Retrospective Analysis of NIST Standard Reference Material 1450, Fibrous Glass Board, for Thermal Insulation Measurements

Abstract

Thermal conductivity data acquired previously for the establishment of Standard Reference Material (SRM) 1450, Fibrous Glass Board, as well as subsequent renewals 1450a, 1450b, 1450c, and 1450d, are re-analyzed collectively and as individual data sets. Additional data sets for proto-1450 material lots are also included in the analysis. The data cover 36 years of activity by the National Institute of Standards and Technology (NIST) in developing and providing thermal insulation SRMs, specifically high-density molded fibrous-glass board, to the public. Collectively, the data sets cover two nominal thicknesses of 13 mm and 25 mm, bulk densities from 60 kg·m−3 to 180 kg·m−3, and mean temperatures from 100 K to 340 K. The analysis repetitively fits six models to the individual data sets. The most general form of the nested set of multilinear models used is given in the following equation: λ(ρ,T)=a0+a1ρ+a2T+a3T3+a4e−(T−a5a6)2where λ(ρ,T) is the predicted thermal conductivity (W·m−1·K−1), ρ is the bulk density (kg·m−3), T is the mean temperature (K) and ai (for i = 1, 2, … 6) are the regression coefficients. The least squares fit results for each model across all data sets are analyzed using both graphical and analytic techniques. The prevailing generic model for the majority of data sets is the bilinear model in ρ and T. λ(ρ,T)=a0+a1ρ+a2TOne data set supports the inclusion of a cubic temperature term and two data sets with low-temperature data support the inclusion of an exponential term in T to improve the model predictions. Physical interpretations of the model function terms are described. Recommendations for future renewals of SRM 1450 are provided. An Addendum provides historical background on the origin of this SRM and the influence of the SRM on external measurement programs.

Development of a Small-Sized Line Heat Source Apparatus for the Thermal Conductivity Measurement of Extraterrestrial Soils

“…It would be also valuable to measure standard materials for insulation. The National Institute of Standards and Technology (NIST) provides fibrous glass board (SRM 1450) for thermal insulation measurements [39]. Their thermal conductivity is about 0.03 W ⋅ m −1 K −1 .…”

Certification of Standard Reference Material 1450e fibrous glass board

“…The production costs of the renewal are recovered, under current Congressional authorization, through the sale of the SRM to end users. Figure 1 also depicts an optional compilation of supplemental material properties that have been previously investigated by NIST researchers for various lots of 1450 materials [5]. The primary purpose of these investigations is to determine what, if any, are the effects of other (secondary) factors on the certified properties of thermal conductivity and thermal resistance.…”

“…4; Ap is the area of the panel (m 2 ) from Eq. (5) Table 2 summarizes the physical properties of Panel IDs 500 to 949 (450 panels) and includes the quantities: mass (m0), length (l2), width (l5), area (As), thickness (L̅ p), and bulk density (ρp). For the nine panels on which three measurements for length and width were acquired, the value for l2 and l5 in Table 2 represent the averages of the three measurements.…”

“…Based on recent renewals of 1450 [5], temperature and bulk density, in that order, are the main factors affecting λ. Figure 15 plots the full factorial design for the three levels of ρ from Table 5 and the five (settable) levels of Tm (based on material and equipment limitations).…”

A difference technique to avoid interface errors in measurement of high-conductance thermal insulation

“…Emphasis may have shifted from the lower values, but it remains important to be able to assess higher conducting components for their role in overall building performance. Additionally, standard reference materials frequently have a thermal resistance below 1.0 m 2 K/W (Zarr et al, 2014) as do materials employed for inter-laboratory comparison (Asia Pacific Laboratory Accreditation Cooperation (APLAC), 2010).…”