Patent ID: 7219534

Claim:
A method for measuring the transpiration characteristics of a permeable membrane having first and second surfaces comprising the steps of: A) attaching the permeable membrane to a site that is a source of water evaporation with the first surface facing the site, B) iteratively sampling the second surface for the determining the accumulation level of moisture at the second surface, and C) measuring the time from a first transient appearance of moisture to the time of the accumulation of a predetermined moisture level at the second surface, the measured time constituting a transpiration characteristic of the permeable membrane wherein said time measurement includes the steps of: i) measuring the equilibrium value of moisture on the second surface, ii) establishing a threshold value as a percentage of said measured equilibrium value, and iii) said time measuring extending from the time from the first transient appearance of moisture until the moisture value reaches a predetermined percentage of the equilibrium value.