Many insulation products do their thermal magic by weaving fibers together to create a multitude of tiny insulating air pockets akin to those in a sweater. A wide range of fibers are now used to create this heat trapping phenomenon. In recent weeks, the Pharos team has added more loose-fill and blown-in insulations to the batts previously displayed. In coming weeks, we’ll add sprayed insulations.

How do the fibers stack up in Pharos? This week we look at the two major players: fiberglass and cellulose. While their R-values per inch are fairly equivalent, recycled content varies widely between the fibers, and formaldehyde and other IAQ questions remain:

Fiberglass has been the standard for blanket batts and is also used in some board, loose-fill/blown and sprayed products. Recycled content is now common in fiberglass product, though mostly in the 20 to 30% range, keeping Pharos scores for Renewable Materials in the 2s and 3s. Anco’s TextraFine is an exception with very high recycled content of 85% - although being primarily post-industrial waste, it only gains the product a one-point bump in the Renewable Materials score to 4.

Most of the major fiberglass brands have received a certification for VOC emissions testing, but concerns identified by HBN research about carcinogenic formaldehyde emitted from the binders used in batt blankets keep them from scoring more than a 5 in Pharos for IAQ. There is encouraging movement toward alternative formaldehyde-free batt binders, but manufacturers are not disclosing what they are using instead. We’ll talk more about that in a future blog.

The loose-fill/blown fiberglass products do not use formaldehyde binders that cause such trouble in the batts. They do, however, face the same scoring limit, often due to a lack of manufacturer disclosure about the additives they use to lubricate and lower dust in the blowing process. We do know that some manufacturers use carcinogenic, heavy paraffinic petroleum distillates for these additives, but don’t have information about the extent of any exposure issues for occupants to these chemicals.

Cellulose has been the biggest player in the loosefill/blown-in market and is also used for sprayed products. As a group, cellulose products are the best scoring in Renewable Materials, with high post-consumer, recycled paper content driving scores up to anywhere from 6 to 8 – the highest Renewable Materials scores we’ve seen in Pharos to date.

IAQ evaluation of cellulose products is uncertain. With no formaldehyde binders to generate controversy, the cellulose industry has not felt any pressure to get VOC testing and so has no IAQ scores. The basic loose-fill and blown products tend to be pretty simple and we don’t expect significant VOC problems with them. However, as the stabilized and sprayed products add adhesives with some problematic components, we’d sure like to see some testing to find out what comes off as they cure.

You can use the Pharos Building Product Library sort function to bring up the top performers in any impact category. For example when viewing the Thermal insulation search results you can click on the RnMTL sort button at the top of the Renewable Materials score column to bring the products scoring highest for renewable material content to the top of the list. You’ll see the celluloses all rise above the fiberglass products.

Fiberglass and cellulose are being challenged by a range of new fibers, including both bio-based and new petro plastics. In a future blog, we’ll look at these alternative fibers as well as the move to formaldehyde-free binders. Stay tuned.