How to Convert RValue to UFactor in Insulation
It makes good sense to properly insulate new walls. Efficient use of insulation keeps a building warmer in winter and cooler in summer, thereby reducing both heating and airconditioning costs.
Many building regulations now specify minimum Rvalues for insulation products, but when you need to find the overall thermal conductance of a wall or building, you need to calculate the Ufactor. Calculating the Ufactor is straightforward when you know the Rvalues of the materials you have used.
Tip
Use an online RvaluetoUfactor calculator to simplify the process. Insulation products have their Rvalue printed on the packaging or in the technical data that accompany the product. Batt insulation is stiff insulating sheeting with an Rvalue of between 3.7 and 4.3 per inch of thickness.

Determine the Rvalues of all the materials you have used, and then add them together. For example, a 2by4inch stud wall has an Rvalue of 5, and a layer of 3inch batt insulation has an Rvalue of 11. The stud wall plus the insulation has an Rvalue of 16 — 5 + 11 = 16.

Calculate the Ufactor by using this formula: Ufactor = 1/Sum of the Rvalues. Using the previous example with an Rvalue of 16, the Ufactor is onesixteenth, or 0.0625.

Check your calculations by reversing the calculation and determining 1/Ufactor. If the result is not the original Rvalue, then there was an error in your calculations. Repeat them until the correct result is obtained.
The Drip Cap
 It makes good sense to properly insulate new walls.
 Many building regulations now specify minimum Rvalues for insulation products, but when you need to find the overall thermal conductance of a wall or building, you need to calculate the Ufactor.
 Calculating the Ufactor is straightforward when you know the Rvalues of the materials you have used.
References
Resources
Writer Bio
David Robinson has written professionally since 2000. He is a Fellow of the Royal Geographical Society and the Royal Meteorological Society. He has written for the "Telegraph" and "Guardian" newspapers in the U.K., government publications, websites, magazines and school textbooks. He holds an honors Bachelor of Arts in geography and education and a teaching certificate from Durham University, England.
Photo Credits
 Brand X Pictures/Brand X Pictures/Getty Images
 Brand X Pictures/Brand X Pictures/Getty Images
More Articles