Mary C. Bogdan

Meeting the Insulation Requirements of the Building Envelope with Polyurethane and Polyisocyanurate Foam

The use of insulating products in the building envelope is defined by many criteria. The specified R-value or k-factor for the structure is an essential component of most specifications. The industry has traditionally reported the R-value measured at a mean temperature of 75°F for use to calculate insulation requirements for the building envelope. With improvements in instrumentation, it is now possible to specify insulation based upon the actual use temperatures for a given building or region. This paper compares the performance of insulating products over a variety of mean temperature ranges including a discussion of measurement methods.

HFC-245fa spray polyurethane foam systems co-blown with water : A quality, cost effective, safe substitute for HCFC-141b

The effective use of insulation is key to energy conservation. The effectiveness of insulation is dependent upon many factors. In the case of rigid foam insulation a key factor is the blowing agent used. Industry evaluations have shown that HFC-245fa produces foams with the highest insulation value of any HCFC-141b alternative-blowing agent in the construction market. Meeting the market needs is critical to the success of any new product. Today’s insulation specifiers are not only concerned about energy savings but also cost. Chemical and manufacturing changes can have a significant effect on product cost. The higher vapor pressure of HFC-245fa and its potential impact on packaging has also been a concern to the spray foam industry. This paper contains the latest results about the use of HFC-245fa foam systems co-blown with water, which meet the needs of the spray foam market. They are cost effective, produce foams with low k-factors, good physical properties, and can be stored and shipped in existing drums. This will allow applicators and manufacturers to safely use existing equipment without significant modifications or safety concerns. HFC-245fa and water used as co-blowing agents provide a wide range of benefits in spray foam. Since less HFC-245fa is used, the vapor pressure is lower, and the cost of the system is reduced while improving the physical properties of the foam. There is however an increase in k-factor. We have determined also that the addition of low levels of •-methyl styrene to a spray foam polyol blend lowers the vapor pressure of the polyol blend and enhances the k-factor of the foams produced. This allows the user to optimize k-factor while lowering the cost. Data from laboratory evaluations of these blends are presented. This paper also includes a discussion of the cost of these blends from a chemical, manufacturing and performance perspective. We consider HFC-245fa/water co-blown spray foam to be a quality, cost effective and safe alternative to HCFC-141b blown foams in the future.