Comparison of Methods Used to Create Estimate of Air-Freezing Index

Abstract

A climatography of 100-year return-period air-freezing indexes (AFIs) has been developed to accompany recommendations for the design of frost-protected shallow foundations (FPSFs) in the U.S. residential construction industry. These design recommendations are based on European FPSF procedures and proposed consensus standards, so this paper investigates and compares the different methods of generating freezing indexes in Norway, Finland, and the United States. Previously overlooked, the differences in these methods have a substantial influence on the estimated AFI and the application of return-period statistics. The method used in the United States to calculate the AFI better represents the ground-freezing effect for all climate regimes. Additional research related to this topic has also shown that the Weibull distribution provides superior predictions of the AFI at long return periods.