From: consultMORT [redacted
Posted At: Monday, September 01, 2003 5:14 PM
Posted To: R-ValueRule Conversation: Comments to Part III FedTradeComm/ 16CFR Part460 - Request To Testify-Labeling and Advertising of Home Insulation
Subject: Comments to Part III FedTradeComm/ 16CFR Part460 - Request To Testify-Labeling and Advertising of Home Insulation
Secretary, Federal Trade Commission
Room H-159, 600 Pennsylvania Avenue NW
Washington, DC 20580
16 CFR Part 460 - Request to Testify - Labeling and Advertising of Home Insulation
Our review of 16 FR 41879 (Cellular Plastics Insulations - Background) revealed areas of inaccurate information deserving of clarification to aid the Commission in its understanding of the performance characteristics of closed-cell plastic thermal insulation materials.
To retain the context of this first paragraph after the inclusion of our suggested clarifying amendments, a revised first paragraph text is provided as follows:
Certain types of cellular plastics insulations (polyurethane, polyisocyanurate and extruded polystyrene boardstock insulations)
are manufactured in a process that results in a gas other than normal air being incorporated into the voids in the products. This
gives the product an initial R-value that is higher than it would have if it contained normal air. A physical process, the permeation of gases through plastic membranes, commonly termed ageing, causes the R-value characteristics of such closed-cell insulations to decrease over time as the cell-gas composition of their cellular strata are sequentially diluted by normal air gases 44FR at 50219-20. How long the ageing process lasts depends on whether the product is faced or unfaced, the permeability of the facing, how well the facing adheres to the product, and other factors 64 FR48024 at 48030-31.
We believe that this background clarification is critical in aiding the Commission to better understand that the thermal resistance characteristics of these closed-cell insulation materials change logarithmically (slowly along a relatively long time continuity) as
air gases first permeate through outer surface cell walls and dilute the non-air gases these cells initially contain. These lower air gas concentrations next begin to permeate through adjoining closed-cell walls, with their successively reducing air gas concentrations resulting in a diminishing driving force and a similarly slower gas transfer or permeation rate.When closed-cells are very small and cell walls relatively thick, central core foam strata may not see air gas dilution for many years, as when thick applications of spray polyurethane foam roof insulations are considered.
This cell-to-cell permeation sequence results in a non-homogeneous body of closed-cell strata ranging from the outer surfaces of the product toward its core center, whose spectrum of differently diluted cell gas compositions yield a spectrum of R-values that range from the most reduced (near the outer surfaces of the material) to strata closer to the core-center and not yet reduced by air gas dilution.When tested across its full product thickness, a practice recommended for non-homogeneous materials in the American Society of Heating, Refrigeration and Air-conditioning Engineers (ASHRAE) "Handbook of Fundamentals", Chap.2" Heat Transfer", these cell strata thermal resistances are added in series (refer to the electricity resistance analogy) to provide
an overall thermal resistance measurement for the non-homogenous material. This overall thermal resistance measurement changes slowly with the passage of time, with rates of change dependent upon cell wall molecular structure, cell wall thickness, temperature gradients and the nature of the involved gases.However, after six months ageing time, thermal resistance measurements appear to change so slowly as to appear asymptotic or plateau-like, with testing variations in the range of
laboratory repeatability. A real-time "steady-state or static" condition might be very difficult to confirm with these unique materials.
Recognizing this reality, the insulation industry evolved an alternative consensus practice for comparing the thermal resistance characteristics of closed-cell plastic thermal insulations:measurements are made after six months (180 days) of conditioning or ageing in a standardized laboratory air environment.This practice has been used and found to be understandable, practical and acceptable by ASTM C16 on Thermal Insulations, GSA, RIC/TIMA producers, product users and the Commission for most of the last twenty years (see FR 41879), a market-validating factor that the Commission certainly takes into consideration.
In the current ASTM Annual Book of Standards (Vol.2002), the following cellular plastic material standards accept and specify 180 day preconditioning of thermal resistance test specimens:
ASTM C578-01 (Rigid Cellular Polystyrene Thermal Insulation
ASTM C591-01 (Unfaced Preformed Rigid Cellular Polyisocyanurate Thermal Insulation
ASTM C1029-96 (Spray-Applied Rigid Cellular Polyurethane Thermal Insulation
ASTM C1126 (Faced or Unfaced Rigid Cellular Phenolic Thermal Insulation
ASTM C 1289 (Faced Rigid Cellular Polyisocyanurate Thermal Insulation Board
Advocates for the consideration of ASTM C1303, Standard Method for Estimating the Long Term Change in the Thermal Resistance of Unfaced Rigid Closed-cell Foams By Slicing and Scaling Under Controlled Laboratory Conditions, ignore significant limitations contained in its Par. 1 "Scope" sections 1.1, 1.2 and 1.6. Particular elements of these limitations include:
(a) this method is limited to unfaced homogeneous materials
(b) this method yields estimates of product thermal resistance over time
(c) this method does not take into account all of the factors pertinent to an estimate of the thermal performance of these materials
More important: since no"steady state or static" condition can be identified until all gas permeation processes have been completed (see Figure 1 in the C1303 document) this document does not establish a specific time for making product comparisons in accordance with the Rule.
In our opinion, the selection of any arbitrary, complex and unnecessarily controversial "estimating" practice such as proposed in using ASTM C1303, Canadian Standard Can/ULF - S77 or a more recently suggested LTTR estimating practice, is inappropriate for FTC regulatory purposes. Such more sophisticated practices are better left to research,
engineering and systems design professionals who are qualified to consider the caveated exceptions referenced in these documents in order to make the necessary technical allowances when developing new insulating systems and product applications. If additional specialized or expensive testing is necessary, this can always be negotiated
between producer and purchaser in an open and competitive marketplace.
Finally, we advocate and encourage the use of surface-to-surface, or full-thickness thermal resistance testing of these unique closed-cell non-homogenous foam plastic thermal insulation products. ASTM testing methods found acceptable include ASTM C518 (Heat Flow Meter Apparatus) and ASTM C1363 (Hot Box Apparatus).
Thank you for this latest opportunity to provide comments to the Commission on this subject.