R-value


Also found in: Dictionary, Legal, Financial, Acronyms, Wikipedia.

R-value

[′är ‚val·yü]
(engineering)
An index of the ability of a substance or material to retard the flow of heat; higher numerical values correspond to higher insulating ability.

R-value

A unit of thermal resistance. A material’s R-value is a measure of the effectiveness of the material in stopping the flow of heat through it. The higher a material’s Rvalue, the greater its insulating properties and the slower the heat flow through it. Examples of higher R-values for residential buildings: R-50 ceilings, R-21 walls, and R-30 floors.

R-value

A measure of the thermal resistance of a material or component.
References in periodicals archive ?
Caption: Kingspan underscores Kooltherm K20's potential to attain higher thermal performance in thinner profiles than conventional insulation boards: R-value up to R17 in 2-in.
Pearson corelation after treatment in this group showed conversion of significant negative correlation prior to intervention (p-value 0.003 and r-value -0.955) to non significant positive correlation (p-value 0.513 and r-value 0.337).
Conversely, through the criteria based only on [pH.sub.45min], on [pH.sub.45min] and R-value (HONIKEL & FISHER, 1977) and only on [L.sup.*] (MAGANHINI et al., 2007), most of the samples (53 to 68%) were classified as RFN, whereas a large part of them (32 to 38%) was classified as PSE.
R-value rates reflect a product's ability to restrict heat flow which, in turn, reduces energy costs: the higher the R-value, the better the product's insulating ability.
Poor sealing characteristics were a problem in some, and many had R-values too low to prevent frost from building on the surface of the door panel.
The performance of the constructed models was evaluated on the basis of R-value and MSE analyses.
The thermal conductivity of the panel with 5-mm layers was 0.0532 W [m.sup.-1] [K.sup.-1], which corresponds with a US R-value of 6.8 (2.7/in.
Density, k-factor, R-value and percent closed-cell content were measured.
* Polyiso (polyisocyanurate) or polyurethane foam installed under the roof system, instead of in the attic floor, helps seal the building against leaks and helps increase the R-value of the roofing system.
Both are available in rolls and batts with an R-value of between three and four per inch of thickness.
Table 1 shows that with a calculated r-value of 0.400, there is significant relationship between multiple taxation and tax evasion in Lagos State.
Griffiths and Zuluaga (2004) used a two-dimensional, steady-state FEM to calculate the effective R-value of ducts buried under three levels of loose-fill insulation, as shown in Figure 1.