watching the installed density. Cellulose-based solutions such as Green Fiber’s Cocoon System are made from recycled newspaper and incorporate EPA-registered fungicide. Some companies are fine-tuning their blends to emphasize fireproofing and acoustical attenuation along with energy-saving insulation.
SPRAY FOAM: Foam-in-place technology is playing an increasingly important role in establishing a tight building envelope. Historically, most of these products utilized high-density, closed-cell polyurethanes, which involved exposure to potentially hazardous chemicals during application. Today they usually flash their VOCs quickly and become fairly innocuous after a short time. Closed-cell foams are very effective at managing air leakage and can have high R-values of up to 7 per inch. Unfortunately, most still use HCFCs as blowing agents (with some notable exceptions such as SuperGreen).
But there are now a number of non-ozone-depleting, open-cell products available. These open-cell foams have lower R-values, but manufacturing them requires fewer hydrocarbon resources. Some are managing to replace petrochemicals with bio-based raw materials. The Icynene insulation system has a very long track record and is the most widely installed open-cell foam used today. BioBased 501 is a polyurethane foam with a soybean-oil base that uses carbon dioxide as a blowing agent. These products seem to be gaining rapid acceptance as builders look for alternatives to traditional insulation.
SIPS: An alternative to installing traditional insulation, Structural Insulated Panels (SIPs) are typically constructed of OSB sandwiching a foam core. Pros appreciate the ease of assembly and the improved performance SIPs can provide. Typical wall system R-values are from 22 to 30; these walls actually perform remarkably well as they have less framing materials thus reducing thermal bridging. This would eliminate the conventional framing approach and provide a faster and very tight enclosure. Still, these are not perfect either and require some training to install them correctly.