That's a good question, but unfortunately the answer is not so simple, Window thermal performance is measured as a U-Value which Is the reciprocal of the R-Value ( R-Value = 1/U-Value. For example. R 2 = U .50, or 1/.50 = 2) A bit of background: the R-Value measures the resistance to heat loss or gain, while the U-Value measures the transmittance of heat through a material. The higher the number in R-Value the better the resistance, so the better the insulating value.

R-value is an assigned number derived from a specific testing procedure to determine a materials (or building assemblage) "resistance to conductive heat transfer". The higher the R-value, the more resistant a material (or building assemblage) is to conductive heat transfer.

All Sun Windows are tested by independent testing agencies and each product lists the tested results. The test values are documented in U-values. U-values measure the amount of energy transferred through a unit, where R-values measure the resistance to energy flow. These values are simply mathematical inverses. Some companies will convert U-values to R-values to try to give the customer an "insulating value" similar to what is provided by wall insulation.

No. Products with R-values reduce rates of "conductive" heat transfer and are tested for this characteristic. Radiant Barriers provide benefit by dramatically reducing "radiant" heat transfer which is just as quantifiable but not related to R-value type performance.

The bin/macosx directory of a CRAN site contains a standard Apple installer package inside a disk image named R.dmg. Once downloaded and executed, the installer will install the current non-developer release of R. RAqua is a native Mac OS X Darwin version of R with a R.app Mac OS X GUI. Inside bin/macosx/powerpc/contrib/x.y there are prebuilt binary packages (for powerpc version of Mac OS X) to be used with RAqua corresponding to the “x.y” release of R.

No. Our products do not operate in this manner. Minimal benefit is netted when the product is doubled.

This is a measurement of heat resistance (the higher the number, the better). R value = the number 1 divided by the U value.

R Value - the measurement of 'insulating ability' of the material. The higher the R Factor number the greater the insulation value. U Value - the measurement of 'heat loss' through the material. The lower the U Value the less heat is escaping.

Every component of the roof (i.e.: GI sheet, concrete, insulation, air space, sheetrock/gypsum, acoustical tiles, etc.) has a given R-value based on its thickness. Basic HVAC data reference books will provide the R-value or the K-value for most construction materials. If you do not have any reference books, we will be happy to tell you the R-value of materials you are considering.

A NRG Block is six to ten times higher in R-Value than a common block, which ranges from 1.5 to 2.5 depending upon the aggregate used.

Other blocks using inserts or hollow core blocks with poured insulation range between 5 and 6 for a 9 and 10" block.

The 4½" inch thick SIP has a rating of R-20. However, it is important to note that SIPs are much more efficient than conventional types of insulation with the same R-Value. A home built with SIPs will use about 25% less energy than a typical stick-framed house. The solid, air-tight construction of these panels is what gives them their superior thermal performance.